// File: contracts/core/abstractV2/PendleYieldContractDeployerBaseV2.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "../../periphery/PermissionsV2.sol";
import "../../interfaces/IPendleYieldContractDeployerV2.sol";
import "./PendleYieldTokenHolderBaseV2.sol";
import "../../interfaces/IPendleForge.sol";
import "../../tokens/PendleFutureYieldToken.sol";
import "../../tokens/PendleOwnershipToken.sol";

contract PendleYieldContractDeployerBaseV2 is IPendleYieldContractDeployerV2, PermissionsV2 {
    bytes32 public override forgeId; // no immutable to save bytecode size
    IPendleForge public forge;

    modifier onlyForge() {
        require(msg.sender == address(forge), "ONLY_FORGE");
        _;
    }

    constructor(address _governanceManager, bytes32 _forgeId) PermissionsV2(_governanceManager) {
        forgeId = _forgeId;
    }

    function initialize(address _forgeAddress) external virtual {
        require(msg.sender == initializer, "FORBIDDEN");

        forge = IPendleForge(_forgeAddress);
        require(forge.forgeId() == forgeId, "FORGE_ID_MISMATCH");
        initializer = address(0);
    }

    function forgeFutureYieldToken(
        address _underlyingAsset,
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _expiry
    ) external virtual override onlyForge returns (address xyt) {
        xyt = address(
            new PendleFutureYieldToken(
                address(forge.router()),
                address(forge),
                _underlyingAsset,
                forge.getYieldBearingToken(_underlyingAsset),
                _name,
                _symbol,
                _decimals,
                block.timestamp,
                _expiry
            )
        );
    }

    function forgeOwnershipToken(
        address _underlyingAsset,
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _expiry
    ) external virtual override onlyForge returns (address ot) {
        ot = address(
            new PendleOwnershipToken(
                address(forge.router()),
                address(forge),
                _underlyingAsset,
                forge.getYieldBearingToken(_underlyingAsset),
                _name,
                _symbol,
                _decimals,
                block.timestamp,
                _expiry
            )
        );
    }

    function deployYieldTokenHolder(
        address _yieldToken,
        uint256 _expiry,
        uint256[] calldata
    ) external virtual override onlyForge returns (address yieldTokenHolder) {
        yieldTokenHolder = address(
            new PendleYieldTokenHolderBaseV2(
                address(governanceManager),
                address(forge),
                _yieldToken,
                _expiry
            )
        );
    }
}

// File: contracts/periphery/PermissionsV2.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "../core/PendleGovernanceManager.sol";
import "../interfaces/IPermissionsV2.sol";

abstract contract PermissionsV2 is IPermissionsV2 {
    PendleGovernanceManager public immutable override governanceManager;
    address internal initializer;

    constructor(address _governanceManager) {
        require(_governanceManager != address(0), "ZERO_ADDRESS");
        initializer = msg.sender;
        governanceManager = PendleGovernanceManager(_governanceManager);
    }

    modifier initialized() {
        require(initializer == address(0), "NOT_INITIALIZED");
        _;
    }

    modifier onlyGovernance() {
        require(msg.sender == _governance(), "ONLY_GOVERNANCE");
        _;
    }

    function _governance() internal view returns (address) {
        return governanceManager.governance();
    }
}

// File: contracts/interfaces/IPendleYieldContractDeployerV2.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

interface IPendleYieldContractDeployerV2 {
    function forgeId() external returns (bytes32);

    function forgeOwnershipToken(
        address underlyingAsset,
        string memory name,
        string memory symbol,
        uint8 decimals,
        uint256 expiry
    ) external returns (address ot);

    function forgeFutureYieldToken(
        address underlyingAsset,
        string memory name,
        string memory symbol,
        uint8 decimals,
        uint256 expiry
    ) external returns (address xyt);

    function deployYieldTokenHolder(
        address yieldToken,
        uint256 expiry,
        uint256[] calldata container
    ) external returns (address yieldTokenHolder);
}

// File: contracts/core/abstractV2/PendleYieldTokenHolderBaseV2.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "../../interfaces/IPendleYieldTokenHolderV2.sol";
import "../../interfaces/IPendleForge.sol";
import "../../periphery/WithdrawableV2.sol";
import "../../libraries/MathLib.sol";

contract PendleYieldTokenHolderBaseV2 is IPendleYieldTokenHolderV2, WithdrawableV2 {
    using SafeERC20 for IERC20;
    using Math for uint256;
    using SafeMath for uint256;

    address public immutable override yieldToken;
    address public immutable override forge;
    address public override rewardToken; // no immutable to save bytecode size
    uint256 public override expiry; // no immutable to save bytecode size

    modifier onlyForge() {
        require(msg.sender == address(forge), "ONLY_FORGE");
        _;
    }

    constructor(
        address _governanceManager,
        address _forge,
        address _yieldToken,
        uint256 _expiry
    ) PermissionsV2(_governanceManager) {
        address _rewardToken = address(IPendleForge(_forge).rewardToken());
        address rewardManager = address(IPendleForge(_forge).rewardManager());

        yieldToken = _yieldToken;
        forge = _forge;
        rewardToken = _rewardToken;
        expiry = _expiry;

        IERC20(_rewardToken).safeApprove(rewardManager, type(uint256).max);
    }

    /**
    @dev function has been depreciated but must still be left here to conform with the interface
    */
    function setUpEmergencyMode(address) external pure override {
        revert("FUNCTION_DEPRECIATED");
    }

    // Only forge can call this function
    // this will allow a spender to spend the whole balance of the specified tokens
    // the spender should ideally be a contract with logic for users to withdraw out their funds.
    function setUpEmergencyModeV2(address spender, bool) external virtual override onlyForge {
        // by default we store all the tokens inside this contract, so just approve
        IERC20(yieldToken).safeApprove(spender, type(uint256).max);
        IERC20(rewardToken).safeApprove(spender, type(uint256).max);
    }

    /// @dev by default the token doesn't have any rewards
    function redeemRewards() external virtual override {}

    /// @dev by default we will keep all tokens in this contract, so no further actions necessary
    function afterReceiveTokens(uint256 amount) external virtual override {}

    function pushYieldTokens(
        address to,
        uint256 amount,
        uint256 minNYieldAfterPush
    ) external virtual override onlyForge {
        uint256 yieldTokenBal = IERC20(yieldToken).balanceOf(address(this));
        require(yieldTokenBal.sub(amount) >= minNYieldAfterPush, "INVARIANCE_ERROR");
        IERC20(yieldToken).safeTransfer(to, amount);
    }

    // The governance address will be able to withdraw any tokens except for
    // the yieldToken and the rewardToken
    function _allowedToWithdraw(address _token)
        internal
        view
        virtual
        override
        returns (bool allowed)
    {
        allowed = _token != yieldToken && _token != rewardToken;
    }
}

// File: contracts/interfaces/IPendleForge.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "./IPendleRouter.sol";
import "./IPendleRewardManager.sol";
import "./IPendleYieldContractDeployer.sol";
import "./IPendleData.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IPendleForge {
    /**
     * @dev Emitted when the Forge has minted the OT and XYT tokens.
     * @param forgeId The forgeId
     * @param underlyingAsset The address of the underlying yield token.
     * @param expiry The expiry of the XYT token
     * @param amountToTokenize The amount of yield bearing assets to tokenize
     * @param amountTokenMinted The amount of OT/XYT minted
     **/
    event MintYieldTokens(
        bytes32 forgeId,
        address indexed underlyingAsset,
        uint256 indexed expiry,
        uint256 amountToTokenize,
        uint256 amountTokenMinted,
        address indexed user
    );

