// File: @openzeppelin/contracts/token/ERC721/ERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver(to).onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) private pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// 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) {
        return msg.data;
    }
}

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



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: contracts/Projects.sol



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

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";

import "./abstract/Operatable.sol";
import "./interfaces/IProjects.sol";

import "./libraries/Operations.sol";

/** 
  @notice 
  Stores project ownership and identifying information.

  @dev
  Projects are represented as ERC-721's.
*/
contract Projects is ERC721, IProjects, Operatable {
    // --- private stored properties --- //

    // The number of seconds in a day.
    uint256 private constant SECONDS_IN_YEAR = 31536000;

    // --- public stored properties --- //

    /// @notice A running count of project IDs.
    uint256 public override count = 0;

    /// @notice Optional mapping for project URIs
    mapping(uint256 => string) public override uriOf;

    /// @notice Each project's handle.
    mapping(uint256 => bytes32) public override handleOf;

    /// @notice The project that each unique handle represents.
    mapping(bytes32 => uint256) public override projectFor;

    /// @notice Handles that have been transfered to the specified address.
    mapping(bytes32 => address) public override transferAddressFor;

    /// @notice The timestamps when each handle is claimable. A value of 0 means a handle isn't being challenged.
    mapping(bytes32 => uint256) public override challengeExpiryOf;

    // --- external views --- //

    /** 
      @notice 
      Whether the specified project exists.

      @param _projectId The project to check the existence of.

      @return A flag indicating if the project exists.
    */
    function exists(uint256 _projectId) external view override returns (bool) {
        return _exists(_projectId);
    }

    // --- external transactions --- //

    /** 
      @param _operatorStore A contract storing operator assignments.
    */
    constructor(IOperatorStore _operatorStore)
        ERC721("Juicebox project", "JUICEBOX PROJECT")
        Operatable(_operatorStore)
    {}

    /**
        @notice 
        Create a new project.

        @dev 
        Anyone can create a project on an owner's behalf.

        @param _owner The owner of the project.
        @param _handle A unique handle for the project.
        @param _uri An ipfs CID to more info about the project.
        @param _terminal The terminal to set for this project so that it can start receiving payments.

        @return The new project's ID.
    */
    function create(
        address _owner,
        bytes32 _handle,
        string calldata _uri,
        ITerminal _terminal
    ) external override returns (uint256) {
        // Handle must exist.
        require(_handle != bytes32(0), "Projects::create: EMPTY_HANDLE");

        // Handle must be unique.
        require(
            projectFor[_handle] == 0 &&
                transferAddressFor[_handle] == address(0),
            "Projects::create: HANDLE_TAKEN"
        );

        // Increment the count, which will be used as the ID.
        count++;

        // Mint the project.
        _safeMint(_owner, count);

        // Set the handle stored values.
        handleOf[count] = _handle;
        projectFor[_handle] = count;

        // Set the URI if one was provided.
        if (bytes(_uri).length > 0) uriOf[count] = _uri;

        // Set the project's terminal if needed.
        if (_terminal != ITerminal(address(0)))
            _terminal.terminalDirectory().setTerminal(count, _terminal);

        emit Create(count, _owner, _handle, _uri, _terminal, msg.sender);

        return count;
    }

    /**
      @notice 
      Allows a project owner to set the project's handle.

      @dev 
      Only a project's owner or operator can set its handle.

      @param _projectId The ID of the project.
      @param _handle The new unique handle for the project.
    */
    function setHandle(uint256 _projectId, bytes32 _handle)
        external
        override
        requirePermission(ownerOf(_projectId), _projectId, Operations.SetHandle)
    {
        // Handle must exist.
        require(_handle != bytes32(0), "Projects::setHandle: EMPTY_HANDLE");

        // Handle must be unique.
        require(
            projectFor[_handle] == 0 &&
                transferAddressFor[_handle] == address(0),
            "Projects::setHandle: HANDLE_TAKEN"
        );

        // Register the change in the resolver.
        projectFor[handleOf[_projectId]] = 0;

        projectFor[_handle] = _projectId;
        handleOf[_projectId] = _handle;

        emit SetHandle(_projectId, _handle, msg.sender);
    }

    /**
      @notice 
      Allows a project owner to set the project's uri.

      @dev 
      Only a project's owner or operator can set its uri.

