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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

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() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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) {
        return msg.data;
    }
}

// File: contracts/ReservoirOracle.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.16;

// OZ libraries
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

// Inspired by https://github.com/ZeframLou/trustus
contract ReservoirOracle is Ownable {
    // --- State --- 

    address public reservoirOracleAddress;

    // --- Structs ---

    struct Message {
        bytes32 id;
        bytes payload;
        // The UNIX timestamp when the message was signed by the oracle
        uint256 timestamp;
        // ECDSA signature or EIP-2098 compact signature
        bytes signature;
    }

    // --- Errors ---

    error InvalidId();
    error InvalidTimestamp();
    error InvalidSignatureLength();
    error InvalidReservoirOracleAddress();

    // --- Events ---
    
    event ReservoirOracleAddressUpdated(address indexed reservoirOracleAddress);

    // --- Constructor ---

    constructor(address _reservoirOracleAddress) {
        if (_reservoirOracleAddress == address(0)) revert InvalidReservoirOracleAddress(); 
        reservoirOracleAddress = _reservoirOracleAddress;
    }

    // --- Methods ---

    function updateReservoirOracleAddress(address _reservoirOracleAddress) external onlyOwner {
        if (_reservoirOracleAddress == address(0)) revert InvalidReservoirOracleAddress(); 
        reservoirOracleAddress = _reservoirOracleAddress;

        emit ReservoirOracleAddressUpdated(_reservoirOracleAddress);
    }

    function verifyMessage(
        bytes32 id,
        uint256 validFor,
        Message memory message
    ) external view returns (bool success) {
        // Ensure the message matches the requested id
        if (id != message.id) {
            revert InvalidId();
        }

        // Ensure the message timestamp is valid
        if (
            message.timestamp > block.timestamp ||
            message.timestamp + validFor < block.timestamp
        ) {
            revert InvalidTimestamp();
        }

        bytes32 r;
        bytes32 s;
        uint8 v;

        // Extract the individual signature fields from the signature
        bytes memory signature = message.signature;
        if (signature.length == 64) {
            // EIP-2098 compact signature
            bytes32 vs;
            assembly {
                r := mload(add(signature, 0x20))
                vs := mload(add(signature, 0x40))
                s := and(
                    vs,
                    0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
                )
                v := add(shr(255, vs), 27)
            }
        } else if (signature.length == 65) {
            // ECDSA signature
            assembly {
                r := mload(add(signature, 0x20))
                s := mload(add(signature, 0x40))
                v := byte(0, mload(add(signature, 0x60)))
            }
        } else {
            revert InvalidSignatureLength();
        }

        address signerAddress = ecrecover(
            keccak256(
                abi.encodePacked(
                    "\x19Ethereum Signed Message:\n32",
                    // EIP-712 structured-data hash
                    keccak256(
                        abi.encode(
                            keccak256(
                                "Message(bytes32 id,bytes payload,uint256 timestamp)"
                            ),
                            message.id,
                            keccak256(message.payload),
                            message.timestamp
                        )
                    )
                )
            ),
            v,
            r,
            s
        );

        // Ensure the signer matches the designated oracle address
        return signerAddress == reservoirOracleAddress;
    }
}