    /**
     * @dev Emitted when the Forge has created new yield token contracts.
     * @param forgeId The forgeId
     * @param underlyingAsset The address of the underlying asset.
     * @param expiry The date in epoch time when the contract will expire.
     * @param ot The address of the ownership token.
     * @param xyt The address of the new future yield token.
     **/
    event NewYieldContracts(
        bytes32 forgeId,
        address indexed underlyingAsset,
        uint256 indexed expiry,
        address ot,
        address xyt,
        address yieldBearingAsset
    );

    /**
     * @dev Emitted when the Forge has redeemed the OT and XYT tokens.
     * @param forgeId The forgeId
     * @param underlyingAsset the address of the underlying asset
     * @param expiry The expiry of the XYT token
     * @param amountToRedeem The amount of OT to be redeemed.
     * @param redeemedAmount The amount of yield token received
     **/
    event RedeemYieldToken(
        bytes32 forgeId,
        address indexed underlyingAsset,
        uint256 indexed expiry,
        uint256 amountToRedeem,
        uint256 redeemedAmount,
        address indexed user
    );

    /**
     * @dev Emitted when interest claim is settled
     * @param forgeId The forgeId
     * @param underlyingAsset the address of the underlying asset
     * @param expiry The expiry of the XYT token
     * @param user Interest receiver Address
     * @param amount The amount of interest claimed
     **/
    event DueInterestsSettled(
        bytes32 forgeId,
        address indexed underlyingAsset,
        uint256 indexed expiry,
        uint256 amount,
        uint256 forgeFeeAmount,
        address indexed user
    );

    /**
     * @dev Emitted when forge fee is withdrawn
     * @param forgeId The forgeId
     * @param underlyingAsset the address of the underlying asset
     * @param expiry The expiry of the XYT token
     * @param amount The amount of interest claimed
     **/
    event ForgeFeeWithdrawn(
        bytes32 forgeId,
        address indexed underlyingAsset,
        uint256 indexed expiry,
        uint256 amount
    );

    function setUpEmergencyMode(
        address _underlyingAsset,
        uint256 _expiry,
        address spender
    ) external;

    function newYieldContracts(address underlyingAsset, uint256 expiry)
        external
        returns (address ot, address xyt);

    function redeemAfterExpiry(
        address user,
        address underlyingAsset,
        uint256 expiry
    ) external returns (uint256 redeemedAmount);

    function redeemDueInterests(
        address user,
        address underlyingAsset,
        uint256 expiry
    ) external returns (uint256 interests);

    function updateDueInterests(
        address underlyingAsset,
        uint256 expiry,
        address user
    ) external;

    function updatePendingRewards(
        address _underlyingAsset,
        uint256 _expiry,
        address _user
    ) external;

    function redeemUnderlying(
        address user,
        address underlyingAsset,
        uint256 expiry,
        uint256 amountToRedeem
    ) external returns (uint256 redeemedAmount);

    function mintOtAndXyt(
        address underlyingAsset,
        uint256 expiry,
        uint256 amountToTokenize,
        address to
    )
        external
        returns (
            address ot,
            address xyt,
            uint256 amountTokenMinted
        );

    function withdrawForgeFee(address underlyingAsset, uint256 expiry) external;

    function getYieldBearingToken(address underlyingAsset) external returns (address);

    /**
     * @notice Gets a reference to the PendleRouter contract.
     * @return Returns the router contract reference.
     **/
    function router() external view returns (IPendleRouter);

    function data() external view returns (IPendleData);

    function rewardManager() external view returns (IPendleRewardManager);

    function yieldContractDeployer() external view returns (IPendleYieldContractDeployer);

    function rewardToken() external view returns (IERC20);

    /**
     * @notice Gets the bytes32 ID of the forge.
     * @return Returns the forge and protocol identifier.
     **/
    function forgeId() external view returns (bytes32);

    function dueInterests(
        address _underlyingAsset,
        uint256 expiry,
        address _user
    ) external view returns (uint256);

    function yieldTokenHolders(address _underlyingAsset, uint256 _expiry)
        external
        view
        returns (address yieldTokenHolder);
}

// File: contracts/tokens/PendleFutureYieldToken.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "./PendleBaseToken.sol";
import "../interfaces/IPendleForge.sol";
import "../interfaces/IPendleYieldTokenCommon.sol";

contract PendleFutureYieldToken is PendleBaseToken, IPendleYieldTokenCommon {
    address public immutable override forge;
    address public immutable override underlyingAsset;
    address public immutable override underlyingYieldToken;

    constructor(
        address _router,
        address _forge,
        address _underlyingAsset,
        address _underlyingYieldToken,
        string memory _name,
        string memory _symbol,
        uint8 _underlyingYieldTokenDecimals,
        uint256 _start,
        uint256 _expiry
    ) PendleBaseToken(_router, _name, _symbol, _underlyingYieldTokenDecimals, _start, _expiry) {
        require(
            _underlyingAsset != address(0) && _underlyingYieldToken != address(0),
            "ZERO_ADDRESS"
        );
        require(_forge != address(0), "ZERO_ADDRESS");
        forge = _forge;
        underlyingAsset = _underlyingAsset;
        underlyingYieldToken = _underlyingYieldToken;
    }

    modifier onlyForge() {
        require(msg.sender == address(forge), "ONLY_FORGE");
        _;
    }

    /**
     * @dev Burns OT or XYT tokens from user, reducing the total supply.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    function burn(address user, uint256 amount) public override onlyForge {
        _burn(user, amount);
        emit Burn(user, amount);
    }

    /**
     * @dev Mints new OT or XYT tokens for user, increasing the total supply.
     * @param user The address to send the minted tokens.
     * @param amount The amount to be minted.
     **/
    function mint(address user, uint256 amount) public override onlyForge {
        _mint(user, amount);
        emit Mint(user, amount);
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        super._beforeTokenTransfer(from, to, amount);
        if (from != address(0))
            IPendleForge(forge).updateDueInterests(underlyingAsset, expiry, from);
        if (to != address(0)) IPendleForge(forge).updateDueInterests(underlyingAsset, expiry, to);
    }

    function approveRouter(address user) external {
        require(msg.sender == address(router), "NOT_ROUTER");
        _approve(user, address(router), type(uint256).max);
    }
}

// File: contracts/tokens/PendleOwnershipToken.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "./PendleBaseToken.sol";
import "../interfaces/IPendleYieldTokenCommon.sol";
import "../interfaces/IPendleForge.sol";

contract PendleOwnershipToken is PendleBaseToken, IPendleYieldTokenCommon {
    address public immutable override forge;
    address public immutable override underlyingAsset;
    address public immutable override underlyingYieldToken;

    constructor(
        address _router,
        address _forge,
        address _underlyingAsset,
        address _underlyingYieldToken,
        string memory _name,
        string memory _symbol,
        uint8 _underlyingYieldTokenDecimals,
        uint256 _start,
        uint256 _expiry
    ) PendleBaseToken(_router, _name, _symbol, _underlyingYieldTokenDecimals, _start, _expiry) {
        require(
            _underlyingAsset != address(0) && _underlyingYieldToken != address(0),
            "ZERO_ADDRESS"
        );
        require(_forge != address(0), "ZERO_ADDRESS");
        forge = _forge;
        underlyingAsset = _underlyingAsset;
        underlyingYieldToken = _underlyingYieldToken;
    }

    modifier onlyForge() {
        require(msg.sender == address(forge), "ONLY_FORGE");
        _;
    }

    /**
     * @dev Burns OT or XYT tokens from user, reducing the total supply.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    function burn(address user, uint256 amount) public override onlyForge {
        _burn(user, amount);
        emit Burn(user, amount);
    }

