// SPDX-License-Identifier: MIT
pragma solidity 0.8.25;

import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "./Interfaces/ICrowdsale.sol";
import "./LisaCrowdsaleBase.sol";

/**
 * @title LisaCrowdsaleSimple
 * @notice Crowdsale is a contract for managing a token crowdsale for selling ArtToken (AT) tokens
 * for BaseToken (BT). USDC can be used as a base token. Deployer can specify start and end dates of the crowdsale,
 * along with the limits of purchase amount per transaction and total purchase amount per buyer.
 * When all funds are collected, the crowdsale finishes and participants can claim their AT tokens, while seller
 * can claim sale proceeds in BT tokens.
 */
contract LisaCrowdsaleSimple is Initializable, LisaCrowdsaleBase {
    using SafeERC20 for IERC20;

    constructor() {
        _disableInitializers();
    }

    /*
     * @notice Initializes the crowdsale contract.
     *
     * @param rate The rate is the conversion between wei and the smallest and indivisible token unit. So, amount_at = amount_bt * r.
     * @param sellerAddress Address where collected funds will be forwarded to
     * @param at Address of the ERC20 token being sold (AT, or Art Token)
     * @param bt Address of the ERC20 token being used to buy AT (BT, or Base Token).
     * @param startDate Unix timestamp of crowdsale start datetime
     * @param endDate Unix timestamp of crowdsale end datetime
     * @param crowdsaleAmount Total amount of AT tokens being sold
     * @param sellerRetainedAmount Total amount of tokens that will be kept by the seller and can be claimed by sellerAddress after successful crowdsale
     * @param minParticipationBT Minimum amount of BT per a single purchase transaction
     * @param maxParticipationBT Maximum total amount of BT for all purchase transactions
     * @param lisaSettings LisaSettings contract to access protocol settings
     */
    function initialize(
        CrowdsaleSimpleInitParams calldata params
    ) external initializer {
        require(params.rate > 0, "Crowdsale: rate is 0");
        require(
            params.sellerAddress != address(0),
            "Crowdsale: wallet is the zero address"
        );
        require(
            address(params.at) != address(0),
            "Crowdsale: at is the zero address"
        );
        require(
            address(params.bt) != address(0),
            "Crowdsale: bt is the zero address"
        );
        require(
            params.startDate < params.endDate,
            "Crowdsale: startDate should be before endDate"
        );
        require(
            params.sellerRetainedAmount <= params.initialSupplyAT,
            "sellerRetainedAmount should be less than crowdsaleAmount"
        );
        require(
            params.minParticipationBT < params.maxParticipationBT,
            "Crowdsale: minParticipationBT should be less then maxParticipationBT"
        );

        rate = params.rate;
        seller = params.sellerAddress;
        tokenAT = params.at;
        tokenBT = params.bt;
        startTimestamp = params.startDate;
        endTimestamp = params.endDate;
        _originalEndTimestamp = params.endDate;
        allocationsBT[params.sellerAddress] = costBT(
            params.sellerRetainedAmount
        );
        minPurchaseBT = params.minParticipationBT;
        maxPurchaseBT = params.maxParticipationBT;
        totalPriceBT = costBT(params.initialSupplyAT);
        totalForSaleAT = params.initialSupplyAT;
        settings = params.lisaSettings;
        protocolFeeAT = (totalForSaleAT * settings.protocolATFeeBps()) / 10000;
        protocolFeeBT = (totalPriceBT * settings.protocolBTFeeBps()) / 10000;
        amountLeftAT =
            params.initialSupplyAT -
            params.sellerRetainedAmount -
            protocolFeeAT;
        targetSaleProceedsBT =
            totalPriceBT -
            costBT(params.sellerRetainedAmount + protocolFeeAT);
        _trustedForwarder = settings.trustedForwarder();
        salesAgreementURI = params.salesAgreement;
    }

    // -------------------  INTERNAL, VIEW  -------------------
    /**
     * @dev Validation of an incoming purchase
     * @param buyer Address performing the token purchase
     * @param amountBT Amount of base tokens sent for purchase
     */
    function _preValidatePurchase(
        address buyer,
        uint256 amountBT
    ) internal view virtual {
        require(amountBT != 0, "Crowdsale: amountBT is 0");
        require(
            getTokenAmount(amountBT) <= amountLeftAT,
            "Crowdsale: not enough tokens left for sale"
        );
        require(
            amountBT >= minPurchaseBT,
            "Crowdsale: purchase amount is below the threshold"
        );
        require(
            getAllocationFor(buyer) + getTokenAmount(amountBT) <=
                getTokenAmount(maxPurchaseBT),
            "Crowdsale: purchase amount is above the threshold"
        );
        require(
            block.timestamp >= startTimestamp,
            "Crowdsale: participation before start date"
        );
        require(
            block.timestamp <= endTimestamp,
            "Crowdsale: participation after end date"
        );
    }

