// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^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: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC20.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 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) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _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: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^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: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^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 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) {
        return msg.sender;
    }

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

// File: @openzeppelin/contracts/utils/math/Math.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library Math {
    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a >= b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow, so we distribute
        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
    }
}

// File: @thesis/solidity-contracts/contracts/token/ERC20WithPermit.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "@openzeppelin/contracts/access/Ownable.sol";

import "./IERC20WithPermit.sol";
import "./IReceiveApproval.sol";

/// @title  ERC20WithPermit
/// @notice Burnable ERC20 token with EIP2612 permit functionality. User can
///         authorize a transfer of their token with a signature conforming
///         EIP712 standard instead of an on-chain transaction from their
///         address. Anyone can submit this signature on the user's behalf by
///         calling the permit function, as specified in EIP2612 standard,
///         paying gas fees, and possibly performing other actions in the same
///         transaction.
contract ERC20WithPermit is IERC20WithPermit, Ownable {
    /// @notice The amount of tokens owned by the given account.
    mapping(address => uint256) public override balanceOf;

    /// @notice The remaining number of tokens that spender will be
    ///         allowed to spend on behalf of owner through `transferFrom` and
    ///         `burnFrom`. This is zero by default.
    mapping(address => mapping(address => uint256)) public override allowance;

    /// @notice Returns the current nonce for EIP2612 permission for the
    ///         provided token owner for a replay protection. Used to construct
    ///         EIP2612 signature provided to `permit` function.
    mapping(address => uint256) public override nonces;

    uint256 public immutable cachedChainId;
    bytes32 public immutable cachedDomainSeparator;

    /// @notice Returns EIP2612 Permit message hash. Used to construct EIP2612
    ///         signature provided to `permit` function.
    bytes32 public constant override PERMIT_TYPEHASH =
        keccak256(
            "Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
        );

    /// @notice The amount of tokens in existence.
    uint256 public override totalSupply;

    /// @notice The name of the token.
    string public override name;

    /// @notice The symbol of the token.
    string public override symbol;

    /// @notice The decimals places of the token.
    uint8 public constant override decimals = 18;

    constructor(string memory _name, string memory _symbol) {
        name = _name;
        symbol = _symbol;

        cachedChainId = block.chainid;
        cachedDomainSeparator = buildDomainSeparator();
    }

    /// @notice Moves `amount` tokens from the caller's account to `recipient`.
    /// @return True if the operation succeeded, reverts otherwise.
    /// @dev Requirements:
    ///       - `recipient` cannot be the zero address,
    ///       - the caller must have a balance of at least `amount`.
    function transfer(address recipient, uint256 amount)
        external
        override
        returns (bool)
    {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    /// @notice Moves `amount` tokens from `sender` to `recipient` using the
    ///         allowance mechanism. `amount` is then deducted from the caller's
    ///         allowance unless the allowance was made for `type(uint256).max`.
    /// @return True if the operation succeeded, reverts otherwise.
    /// @dev 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
    ) external override returns (bool) {
        uint256 currentAllowance = allowance[sender][msg.sender];
        if (currentAllowance != type(uint256).max) {
            require(
                currentAllowance >= amount,
                "Transfer amount exceeds allowance"
            );
            _approve(sender, msg.sender, currentAllowance - amount);
        }
        _transfer(sender, recipient, amount);
        return true;
    }

    /// @notice EIP2612 approval made with secp256k1 signature.
    ///         Users can authorize a transfer of their tokens with a signature
    ///         conforming EIP712 standard, rather than an on-chain transaction
    ///         from their address. Anyone can submit this signature on the
    ///         user's behalf by calling the permit function, paying gas fees,
    ///         and possibly performing other actions in the same transaction.
    /// @dev    The deadline argument can be set to `type(uint256).max to create
    ///         permits that effectively never expire.  If the `amount` is set
    ///         to `type(uint256).max` then `transferFrom` and `burnFrom` will
    ///         not reduce an allowance.
    function permit(
        address owner,
        address spender,
        uint256 amount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external override {
        /* solhint-disable-next-line not-rely-on-time */
        require(deadline >= block.timestamp, "Permission expired");

        // Validate `s` and `v` values for a malleability concern described in EIP2.
        // Only signatures with `s` value in the lower half of the secp256k1
        // curve's order and `v` value of 27 or 28 are considered valid.
        require(
            uint256(s) <=
                0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
            "Invalid signature 's' value"
        );
        require(v == 27 || v == 28, "Invalid signature 'v' value");

        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR(),
                keccak256(
                    abi.encode(
                        PERMIT_TYPEHASH,
                        owner,
                        spender,
                        amount,
                        nonces[owner]++,
                        deadline
                    )
                )
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(
            recoveredAddress != address(0) && recoveredAddress == owner,
            "Invalid signature"
        );
        _approve(owner, spender, amount);
    }

    /// @notice Creates `amount` tokens and assigns them to `account`,
    ///         increasing the total supply.
    /// @dev Requirements:
    ///      - `recipient` cannot be the zero address.
    function mint(address recipient, uint256 amount) external onlyOwner {
        require(recipient != address(0), "Mint to the zero address");

        beforeTokenTransfer(address(0), recipient, amount);

        totalSupply += amount;
        balanceOf[recipient] += amount;
        emit Transfer(address(0), recipient, amount);
    }

    /// @notice Destroys `amount` tokens from the caller.
    /// @dev Requirements:
    ///       - the caller must have a balance of at least `amount`.
    function burn(uint256 amount) external override {
        _burn(msg.sender, amount);
    }

    /// @notice Destroys `amount` of tokens from `account` using the allowance
    ///         mechanism. `amount` is then deducted from the caller's allowance
    ///         unless the allowance was made for `type(uint256).max`.
    /// @dev Requirements:
    ///      - `account` must have a balance of at least `amount`,
    ///      - the caller must have allowance for `account`'s tokens of at least
    ///        `amount`.
    function burnFrom(address account, uint256 amount) external override {
        uint256 currentAllowance = allowance[account][msg.sender];
        if (currentAllowance != type(uint256).max) {
            require(
                currentAllowance >= amount,
                "Burn amount exceeds allowance"
            );
            _approve(account, msg.sender, currentAllowance - amount);
        }
        _burn(account, amount);
    }