    /**
     * @dev Mints new OT or XYT tokens for user, increasing the total supply.
     * @param user The address to send the minted tokens.
     * @param amount The amount to be minted.
     **/
    function mint(address user, uint256 amount) public override onlyForge {
        _mint(user, amount);
        emit Mint(user, amount);
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual override {
        super._beforeTokenTransfer(from, to, amount);
        if (from != address(0))
            IPendleForge(forge).updatePendingRewards(underlyingAsset, expiry, from);
        if (to != address(0))
            IPendleForge(forge).updatePendingRewards(underlyingAsset, expiry, to);
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: contracts/core/PendleGovernanceManager.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

contract PendleGovernanceManager {
    address public governance;
    address public pendingGovernance;

    event GovernanceClaimed(address newGovernance, address previousGovernance);

    event TransferGovernancePending(address pendingGovernance);

    constructor(address _governance) {
        require(_governance != address(0), "ZERO_ADDRESS");
        governance = _governance;
    }

    modifier onlyGovernance() {
        require(msg.sender == governance, "ONLY_GOVERNANCE");
        _;
    }

    /**
     * @dev Allows the pendingGovernance address to finalize the change governance process.
     */
    function claimGovernance() external {
        require(pendingGovernance == msg.sender, "WRONG_GOVERNANCE");
        emit GovernanceClaimed(pendingGovernance, governance);
        governance = pendingGovernance;
        pendingGovernance = address(0);
    }

    /**
     * @dev Allows the current governance to set the pendingGovernance address.
     * @param _governance The address to transfer ownership to.
     */
    function transferGovernance(address _governance) external onlyGovernance {
        require(_governance != address(0), "ZERO_ADDRESS");
        pendingGovernance = _governance;

        emit TransferGovernancePending(pendingGovernance);
    }
}

// File: contracts/interfaces/IPermissionsV2.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;
pragma abicoder v2;

import "../core/PendleGovernanceManager.sol";

interface IPermissionsV2 {
    function governanceManager() external returns (PendleGovernanceManager);
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// File: contracts/interfaces/IPendleYieldTokenHolderV2.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

import "./IPendleYieldTokenHolder.sol";

interface IPendleYieldTokenHolderV2 is IPendleYieldTokenHolder {
    function setUpEmergencyModeV2(address spender, bool extraFlag) external;

    function pushYieldTokens(
        address to,
        uint256 amount,
        uint256 minNYieldAfterPush
    ) external;

    function afterReceiveTokens(uint256 amount) external;
}

// File: contracts/periphery/WithdrawableV2.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "./PermissionsV2.sol";

abstract contract WithdrawableV2 is PermissionsV2 {
    using SafeERC20 for IERC20;

    event EtherWithdraw(uint256 amount, address sendTo);
    event TokenWithdraw(IERC20 token, uint256 amount, address sendTo);

    /**
     * @dev Allows governance to withdraw Ether in a Pendle contract
     *      in case of accidental ETH transfer into the contract.
     * @param amount The amount of Ether to withdraw.
     * @param sendTo The recipient address.
     */
    function withdrawEther(uint256 amount, address payable sendTo) external onlyGovernance {
        (bool success, ) = sendTo.call{value: amount}("");
        require(success, "WITHDRAW_FAILED");
        emit EtherWithdraw(amount, sendTo);
    }

    /**
     * @dev Allows governance to withdraw all IERC20 compatible tokens in a Pendle
     *      contract in case of accidental token transfer into the contract.
     * @param token IERC20 The address of the token contract.
     * @param amount The amount of IERC20 tokens to withdraw.
     * @param sendTo The recipient address.
     */
    function withdrawToken(
        IERC20 token,
        uint256 amount,
        address sendTo
    ) external onlyGovernance {
        require(_allowedToWithdraw(address(token)), "TOKEN_NOT_ALLOWED");
        token.safeTransfer(sendTo, amount);
        emit TokenWithdraw(token, amount, sendTo);
    }

    // must be overridden by the sub contracts, so we must consider explicitly
    // in each and every contract which tokens are allowed to be withdrawn
    function _allowedToWithdraw(address) internal view virtual returns (bool allowed);
}

// File: contracts/libraries/MathLib.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity ^0.7.0;
pragma abicoder v2;

import "@openzeppelin/contracts/math/SafeMath.sol";

library Math {
    using SafeMath for uint256;

    uint256 internal constant BIG_NUMBER = (uint256(1) << uint256(200));
    uint256 internal constant PRECISION_BITS = 40;
    uint256 internal constant RONE = uint256(1) << PRECISION_BITS;
    uint256 internal constant PI = (314 * RONE) / 10**2;
    uint256 internal constant PI_PLUSONE = (414 * RONE) / 10**2;
    uint256 internal constant PRECISION_POW = 1e2;

    function checkMultOverflow(uint256 _x, uint256 _y) internal pure returns (bool) {
        if (_y == 0) return false;
        return (((_x * _y) / _y) != _x);
    }

    /**
    @notice find the integer part of log2(p/q)
        => find largest x s.t p >= q * 2^x
        => find largest x s.t 2^x <= p / q
     */
    function log2Int(uint256 _p, uint256 _q) internal pure returns (uint256) {
        uint256 res = 0;
        uint256 remain = _p / _q;
        while (remain > 0) {
            res++;
            remain /= 2;
        }
        return res - 1;
    }

    /**
    @notice log2 for a number that it in [1,2)
    @dev _x is FP, return a FP
    @dev function is from Kyber. Long modified the condition to be (_x >= one) && (_x < two)
    to avoid the case where x = 2 may lead to incorrect result
     */
    function log2ForSmallNumber(uint256 _x) internal pure returns (uint256) {
        uint256 res = 0;
        uint256 one = (uint256(1) << PRECISION_BITS);
        uint256 two = 2 * one;
        uint256 addition = one;

        require((_x >= one) && (_x < two), "MATH_ERROR");
        require(PRECISION_BITS < 125, "MATH_ERROR");

        for (uint256 i = PRECISION_BITS; i > 0; i--) {
            _x = (_x * _x) / one;
            addition = addition / 2;
            if (_x >= two) {
                _x = _x / 2;
                res += addition;
            }
        }

        return res;
    }

    /**
    @notice log2 of (p/q). returns result in FP form
    @dev function is from Kyber.
    @dev _p & _q is FP, return a FP
     */
    function logBase2(uint256 _p, uint256 _q) internal pure returns (uint256) {
        uint256 n = 0;

        if (_p > _q) {
            n = log2Int(_p, _q);
        }

        require(n * RONE <= BIG_NUMBER, "MATH_ERROR");
        require(!checkMultOverflow(_p, RONE), "MATH_ERROR");
        require(!checkMultOverflow(n, RONE), "MATH_ERROR");
        require(!checkMultOverflow(uint256(1) << n, _q), "MATH_ERROR");

        uint256 y = (_p * RONE) / (_q * (uint256(1) << n));
        uint256 log2Small = log2ForSmallNumber(y);

        assert(log2Small <= BIG_NUMBER);

        return n * RONE + log2Small;
    }

    /**
    @notice calculate ln(p/q). returned result >= 0
    @dev function is from Kyber.
    @dev _p & _q is FP, return a FP
    */
    function ln(uint256 p, uint256 q) internal pure returns (uint256) {
        uint256 ln2Numerator = 6931471805599453094172;
        uint256 ln2Denomerator = 10000000000000000000000;

        uint256 log2x = logBase2(p, q);

        require(!checkMultOverflow(ln2Numerator, log2x), "MATH_ERROR");

        return (ln2Numerator * log2x) / ln2Denomerator;
    }

    /**
    @notice extract the fractional part of a FP
    @dev value is a FP, return a FP
     */
    function fpart(uint256 value) internal pure returns (uint256) {
        return value % RONE;
    }