    /**
     * @dev Validation of an executed purchase.
     * @param buyer Address performing the token purchase
     * @param amountAT Value in wei involved in the purchase
     */
    function _postValidatePurchase(
        address buyer,
        uint256 amountAT
    ) internal view virtual {
        assert(
            costBT(
                totalForSaleAT -
                    amountLeftAT -
                    getTokenAmount(allocationsBT[seller]) -
                    protocolFeeAT
            ) == collectedBT
        );
        assert(amountAT <= getTokenAmount(allocationsBT[buyer]));
        assert(getAllocationFor(buyer) <= getTokenAmount(maxPurchaseBT));
        assert(collectedBT <= tokenBT.balanceOf(address(this)));
    }

    // -------------------  INTERNAL, MUTATING  -------------------

    /**
     * @dev Updates token balances of crowdsale participants and the amount of tokens sold.
     * @param buyer Address receiving the tokens
     * @param amountBT Purchase amount in BaseTokens
     */
    function _updatePurchasingState(
        address buyer,
        uint256 amountAT,
        uint256 amountBT
    ) internal override {
        amountLeftAT = amountLeftAT - amountAT;
        collectedBT = collectedBT + amountBT;
        allocationsBT[buyer] += amountBT;
    }

    // -------------------  EXTERNAL, VIEW  -------------------

    /**
     * @notice  Returns the name of the crowdsale contract.
     * @return  byte32  Name of the crowdsale contract.
     */
    function name() public pure virtual returns (string memory) {
        return "LisaCrowdsaleSimple";
    }

    /**
     * @notice  Returns AT allocation for a given buyer.
     * @param   owner Address of the seller or a participant of this crowdsale.
     * @return  uint256 Amount of AT tokens allocated for a given buyer.
     */
    function getAllocationFor(
        address owner
    ) public view override returns (uint256) {
        if (status() == CrowdsaleStatus.SUCCESSFUL && owner != seller) {
            return 0;
        }
        return getTokenAmount(allocationsBT[owner]);
    }

    /**
     * @notice  Returns the crowdsale status at the moment of the call.
     * @dev     Uses current timestamp to compare against startTimestamp and endTimestamp.
     * @return  CrowdsaleStatus enum value.
     */
    function status() public view virtual override returns (CrowdsaleStatus) {
        if (block.timestamp < startTimestamp) {
            return CrowdsaleStatus.NOT_STARTED;
        } else if (block.timestamp <= endTimestamp) {
            if (amountLeftAT > 0) {
                return CrowdsaleStatus.IN_PROGRESS;
            } else {
                return CrowdsaleStatus.SUCCESSFUL;
            }
        } else if (amountLeftAT > 0) {
            return CrowdsaleStatus.UNSUCCESSFUL;
        } else {
            return CrowdsaleStatus.SUCCESSFUL;
        }
    }

    // -------------------  EXTERNAL, MUTATING  -------------------

    /**
     * @notice Buy tokens for the sender. The sender must have amountBT tokens on their balance.
     * @dev This function has a non-reentrancy guard, so it shouldn't be called by
     * another `nonReentrant` function.
     * @param amountBT amount of purchase in base tokens
     */
    function buyTokens(uint256 amountBT) public override nonReentrant {
        amountBT = amountBT + collectedBT > targetSaleProceedsBT
            ? targetSaleProceedsBT - collectedBT
            : amountBT;
        _preValidatePurchase(_msgSender(), amountBT);

        uint256 amountAT = getTokenAmount(amountBT);

        _updatePurchasingState(_msgSender(), amountAT, amountBT);

        _processPurchase(_msgSender(), amountBT);
        emit TokensClaimed(_msgSender(), amountAT);