    /// @notice Calls `receiveApproval` function on spender previously approving
    ///         the spender to withdraw from the caller multiple times, up to
    ///         the `amount` amount. If this function is called again, it
    ///         overwrites the current allowance with `amount`. Reverts if the
    ///         approval reverted or if `receiveApproval` call on the spender
    ///         reverted.
    /// @return True if both approval and `receiveApproval` calls succeeded.
    /// @dev If the `amount` is set to `type(uint256).max` then
    ///      `transferFrom` and `burnFrom` will not reduce an allowance.
    function approveAndCall(
        address spender,
        uint256 amount,
        bytes memory extraData
    ) external override returns (bool) {
        if (approve(spender, amount)) {
            IReceiveApproval(spender).receiveApproval(
                msg.sender,
                amount,
                address(this),
                extraData
            );
            return true;
        }
        return false;
    }

    /// @notice Sets `amount` as the allowance of `spender` over the caller's
    ///         tokens.
    /// @return True if the operation succeeded.
    /// @dev If the `amount` is set to `type(uint256).max` then
    ///      `transferFrom` and `burnFrom` will not reduce an allowance.
    ///      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
    function approve(address spender, uint256 amount)
        public
        override
        returns (bool)
    {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /// @notice Returns hash of EIP712 Domain struct with the token name as
    ///         a signing domain and token contract as a verifying contract.
    ///         Used to construct EIP2612 signature provided to `permit`
    ///         function.
    /* solhint-disable-next-line func-name-mixedcase */
    function DOMAIN_SEPARATOR() public view override returns (bytes32) {
        // As explained in EIP-2612, if the DOMAIN_SEPARATOR contains the
        // chainId and is defined at contract deployment instead of
        // reconstructed for every signature, there is a risk of possible replay
        // attacks between chains in the event of a future chain split.
        // To address this issue, we check the cached chain ID against the
        // current one and in case they are different, we build domain separator
        // from scratch.
        if (block.chainid == cachedChainId) {
            return cachedDomainSeparator;
        } else {
            return buildDomainSeparator();
        }
    }

    /// @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.
    // slither-disable-next-line dead-code
    function beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    function _burn(address account, uint256 amount) internal {
        uint256 currentBalance = balanceOf[account];
        require(currentBalance >= amount, "Burn amount exceeds balance");

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

        balanceOf[account] = currentBalance - amount;
        totalSupply -= amount;
        emit Transfer(account, address(0), amount);
    }

    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) private {
        require(sender != address(0), "Transfer from the zero address");
        require(recipient != address(0), "Transfer to the zero address");
        require(recipient != address(this), "Transfer to the token address");

        beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = balanceOf[sender];
        require(senderBalance >= amount, "Transfer amount exceeds balance");
        balanceOf[sender] = senderBalance - amount;
        balanceOf[recipient] += amount;
        emit Transfer(sender, recipient, amount);
    }

    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) private {
        require(owner != address(0), "Approve from the zero address");
        require(spender != address(0), "Approve to the zero address");
        allowance[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function buildDomainSeparator() private view returns (bytes32) {
        return
            keccak256(
                abi.encode(
                    keccak256(
                        "EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
                    ),
                    keccak256(bytes(name)),
                    keccak256(bytes("1")),
                    block.chainid,
                    address(this)
                )
            );
    }
}

// File: @thesis/solidity-contracts/contracts/token/IApproveAndCall.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

/// @notice An interface that should be implemented by tokens supporting
///         `approveAndCall`/`receiveApproval` pattern.
interface IApproveAndCall {
    /// @notice Executes `receiveApproval` function on spender as specified in
    ///         `IReceiveApproval` interface. Approves spender to withdraw from
    ///         the caller multiple times, up to the `amount`. If this
    ///         function is called again, it overwrites the current allowance
    ///         with `amount`. Reverts if the approval reverted or if
    ///         `receiveApproval` call on the spender reverted.
    function approveAndCall(
        address spender,
        uint256 amount,
        bytes memory extraData
    ) external returns (bool);
}

// File: @thesis/solidity-contracts/contracts/token/IERC20WithPermit.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";

import "./IApproveAndCall.sol";

/// @title  IERC20WithPermit
/// @notice Burnable ERC20 token with EIP2612 permit functionality. User can
///         authorize a transfer of their token with a signature conforming
///         EIP712 standard instead of an on-chain transaction from their
///         address. Anyone can submit this signature on the user's behalf by
///         calling the permit function, as specified in EIP2612 standard,
///         paying gas fees, and possibly performing other actions in the same
///         transaction.
interface IERC20WithPermit is IERC20, IERC20Metadata, IApproveAndCall {
    /// @notice EIP2612 approval made with secp256k1 signature.
    ///         Users can authorize a transfer of their tokens with a signature
    ///         conforming EIP712 standard, rather than an on-chain transaction
    ///         from their address. Anyone can submit this signature on the
    ///         user's behalf by calling the permit function, paying gas fees,
    ///         and possibly performing other actions in the same transaction.
    /// @dev    The deadline argument can be set to `type(uint256).max to create
    ///         permits that effectively never expire.
    function permit(
        address owner,
        address spender,
        uint256 amount,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /// @notice Destroys `amount` tokens from the caller.
    function burn(uint256 amount) external;

    /// @notice Destroys `amount` of tokens from `account`, deducting the amount
    ///         from caller's allowance.
    function burnFrom(address account, uint256 amount) external;

    /// @notice Returns hash of EIP712 Domain struct with the token name as
    ///         a signing domain and token contract as a verifying contract.
    ///         Used to construct EIP2612 signature provided to `permit`
    ///         function.
    /* solhint-disable-next-line func-name-mixedcase */
    function DOMAIN_SEPARATOR() external view returns (bytes32);

    /// @notice Returns the current nonce for EIP2612 permission for the
    ///         provided token owner for a replay protection. Used to construct
    ///         EIP2612 signature provided to `permit` function.
    function nonces(address owner) external view returns (uint256);

    /// @notice Returns EIP2612 Permit message hash. Used to construct EIP2612
    ///         signature provided to `permit` function.
    /* solhint-disable-next-line func-name-mixedcase */
    function PERMIT_TYPEHASH() external pure returns (bytes32);
}

// File: @thesis/solidity-contracts/contracts/token/IReceiveApproval.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.4;

/// @notice An interface that should be implemented by contracts supporting
///         `approveAndCall`/`receiveApproval` pattern.
interface IReceiveApproval {
    /// @notice Receives approval to spend tokens. Called as a result of
    ///         `approveAndCall` call on the token.
    function receiveApproval(
        address from,
        uint256 amount,
        address token,
        bytes calldata extraData
    ) external;
}

