// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;

// File contracts/interfaces/IOracle.sol
// License-Identifier: MIT

interface IOracle {
    /// @notice Get the latest exchange rate.
    /// @param data Usually abi encoded, implementation specific data that contains information and arguments to & about the oracle.
    /// For example:
    /// (string memory collateralSymbol, string memory assetSymbol, uint256 division) = abi.decode(data, (string, string, uint256));
    /// @return success if no valid (recent) rate is available, return false else true.
    /// @return rate The rate of the requested asset / pair / pool.
    function get(bytes calldata data) external returns (bool success, uint256 rate);

    /// @notice Check the last exchange rate without any state changes.
    /// @param data Usually abi encoded, implementation specific data that contains information and arguments to & about the oracle.
    /// For example:
    /// (string memory collateralSymbol, string memory assetSymbol, uint256 division) = abi.decode(data, (string, string, uint256));
    /// @return success if no valid (recent) rate is available, return false else true.
    /// @return rate The rate of the requested asset / pair / pool.
    function peek(bytes calldata data) external view returns (bool success, uint256 rate);

    /// @notice Check the current spot exchange rate without any state changes. For oracles like TWAP this will be different from peek().
    /// @param data Usually abi encoded, implementation specific data that contains information and arguments to & about the oracle.
    /// For example:
    /// (string memory collateralSymbol, string memory assetSymbol, uint256 division) = abi.decode(data, (string, string, uint256));
    /// @return rate The rate of the requested asset / pair / pool.
    function peekSpot(bytes calldata data) external view returns (uint256 rate);

    /// @notice Returns a human readable (short) name about this oracle.
    /// @param data Usually abi encoded, implementation specific data that contains information and arguments to & about the oracle.
    /// For example:
    /// (string memory collateralSymbol, string memory assetSymbol, uint256 division) = abi.decode(data, (string, string, uint256));
    /// @return (string) A human readable symbol name about this oracle.
    function symbol(bytes calldata data) external view returns (string memory);

    /// @notice Returns a human readable name about this oracle.
    /// @param data Usually abi encoded, implementation specific data that contains information and arguments to & about the oracle.
    /// For example:
    /// (string memory collateralSymbol, string memory assetSymbol, uint256 division) = abi.decode(data, (string, string, uint256));
    /// @return (string) A human readable name about this oracle.
    function name(bytes calldata data) external view returns (string memory);
}

// File contracts/oracles/PeggedOracle.sol
// License-Identifier: MIT

/// @title PeggedOracle
/// @author BoringCrypto
/// @notice Oracle used for pegged prices that don't change
/// @dev
contract PeggedOracleV1 is IOracle {
    /// @notice
    /// @dev
    /// @param rate (uint256) The fixed exchange rate
    /// @return  (bytes)
    function getDataParameter(uint256 rate) public pure returns (bytes memory) {
        return abi.encode(rate);
    }

    // Get the exchange rate
    /// @inheritdoc IOracle
    function get(bytes calldata data) public override returns (bool, uint256) {
        uint256 rate = abi.decode(data, (uint256));
        return (rate != 0, rate);
    }

    // Check the exchange rate without any state changes
    /// @inheritdoc IOracle
    function peek(bytes calldata data) public view override returns (bool, uint256) {
        uint256 rate = abi.decode(data, (uint256));
        return (rate != 0, rate);
    }

    // Check the current spot exchange rate without any state changes
    /// @inheritdoc IOracle
    function peekSpot(bytes calldata data) external view override returns (uint256 rate) {
        (, rate) = peek(data);
    }

    /// @inheritdoc IOracle
    function name(bytes calldata) public view override returns (string memory) {
        return "Pegged";
    }

    /// @inheritdoc IOracle
    function symbol(bytes calldata) public view override returns (string memory) {
        return "PEG";
    }
}