// 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/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) external returns (bool);
}

// 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/Launchpad.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "./MintableNFT.sol";

/**
 * Launchpad for NFT-s
 */
contract Launchpad is Context, Ownable {
    // NFT address
    address public nftAddress;

    // Payment token addresses
    address[] private _paymentTokenAddresses;

    // Mapping payment tokens to the price per single NFT
    mapping(address => uint256) public prices;

    // Target wallet for the collected amount
    address public wallet;

    // The address that authorizes special offers
    address public authorizer;

    // This value must be included whenever signature is generated
    mapping(address => uint256) public nonces;

    bytes32 public constant BUY_TOKENS_TYPEHASH = keccak256(
        bytes("buyTokens(uint256[] tokenIds,address paymentTokenAddress,uint256 pricePerToken)")
    );

    error EmptyAddress();
    error InvalidPaymentSettings();
    error InvalidPaymentToken(address);
    error TokenTransferFailed();
    error InvalidSigner();
    error InvalidSignature();

    event TokensPurchased(
        address indexed nftAddress,
        uint256 indexed amount,
        address indexed paymentToken,
        uint256 pricePerToken
    );
    event PaymentSettingsChanged(
        address[] paymentTokenAddresses,
        uint256[] prices
    );

    constructor(
        address nftAddress_,
        address[] memory paymentTokenAddresses_,
        uint256[] memory prices_,
        address wallet_,
        address authorizer_
    ) {
        if (nftAddress_ == address(0) || wallet_ == address(0) || authorizer_ == address(0))
            revert EmptyAddress();
        if (paymentTokenAddresses_.length != prices_.length)
            revert InvalidPaymentSettings();

        nftAddress = nftAddress_;
        _paymentTokenAddresses = paymentTokenAddresses_;
        wallet = wallet_;
        authorizer = authorizer_;

        for (uint256 i = 0; i < paymentTokenAddresses_.length; i++)
            prices[paymentTokenAddresses_[i]] = prices_[i];
    }

    /**
     * Buy NFTs for ERC-20 tokens
     */
    function buyTokens(
        uint256[] memory tokenIds,
        address paymentTokenAddress
    ) external {
        if (!isPaymentToken(paymentTokenAddress))
            revert InvalidPaymentToken(paymentTokenAddress);

        uint256 pricePerToken = prices[paymentTokenAddress];
        uint256 totalPrice = tokenIds.length * pricePerToken;

        emit TokensPurchased(
            nftAddress,
            tokenIds.length,
            paymentTokenAddress,
            pricePerToken
        );

        // Transfer payment to the target wallet
        bool success = IERC20(paymentTokenAddress).transferFrom(
            _msgSender(),
            wallet,
            totalPrice
        );
        if (!success) revert TokenTransferFailed();

        // Mint bought tokens to the buyer
        MintableNFT(nftAddress).mintTo(_msgSender(), tokenIds);
    }

    /**
    * Buy NFTs for ERC-20 tokens for custom/special prices
    */
    function buyTokensSig(
        uint256[] memory tokenIds,
        address paymentTokenAddress,
        uint256 pricePerToken,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        bytes32 hashStruct = keccak256(
            abi.encodePacked(
                BUY_TOKENS_TYPEHASH,
                address(this),
                _msgSender(),
                tokenIds,
                paymentTokenAddress,
                pricePerToken,
                nonces[_msgSender()]
            ));

        if (!verifySignature(authorizer, hashStruct, v, r, s))
            revert InvalidSignature();

        nonces[_msgSender()] += 1;

        emit TokensPurchased(
            nftAddress,
            tokenIds.length,
            paymentTokenAddress,
            pricePerToken
        );

        // Transfer payment to the target wallet
        uint256 totalPrice = tokenIds.length * pricePerToken;
        bool success = IERC20(paymentTokenAddress).transferFrom(
            _msgSender(),
            wallet,
            totalPrice
        );
        if (!success) revert TokenTransferFailed();

        // Mint bought tokens to the buyer
        MintableNFT(nftAddress).mintTo(_msgSender(), tokenIds);
    }

    /**
     * Checks if the caller can buy NFT-s with specified ID-s
     */
    function canBuyTokens(
        uint256[] memory tokenIds
    ) external view returns (bool) {
        return MintableNFT(nftAddress).canMint(tokenIds);
    }

    /**
     * Checks if the token address is valid payment token address
     */
    function isPaymentToken(
        address paymentTokenAddress
    ) public view returns (bool) {
        for (uint256 i = 0; i < _paymentTokenAddresses.length; i++) {
            if (_paymentTokenAddresses[i] == paymentTokenAddress) {
                return true;
            }
        }
        return false;
    }

    /**
     * Returns list of valid payment token addresses
     */
    function paymentTokenAddresses() public view returns (address[] memory) {
        return _paymentTokenAddresses;
    }

    function setNFTAddress(address nftAddress_) external onlyOwner {
        if (nftAddress_ == address(0)) revert EmptyAddress();
        nftAddress = nftAddress_;
    }

    function setWallet(address wallet_) external onlyOwner {
        if (wallet_ == address(0)) revert EmptyAddress();
        wallet = wallet_;
    }

    function setPaymentSettings(
        address[] memory paymentTokenAddresses_,
        uint256[] memory prices_
    ) external onlyOwner {
        if (paymentTokenAddresses_.length != prices_.length)
            revert InvalidPaymentSettings();

        _paymentTokenAddresses = paymentTokenAddresses_;
        for (uint256 i = 0; i < paymentTokenAddresses_.length; i++)
            prices[paymentTokenAddresses_[i]] = prices_[i];

        emit PaymentSettingsChanged(paymentTokenAddresses_, prices_);
    }

    function transferAuthorizer(address newAuthorizer) external onlyOwner {
        authorizer = newAuthorizer;
    }

    function verifySignature(
        address signer,
        bytes32 hashStruct,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (bool) {
        bytes32 hash = prefixed(hashStruct);
        return signer == ecrecover(hash, v, r, s);
    }

    // Builds a prefixed hash to mimic the behavior of eth_sign.
    function prefixed(bytes32 hash) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

// File: contracts/MintableNFT.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface MintableNFT {
    function mintTo(address to, uint256 tokenId) external;

    function mintTo(address to, uint256[] memory tokenId) external;

    function canMint(uint256[] memory tokenIds) external view returns (bool);
}