// File: contracts/AssetPool.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

import "./interfaces/IAssetPool.sol";
import "./interfaces/IAssetPoolUpgrade.sol";
import "./RewardsPool.sol";
import "./UnderwriterToken.sol";
import "./GovernanceUtils.sol";

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

/// @title Asset Pool
/// @notice Asset pool is a component of a Coverage Pool. Asset Pool
///         accepts a single ERC20 token as collateral, and returns an
///         underwriter token. For example, an asset pool might accept deposits
///         in KEEP in return for covKEEP underwriter tokens. Underwriter tokens
///         represent an ownership share in the underlying collateral of the
///         Asset Pool.
contract AssetPool is Ownable, IAssetPool {
    using SafeERC20 for IERC20;
    using SafeERC20 for UnderwriterToken;

    IERC20 public immutable collateralToken;
    UnderwriterToken public immutable underwriterToken;

    RewardsPool public immutable rewardsPool;

    IAssetPoolUpgrade public newAssetPool;

    /// @notice The time it takes the underwriter to withdraw their collateral
    ///         and rewards from the pool. This is the time that needs to pass
    ///         between initiating and completing the withdrawal. During that
    ///         time, underwriter is still earning rewards and their share of
    ///         the pool is still a subject of a possible coverage claim.
    uint256 public withdrawalDelay = 21 days;
    uint256 public newWithdrawalDelay;
    uint256 public withdrawalDelayChangeInitiated;

    /// @notice The time the underwriter has after the withdrawal delay passed
    ///         to complete the withdrawal. During that time, underwriter is
    ///         still earning rewards and their share of the pool is still
    ///         a subject of a possible coverage claim.
    ///         After the withdrawal timeout elapses, tokens stay in the pool
    ///         and the underwriter has to initiate the withdrawal again and
    ///         wait for the full withdrawal delay to complete the withdrawal.
    uint256 public withdrawalTimeout = 2 days;
    uint256 public newWithdrawalTimeout;
    uint256 public withdrawalTimeoutChangeInitiated;

    mapping(address => uint256) public withdrawalInitiatedTimestamp;
    mapping(address => uint256) public pendingWithdrawal;

    event Deposited(
        address indexed underwriter,
        uint256 amount,
        uint256 covAmount
    );

    event CoverageClaimed(
        address indexed recipient,
        uint256 amount,
        uint256 timestamp
    );

    event WithdrawalInitiated(
        address indexed underwriter,
        uint256 covAmount,
        uint256 timestamp
    );
    event WithdrawalCompleted(
        address indexed underwriter,
        uint256 amount,
        uint256 covAmount,
        uint256 timestamp
    );

    event ApprovedAssetPoolUpgrade(address newAssetPool);
    event CancelledAssetPoolUpgrade(address cancelledAssetPool);
    event AssetPoolUpgraded(
        address indexed underwriter,
        uint256 collateralAmount,
        uint256 covAmount,
        uint256 timestamp
    );

    event WithdrawalDelayUpdateStarted(
        uint256 withdrawalDelay,
        uint256 timestamp
    );
    event WithdrawalDelayUpdated(uint256 withdrawalDelay);
    event WithdrawalTimeoutUpdateStarted(
        uint256 withdrawalTimeout,
        uint256 timestamp
    );
    event WithdrawalTimeoutUpdated(uint256 withdrawalTimeout);

    /// @notice Reverts if the withdrawal governance delay has not passed yet or
    ///         if the change was not yet initiated.
    /// @param changeInitiatedTimestamp The timestamp at which the change has
    ///        been initiated
    modifier onlyAfterWithdrawalGovernanceDelay(
        uint256 changeInitiatedTimestamp
    ) {
        require(changeInitiatedTimestamp > 0, "Change not initiated");
        require(
            /* solhint-disable-next-line not-rely-on-time */
            block.timestamp - changeInitiatedTimestamp >=
                withdrawalGovernanceDelay(),
            "Governance delay has not elapsed"
        );
        _;
    }

    constructor(
        IERC20 _collateralToken,
        UnderwriterToken _underwriterToken,
        address rewardsManager
    ) {
        collateralToken = _collateralToken;
        underwriterToken = _underwriterToken;

        rewardsPool = new RewardsPool(
            _collateralToken,
            address(this),
            rewardsManager
        );
    }

    /// @notice Accepts the given amount of collateral token as a deposit and
    ///         mints underwriter tokens representing pool's ownership.
    ///         Optional data in extraData may include a minimal amount of
    ///         underwriter tokens expected to be minted for a depositor. There
    ///         are cases when an amount of minted tokens matters for a
    ///         depositor, as tokens might be used in third party exchanges.
    /// @dev This function is a shortcut for approve + deposit.
    function receiveApproval(
        address from,
        uint256 amount,
        address token,
        bytes calldata extraData
    ) external {
        require(msg.sender == token, "Only token caller allowed");
        require(
            token == address(collateralToken),
            "Unsupported collateral token"
        );

        uint256 toMint = _calculateTokensToMint(amount);
        if (extraData.length != 0) {
            require(extraData.length == 32, "Unexpected data length");
            uint256 minAmountToMint = abi.decode(extraData, (uint256));
            require(
                minAmountToMint <= toMint,
                "Amount to mint is smaller than the required minimum"
            );
        }

        _deposit(from, amount, toMint);
    }

    /// @notice Accepts the given amount of collateral token as a deposit and
    ///         mints underwriter tokens representing pool's ownership.
    /// @dev Before calling this function, collateral token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    /// @param amountToDeposit Collateral tokens amount that a user deposits to
    ///                        the asset pool
    /// @return The amount of minted underwriter tokens
    function deposit(uint256 amountToDeposit)
        external
        override
        returns (uint256)
    {
        uint256 toMint = _calculateTokensToMint(amountToDeposit);
        _deposit(msg.sender, amountToDeposit, toMint);
        return toMint;
    }

    /// @notice Accepts the given amount of collateral token as a deposit and
    ///         mints at least a minAmountToMint underwriter tokens representing
    ///         pool's ownership.
    /// @dev Before calling this function, collateral token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    /// @param amountToDeposit Collateral tokens amount that a user deposits to
    ///                        the asset pool
    /// @param minAmountToMint Underwriter minimal tokens amount that a user
    ///                        expects to receive in exchange for the deposited
    ///                        collateral tokens
    /// @return The amount of minted underwriter tokens
    function depositWithMin(uint256 amountToDeposit, uint256 minAmountToMint)
        external
        override
        returns (uint256)
    {
        uint256 toMint = _calculateTokensToMint(amountToDeposit);

        require(
            minAmountToMint <= toMint,
            "Amount to mint is smaller than the required minimum"
        );