      @param _projectId The ID of the project.
      @param _uri An ipfs CDN to more info about the project. Don't include the leading ipfs://
    */
    function setUri(uint256 _projectId, string calldata _uri)
        external
        override
        requirePermission(ownerOf(_projectId), _projectId, Operations.SetUri)
    {
        // Set the new uri.
        uriOf[_projectId] = _uri;

        emit SetUri(_projectId, _uri, msg.sender);
    }

    /**
      @notice 
      Allows a project owner to transfer its handle to another address.

      @dev 
      Only a project's owner or operator can transfer its handle.

      @param _projectId The ID of the project to transfer the handle from.
      @param _to The address that can now reallocate the handle.
      @param _newHandle The new unique handle for the project that will replace the transfered one.
    */
    function transferHandle(
        uint256 _projectId,
        address _to,
        bytes32 _newHandle
    )
        external
        override
        requirePermission(ownerOf(_projectId), _projectId, Operations.SetHandle)
        returns (bytes32 _handle)
    {
        require(
            _newHandle != bytes32(0),
            "Projects::transferHandle: EMPTY_HANDLE"
        );

        require(
            projectFor[_newHandle] == 0 &&
                transferAddressFor[_handle] == address(0),
            "Projects::transferHandle: HANDLE_TAKEN"
        );

        // Get a reference to the project's currency handle.
        _handle = handleOf[_projectId];

        // Remove the resolver for the transfered handle.
        projectFor[_handle] = 0;

        // If the handle is changing, register the change in the resolver.
        projectFor[_newHandle] = _projectId;
        handleOf[_projectId] = _newHandle;

        // Transfer the current handle.
        transferAddressFor[_handle] = _to;

        emit TransferHandle(_projectId, _to, _handle, _newHandle, msg.sender);
    }

    /**
      @notice 
      Allows an address to claim and handle that has been transfered to them and apply it to a project of theirs.

      @dev 
      Only a project's owner or operator can claim a handle onto it.

      @param _handle The handle being claimed.
      @param _for The address that the handle has been transfered to.
      @param _projectId The ID of the project to use the claimed handle.
    */
    function claimHandle(
        bytes32 _handle,
        address _for,
        uint256 _projectId
    )
        external
        override
        requirePermissionAllowingWildcardDomain(
            _for,
            _projectId,
            Operations.ClaimHandle
        )
        requirePermission(
            ownerOf(_projectId),
            _projectId,
            Operations.ClaimHandle
        )
    {
        // The handle must have been transfered to the specified address,
        // or the handle challange must have expired before being renewed.
        require(
            transferAddressFor[_handle] == _for ||
                (challengeExpiryOf[_handle] > 0 &&
                    block.timestamp > challengeExpiryOf[_handle]),
            "Projects::claimHandle: UNAUTHORIZED"
        );

        // Register the change in the resolver.
        projectFor[handleOf[_projectId]] = 0;

        // Register the change in the resolver.
        projectFor[_handle] = _projectId;

        // Set the new handle.
        handleOf[_projectId] = _handle;

        // Set the handle as not being transfered.
        transferAddressFor[_handle] = address(0);

        // Reset the challenge to 0.
        challengeExpiryOf[_handle] = 0;

        emit ClaimHandle(_for, _projectId, _handle, msg.sender);
    }

    /** 
      @notice
      Allows anyone to challenge a project's handle. After one year, the handle can be claimed by the public if the challenge isn't answered by the handle's project.
      This can be used to make sure a handle belonging to an unattended to project isn't lost forever.

      @param _handle The handle to challenge.
    */
    function challengeHandle(bytes32 _handle) external {
        // No need to challenge a handle that's not taken.
        require(
            projectFor[_handle] > 0,
            "Projects::challenge: HANDLE_NOT_TAKEN"
        );

        // No need to challenge again if a handle is already being challenged.
        require(
            challengeExpiryOf[_handle] == 0,
            "Projects::challenge: HANDLE_ALREADY_BEING_CHALLENGED"
        );

        // The challenge will expire in a year, at which point the handle can be claimed if the challenge hasn't been answered.
        uint256 _challengeExpiry = block.timestamp + SECONDS_IN_YEAR;

        challengeExpiryOf[_handle] = _challengeExpiry;

        emit ChallengeHandle(_handle, _challengeExpiry, msg.sender);
    }

    /** 
      @notice
      Allows a project to renew its handle so it can't be claimed until a year after its challenged again.

