// 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/metatx/ERC2771Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/*
 * @dev Context variant with ERC2771 support.
 */
abstract contract ERC2771Context is Context {
    address constant _trustedForwarder = 0xAa3E82b4c4093b4bA13Cb5714382C99ADBf750cA;

    constructor() {        
    }

    function isTrustedForwarder(address forwarder) public view virtual returns(bool) {
        return forwarder == _trustedForwarder;
    }

    function _msgSender() internal view virtual override returns (address sender) {
        if (isTrustedForwarder(msg.sender)) {
            // The assembly code is more direct than the Solidity version using `abi.decode`.
            assembly { sender := shr(96, calldataload(sub(calldatasize(), 20))) }
        } else {
            return super._msgSender();
        }
    }

    function _msgData() internal view virtual override returns (bytes calldata) {
        if (isTrustedForwarder(msg.sender)) {
            return msg.data[:msg.data.length-20];
        } else {
            return super._msgData();
        }
    }
}

// File: @openzeppelin/contracts/security/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!paused(), "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(paused(), "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

// 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: contracts/Bakc.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.6;

abstract contract Bakc {
    function ownerOf(uint256 tokenId) public view virtual returns (address);
}

// File: contracts/BakcAmendmentReciever.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.6;

import "@openzeppelin/contracts/security/Pausable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/metatx/ERC2771Context.sol";
import "./Bakc.sol";

contract BakcAmendmentReceiver is ERC2771Context, Pausable, Ownable {	
    struct AmendmentMetadata {
        address amender;
        uint timestamp;
        bool isAmendable;
    }

    mapping (uint => AmendmentMetadata) private _amendmentsRequests;
    Bakc private bakc;

    constructor(address dependentContractAddress) 
        ERC2771Context() {
        bakc = Bakc(dependentContractAddress);
    }

    function initializeMetadata(uint[] memory ids) external onlyOwner {
        for(uint i = 0; i < ids.length; i++) {
            _amendmentsRequests[ids[i]] = AmendmentMetadata(address(0), 0, true);
        }
    }

    function amendmentRequested(uint tokenId) public view returns (bool) {
        return 
            _amendmentsRequests[tokenId].isAmendable && 
            _amendmentsRequests[tokenId].amender != address(0);        
    }

    function isAmendable(uint tokenId) public view returns (bool) {
        return _amendmentsRequests[tokenId].isAmendable;
    }

    function togglePausedState() public onlyOwner {
        paused() ? _unpause() : _pause();
    }
    
    function requestAmendment(uint tokenId) external whenNotPaused {
        require(_amendmentsRequests[tokenId].isAmendable, "Requested Token ID isn't amendable");
        require(!amendmentRequested(tokenId), "Can only request an amendment once");
        require(bakc.ownerOf(tokenId) == _msgSender(), "Token ID must be owned by amender");
        _amendmentsRequests[tokenId] = AmendmentMetadata(_msgSender(), block.timestamp, true);
    }

    function amendmentRequestDetails(uint tokenId) public view returns(address, uint) {        
        require(amendmentRequested(tokenId), "Token hasn't been amended");
        AmendmentMetadata memory amendment = _amendmentsRequests[tokenId];
        return (amendment.amender, amendment.timestamp);
    }
    
    function _msgSender() internal view override(Context, ERC2771Context)
        returns (address sender) {
        sender = ERC2771Context._msgSender();
    }    

    function _msgData() internal view override(Context, ERC2771Context)
        returns (bytes calldata) {
        return ERC2771Context._msgData();
    }
}