        _deposit(msg.sender, amountToDeposit, toMint);
        return toMint;
    }

    /// @notice Initiates the withdrawal of collateral and rewards from the
    ///         pool. Must be followed with completeWithdrawal call after the
    ///         withdrawal delay passes. Accepts the amount of underwriter
    ///         tokens representing the share of the pool that should be
    ///         withdrawn. Can be called multiple times increasing the pool share
    ///         to withdraw and resetting the withdrawal initiated timestamp for
    ///         each call. Can be called with 0 covAmount to reset the
    ///         withdrawal initiated timestamp if the underwriter has a pending
    ///         withdrawal. In practice 0 covAmount should be used only to
    ///         initiate the withdrawal again in case one did not complete the
    ///         withdrawal before the withdrawal timeout elapsed.
    /// @dev Before calling this function, underwriter token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    function initiateWithdrawal(uint256 covAmount) external override {
        uint256 pending = pendingWithdrawal[msg.sender];
        require(
            covAmount > 0 || pending > 0,
            "Underwriter token amount must be greater than 0"
        );

        pending += covAmount;
        pendingWithdrawal[msg.sender] = pending;
        /* solhint-disable not-rely-on-time */
        withdrawalInitiatedTimestamp[msg.sender] = block.timestamp;

        emit WithdrawalInitiated(msg.sender, pending, block.timestamp);
        /* solhint-enable not-rely-on-time */

        if (covAmount > 0) {
            underwriterToken.safeTransferFrom(
                msg.sender,
                address(this),
                covAmount
            );
        }
    }

    /// @notice Completes the previously initiated withdrawal for the
    ///         underwriter. Anyone can complete the withdrawal for the
    ///         underwriter. The withdrawal has to be completed before the
    ///         withdrawal timeout elapses. Otherwise, the withdrawal has to
    ///         be initiated again and the underwriter has to wait for the
    ///         entire withdrawal delay again before being able to complete
    ///         the withdrawal.
    /// @return The amount of collateral withdrawn
    function completeWithdrawal(address underwriter)
        external
        override
        returns (uint256)
    {
        /* solhint-disable not-rely-on-time */
        uint256 initiatedAt = withdrawalInitiatedTimestamp[underwriter];
        require(initiatedAt > 0, "No withdrawal initiated for the underwriter");

        uint256 withdrawalDelayEndTimestamp = initiatedAt + withdrawalDelay;
        require(
            withdrawalDelayEndTimestamp < block.timestamp,
            "Withdrawal delay has not elapsed"
        );

        require(
            withdrawalDelayEndTimestamp + withdrawalTimeout >= block.timestamp,
            "Withdrawal timeout elapsed"
        );

        uint256 covAmount = pendingWithdrawal[underwriter];
        uint256 covSupply = underwriterToken.totalSupply();
        delete withdrawalInitiatedTimestamp[underwriter];
        delete pendingWithdrawal[underwriter];

        // slither-disable-next-line reentrancy-events
        rewardsPool.withdraw();

        uint256 collateralBalance = collateralToken.balanceOf(address(this));

        uint256 amountToWithdraw = (covAmount * collateralBalance) / covSupply;

        emit WithdrawalCompleted(
            underwriter,
            amountToWithdraw,
            covAmount,
            block.timestamp
        );
        collateralToken.safeTransfer(underwriter, amountToWithdraw);

        /* solhint-enable not-rely-on-time */
        underwriterToken.burn(covAmount);

        return amountToWithdraw;
    }

    /// @notice Transfers collateral tokens to a new Asset Pool which previously
    ///         was approved by the governance. Upgrade does not have to obey
    ///         withdrawal delay.
    ///         Old underwriter tokens are burned in favor of new tokens minted
    ///         in a new Asset Pool. New tokens are sent directly to the
    ///         underwriter from a new Asset Pool.
    /// @param covAmount Amount of underwriter tokens used to calculate collateral
    ///                  tokens which are transferred to a new asset pool
    /// @param _newAssetPool New Asset Pool address to check validity with the one
    ///                      that was approved by the governance
    function upgradeToNewAssetPool(uint256 covAmount, address _newAssetPool)
        external
    {
        /* solhint-disable not-rely-on-time */
        require(
            address(newAssetPool) != address(0),
            "New asset pool must be assigned"
        );

        require(
            address(newAssetPool) == _newAssetPool,
            "Addresses of a new asset pool must match"
        );

        require(
            covAmount > 0,
            "Underwriter token amount must be greater than 0"
        );

        uint256 covSupply = underwriterToken.totalSupply();

        // slither-disable-next-line reentrancy-events
        rewardsPool.withdraw();

        uint256 collateralBalance = collateralToken.balanceOf(address(this));

        uint256 collateralToTransfer = (covAmount * collateralBalance) /
            covSupply;

        collateralToken.safeApprove(
            address(newAssetPool),
            collateralToTransfer
        );
        // old underwriter tokens are burned in favor of new minted in a new
        // asset pool
        underwriterToken.burnFrom(msg.sender, covAmount);
        // collateralToTransfer will be sent to a new AssetPool and new
        // underwriter tokens will be minted and transferred back to the underwriter
        newAssetPool.depositFor(msg.sender, collateralToTransfer);

        emit AssetPoolUpgraded(
            msg.sender,
            collateralToTransfer,
            covAmount,
            block.timestamp
        );
    }

    /// @notice Allows governance to set a new asset pool so the underwriters
    ///         can move their collateral tokens to a new asset pool without
    ///         having to wait for the withdrawal delay.
    function approveNewAssetPoolUpgrade(IAssetPoolUpgrade _newAssetPool)
        external
        onlyOwner
    {
        require(
            address(_newAssetPool) != address(0),
            "New asset pool can't be zero address"
        );

        newAssetPool = _newAssetPool;

        emit ApprovedAssetPoolUpgrade(address(_newAssetPool));
    }

    /// @notice Allows governance to cancel already approved new asset pool
    ///         in case of some misconfiguration.
    function cancelNewAssetPoolUpgrade() external onlyOwner {
        emit CancelledAssetPoolUpgrade(address(newAssetPool));

        newAssetPool = IAssetPoolUpgrade(address(0));
    }

    /// @notice Allows the coverage pool to demand coverage from the asset hold
    ///         by this pool and send it to the provided recipient address.
    function claim(address recipient, uint256 amount) external onlyOwner {
        emit CoverageClaimed(recipient, amount, block.timestamp);
        rewardsPool.withdraw();
        collateralToken.safeTransfer(recipient, amount);
    }