      @dev 
      Only a project's owner or operator can renew its handle.

      @param _projectId The ID of the project that current has the handle being renewed.
    */
    function renewHandle(uint256 _projectId)
        external
        requirePermission(
            ownerOf(_projectId),
            _projectId,
            Operations.RenewHandle
        )
    {
        // Get the handle of the project.
        bytes32 _handle = handleOf[_projectId];

        // Reset the challenge to 0.
        challengeExpiryOf[_handle] = 0;

        emit RenewHandle(_handle, _projectId, msg.sender);
    }
}

// File: contracts/abstract/Operatable.sol



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

import "./../interfaces/IOperatable.sol";

abstract contract Operatable is IOperatable {
    modifier requirePermission(
        address _account,
        uint256 _domain,
        uint256 _index
    ) {
        require(
            msg.sender == _account ||
                operatorStore.hasPermission(
                    msg.sender,
                    _account,
                    _domain,
                    _index
                ),
            "Operatable: UNAUTHORIZED"
        );
        _;
    }

    modifier requirePermissionAllowingWildcardDomain(
        address _account,
        uint256 _domain,
        uint256 _index
    ) {
        require(
            msg.sender == _account ||
                operatorStore.hasPermission(
                    msg.sender,
                    _account,
                    _domain,
                    _index
                ) ||
                operatorStore.hasPermission(msg.sender, _account, 0, _index),
            "Operatable: UNAUTHORIZED"
        );
        _;
    }

    modifier requirePermissionAcceptingAlternateAddress(
        address _account,
        uint256 _domain,
        uint256 _index,
        address _alternate
    ) {
        require(
            msg.sender == _account ||
                operatorStore.hasPermission(
                    msg.sender,
                    _account,
                    _domain,
                    _index
                ) ||
                msg.sender == _alternate,
            "Operatable: UNAUTHORIZED"
        );
        _;
    }

    /// @notice A contract storing operator assignments.
    IOperatorStore public immutable override operatorStore;

    /** 
      @param _operatorStore A contract storing operator assignments.
    */
    constructor(IOperatorStore _operatorStore) {
        operatorStore = _operatorStore;
    }
}

// File: contracts/interfaces/IDirectPaymentAddress.sol



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

import "./ITerminalDirectory.sol";
import "./ITerminal.sol";

interface IDirectPaymentAddress {
    event Forward(
        address indexed payer,
        uint256 indexed projectId,
        address beneficiary,
        uint256 value,
        string memo,
        bool preferUnstakedTickets
    );

    function terminalDirectory() external returns (ITerminalDirectory);

    function projectId() external returns (uint256);

    function memo() external returns (string memory);
}

// File: contracts/interfaces/IOperatable.sol



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

import "./IOperatorStore.sol";

interface IOperatable {
    function operatorStore() external view returns (IOperatorStore);
}

// File: contracts/interfaces/IOperatorStore.sol



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

interface IOperatorStore {
    event SetOperator(
        address indexed operator,
        address indexed account,
        uint256 indexed domain,
        uint256[] permissionIndexes,
        uint256 packed
    );

    function permissionsOf(
        address _operator,
        address _account,
        uint256 _domain
    ) external view returns (uint256);

    function hasPermission(
        address _operator,
        address _account,
        uint256 _domain,
        uint256 _permissionIndex
    ) external view returns (bool);

    function hasPermissions(
        address _operator,
        address _account,
        uint256 _domain,
        uint256[] calldata _permissionIndexes
    ) external view returns (bool);

    function setOperator(
        address _operator,
        uint256 _domain,
        uint256[] calldata _permissionIndexes
    ) external;

    function setOperators(
        address[] calldata _operators,
        uint256[] calldata _domains,
        uint256[][] calldata _permissionIndexes
    ) external;
}