    /**
    @notice convert a FP to an Int
    @dev value is a FP, return an Int
     */
    function toInt(uint256 value) internal pure returns (uint256) {
        return value / RONE;
    }

    /**
    @notice convert an Int to a FP
    @dev value is an Int, return a FP
     */
    function toFP(uint256 value) internal pure returns (uint256) {
        return value * RONE;
    }

    /**
    @notice return e^exp in FP form
    @dev estimation by formula at http://pages.mtu.edu/~shene/COURSES/cs201/NOTES/chap04/exp.html
        the function is based on exp function of:
        https://github.com/NovakDistributed/macroverse/blob/master/contracts/RealMath.sol
    @dev the function is expected to converge quite fast, after about 20 iteration
    @dev exp is a FP, return a FP
     */
    function rpowe(uint256 exp) internal pure returns (uint256) {
        uint256 res = 0;

        uint256 curTerm = RONE;

        for (uint256 n = 0; ; n++) {
            res += curTerm;
            curTerm = rmul(curTerm, rdiv(exp, toFP(n + 1)));
            if (curTerm == 0) {
                break;
            }
            if (n == 500) {
                /*
                testing shows that in the most extreme case, it will take 430 turns to converge.
                however, it's expected that the numbers will not exceed 2^120 in normal situation
                the most extreme case is rpow((1<<256)-1,(1<<40)-1) (equal to rpow((2^256-1)/2^40,0.99..9))
                */
                revert("RPOWE_SLOW_CONVERGE");
            }
        }

        return res;
    }

    /**
    @notice calculate base^exp with base and exp being FP int
    @dev to improve accuracy, base^exp = base^(int(exp)+frac(exp))
                                       = base^int(exp) * base^frac
    @dev base & exp are FP, return a FP
     */
    function rpow(uint256 base, uint256 exp) internal pure returns (uint256) {
        if (exp == 0) {
            // Anything to the 0 is 1
            return RONE;
        }
        if (base == 0) {
            // 0 to anything except 0 is 0
            return 0;
        }

        uint256 frac = fpart(exp); // get the fractional part
        uint256 whole = exp - frac;

        uint256 wholePow = rpowi(base, toInt(whole)); // whole is a FP, convert to Int
        uint256 fracPow;

        // instead of calculating base ^ frac, we will calculate e ^ (frac*ln(base))
        if (base < RONE) {
            /* since the base is smaller than 1.0, ln(base) < 0.
            Since 1 / (e^(frac*ln(1/base))) = e ^ (frac*ln(base)),
            we will calculate 1 / (e^(frac*ln(1/base))) instead.
            */
            uint256 newExp = rmul(frac, ln(rdiv(RONE, base), RONE));
            fracPow = rdiv(RONE, rpowe(newExp));
        } else {
            /* base is greater than 1, calculate normally */
            uint256 newExp = rmul(frac, ln(base, RONE));
            fracPow = rpowe(newExp);
        }
        return rmul(wholePow, fracPow);
    }

    /**
    @notice return base^exp with base in FP form and exp in Int
    @dev this function use a technique called: exponentiating by squaring
        complexity O(log(q))
    @dev function is from Kyber.
    @dev base is a FP, exp is an Int, return a FP
     */
    function rpowi(uint256 base, uint256 exp) internal pure returns (uint256) {
        uint256 res = exp % 2 != 0 ? base : RONE;

        for (exp /= 2; exp != 0; exp /= 2) {
            base = rmul(base, base);

            if (exp % 2 != 0) {
                res = rmul(res, base);
            }
        }
        return res;
    }

    /**
    @dev y is an Int, returns an Int
    @dev babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    @dev from Uniswap
     */
    function sqrt(uint256 y) internal pure returns (uint256 z) {
        if (y > 3) {
            z = y;
            uint256 x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }

    /**
    @notice divide 2 FP, return a FP
    @dev function is from Balancer.
    @dev x & y are FP, return a FP
     */
    function rdiv(uint256 x, uint256 y) internal pure returns (uint256) {
        return (y / 2).add(x.mul(RONE)).div(y);
    }

    /**
    @notice multiply 2 FP, return a FP
    @dev function is from Balancer.
    @dev x & y are FP, return a FP
     */
    function rmul(uint256 x, uint256 y) internal pure returns (uint256) {
        return (RONE / 2).add(x.mul(y)).div(RONE);
    }

    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    function subMax0(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a - b : 0;
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: contracts/interfaces/IPendleYieldTokenHolder.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

interface IPendleYieldTokenHolder {
    function redeemRewards() external;

    function setUpEmergencyMode(address spender) external;

    function yieldToken() external returns (address);

    function forge() external returns (address);

    function rewardToken() external returns (address);

    function expiry() external returns (uint256);
}

// File: contracts/interfaces/IPendleRouter.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;
pragma abicoder v2;

import "../interfaces/IWETH.sol";
import "./IPendleData.sol";
import "../libraries/PendleStructs.sol";
import "./IPendleMarketFactory.sol";

interface IPendleRouter {
    /**
     * @notice Emitted when a market for a future yield token and an ERC20 token is created.
     * @param marketFactoryId Forge identifier.
     * @param xyt The address of the tokenized future yield token as the base asset.
     * @param token The address of an ERC20 token as the quote asset.
     * @param market The address of the newly created market.
     **/
    event MarketCreated(
        bytes32 marketFactoryId,
        address indexed xyt,
        address indexed token,
        address indexed market
    );

    /**
     * @notice Emitted when a swap happens on the market.
     * @param trader The address of msg.sender.
     * @param inToken The input token.
     * @param outToken The output token.
     * @param exactIn The exact amount being traded.
     * @param exactOut The exact amount received.
     * @param market The market address.
     **/
    event SwapEvent(
        address indexed trader,
        address inToken,
        address outToken,
        uint256 exactIn,
        uint256 exactOut,
        address market
    );

    /**
     * @dev Emitted when user adds liquidity
     * @param sender The user who added liquidity.
     * @param token0Amount the amount of token0 (xyt) provided by user
     * @param token1Amount the amount of token1 provided by user
     * @param market The market address.
     * @param exactOutLp The exact LP minted
     */
    event Join(
        address indexed sender,
        uint256 token0Amount,
        uint256 token1Amount,
        address market,
        uint256 exactOutLp
    );

    /**
     * @dev Emitted when user removes liquidity
     * @param sender The user who removed liquidity.
     * @param token0Amount the amount of token0 (xyt) given to user
     * @param token1Amount the amount of token1 given to user
     * @param market The market address.
     * @param exactInLp The exact Lp to remove
     */
    event Exit(
        address indexed sender,
        uint256 token0Amount,
        uint256 token1Amount,
        address market,
        uint256 exactInLp
    );

    /**
     * @notice Gets a reference to the PendleData contract.
     * @return Returns the data contract reference.
     **/
    function data() external view returns (IPendleData);

    /**
     * @notice Gets a reference of the WETH9 token contract address.
     * @return WETH token reference.
     **/
    function weth() external view returns (IWETH);