    /// @notice Lets the contract owner to begin an update of withdrawal delay
    ///         parameter value. Withdrawal delay is the time it takes the
    ///         underwriter to withdraw their collateral and rewards from the
    ///         pool. This is the time that needs to pass between initiating and
    ///         completing the withdrawal. The change needs to be finalized with
    ///         a call to finalizeWithdrawalDelayUpdate after the required
    ///         governance delay passes. It is up to the contract owner to
    ///         decide what the withdrawal delay value should be but it should
    ///         be long enough so that the possibility of having free-riding
    ///         underwriters escaping from a potential coverage claim by
    ///         withdrawing their positions from the pool is negligible.
    /// @param _newWithdrawalDelay The new value of withdrawal delay
    function beginWithdrawalDelayUpdate(uint256 _newWithdrawalDelay)
        external
        onlyOwner
    {
        newWithdrawalDelay = _newWithdrawalDelay;
        withdrawalDelayChangeInitiated = block.timestamp;
        emit WithdrawalDelayUpdateStarted(_newWithdrawalDelay, block.timestamp);
    }

    /// @notice Lets the contract owner to finalize an update of withdrawal
    ///         delay parameter value. This call has to be preceded with
    ///         a call to beginWithdrawalDelayUpdate and the governance delay
    ///         has to pass.
    function finalizeWithdrawalDelayUpdate()
        external
        onlyOwner
        onlyAfterWithdrawalGovernanceDelay(withdrawalDelayChangeInitiated)
    {
        withdrawalDelay = newWithdrawalDelay;
        emit WithdrawalDelayUpdated(withdrawalDelay);
        newWithdrawalDelay = 0;
        withdrawalDelayChangeInitiated = 0;
    }

    /// @notice Lets the contract owner to begin an update of withdrawal timeout
    ///         parameter value. The withdrawal timeout is the time the
    ///         underwriter has - after the withdrawal delay passed - to
    ///         complete the withdrawal. The change needs to be finalized with
    ///         a call to finalizeWithdrawalTimeoutUpdate after the required
    ///         governance delay passes. It is up to the contract owner to
    ///         decide what the withdrawal timeout value should be but it should
    ///         be short enough so that the time of free-riding by being able to
    ///         immediately escape from the claim is minimal and long enough so
    ///         that honest underwriters have a possibility to finalize the
    ///         withdrawal. It is all about the right proportions with
    ///         a relation to withdrawal delay value.
    /// @param  _newWithdrawalTimeout The new value of the withdrawal timeout
    function beginWithdrawalTimeoutUpdate(uint256 _newWithdrawalTimeout)
        external
        onlyOwner
    {
        newWithdrawalTimeout = _newWithdrawalTimeout;
        withdrawalTimeoutChangeInitiated = block.timestamp;
        emit WithdrawalTimeoutUpdateStarted(
            _newWithdrawalTimeout,
            block.timestamp
        );
    }

    /// @notice Lets the contract owner to finalize an update of withdrawal
    ///         timeout parameter value. This call has to be preceded with
    ///         a call to beginWithdrawalTimeoutUpdate and the governance delay
    ///         has to pass.
    function finalizeWithdrawalTimeoutUpdate()
        external
        onlyOwner
        onlyAfterWithdrawalGovernanceDelay(withdrawalTimeoutChangeInitiated)
    {
        withdrawalTimeout = newWithdrawalTimeout;
        emit WithdrawalTimeoutUpdated(withdrawalTimeout);
        newWithdrawalTimeout = 0;
        withdrawalTimeoutChangeInitiated = 0;
    }

    /// @notice Grants pool shares by minting a given amount of the underwriter
    ///         tokens for the recipient address. In result, the recipient
    ///         obtains part of the pool ownership without depositing any
    ///         collateral tokens. Shares are usually granted for notifiers
    ///         reporting about various contract state changes.
    /// @dev Can be called only by the contract owner.
    /// @param recipient Address of the underwriter tokens recipient
    /// @param covAmount Amount of the underwriter tokens which should be minted
    function grantShares(address recipient, uint256 covAmount)
        external
        onlyOwner
    {
        rewardsPool.withdraw();
        underwriterToken.mint(recipient, covAmount);
    }

    /// @notice Returns the remaining time that has to pass before the contract
    ///         owner will be able to finalize withdrawal delay update.
    ///         Bear in mind the contract owner may decide to wait longer and
    ///         this value is just an absolute minimum.
    /// @return The time left until withdrawal delay update can be finalized
    function getRemainingWithdrawalDelayUpdateTime()
        external
        view
        returns (uint256)
    {
        return
            GovernanceUtils.getRemainingChangeTime(
                withdrawalDelayChangeInitiated,
                withdrawalGovernanceDelay()
            );
    }

    /// @notice Returns the remaining time that has to pass before the contract
    ///         owner will be able to finalize withdrawal timeout update.
    ///         Bear in mind the contract owner may decide to wait longer and
    ///         this value is just an absolute minimum.
    /// @return The time left until withdrawal timeout update can be finalized
    function getRemainingWithdrawalTimeoutUpdateTime()
        external
        view
        returns (uint256)
    {
        return
            GovernanceUtils.getRemainingChangeTime(
                withdrawalTimeoutChangeInitiated,
                withdrawalGovernanceDelay()
            );
    }

    /// @notice Returns the current collateral token balance of the asset pool
    ///         plus the reward amount (in collateral token) earned by the asset
    ///         pool and not yet withdrawn to the asset pool.
    /// @return The total value of asset pool in collateral token.
    function totalValue() external view returns (uint256) {
        return collateralToken.balanceOf(address(this)) + rewardsPool.earned();
    }

    /// @notice The time it takes to initiate and complete the withdrawal from
    ///         the pool plus 2 days to make a decision. This governance delay
    ///         should be used for all changes directly affecting underwriter
    ///         positions. This time is a minimum and the governance may choose
    ///         to wait longer before finalizing the update.
    /// @return The withdrawal governance delay in seconds
    function withdrawalGovernanceDelay() public view returns (uint256) {
        return withdrawalDelay + withdrawalTimeout + 2 days;
    }