        _postValidatePurchase(_msgSender(), amountBT);
    }

    /**
     * @notice Buy tokens for a buyer. The sender must have amountBT tokens on their balance.
     * Transfers the BT tokens from sender to this contract and the AT tokens to the buyer.
     * If the request cannot be fully filled, the contract receives the exact amount of BT that can be filled.
     * @param buyer address of the buyer who receives AT tokens
     * @param amountBT amount of purchase in base tokens
     * @return amountAT Amount of AT tokens filled
     * @return costBT Amount of BT tokens filled
     */
    function buyTokensFor(
        address buyer,
        uint256 amountBT
    ) public override nonReentrant returns (uint256, uint256) {
        uint256 costBT = amountBT + collectedBT > targetSaleProceedsBT
            ? targetSaleProceedsBT - collectedBT
            : amountBT;
        _preValidatePurchase(buyer, costBT);

        uint256 amountAT = getTokenAmount(costBT);

        _updatePurchasingState(buyer, amountAT, costBT);
        tokenBT.safeTransferFrom(_msgSender(), address(this), costBT);
        tokenAT.safeTransfer(buyer, amountAT);

        emit TokensClaimed(buyer, amountAT);

        _postValidatePurchase(buyer, costBT);

        return (amountAT, costBT);
    }

    /**
     * @notice  Claim the AT tokens. Can only be called by the seller.
     * Transfers the AT tokens to the caller.
     */
    function claimTokens()
        external
        virtual
        nonReentrant
        onlySeller
        returns (uint256)
    {
        require(
            status() == CrowdsaleStatus.SUCCESSFUL,
            "Crowdsale should be successful to claim tokens"
        );
        uint256 amountAT = getAllocationFor(_msgSender());
        if (amountAT > 0) {
            allocationsBT[_msgSender()] = 0;
            emit TokensClaimed(_msgSender(), amountAT);
            tokenAT.safeTransfer(_msgSender(), amountAT);
        }
        return amountAT;
    }

    /**
     * @notice  Claim the sale proceeds. Can only be called once by the seller when the crowdsale is successful.
     * Transfers the sale proceeds BT tokens to the caller.
     */
    function claimSaleProceeds()
        external
        override
        nonReentrant
        onlySeller
        returns (uint256)
    {
        require(
            status() == CrowdsaleStatus.SUCCESSFUL,
            "Crowdsale should be successful to claim sale proceeds"
        );
        uint256 amountBT = collectedBT - protocolFeeBT;
        collectedBT = 0;
        tokenBT.safeTransfer(seller, amountBT);
        _claimProtocolFee();
        return amountBT;
    }

    /**
     * @notice Request a refund. Can only be called by a participant after the crowdsale is unsuccessful.
     * Transfers the BT tokens to the caller and the AT tokens are returned back to the crowdsale contract.
     * @dev Requires approval or permit to transfer AT tokens by the crowdsale contract.
     * @return Amount of BT tokens refunded
     */
    function refund() public override nonReentrant returns (uint256) {
        require(
            status() == CrowdsaleStatus.UNSUCCESSFUL,
            "Crowdsale should be unsuccessful to claim tokens"
        );
        require(
            _msgSender() != seller,
            "Crowdsale: Seller cannot request refund"
        );
        uint256 refundBT = costBT(tokenAT.balanceOf(_msgSender()));
        if (refundBT > 0) {
            tokenBT.safeTransfer(_msgSender(), refundBT);
            tokenAT.safeTransferFrom(
                _msgSender(),
                address(this),
                getTokenAmount(refundBT)
            );
            emit TokensRefunded(_msgSender(), refundBT);
        }
        return refundBT;
    }

    // -------------------  INTERNAL, MUTATING  -------------------
    /**
     * @dev Executed when a purchase has been validated and is ready to be executed
     * @param buyer Address paying for the tokens
     * @param amountBT Number of baseTokens to be paid
     */
    function _processPurchase(
        address buyer,
        uint256 amountBT
    ) internal override {
        tokenBT.safeTransferFrom(buyer, address(this), amountBT);
        tokenAT.safeTransfer(buyer, getTokenAmount(amountBT));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.20;

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```solidity
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 *
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Storage of the initializable contract.
     *
     * It's implemented on a custom ERC-7201 namespace to reduce the risk of storage collisions
     * when using with upgradeable contracts.
     *
     * @custom:storage-location erc7201:openzeppelin.storage.Initializable
     */
    struct InitializableStorage {
        /**
         * @dev Indicates that the contract has been initialized.
         */
        uint64 _initialized;
        /**
         * @dev Indicates that the contract is in the process of being initialized.
         */
        bool _initializing;
    }

    // keccak256(abi.encode(uint256(keccak256("openzeppelin.storage.Initializable")) - 1)) & ~bytes32(uint256(0xff))
    bytes32 private constant INITIALIZABLE_STORAGE = 0xf0c57e16840df040f15088dc2f81fe391c3923bec73e23a9662efc9c229c6a00;