    /***********
     *  FORGE  *
     ***********/

    function newYieldContracts(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external returns (address ot, address xyt);

    function redeemAfterExpiry(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external returns (uint256 redeemedAmount);

    function redeemDueInterests(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        address user
    ) external returns (uint256 interests);

    function redeemUnderlying(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        uint256 amountToRedeem
    ) external returns (uint256 redeemedAmount);

    function renewYield(
        bytes32 forgeId,
        uint256 oldExpiry,
        address underlyingAsset,
        uint256 newExpiry,
        uint256 renewalRate
    )
        external
        returns (
            uint256 redeemedAmount,
            uint256 amountRenewed,
            address ot,
            address xyt,
            uint256 amountTokenMinted
        );

    function tokenizeYield(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        uint256 amountToTokenize,
        address to
    )
        external
        returns (
            address ot,
            address xyt,
            uint256 amountTokenMinted
        );

    /***********
     *  MARKET *
     ***********/

    function addMarketLiquidityDual(
        bytes32 _marketFactoryId,
        address _xyt,
        address _token,
        uint256 _desiredXytAmount,
        uint256 _desiredTokenAmount,
        uint256 _xytMinAmount,
        uint256 _tokenMinAmount
    )
        external
        payable
        returns (
            uint256 amountXytUsed,
            uint256 amountTokenUsed,
            uint256 lpOut
        );

    function addMarketLiquiditySingle(
        bytes32 marketFactoryId,
        address xyt,
        address token,
        bool forXyt,
        uint256 exactInAsset,
        uint256 minOutLp
    ) external payable returns (uint256 exactOutLp);

    function removeMarketLiquidityDual(
        bytes32 marketFactoryId,
        address xyt,
        address token,
        uint256 exactInLp,
        uint256 minOutXyt,
        uint256 minOutToken
    ) external returns (uint256 exactOutXyt, uint256 exactOutToken);

    function removeMarketLiquiditySingle(
        bytes32 marketFactoryId,
        address xyt,
        address token,
        bool forXyt,
        uint256 exactInLp,
        uint256 minOutAsset
    ) external returns (uint256 exactOutXyt, uint256 exactOutToken);

    /**
     * @notice Creates a market given a protocol ID, future yield token, and an ERC20 token.
     * @param marketFactoryId Market Factory identifier.
     * @param xyt Token address of the future yield token as base asset.
     * @param token Token address of an ERC20 token as quote asset.
     * @return market Returns the address of the newly created market.
     **/
    function createMarket(
        bytes32 marketFactoryId,
        address xyt,
        address token
    ) external returns (address market);

    function bootstrapMarket(
        bytes32 marketFactoryId,
        address xyt,
        address token,
        uint256 initialXytLiquidity,
        uint256 initialTokenLiquidity
    ) external payable;

    function swapExactIn(
        address tokenIn,
        address tokenOut,
        uint256 inTotalAmount,
        uint256 minOutTotalAmount,
        bytes32 marketFactoryId
    ) external payable returns (uint256 outTotalAmount);

    function swapExactOut(
        address tokenIn,
        address tokenOut,
        uint256 outTotalAmount,
        uint256 maxInTotalAmount,
        bytes32 marketFactoryId
    ) external payable returns (uint256 inTotalAmount);

    function redeemLpInterests(address market, address user) external returns (uint256 interests);
}

// File: contracts/interfaces/IPendleRewardManager.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

interface IPendleRewardManager {
    /*
    the on-chain contracts does not have names for the UpdateFrequencySet. The name is temporarily added to work with
    Typechain
    */
    event UpdateFrequencySet(address[] underlyingAssets, uint256[] frequencies);
    event SkippingRewardsSet(bool);

    event DueRewardsSettled(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        uint256 amountOut,
        address user
    );

    function redeemRewards(
        address _underlyingAsset,
        uint256 _expiry,
        address _user
    ) external returns (uint256 dueRewards);

    function updatePendingRewards(
        address _underlyingAsset,
        uint256 _expiry,
        address _user
    ) external;

    function updateParamLManual(address _underlyingAsset, uint256 _expiry) external;

    function setUpdateFrequency(
        address[] calldata underlyingAssets,
        uint256[] calldata frequencies
    ) external;

    function setSkippingRewards(bool skippingRewards) external;

    function forgeId() external returns (bytes32);
}

// File: contracts/interfaces/IPendleYieldContractDeployer.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

interface IPendleYieldContractDeployer {
    function forgeId() external returns (bytes32);

    function forgeOwnershipToken(
        address _underlyingAsset,
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _expiry
    ) external returns (address ot);

    function forgeFutureYieldToken(
        address _underlyingAsset,
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _expiry
    ) external returns (address xyt);

    function deployYieldTokenHolder(address yieldToken, uint256 expiry)
        external
        returns (address yieldTokenHolder);
}

// File: contracts/interfaces/IPendleData.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "./IPendleRouter.sol";
import "./IPendleYieldToken.sol";
import "./IPendlePausingManager.sol";
import "./IPendleMarket.sol";

interface IPendleData {
    /**
     * @notice Emitted when validity of a forge-factory pair is updated
     * @param _forgeId the forge id
     * @param _marketFactoryId the market factory id
     * @param _valid valid or not
     **/
    event ForgeFactoryValiditySet(bytes32 _forgeId, bytes32 _marketFactoryId, bool _valid);

    /**
     * @notice Emitted when Pendle and PendleFactory addresses have been updated.
     * @param treasury The address of the new treasury contract.
     **/
    event TreasurySet(address treasury);

    /**
     * @notice Emitted when LockParams is changed
     **/
    event LockParamsSet(uint256 lockNumerator, uint256 lockDenominator);

    /**
     * @notice Emitted when ExpiryDivisor is changed
     **/
    event ExpiryDivisorSet(uint256 expiryDivisor);

    /**
     * @notice Emitted when forge fee is changed
     **/
    event ForgeFeeSet(uint256 forgeFee);

    /**
     * @notice Emitted when interestUpdateRateDeltaForMarket is changed
     * @param interestUpdateRateDeltaForMarket new interestUpdateRateDeltaForMarket setting
     **/
    event InterestUpdateRateDeltaForMarketSet(uint256 interestUpdateRateDeltaForMarket);

    /**
     * @notice Emitted when market fees are changed
     * @param _swapFee new swapFee setting
     * @param _protocolSwapFee new protocolSwapFee setting
     **/
    event MarketFeesSet(uint256 _swapFee, uint256 _protocolSwapFee);

    /**
     * @notice Emitted when the curve shift block delta is changed
     * @param _blockDelta new block delta setting
     **/
    event CurveShiftBlockDeltaSet(uint256 _blockDelta);

    /**
     * @dev Emitted when new forge is added
     * @param marketFactoryId Human Readable Market Factory ID in Bytes
     * @param marketFactoryAddress The Market Factory Address
     */
    event NewMarketFactory(bytes32 indexed marketFactoryId, address indexed marketFactoryAddress);

    /**
     * @notice Set/update validity of a forge-factory pair
     * @param _forgeId the forge id
     * @param _marketFactoryId the market factory id
     * @param _valid valid or not
     **/
    function setForgeFactoryValidity(
        bytes32 _forgeId,
        bytes32 _marketFactoryId,
        bool _valid
    ) external;

    /**
     * @notice Sets the PendleTreasury contract addresses.
     * @param newTreasury Address of new treasury contract.
     **/
    function setTreasury(address newTreasury) external;

    /**
     * @notice Gets a reference to the PendleRouter contract.
     * @return Returns the router contract reference.
     **/
    function router() external view returns (IPendleRouter);

    /**
     * @notice Gets a reference to the PendleRouter contract.
     * @return Returns the router contract reference.
     **/
    function pausingManager() external view returns (IPendlePausingManager);

    /**
     * @notice Gets the treasury contract address where fees are being sent to.
     * @return Address of the treasury contract.
     **/
    function treasury() external view returns (address);