    /// @dev Calculates underwriter tokens to mint.
    function _calculateTokensToMint(uint256 amountToDeposit)
        internal
        returns (uint256)
    {
        rewardsPool.withdraw();

        uint256 covSupply = underwriterToken.totalSupply();
        uint256 collateralBalance = collateralToken.balanceOf(address(this));

        if (covSupply == 0) {
            return amountToDeposit;
        }

        return (amountToDeposit * covSupply) / collateralBalance;
    }

    function _deposit(
        address depositor,
        uint256 amountToDeposit,
        uint256 amountToMint
    ) internal {
        require(depositor != address(this), "Self-deposit not allowed");

        require(
            amountToMint > 0,
            "Minted tokens amount must be greater than 0"
        );

        emit Deposited(depositor, amountToDeposit, amountToMint);

        underwriterToken.mint(depositor, amountToMint);
        collateralToken.safeTransferFrom(
            depositor,
            address(this),
            amountToDeposit
        );
    }
}

// File: contracts/CoveragePool.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

import "./interfaces/IAssetPoolUpgrade.sol";
import "./AssetPool.sol";
import "./CoveragePoolConstants.sol";
import "./GovernanceUtils.sol";

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

/// @title Coverage Pool
/// @notice A contract that manages a single asset pool. Handles approving and
///         unapproving of risk managers and allows them to seize funds from the
///         asset pool if they are approved.
/// @dev Coverage pool contract is owned by the governance. Coverage pool is the
///      owner of the asset pool contract.
contract CoveragePool is Ownable {
    AssetPool public immutable assetPool;
    IERC20 public immutable collateralToken;

    bool public firstRiskManagerApproved = false;

    // Currently approved risk managers
    mapping(address => bool) public approvedRiskManagers;
    // Timestamps of risk managers whose approvals have been initiated
    mapping(address => uint256) public riskManagerApprovalTimestamps;

    event RiskManagerApprovalStarted(address riskManager, uint256 timestamp);
    event RiskManagerApprovalCompleted(address riskManager, uint256 timestamp);
    event RiskManagerUnapproved(address riskManager, uint256 timestamp);

    /// @notice Reverts if called by a risk manager that is not approved
    modifier onlyApprovedRiskManager() {
        require(approvedRiskManagers[msg.sender], "Risk manager not approved");
        _;
    }

    constructor(AssetPool _assetPool) {
        assetPool = _assetPool;
        collateralToken = _assetPool.collateralToken();
    }

    /// @notice Approves the first risk manager
    /// @dev Can be called only by the contract owner. Can be called only once.
    ///      Does not require any further calls to any functions.
    /// @param riskManager Risk manager that will be approved
    function approveFirstRiskManager(address riskManager) external onlyOwner {
        require(
            !firstRiskManagerApproved,
            "The first risk manager was approved"
        );
        approvedRiskManagers[riskManager] = true;
        firstRiskManagerApproved = true;
    }

    /// @notice Begins risk manager approval process.
    /// @dev Can be called only by the contract owner and only when the first
    ///      risk manager is already approved. For a risk manager to be
    ///      approved, a call to `finalizeRiskManagerApproval` must follow
    ///      (after a governance delay).
    /// @param riskManager Risk manager that will be approved
    function beginRiskManagerApproval(address riskManager) external onlyOwner {
        require(
            firstRiskManagerApproved,
            "The first risk manager is not yet approved; Please use "
            "approveFirstRiskManager instead"
        );

        require(
            !approvedRiskManagers[riskManager],
            "Risk manager already approved"
        );

        /* solhint-disable-next-line not-rely-on-time */
        riskManagerApprovalTimestamps[riskManager] = block.timestamp;
        /* solhint-disable-next-line not-rely-on-time */
        emit RiskManagerApprovalStarted(riskManager, block.timestamp);
    }

    /// @notice Finalizes risk manager approval process.
    /// @dev Can be called only by the contract owner. Must be preceded with a
    ///      call to beginRiskManagerApproval and a governance delay must elapse.
    /// @param riskManager Risk manager that will be approved
    function finalizeRiskManagerApproval(address riskManager)
        external
        onlyOwner
    {
        require(
            riskManagerApprovalTimestamps[riskManager] > 0,
            "Risk manager approval not initiated"
        );
        require(
            /* solhint-disable-next-line not-rely-on-time */
            block.timestamp - riskManagerApprovalTimestamps[riskManager] >=
                assetPool.withdrawalGovernanceDelay(),
            "Risk manager governance delay has not elapsed"
        );
        approvedRiskManagers[riskManager] = true;
        /* solhint-disable-next-line not-rely-on-time */
        emit RiskManagerApprovalCompleted(riskManager, block.timestamp);
        delete riskManagerApprovalTimestamps[riskManager];
    }

    /// @notice Unapproves an already approved risk manager or cancels the
    ///         approval process of a risk manager (the latter happens if called
    ///         between `beginRiskManagerApproval` and `finalizeRiskManagerApproval`).
    ///         The change takes effect immediately.
    /// @dev Can be called only by the contract owner.
    /// @param riskManager Risk manager that will be unapproved
    function unapproveRiskManager(address riskManager) external onlyOwner {
        require(
            riskManagerApprovalTimestamps[riskManager] > 0 ||
                approvedRiskManagers[riskManager],
            "Risk manager is neither approved nor with a pending approval"
        );
        delete riskManagerApprovalTimestamps[riskManager];
        delete approvedRiskManagers[riskManager];
        /* solhint-disable-next-line not-rely-on-time */
        emit RiskManagerUnapproved(riskManager, block.timestamp);
    }

    /// @notice Approves upgradeability to the new asset pool.
    ///         Allows governance to set a new asset pool so the underwriters
    ///         can move their collateral tokens to a new asset pool without
    ///         having to wait for the withdrawal delay.
    /// @param _newAssetPool New asset pool
    function approveNewAssetPoolUpgrade(IAssetPoolUpgrade _newAssetPool)
        external
        onlyOwner
    {
        assetPool.approveNewAssetPoolUpgrade(_newAssetPool);
    }

    /// @notice Lets the governance to begin an update of withdrawal delay
    ///         parameter value. Withdrawal delay is the time it takes the
    ///         underwriter to withdraw their collateral and rewards from the
    ///         pool. This is the time that needs to pass between initiating and
    ///         completing the withdrawal. The change needs to be finalized with
    ///         a call to finalizeWithdrawalDelayUpdate after the required
    ///         governance delay passes. It is up to the governance to
    ///         decide what the withdrawal delay value should be but it should
    ///         be long enough so that the possibility of having free-riding
    ///         underwriters escaping from a potential coverage claim by
    ///         withdrawing their positions from the pool is negligible.
    /// @param newWithdrawalDelay The new value of withdrawal delay
    function beginWithdrawalDelayUpdate(uint256 newWithdrawalDelay)
        external
        onlyOwner
    {
        assetPool.beginWithdrawalDelayUpdate(newWithdrawalDelay);
    }