    /**
     * @dev The contract is already initialized.
     */
    error InvalidInitialization();

    /**
     * @dev The contract is not initializing.
     */
    error NotInitializing();

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint64 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts.
     *
     * Similar to `reinitializer(1)`, except that in the context of a constructor an `initializer` may be invoked any
     * number of times. This behavior in the constructor can be useful during testing and is not expected to be used in
     * production.
     *
     * Emits an {Initialized} event.
     */
    modifier initializer() {
        // solhint-disable-next-line var-name-mixedcase
        InitializableStorage storage $ = _getInitializableStorage();

        // Cache values to avoid duplicated sloads
        bool isTopLevelCall = !$._initializing;
        uint64 initialized = $._initialized;

        // Allowed calls:
        // - initialSetup: the contract is not in the initializing state and no previous version was
        //                 initialized
        // - construction: the contract is initialized at version 1 (no reininitialization) and the
        //                 current contract is just being deployed
        bool initialSetup = initialized == 0 && isTopLevelCall;
        bool construction = initialized == 1 && address(this).code.length == 0;

        if (!initialSetup && !construction) {
            revert InvalidInitialization();
        }
        $._initialized = 1;
        if (isTopLevelCall) {
            $._initializing = true;
        }
        _;
        if (isTopLevelCall) {
            $._initializing = false;
            emit Initialized(1);
        }
    }

    /**
     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
     * used to initialize parent contracts.
     *
     * A reinitializer may be used after the original initialization step. This is essential to configure modules that
     * are added through upgrades and that require initialization.
     *
     * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
     * cannot be nested. If one is invoked in the context of another, execution will revert.
     *
     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
     * a contract, executing them in the right order is up to the developer or operator.
     *
     * WARNING: Setting the version to 2**64 - 1 will prevent any future reinitialization.
     *
     * Emits an {Initialized} event.
     */
    modifier reinitializer(uint64 version) {
        // solhint-disable-next-line var-name-mixedcase
        InitializableStorage storage $ = _getInitializableStorage();

        if ($._initializing || $._initialized >= version) {
            revert InvalidInitialization();
        }
        $._initialized = version;
        $._initializing = true;
        _;
        $._initializing = false;
        emit Initialized(version);
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} and {reinitializer} modifiers, directly or indirectly.
     */
    modifier onlyInitializing() {
        _checkInitializing();
        _;
    }

    /**
     * @dev Reverts if the contract is not in an initializing state. See {onlyInitializing}.
     */
    function _checkInitializing() internal view virtual {
        if (!_isInitializing()) {
            revert NotInitializing();
        }
    }

    /**
     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
     * through proxies.
     *
     * Emits an {Initialized} event the first time it is successfully executed.
     */
    function _disableInitializers() internal virtual {
        // solhint-disable-next-line var-name-mixedcase
        InitializableStorage storage $ = _getInitializableStorage();

        if ($._initializing) {
            revert InvalidInitialization();
        }
        if ($._initialized != type(uint64).max) {
            $._initialized = type(uint64).max;
            emit Initialized(type(uint64).max);
        }
    }

    /**
     * @dev Returns the highest version that has been initialized. See {reinitializer}.
     */
    function _getInitializedVersion() internal view returns (uint64) {
        return _getInitializableStorage()._initialized;
    }

    /**
     * @dev Returns `true` if the contract is currently initializing. See {onlyInitializing}.
     */
    function _isInitializing() internal view returns (bool) {
        return _getInitializableStorage()._initializing;
    }

    /**
     * @dev Returns a pointer to the storage namespace.
     */
    // solhint-disable-next-line var-name-mixedcase
    function _getInitializableStorage() private pure returns (InitializableStorage storage $) {
        assembly {
            $.slot := INITIALIZABLE_STORAGE
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 *
 * ==== Security Considerations
 *
 * There are two important considerations concerning the use of `permit`. The first is that a valid permit signature
 * expresses an allowance, and it should not be assumed to convey additional meaning. In particular, it should not be
 * considered as an intention to spend the allowance in any specific way. The second is that because permits have
 * built-in replay protection and can be submitted by anyone, they can be frontrun. A protocol that uses permits should
 * take this into consideration and allow a `permit` call to fail. Combining these two aspects, a pattern that may be
 * generally recommended is:
 *
 * ```solidity
 * function doThingWithPermit(..., uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) public {
 *     try token.permit(msg.sender, address(this), value, deadline, v, r, s) {} catch {}
 *     doThing(..., value);
 * }
 *
 * function doThing(..., uint256 value) public {
 *     token.safeTransferFrom(msg.sender, address(this), value);
 *     ...
 * }
 * ```
 *
 * Observe that: 1) `msg.sender` is used as the owner, leaving no ambiguity as to the signer intent, and 2) the use of
 * `try/catch` allows the permit to fail and makes the code tolerant to frontrunning. (See also
 * {SafeERC20-safeTransferFrom}).
 *
 * Additionally, note that smart contract wallets (such as Argent or Safe) are not able to produce permit signatures, so
 * contracts should have entry points that don't rely on permit.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     *
     * CAUTION: See Security Considerations above.
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @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 value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` 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 value) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.20;