    /***********
     *  FORGE  *
     ***********/

    /**
     * @notice Emitted when a forge for a protocol is added.
     * @param forgeId Forge and protocol identifier.
     * @param forgeAddress The address of the added forge.
     **/
    event ForgeAdded(bytes32 indexed forgeId, address indexed forgeAddress);

    /**
     * @notice Adds a new forge for a protocol.
     * @param forgeId Forge and protocol identifier.
     * @param forgeAddress The address of the added forge.
     **/
    function addForge(bytes32 forgeId, address forgeAddress) external;

    /**
     * @notice Store new OT and XYT details.
     * @param forgeId Forge and protocol identifier.
     * @param ot The address of the new XYT.
     * @param xyt The address of the new XYT.
     * @param underlyingAsset Token address of the underlying asset.
     * @param expiry Yield contract expiry in epoch time.
     **/
    function storeTokens(
        bytes32 forgeId,
        address ot,
        address xyt,
        address underlyingAsset,
        uint256 expiry
    ) external;

    /**
     * @notice Set a new forge fee
     * @param _forgeFee new forge fee
     **/
    function setForgeFee(uint256 _forgeFee) external;

    /**
     * @notice Gets the OT and XYT tokens.
     * @param forgeId Forge and protocol identifier.
     * @param underlyingYieldToken Token address of the underlying yield token.
     * @param expiry Yield contract expiry in epoch time.
     * @return ot The OT token references.
     * @return xyt The XYT token references.
     **/
    function getPendleYieldTokens(
        bytes32 forgeId,
        address underlyingYieldToken,
        uint256 expiry
    ) external view returns (IPendleYieldToken ot, IPendleYieldToken xyt);

    /**
     * @notice Gets a forge given the identifier.
     * @param forgeId Forge and protocol identifier.
     * @return forgeAddress Returns the forge address.
     **/
    function getForgeAddress(bytes32 forgeId) external view returns (address forgeAddress);

    /**
     * @notice Checks if an XYT token is valid.
     * @param forgeId The forgeId of the forge.
     * @param underlyingAsset Token address of the underlying asset.
     * @param expiry Yield contract expiry in epoch time.
     * @return True if valid, false otherwise.
     **/
    function isValidXYT(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external view returns (bool);

    /**
     * @notice Checks if an OT token is valid.
     * @param forgeId The forgeId of the forge.
     * @param underlyingAsset Token address of the underlying asset.
     * @param expiry Yield contract expiry in epoch time.
     * @return True if valid, false otherwise.
     **/
    function isValidOT(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external view returns (bool);

    function validForgeFactoryPair(bytes32 _forgeId, bytes32 _marketFactoryId)
        external
        view
        returns (bool);

    /**
     * @notice Gets a reference to a specific OT.
     * @param forgeId Forge and protocol identifier.
     * @param underlyingYieldToken Token address of the underlying yield token.
     * @param expiry Yield contract expiry in epoch time.
     * @return ot Returns the reference to an OT.
     **/
    function otTokens(
        bytes32 forgeId,
        address underlyingYieldToken,
        uint256 expiry
    ) external view returns (IPendleYieldToken ot);

    /**
     * @notice Gets a reference to a specific XYT.
     * @param forgeId Forge and protocol identifier.
     * @param underlyingAsset Token address of the underlying asset
     * @param expiry Yield contract expiry in epoch time.
     * @return xyt Returns the reference to an XYT.
     **/
    function xytTokens(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external view returns (IPendleYieldToken xyt);

    /***********
     *  MARKET *
     ***********/

    event MarketPairAdded(address indexed market, address indexed xyt, address indexed token);

    function addMarketFactory(bytes32 marketFactoryId, address marketFactoryAddress) external;

    function isMarket(address _addr) external view returns (bool result);

    function isXyt(address _addr) external view returns (bool result);

    function addMarket(
        bytes32 marketFactoryId,
        address xyt,
        address token,
        address market
    ) external;

    function setMarketFees(uint256 _swapFee, uint256 _protocolSwapFee) external;

    function setInterestUpdateRateDeltaForMarket(uint256 _interestUpdateRateDeltaForMarket)
        external;

    function setLockParams(uint256 _lockNumerator, uint256 _lockDenominator) external;

    function setExpiryDivisor(uint256 _expiryDivisor) external;

    function setCurveShiftBlockDelta(uint256 _blockDelta) external;

    /**
     * @notice Displays the number of markets currently existing.
     * @return Returns markets length,
     **/
    function allMarketsLength() external view returns (uint256);

    function forgeFee() external view returns (uint256);

    function interestUpdateRateDeltaForMarket() external view returns (uint256);

    function expiryDivisor() external view returns (uint256);

    function lockNumerator() external view returns (uint256);

    function lockDenominator() external view returns (uint256);

    function swapFee() external view returns (uint256);

    function protocolSwapFee() external view returns (uint256);

    function curveShiftBlockDelta() external view returns (uint256);

    function getMarketByIndex(uint256 index) external view returns (address market);

    /**
     * @notice Gets a market given a future yield token and an ERC20 token.
     * @param xyt Token address of the future yield token as base asset.
     * @param token Token address of an ERC20 token as quote asset.
     * @return market Returns the market address.
     **/
    function getMarket(
        bytes32 marketFactoryId,
        address xyt,
        address token
    ) external view returns (address market);

    /**
     * @notice Gets a market factory given the identifier.
     * @param marketFactoryId MarketFactory identifier.
     * @return marketFactoryAddress Returns the factory address.
     **/
    function getMarketFactoryAddress(bytes32 marketFactoryId)
        external
        view
        returns (address marketFactoryAddress);

    function getMarketFromKey(
        address xyt,
        address token,
        bytes32 marketFactoryId
    ) external view returns (address market);
}

// File: contracts/interfaces/IWETH.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IWETH is IERC20 {
    event Deposit(address indexed dst, uint256 wad);
    event Withdrawal(address indexed src, uint256 wad);

    function deposit() external payable;

    function withdraw(uint256 wad) external;
}

// File: contracts/libraries/PendleStructs.sol



// SPDX-License-Identifier: GPL-2.0-or-later
pragma solidity 0.7.6;

struct TokenReserve {
    uint256 weight;
    uint256 balance;
}

struct PendingTransfer {
    uint256 amount;
    bool isOut;
}

// File: contracts/interfaces/IPendleMarketFactory.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "./IPendleRouter.sol";

interface IPendleMarketFactory {
    /**
     * @notice Creates a market given a protocol ID, future yield token, and an ERC20 token.
     * @param xyt Token address of the futuonlyCorere yield token as base asset.
     * @param token Token address of an ERC20 token as quote asset.
     * @return market Returns the address of the newly created market.
     **/
    function createMarket(address xyt, address token) external returns (address market);

    /**
     * @notice Gets a reference to the PendleRouter contract.
     * @return Returns the router contract reference.
     **/
    function router() external view returns (IPendleRouter);

    function marketFactoryId() external view returns (bytes32);
}

// File: contracts/interfaces/IPendleYieldToken.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./IPendleBaseToken.sol";
import "./IPendleForge.sol";

interface IPendleYieldToken is IERC20, IPendleBaseToken {
    /**
     * @notice Emitted when burning OT or XYT tokens.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    event Burn(address indexed user, uint256 amount);

    /**
     * @notice Emitted when minting OT or XYT tokens.
     * @param user The address performing the mint.
     * @param amount The amount to be minted.
     **/
    event Mint(address indexed user, uint256 amount);

    /**
     * @notice Burns OT or XYT tokens from user, reducing the total supply.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    function burn(address user, uint256 amount) external;

    /**
     * @notice Mints new OT or XYT tokens for user, increasing the total supply.
     * @param user The address to send the minted tokens.
     * @param amount The amount to be minted.
     **/
    function mint(address user, uint256 amount) external;