    /// @notice Lets the governance to finalize an update of withdrawal
    ///         delay parameter value. This call has to be preceded with
    ///         a call to beginWithdrawalDelayUpdate and the governance delay
    ///         has to pass.
    function finalizeWithdrawalDelayUpdate() external onlyOwner {
        assetPool.finalizeWithdrawalDelayUpdate();
    }

    /// @notice Lets the governance to begin an update of withdrawal timeout
    ///         parameter value. The withdrawal timeout is the time the
    ///         underwriter has - after the withdrawal delay passed - to
    ///         complete the withdrawal. The change needs to be finalized with
    ///         a call to finalizeWithdrawalTimeoutUpdate after the required
    ///         governance delay passes. It is up to the governance to
    ///         decide what the withdrawal timeout value should be but it should
    ///         be short enough so that the time of free-riding by being able to
    ///         immediately escape from the claim is minimal and long enough so
    ///         that honest underwriters have a possibility to finalize the
    ///         withdrawal. It is all about the right proportions with
    ///         a relation to withdrawal delay value.
    /// @param  newWithdrawalTimeout The new value of the withdrawal timeout
    function beginWithdrawalTimeoutUpdate(uint256 newWithdrawalTimeout)
        external
        onlyOwner
    {
        assetPool.beginWithdrawalTimeoutUpdate(newWithdrawalTimeout);
    }

    /// @notice Lets the governance to finalize an update of withdrawal
    ///         timeout parameter value. This call has to be preceded with
    ///         a call to beginWithdrawalTimeoutUpdate and the governance delay
    ///         has to pass.
    function finalizeWithdrawalTimeoutUpdate() external onlyOwner {
        assetPool.finalizeWithdrawalTimeoutUpdate();
    }

    /// @notice Seizes funds from the coverage pool and puts them aside for the
    ///         recipient to withdraw.
    /// @dev `portionToSeize` value was multiplied by `FLOATING_POINT_DIVISOR`
    ///      for calculation precision purposes. Further calculations in this
    ///      function will need to take this divisor into account.
    /// @param recipient Address that will receive the pool's seized funds
    /// @param portionToSeize Portion of the pool to seize in the range (0, 1]
    ///        multiplied by `FLOATING_POINT_DIVISOR`
    function seizeFunds(address recipient, uint256 portionToSeize)
        external
        onlyApprovedRiskManager
    {
        require(
            portionToSeize > 0 &&
                portionToSeize <= CoveragePoolConstants.FLOATING_POINT_DIVISOR,
            "Portion to seize is not within the range (0, 1]"
        );

        assetPool.claim(recipient, amountToSeize(portionToSeize));
    }

    /// @notice Grants asset pool shares by minting a given amount of the
    ///         underwriter tokens for the recipient address. In result, the
    ///         recipient obtains part of the pool ownership without depositing
    ///         any collateral tokens. Shares are usually granted for notifiers
    ///         reporting about various contract state changes.
    /// @dev Can be called only by an approved risk manager.
    /// @param recipient Address of the underwriter tokens recipient
    /// @param covAmount Amount of the underwriter tokens which should be minted
    function grantAssetPoolShares(address recipient, uint256 covAmount)
        external
        onlyApprovedRiskManager
    {
        assetPool.grantShares(recipient, covAmount);
    }

    /// @notice Returns the time remaining until the risk manager approval
    ///         process can be finalized
    /// @param riskManager Risk manager in the process of approval
    /// @return Remaining time in seconds.
    function getRemainingRiskManagerApprovalTime(address riskManager)
        external
        view
        returns (uint256)
    {
        return
            GovernanceUtils.getRemainingChangeTime(
                riskManagerApprovalTimestamps[riskManager],
                assetPool.withdrawalGovernanceDelay()
            );
    }

    /// @notice Calculates amount of tokens to be seized from the coverage pool.
    /// @param portionToSeize Portion of the pool to seize in the range (0, 1]
    ///        multiplied by FLOATING_POINT_DIVISOR
    function amountToSeize(uint256 portionToSeize)
        public
        view
        returns (uint256)
    {
        return
            (collateralToken.balanceOf(address(assetPool)) * portionToSeize) /
            CoveragePoolConstants.FLOATING_POINT_DIVISOR;
    }
}

// File: contracts/CoveragePoolConstants.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

library CoveragePoolConstants {
    // This divisor is for precision purposes only. We use this divisor around
    // auction related code to get the precise values without rounding it down
    // when dealing with floating numbers.
    uint256 public constant FLOATING_POINT_DIVISOR = 1e18;
}

// File: contracts/GovernanceUtils.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

library GovernanceUtils {
    /// @notice Gets the time remaining until the governable parameter update
    ///         can be committed.
    /// @param changeTimestamp Timestamp indicating the beginning of the change.
    /// @param delay Governance delay.
    /// @return Remaining time in seconds.
    function getRemainingChangeTime(uint256 changeTimestamp, uint256 delay)
        internal
        view
        returns (uint256)
    {
        require(changeTimestamp > 0, "Change not initiated");
        /* solhint-disable-next-line not-rely-on-time */
        uint256 elapsed = block.timestamp - changeTimestamp;
        if (elapsed >= delay) {
            return 0;
        } else {
            return delay - elapsed;
        }
    }
}

// File: contracts/RewardsPool.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/utils/math/Math.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

/// @title Rewards Pool
/// @notice RewardsPool accepts a single reward token and releases it to the
///         AssetPool over time in one week reward intervals. The owner of this
///         contract is the reward distribution address funding it with reward
///         tokens.
contract RewardsPool is Ownable {
    using SafeERC20 for IERC20;

    uint256 public constant DURATION = 7 days;

    IERC20 public immutable rewardToken;
    address public immutable assetPool;

    // timestamp of the current reward interval end or the timestamp of the
    // last interval end in case a new reward interval has not been allocated
    uint256 public intervalFinish = 0;
    // rate per second with which reward tokens are unlocked
    uint256 public rewardRate = 0;
    // amount of rewards accumulated and not yet withdrawn from the previous
    // reward interval(s)
    uint256 public rewardAccumulated = 0;
    // the last time information in this contract was updated
    uint256 public lastUpdateTime = 0;

    event RewardToppedUp(uint256 amount);
    event RewardWithdrawn(uint256 amount);

    constructor(
        IERC20 _rewardToken,
        address _assetPool,
        address owner
    ) {
        rewardToken = _rewardToken;
        // slither-disable-next-line missing-zero-check
        assetPool = _assetPool;
        transferOwnership(owner);
    }