import {IERC20} from "../IERC20.sol";
import {IERC20Permit} from "../extensions/IERC20Permit.sol";
import {Address} from "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev An operation with an ERC20 token failed.
     */
    error SafeERC20FailedOperation(address token);

    /**
     * @dev Indicates a failed `decreaseAllowance` request.
     */
    error SafeERC20FailedDecreaseAllowance(address spender, uint256 currentAllowance, uint256 requestedDecrease);

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transfer, (to, value)));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeCall(token.transferFrom, (from, to, value)));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        forceApprove(token, spender, oldAllowance + value);
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `requestedDecrease`. If `token` returns no
     * value, non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 requestedDecrease) internal {
        unchecked {
            uint256 currentAllowance = token.allowance(address(this), spender);
            if (currentAllowance < requestedDecrease) {
                revert SafeERC20FailedDecreaseAllowance(spender, currentAllowance, requestedDecrease);
            }
            forceApprove(token, spender, currentAllowance - requestedDecrease);
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
     * to be set to zero before setting it to a non-zero value, such as USDT.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeCall(token.approve, (spender, 0)));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data);
        if (returndata.length != 0 && !abi.decode(returndata, (bool))) {
            revert SafeERC20FailedOperation(address(token));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return success && (returndata.length == 0 || abi.decode(returndata, (bool))) && address(token).code.length > 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/Address.sol)

pragma solidity ^0.8.20;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev The ETH balance of the account is not enough to perform the operation.
     */
    error AddressInsufficientBalance(address account);

    /**
     * @dev There's no code at `target` (it is not a contract).
     */
    error AddressEmptyCode(address target);

    /**
     * @dev A call to an address target failed. The target may have reverted.
     */
    error FailedInnerCall();

    /**
     * @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://consensys.net/diligence/blog/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/v0.8.20/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        if (address(this).balance < amount) {
            revert AddressInsufficientBalance(address(this));
        }

        (bool success, ) = recipient.call{value: amount}("");
        if (!success) {
            revert FailedInnerCall();
        }
    }

    /**
     * @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 or custom error, it is bubbled
     * up by this function (like regular Solidity function calls). However, if
     * the call reverted with no returned reason, this function reverts with a
     * {FailedInnerCall} error.
     *
     * 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.
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0);
    }

    /**
     * @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`.
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        if (address(this).balance < value) {
            revert AddressInsufficientBalance(address(this));
        }
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and reverts if the target
     * was not a contract or bubbling up the revert reason (falling back to {FailedInnerCall}) in case of an
     * unsuccessful call.
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata
    ) internal view returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            // only check if target is a contract if the call was successful and the return data is empty
            // otherwise we already know that it was a contract
            if (returndata.length == 0 && target.code.length == 0) {
                revert AddressEmptyCode(target);
            }
            return returndata;
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and reverts if it wasn't, either by bubbling the
     * revert reason or with a default {FailedInnerCall} error.
     */
    function verifyCallResult(bool success, bytes memory returndata) internal pure returns (bytes memory) {
        if (!success) {
            _revert(returndata);
        } else {
            return returndata;
        }
    }

    /**
     * @dev Reverts with returndata if present. Otherwise reverts with {FailedInnerCall}.
     */
    function _revert(bytes memory returndata) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert FailedInnerCall();
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.1) (utils/Context.sol)

pragma solidity ^0.8.20;

/**
 * @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;
    }

    function _contextSuffixLength() internal view virtual returns (uint256) {
        return 0;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.0.0) (utils/ReentrancyGuard.sol)

pragma solidity ^0.8.20;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant NOT_ENTERED = 1;
    uint256 private constant ENTERED = 2;

    uint256 private _status;