// File: contracts/interfaces/IProjects.sol



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

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

import "./ITerminal.sol";
import "./IOperatorStore.sol";

interface IProjects is IERC721 {
    event Create(
        uint256 indexed projectId,
        address indexed owner,
        bytes32 indexed handle,
        string uri,
        ITerminal terminal,
        address caller
    );

    event SetHandle(
        uint256 indexed projectId,
        bytes32 indexed handle,
        address caller
    );

    event SetUri(uint256 indexed projectId, string uri, address caller);

    event TransferHandle(
        uint256 indexed projectId,
        address indexed to,
        bytes32 indexed handle,
        bytes32 newHandle,
        address caller
    );

    event ClaimHandle(
        address indexed account,
        uint256 indexed projectId,
        bytes32 indexed handle,
        address caller
    );

    event ChallengeHandle(
        bytes32 indexed handle,
        uint256 challengeExpiry,
        address caller
    );

    event RenewHandle(
        bytes32 indexed handle,
        uint256 indexed projectId,
        address caller
    );

    function count() external view returns (uint256);

    function uriOf(uint256 _projectId) external view returns (string memory);

    function handleOf(uint256 _projectId) external returns (bytes32 handle);

    function projectFor(bytes32 _handle) external returns (uint256 projectId);

    function transferAddressFor(bytes32 _handle)
        external
        returns (address receiver);

    function challengeExpiryOf(bytes32 _handle) external returns (uint256);

    function exists(uint256 _projectId) external view returns (bool);

    function create(
        address _owner,
        bytes32 _handle,
        string calldata _uri,
        ITerminal _terminal
    ) external returns (uint256 id);

    function setHandle(uint256 _projectId, bytes32 _handle) external;

    function setUri(uint256 _projectId, string calldata _uri) external;

    function transferHandle(
        uint256 _projectId,
        address _to,
        bytes32 _newHandle
    ) external returns (bytes32 _handle);

    function claimHandle(
        bytes32 _handle,
        address _for,
        uint256 _projectId
    ) external;
}

// File: contracts/interfaces/ITerminal.sol



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

import './ITerminalDirectory.sol';

interface ITerminal {
  function terminalDirectory() external view returns (ITerminalDirectory);

  function migrationIsAllowed(ITerminal _terminal) external view returns (bool);

  function pay(
    uint256 _projectId,
    address _beneficiary,
    string calldata _memo,
    bool _preferUnstakedTickets
  ) external payable returns (uint256 fundingCycleId);

  function addToBalance(uint256 _projectId) external payable;

  function allowMigration(ITerminal _contract) external;

  function migrate(uint256 _projectId, ITerminal _to) external;
}

// File: contracts/interfaces/ITerminalDirectory.sol



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

import "./IDirectPaymentAddress.sol";
import "./ITerminal.sol";
import "./IProjects.sol";
import "./IProjects.sol";

interface ITerminalDirectory {
    event DeployAddress(
        uint256 indexed projectId,
        string memo,
        address indexed caller
    );

    event SetTerminal(
        uint256 indexed projectId,
        ITerminal indexed terminal,
        address caller
    );

    event SetPayerPreferences(
        address indexed account,
        address beneficiary,
        bool preferUnstakedTickets
    );

    function projects() external view returns (IProjects);

    function terminalOf(uint256 _projectId) external view returns (ITerminal);

    function beneficiaryOf(address _account) external returns (address);

    function unstakedTicketsPreferenceOf(address _account)
        external
        returns (bool);

    function addressesOf(uint256 _projectId)
        external
        view
        returns (IDirectPaymentAddress[] memory);

    function deployAddress(uint256 _projectId, string calldata _memo) external;

    function setTerminal(uint256 _projectId, ITerminal _terminal) external;

    function setPayerPreferences(
        address _beneficiary,
        bool _preferUnstakedTickets
    ) external;
}

// File: contracts/libraries/Operations.sol



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

library Operations {
  uint256 public constant Configure = 1;
  uint256 public constant PrintPreminedTickets = 2;
  uint256 public constant Redeem = 3;
  uint256 public constant Migrate = 4;
  uint256 public constant SetHandle = 5;
  uint256 public constant SetUri = 6;
  uint256 public constant ClaimHandle = 7;
  uint256 public constant RenewHandle = 8;
  uint256 public constant Issue = 9;
  uint256 public constant Stake = 10;
  uint256 public constant Unstake = 11;
  uint256 public constant Transfer = 12;
  uint256 public constant Lock = 13;
  uint256 public constant SetPayoutMods = 14;
  uint256 public constant SetTicketMods = 15;
  uint256 public constant SetTerminal = 16;
  uint256 public constant PrintTickets = 17;
}