    /// @notice Transfers the provided reward amount into RewardsPool and
    ///         creates a new, one-week reward interval starting from now.
    ///         Reward tokens from the previous reward interval that unlocked
    ///         over the time will be available for withdrawal immediately.
    ///         Reward tokens from the previous interval that has not been yet
    ///         unlocked, are added to the new interval being created.
    /// @dev This function can be called only by the owner given that it creates
    ///      a new interval with one week length, starting from now.
    function topUpReward(uint256 reward) external onlyOwner {
        rewardAccumulated = earned();

        /* solhint-disable not-rely-on-time */
        if (block.timestamp >= intervalFinish) {
            // see https://github.com/crytic/slither/issues/844
            // slither-disable-next-line divide-before-multiply
            rewardRate = reward / DURATION;
        } else {
            uint256 remaining = intervalFinish - block.timestamp;
            uint256 leftover = remaining * rewardRate;
            rewardRate = (reward + leftover) / DURATION;
        }
        intervalFinish = block.timestamp + DURATION;
        lastUpdateTime = block.timestamp;
        /* solhint-enable avoid-low-level-calls */

        emit RewardToppedUp(reward);
        rewardToken.safeTransferFrom(msg.sender, address(this), reward);
    }

    /// @notice Withdraws all unlocked reward tokens to the AssetPool.
    function withdraw() external {
        uint256 amount = earned();
        rewardAccumulated = 0;
        lastUpdateTime = lastTimeRewardApplicable();
        emit RewardWithdrawn(amount);
        rewardToken.safeTransfer(assetPool, amount);
    }

    /// @notice Returns the amount of earned and not yet withdrawn reward
    /// tokens.
    function earned() public view returns (uint256) {
        return
            rewardAccumulated +
            ((lastTimeRewardApplicable() - lastUpdateTime) * rewardRate);
    }

    /// @notice Returns the timestamp at which a reward was last time applicable.
    ///         When reward interval is pending, returns current block's
    ///         timestamp. If the last reward interval ended and no other reward
    ///         interval had been allocated, returns the last reward interval's
    ///         end timestamp.
    function lastTimeRewardApplicable() public view returns (uint256) {
        return Math.min(block.timestamp, intervalFinish);
    }
}

// File: contracts/UnderwriterToken.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

import "@thesis/solidity-contracts/contracts/token/ERC20WithPermit.sol";

/// @title  UnderwriterToken
/// @notice Underwriter tokens represent an ownership share in the underlying
///         collateral of the asset-specific pool. Underwriter tokens are minted
///         when a user deposits ERC20 tokens into asset-specific pool and they
///         are burned when a user exits the position. Underwriter tokens
///         natively support meta transactions. Users can authorize a transfer
///         of their underwriter tokens with a signature conforming EIP712
///         standard instead of an on-chain transaction from their address.
///         Anyone can submit this signature on the user's behalf by calling the
///         permit function, as specified in EIP2612 standard, paying gas fees,
///         and possibly performing other actions in the same transaction.
contract UnderwriterToken is ERC20WithPermit {
    constructor(string memory _name, string memory _symbol)
        ERC20WithPermit(_name, _symbol)
    {}
}

// File: contracts/interfaces/IAssetPool.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

/// @title Asset Pool interface
/// @notice Asset Pool accepts a single ERC20 token as collateral, and returns
///         an underwriter token. For example, an asset pool might accept deposits
///         in KEEP in return for covKEEP underwriter tokens. Underwriter tokens
///         represent an ownership share in the underlying collateral of the
///         Asset Pool.
interface IAssetPool {
    /// @notice Accepts the given amount of collateral token as a deposit and
    ///         mints underwriter tokens representing pool's ownership.
    /// @dev Before calling this function, collateral token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    /// @return The amount of minted underwriter tokens
    function deposit(uint256 amount) external returns (uint256);

    /// @notice Accepts the given amount of collateral token as a deposit and
    ///         mints at least a minAmountToMint underwriter tokens representing
    ///         pool's ownership.
    /// @dev Before calling this function, collateral token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    /// @return The amount of minted underwriter tokens
    function depositWithMin(uint256 amountToDeposit, uint256 minAmountToMint)
        external
        returns (uint256);

    /// @notice Initiates the withdrawal of collateral and rewards from the pool.
    /// @dev Before calling this function, underwriter token needs to have the
    ///      required amount accepted to transfer to the asset pool.
    function initiateWithdrawal(uint256 covAmount) external;

    /// @notice Completes the previously initiated withdrawal for the
    ///         underwriter.
    /// @return The amount of collateral withdrawn
    function completeWithdrawal(address underwriter) external returns (uint256);
}

// File: contracts/interfaces/IAssetPoolUpgrade.sol



// ▓▓▌ ▓▓ ▐▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▄
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▌▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓    ▓▓▓▓▓▓▓▀    ▐▓▓▓▓▓▓    ▐▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▄▄▓▓▓▓▓▓▓▀      ▐▓▓▓▓▓▓▄▄▄▄         ▓▓▓▓▓▓▄▄▄▄         ▐▓▓▓▓▓▌   ▐▓▓▓▓▓▓
//   ▓▓▓▓▓▓▓▓▓▓▓▓▓▀        ▐▓▓▓▓▓▓▓▓▓▓         ▓▓▓▓▓▓▓▓▓▓         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓
//   ▓▓▓▓▓▓▀▀▓▓▓▓▓▓▄       ▐▓▓▓▓▓▓▀▀▀▀         ▓▓▓▓▓▓▀▀▀▀         ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▀
//   ▓▓▓▓▓▓   ▀▓▓▓▓▓▓▄     ▐▓▓▓▓▓▓     ▓▓▓▓▓   ▓▓▓▓▓▓     ▓▓▓▓▓   ▐▓▓▓▓▓▌
// ▓▓▓▓▓▓▓▓▓▓ █▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
// ▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓ ▐▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  ▓▓▓▓▓▓▓▓▓▓
//
//                           Trust math, not hardware.

// SPDX-License-Identifier: MIT

pragma solidity 0.8.5;

/// @title Asset Pool upgrade interface
/// @notice Interface that has to be implemented by an Asset Pool accepting
///         upgrades from another asset pool.
interface IAssetPoolUpgrade {
    /// @notice Accepts the given underwriter with collateral tokens amount as a
    ///         deposit. In exchange new underwriter tokens will be calculated,
    ///         minted and then transferred back to the underwriter.
    function depositFor(address underwriter, uint256 amount) external;
}