    /**
     * @notice Gets the forge address of the PendleForge contract for this yield token.
     * @return Retuns the forge address.
     **/
    function forge() external view returns (IPendleForge);

    /**
     * @notice Returns the address of the underlying asset.
     * @return Returns the underlying asset address.
     **/
    function underlyingAsset() external view returns (address);

    /**
     * @notice Returns the address of the underlying yield token.
     * @return Returns the underlying yield token address.
     **/
    function underlyingYieldToken() external view returns (address);

    /**
     * @notice let the router approve itself to spend OT/XYT/LP from any wallet
     * @param user user to approve
     **/
    function approveRouter(address user) external;
}

// File: contracts/interfaces/IPendlePausingManager.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */
pragma solidity 0.7.6;

interface IPendlePausingManager {
    event AddPausingAdmin(address admin);
    event RemovePausingAdmin(address admin);
    event PendingForgeEmergencyHandler(address _pendingForgeHandler);
    event PendingMarketEmergencyHandler(address _pendingMarketHandler);
    event PendingLiqMiningEmergencyHandler(address _pendingLiqMiningHandler);
    event ForgeEmergencyHandlerSet(address forgeEmergencyHandler);
    event MarketEmergencyHandlerSet(address marketEmergencyHandler);
    event LiqMiningEmergencyHandlerSet(address liqMiningEmergencyHandler);

    event PausingManagerLocked();
    event ForgeHandlerLocked();
    event MarketHandlerLocked();
    event LiqMiningHandlerLocked();

    event SetForgePaused(bytes32 forgeId, bool settingToPaused);
    event SetForgeAssetPaused(bytes32 forgeId, address underlyingAsset, bool settingToPaused);
    event SetForgeAssetExpiryPaused(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        bool settingToPaused
    );

    event SetForgeLocked(bytes32 forgeId);
    event SetForgeAssetLocked(bytes32 forgeId, address underlyingAsset);
    event SetForgeAssetExpiryLocked(bytes32 forgeId, address underlyingAsset, uint256 expiry);

    event SetMarketFactoryPaused(bytes32 marketFactoryId, bool settingToPaused);
    event SetMarketPaused(bytes32 marketFactoryId, address market, bool settingToPaused);

    event SetMarketFactoryLocked(bytes32 marketFactoryId);
    event SetMarketLocked(bytes32 marketFactoryId, address market);

    event SetLiqMiningPaused(address liqMiningContract, bool settingToPaused);
    event SetLiqMiningLocked(address liqMiningContract);

    function forgeEmergencyHandler()
        external
        view
        returns (
            address handler,
            address pendingHandler,
            uint256 timelockDeadline
        );

    function marketEmergencyHandler()
        external
        view
        returns (
            address handler,
            address pendingHandler,
            uint256 timelockDeadline
        );

    function liqMiningEmergencyHandler()
        external
        view
        returns (
            address handler,
            address pendingHandler,
            uint256 timelockDeadline
        );

    function permLocked() external view returns (bool);

    function permForgeHandlerLocked() external view returns (bool);

    function permMarketHandlerLocked() external view returns (bool);

    function permLiqMiningHandlerLocked() external view returns (bool);

    function isPausingAdmin(address) external view returns (bool);

    function setPausingAdmin(address admin, bool isAdmin) external;

    function requestForgeHandlerChange(address _pendingForgeHandler) external;

    function requestMarketHandlerChange(address _pendingMarketHandler) external;

    function requestLiqMiningHandlerChange(address _pendingLiqMiningHandler) external;

    function applyForgeHandlerChange() external;

    function applyMarketHandlerChange() external;

    function applyLiqMiningHandlerChange() external;

    function lockPausingManagerPermanently() external;

    function lockForgeHandlerPermanently() external;

    function lockMarketHandlerPermanently() external;

    function lockLiqMiningHandlerPermanently() external;

    function setForgePaused(bytes32 forgeId, bool paused) external;

    function setForgeAssetPaused(
        bytes32 forgeId,
        address underlyingAsset,
        bool paused
    ) external;

    function setForgeAssetExpiryPaused(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry,
        bool paused
    ) external;

    function setForgeLocked(bytes32 forgeId) external;

    function setForgeAssetLocked(bytes32 forgeId, address underlyingAsset) external;

    function setForgeAssetExpiryLocked(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external;

    function checkYieldContractStatus(
        bytes32 forgeId,
        address underlyingAsset,
        uint256 expiry
    ) external returns (bool _paused, bool _locked);

    function setMarketFactoryPaused(bytes32 marketFactoryId, bool paused) external;

    function setMarketPaused(
        bytes32 marketFactoryId,
        address market,
        bool paused
    ) external;

    function setMarketFactoryLocked(bytes32 marketFactoryId) external;

    function setMarketLocked(bytes32 marketFactoryId, address market) external;

    function checkMarketStatus(bytes32 marketFactoryId, address market)
        external
        returns (bool _paused, bool _locked);

    function setLiqMiningPaused(address liqMiningContract, bool settingToPaused) external;

    function setLiqMiningLocked(address liqMiningContract) external;

    function checkLiqMiningStatus(address liqMiningContract)
        external
        returns (bool _paused, bool _locked);
}

// File: contracts/interfaces/IPendleMarket.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;
pragma abicoder v2;

import "./IPendleRouter.sol";
import "./IPendleBaseToken.sol";
import "../libraries/PendleStructs.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IPendleMarket is IERC20 {
    /**
     * @notice Emitted when reserves pool has been updated
     * @param reserve0 The XYT reserves.
     * @param weight0  The XYT weight
     * @param reserve1 The generic token reserves.
     * For the generic Token weight it can be inferred by (2^40) - weight0
     **/
    event Sync(uint256 reserve0, uint256 weight0, uint256 reserve1);
    event RedeemLpInterests(address user, uint256 interests);

    function setUpEmergencyMode(address spender) external;

    function bootstrap(
        address user,
        uint256 initialXytLiquidity,
        uint256 initialTokenLiquidity
    ) external returns (PendingTransfer[2] memory transfers, uint256 exactOutLp);

    function addMarketLiquiditySingle(
        address user,
        address inToken,
        uint256 inAmount,
        uint256 minOutLp
    ) external returns (PendingTransfer[2] memory transfers, uint256 exactOutLp);

    function addMarketLiquidityDual(
        address user,
        uint256 _desiredXytAmount,
        uint256 _desiredTokenAmount,
        uint256 _xytMinAmount,
        uint256 _tokenMinAmount
    ) external returns (PendingTransfer[2] memory transfers, uint256 lpOut);

    function removeMarketLiquidityDual(
        address user,
        uint256 inLp,
        uint256 minOutXyt,
        uint256 minOutToken
    ) external returns (PendingTransfer[2] memory transfers);

    function removeMarketLiquiditySingle(
        address user,
        address outToken,
        uint256 exactInLp,
        uint256 minOutToken
    ) external returns (PendingTransfer[2] memory transfers);

    function swapExactIn(
        address inToken,
        uint256 inAmount,
        address outToken,
        uint256 minOutAmount
    ) external returns (uint256 outAmount, PendingTransfer[2] memory transfers);

    function swapExactOut(
        address inToken,
        uint256 maxInAmount,
        address outToken,
        uint256 outAmount
    ) external returns (uint256 inAmount, PendingTransfer[2] memory transfers);

    function redeemLpInterests(address user) external returns (uint256 interests);

    function getReserves()
        external
        view
        returns (
            uint256 xytBalance,
            uint256 xytWeight,
            uint256 tokenBalance,
            uint256 tokenWeight,
            uint256 currentBlock
        );

    function factoryId() external view returns (bytes32);

    function token() external view returns (address);

    function xyt() external view returns (address);
}

// File: contracts/interfaces/IPendleBaseToken.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface IPendleBaseToken is IERC20 {
    /**
     * @notice Decreases the allowance granted to spender by the caller.
     * @param spender The address to reduce the allowance from.
     * @param subtractedValue The amount allowance to subtract.
     * @return Returns true if allowance has decreased, otherwise false.
     **/
    function decreaseAllowance(address spender, uint256 subtractedValue) external returns (bool);

