// File: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/interfaces/ERC20Interface.sol



/**
 * SPDX-License-Identifier: UNLICENSED
 */
pragma solidity 0.6.10;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface ERC20Interface {
    /**
     * @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);

    function decimals() external view returns (uint8);

    /**
     * @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: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/interfaces/OpynPricerInterface.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.10;

interface OpynPricerInterface {
    function getPrice() external view returns (uint256);

    function getHistoricalPrice(uint80 _roundId) external view returns (uint256, uint256);
}

// File: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/interfaces/OracleInterface.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.10;

interface OracleInterface {
    function isLockingPeriodOver(address _asset, uint256 _expiryTimestamp) external view returns (bool);

    function isDisputePeriodOver(address _asset, uint256 _expiryTimestamp) external view returns (bool);

    function getExpiryPrice(address _asset, uint256 _expiryTimestamp) external view returns (uint256, bool);

    function getDisputer() external view returns (address);

    function getPricer(address _asset) external view returns (address);

    function getPrice(address _asset) external view returns (uint256);

    function getPricerLockingPeriod(address _pricer) external view returns (uint256);

    function getPricerDisputePeriod(address _pricer) external view returns (uint256);

    function getChainlinkRoundData(address _asset, uint80 _roundId) external view returns (uint256, uint256);

    // Non-view function

    function setAssetPricer(address _asset, address _pricer) external;

    function setLockingPeriod(address _pricer, uint256 _lockingPeriod) external;

    function setDisputePeriod(address _pricer, uint256 _disputePeriod) external;

    function setExpiryPrice(
        address _asset,
        uint256 _expiryTimestamp,
        uint256 _price
    ) external;

    function disputeExpiryPrice(
        address _asset,
        uint256 _expiryTimestamp,
        uint256 _price
    ) external;

    function setDisputer(address _disputer) external;
}

// File: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/interfaces/YearnVaultInterface.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.6.10;

interface YearnVaultInterface {
    function name() external view returns (string memory);

    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);

    function pricePerShare() external view returns (uint256);

    function deposit(uint256) external;

    function withdraw(uint256) external;
}

// File: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/packages/oz/SafeMath.sol



// SPDX-License-Identifier: MIT
// openzeppelin-contracts v3.1.0

/* solhint-disable */
pragma solidity ^0.6.0;

/**
 * @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, 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) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * 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);
        uint256 c = a - b;

        return c;
    }

    /**
     * @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) {
        // 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 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts 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) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message 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,
        string memory errorMessage
    ) internal pure returns (uint256) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts 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) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message 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,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: /Users/haythem96/Projects/Opyn/GammaProtocol/contracts/pricers/YearnPricer.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.10;

import {OracleInterface} from "../interfaces/OracleInterface.sol";
import {OpynPricerInterface} from "../interfaces/OpynPricerInterface.sol";
import {YearnVaultInterface} from "../interfaces/YearnVaultInterface.sol";
import {ERC20Interface} from "../interfaces/ERC20Interface.sol";
import {SafeMath} from "../packages/oz/SafeMath.sol";

/**
 * @notice A Pricer contract for a Yearn yToken
 */
contract YearnPricer is OpynPricerInterface {
    using SafeMath for uint256;

    /// @notice opyn oracle address
    OracleInterface public oracle;

    /// @notice yToken that this pricer will a get price for
    YearnVaultInterface public yToken;

    /// @notice underlying asset for this yToken
    ERC20Interface public underlying;

    /**
     * @param _yToken yToken asset
     * @param _underlying underlying asset for this yToken
     * @param _oracle Opyn Oracle contract address
     */
    constructor(
        address _yToken,
        address _underlying,
        address _oracle
    ) public {
        require(_yToken != address(0), "YearnPricer: yToken address can not be 0");
        require(_underlying != address(0), "YearnPricer: underlying address can not be 0");
        require(_oracle != address(0), "YearnPricer: oracle address can not be 0");

        yToken = YearnVaultInterface(_yToken);
        underlying = ERC20Interface(_underlying);
        oracle = OracleInterface(_oracle);
    }

    /**
     * @notice get the live price for the asset
     * @dev overrides the getPrice function in OpynPricerInterface
     * @return price of 1e8 yToken in USD, scaled by 1e8
     */
    function getPrice() external override view returns (uint256) {
        uint256 underlyingPrice = oracle.getPrice(address(underlying));
        require(underlyingPrice > 0, "YearnPricer: underlying price is 0");
        return _underlyingPriceToYtokenPrice(underlyingPrice);
    }

    /**
     * @notice set the expiry price in the oracle
     * @dev requires that the underlying price has been set before setting a yToken price
     * @param _expiryTimestamp expiry to set a price for
     */
    function setExpiryPriceInOracle(uint256 _expiryTimestamp) external {
        (uint256 underlyingPriceExpiry, ) = oracle.getExpiryPrice(address(underlying), _expiryTimestamp);
        require(underlyingPriceExpiry > 0, "YearnPricer: underlying price not set yet");
        uint256 yTokenPrice = _underlyingPriceToYtokenPrice(underlyingPriceExpiry);
        oracle.setExpiryPrice(address(yToken), _expiryTimestamp, yTokenPrice);
    }

    /**
     * @dev convert underlying price to yToken price with the yToken to underlying exchange rate
     * @param _underlyingPrice price of 1 underlying token (ie 1e6 USDC, 1e18 WETH) in USD, scaled by 1e8
     * @return price of 1e8 yToken in USD, scaled by 1e8
     */
    function _underlyingPriceToYtokenPrice(uint256 _underlyingPrice) private view returns (uint256) {
        uint256 pricePerShare = yToken.pricePerShare();
        uint8 underlyingDecimals = underlying.decimals();

        return pricePerShare.mul(_underlyingPrice).div(10**uint256(underlyingDecimals));
    }

    function getHistoricalPrice(uint80 _roundId) external override view returns (uint256, uint256) {
        revert("YearnPricer: Deprecated");
    }
}