pragma solidity 0.6.10;

/**
 * @dev Interface of the Chainlink aggregator
 */
interface AggregatorInterface {
    function decimals() external view returns (uint8);

    function description() external view returns (string memory);

    function version() external view returns (uint256);

    // getRoundData and latestRoundData should both raise "No data present"
    // if they do not have data to report, instead of returning unset values
    // which could be misinterpreted as actual reported values.
    function getRoundData(uint80 _roundId)
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );

    function latestRoundData()
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );
}

// File: contracts/interfaces/OracleInterface.sol


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: contracts/interfaces/OpynPricerInterface.sol


pragma solidity 0.6.10;

interface OpynPricerInterface {
    function getPrice() external view returns (uint256);

    function getHistoricalPrice(uint80 _roundId) external view returns (uint256, uint256);
}

// File: contracts/packages/oz/SafeMath.sol


// 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: contracts/pricers/ChainlinkPricer.sol

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.6.10;




/**
 * @notice A Pricer contract for one asset as reported by Chainlink
 */
contract ChainLinkPricer is OpynPricerInterface {
    using SafeMath for uint256;

    /// @dev base decimals
    uint256 internal constant BASE = 8;

    /// @notice chainlink response decimals
    uint256 public aggregatorDecimals;

    /// @notice the opyn oracle address
    OracleInterface public oracle;
    /// @notice the aggregator for an asset
    AggregatorInterface public aggregator;

    /// @notice asset that this pricer will a get price for
    address public asset;
    /// @notice bot address that is allowed to call setExpiryPriceInOracle
    address public bot;

    /**
     * @param _bot priveleged address that can call setExpiryPriceInOracle
     * @param _asset asset that this pricer will get a price for
     * @param _aggregator Chainlink aggregator contract for the asset
     * @param _oracle Opyn Oracle address
     */
    constructor(
        address _bot,
        address _asset,
        address _aggregator,
        address _oracle
    ) public {
        require(_bot != address(0), "ChainLinkPricer: Cannot set 0 address as bot");
        require(_oracle != address(0), "ChainLinkPricer: Cannot set 0 address as oracle");
        require(_aggregator != address(0), "ChainLinkPricer: Cannot set 0 address as aggregator");

        bot = _bot;
        oracle = OracleInterface(_oracle);
        aggregator = AggregatorInterface(_aggregator);
        asset = _asset;

        aggregatorDecimals = uint256(aggregator.decimals());
    }

    /**
     * @notice modifier to check if sender address is equal to bot address
     */
    modifier onlyBot() {
        require(msg.sender == bot, "ChainLinkPricer: unauthorized sender");

        _;
    }

    /**
     * @notice set the expiry price in the oracle, can only be called by Bot address
     * @dev a roundId must be provided to confirm price validity, which is the first Chainlink price provided after the expiryTimestamp
     * @param _expiryTimestamp expiry to set a price for
     * @param _roundId the first roundId after expiryTimestamp
     */
    function setExpiryPriceInOracle(uint256 _expiryTimestamp, uint80 _roundId) external onlyBot {
        (, int256 price, , uint256 roundTimestamp, ) = aggregator.getRoundData(_roundId);

        oracle.setExpiryPrice(asset, _expiryTimestamp, uint256(price));
    }

    /**
     * @notice get the live price for the asset
     * @dev overides the getPrice function in OpynPricerInterface
     * @return price of the asset in USD, scaled by 1e8
     */
    function getPrice() external view override returns (uint256) {
        (, int256 answer, , , ) = aggregator.latestRoundData();
        require(answer > 0, "ChainLinkPricer: price is lower than 0");
        // chainlink's answer is already 1e8
        return _scaleToBase(uint256(answer));
    }

    /**
     * @notice get historical chainlink price
     * @param _roundId chainlink round id
     * @return round price and timestamp
     */
    function getHistoricalPrice(uint80 _roundId) external view override returns (uint256, uint256) {
        (, int256 price, , uint256 roundTimestamp, ) = aggregator.getRoundData(_roundId);
        return (_scaleToBase(uint256(price)), roundTimestamp);
    }

    /**
     * @notice scale aggregator response to base decimals (1e8)
     * @param _price aggregator price
     * @return price scaled to 1e8
     */
    function _scaleToBase(uint256 _price) internal view returns (uint256) {
        if (aggregatorDecimals > BASE) {
            uint256 exp = aggregatorDecimals.sub(BASE);
            _price = _price.div(10**exp);
        } else if (aggregatorDecimals < BASE) {
            uint256 exp = BASE.sub(aggregatorDecimals);
            _price = _price.mul(10**exp);
        }

        return _price;
    }
}