    /**
     * @notice The yield contract start in epoch time.
     * @return Returns the yield start date.
     **/
    function start() external view returns (uint256);

    /**
     * @notice The yield contract expiry in epoch time.
     * @return Returns the yield expiry date.
     **/
    function expiry() external view returns (uint256);

    /**
     * @notice Increases the allowance granted to spender by the caller.
     * @param spender The address to increase the allowance from.
     * @param addedValue The amount allowance to add.
     * @return Returns true if allowance has increased, otherwise false
     **/
    function increaseAllowance(address spender, uint256 addedValue) external returns (bool);

    /**
     * @notice Returns the number of decimals the token uses.
     * @return Returns the token's decimals.
     **/
    function decimals() external view returns (uint8);

    /**
     * @notice Returns the name of the token.
     * @return Returns the token's name.
     **/
    function name() external view returns (string memory);

    /**
     * @notice Returns the symbol of the token.
     * @return Returns the token's symbol.
     **/
    function symbol() external view returns (string memory);

    /**
     * @notice approve using the owner's signature
     **/
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
}

// File: contracts/tokens/PendleBaseToken.sol



// SPDX-License-Identifier: BUSL-1.1
pragma solidity 0.7.6;

import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/cryptography/ECDSA.sol";
import "../interfaces/IPendleBaseToken.sol";
import "../interfaces/IPendleRouter.sol";

/**
 *   @title PendleBaseToken
 *   @dev The contract implements the standard ERC20 functions, plus some
 *        Pendle specific fields and functions, namely:
 *          - expiry
 *
 *        This abstract contract is inherited by PendleFutureYieldToken
 *        and PendleOwnershipToken contracts.
 **/
abstract contract PendleBaseToken is ERC20 {
    using SafeMath for uint256;

    uint256 public immutable start;
    uint256 public immutable expiry;
    IPendleRouter public immutable router;

    //// Start of EIP-2612 related part, exactly the same as UniswapV2ERC20.sol
    bytes32 public immutable DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH =
        0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint256) public nonces;

    //// End of EIP-2612 related part

    constructor(
        address _router,
        string memory _name,
        string memory _symbol,
        uint8 _decimals,
        uint256 _start,
        uint256 _expiry
    ) ERC20(_name, _symbol) {
        _setupDecimals(_decimals);
        start = _start;
        expiry = _expiry;
        router = IPendleRouter(_router);

        //// Start of EIP-2612 related part, exactly the same as UniswapV2ERC20.sol, except for the noted parts below
        uint256 chainId;
        assembly {
            chainId := chainid() // chainid() is a function in assembly in this solidity version
        }

        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256(
                    "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                ),
                keccak256(bytes(_name)), // use our own _name here
                keccak256(bytes("1")),
                chainId,
                address(this)
            )
        );
        //// End of EIP-2612 related part
    }

    //// Start of EIP-2612 related part, exactly the same as UniswapV2ERC20.sol
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        require(deadline >= block.timestamp, "PERMIT_EXPIRED");
        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR,
                keccak256(
                    abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline)
                )
            )
        );
        address recoveredAddress = ECDSA.recover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, "INVALID_SIGNATURE");
        _approve(owner, spender, value);
    }

    //// End of EIP-2612 related part

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256
    ) internal virtual override {
        require(to != address(this), "SEND_TO_TOKEN_CONTRACT");
        require(to != from, "SEND_TO_SELF");
    }
}

// File: contracts/interfaces/IPendleYieldTokenCommon.sol



// SPDX-License-Identifier: MIT
/*
 * MIT License
 * ===========
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 */

pragma solidity 0.7.6;

interface IPendleYieldTokenCommon {
    /**
     * @notice Emitted when burning OT or XYT tokens.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    event Burn(address indexed user, uint256 amount);

    /**
     * @notice Emitted when minting OT or XYT tokens.
     * @param user The address performing the mint.
     * @param amount The amount to be minted.
     **/
    event Mint(address indexed user, uint256 amount);

    /**
     * @notice Burns OT or XYT tokens from user, reducing the total supply.
     * @param user The address performing the burn.
     * @param amount The amount to be burned.
     **/
    function burn(address user, uint256 amount) external;

    /**
     * @notice Mints new OT or XYT tokens for user, increasing the total supply.
     * @param user The address to send the minted tokens.
     * @param amount The amount to be minted.
     **/
    function mint(address user, uint256 amount) external;

    /**
     * @notice Gets the forge address of the PendleForge contract for this yield token.
     * @return Retuns the forge address.
     **/
    function forge() external view returns (address);

    /**
     * @notice Returns the address of the underlying asset.
     * @return Returns the underlying asset address.
     **/
    function underlyingAsset() external view returns (address);

    /**
     * @notice Returns the address of the underlying yield token.
     * @return Returns the underlying yield token address.
     **/
    function underlyingYieldToken() external view returns (address);
}

// File: @openzeppelin/contracts/token/ERC20/ERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

import "../../utils/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) public {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

// File: @openzeppelin/contracts/cryptography/ECDSA.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
 *
 * These functions can be used to verify that a message was signed by the holder
 * of the private keys of a given address.
 */
library ECDSA {
    /**
     * @dev Returns the address that signed a hashed message (`hash`) with
     * `signature`. This address can then be used for verification purposes.
     *
     * The `ecrecover` EVM opcode allows for malleable (non-unique) signatures:
     * this function rejects them by requiring the `s` value to be in the lower
     * half order, and the `v` value to be either 27 or 28.
     *
     * IMPORTANT: `hash` _must_ be the result of a hash operation for the
     * verification to be secure: it is possible to craft signatures that
     * recover to arbitrary addresses for non-hashed data. A safe way to ensure
     * this is by receiving a hash of the original message (which may otherwise
     * be too long), and then calling {toEthSignedMessageHash} on it.
     */
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        // Check the signature length
        if (signature.length != 65) {
            revert("ECDSA: invalid signature length");
        }

        // Divide the signature in r, s and v variables
        bytes32 r;
        bytes32 s;
        uint8 v;

        // ecrecover takes the signature parameters, and the only way to get them
        // currently is to use assembly.
        // solhint-disable-next-line no-inline-assembly
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        return recover(hash, v, r, s);
    }

    /**
     * @dev Overload of {ECDSA-recover-bytes32-bytes-} that receives the `v`,
     * `r` and `s` signature fields separately.
     */
    function recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        require(uint256(s) <= 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0, "ECDSA: invalid signature 's' value");
        require(v == 27 || v == 28, "ECDSA: invalid signature 'v' value");

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(hash, v, r, s);
        require(signer != address(0), "ECDSA: invalid signature");

        return signer;
    }

    /**
     * @dev Returns an Ethereum Signed Message, created from a `hash`. This
     * replicates the behavior of the
     * https://github.com/ethereum/wiki/wiki/JSON-RPC#eth_sign[`eth_sign`]
     * JSON-RPC method.
     *
     * See {recover}.
     */
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        // 32 is the length in bytes of hash,
        // enforced by the type signature above
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}