    /**
     * @dev Unauthorized reentrant call.
     */
    error ReentrancyGuardReentrantCall();

    constructor() {
        _status = NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be NOT_ENTERED
        if (_status == ENTERED) {
            revert ReentrancyGuardReentrantCall();
        }

        // Any calls to nonReentrant after this point will fail
        _status = ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == ENTERED;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (metatx/ERC2771Context.sol)

pragma solidity ^0.8.9;

import "@openzeppelin/contracts/utils/Context.sol";

/**
 * @dev Context variant with ERC2771 support.
 */
abstract contract ERC2771Context is Context {
    /// @custom:oz-upgrades-unsafe-allow state-variable-immutable
    address internal _trustedForwarder;

    function isTrustedForwarder(
        address forwarder
    ) public view virtual returns (bool) {
        return
            _trustedForwarder != address(0) && 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`.
            /// @solidity memory-safe-assembly
            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();
        }
    }
}

// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.25;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./ILisaSettings.sol";

enum CrowdsaleStatus {
    NOT_PLANNED,
    NOT_STARTED,
    IN_PROGRESS,
    SUCCESSFUL,
    UNSUCCESSFUL
}

struct CrowdsaleSimpleInitParams {
    uint256 rate;
    address sellerAddress;
    IERC20 at;
    IERC20 bt;
    uint256 startDate;
    uint256 endDate;
    uint256 initialSupplyAT;
    uint256 sellerRetainedAmount;
    uint256 minParticipationBT;
    uint256 maxParticipationBT;
    ILisaSettings lisaSettings;
    string salesAgreement;
}

struct CrowdsaleProportionalInitParams {
    uint256 rate;
    address sellerAddress;
    IERC20 at;
    IERC20 bt;
    uint256 presaleStartDate;
    uint256 startDate;
    uint256 endDate;
    uint256 initialSupplyAT;
    uint256 sellerRetainedAmount;
    uint256 minParticipationBT;
    uint256 maxParticipationBT;
    ILisaSettings lisaSettings;
    string salesAgreement;
}

interface ICrowdsale {
    function name() external pure returns (string memory);

    function amountLeftAT() external view returns (uint256);

    function targetSaleProceedsBT() external view returns (uint256);

    function collectedBT() external view returns (uint256);

    function rate() external view returns (uint256);

    function seller() external view returns (address);

    function startTimestamp() external view returns (uint256);

    function endTimestamp() external view returns (uint256);

    function minPurchaseBT() external view returns (uint256);

    function maxPurchaseBT() external view returns (uint256);

    function token() external view returns (address);

    function totalForSaleAT() external view returns (uint256);

    function protocolFeeAT() external view returns (uint256);

    function protocolFeeBT() external view returns (uint256);

    function getAllocationFor(
        address participant
    ) external view returns (uint256);

    function buyTokens(uint256 amountBT) external;

    function buyTokensFor(
        address buyer,
        uint256 amountBT
    ) external returns (uint256, uint256);

    function buyTokensWithPermit(
        uint256 amountBT,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    function claimSaleProceeds() external returns (uint256);

    function claimProtocolFee() external;

    function updateEndTimestamp(uint256 newEndTimestamp) external;

    function updateSellerRetainedAmount(
        uint256 newSellerRetainedAmountAT
    ) external;

    function claimTokens() external returns (uint256);

    function costBT(uint256 amountAT) external view returns (uint256);

    function status() external view returns (CrowdsaleStatus);

    function refund() external returns (uint256);

    function remainingToBuyAT(address buyer) external view returns (uint256);

    function totalPriceBT() external view returns (uint256);

    function tokenBT() external view returns (IERC20);

    function getTokenAmount(uint256 amountBT) external view returns (uint256);

    // --------------------------  EVENTS  --------------------------

    /**
     * @notice Emitted when a buyer reserves tokens
     * @param buyer who reserved the tokens
     * @param tokensAT amount of AT tokens reserved
     */
    event TokensReserved(address indexed buyer, uint256 tokensAT);

    /**
     * @notice Emitted when a buyer claims tokens after a successful crowdsale
     * @param buyer who claimed the tokens
     * @param tokensAT amount of AT tokens claimed
     */
    event TokensClaimed(address indexed buyer, uint256 tokensAT);

    /**
     * @notice Emitted when a buyer receives a refund after an unsuccessful crowdsale or in case of oversubscription
     * @param buyer who received the refund
     * @param tokensBT amount of BT tokens refunded
     */
    event TokensRefunded(address indexed buyer, uint256 tokensBT);
}

//SPDX-License-Identifier: MIT
pragma solidity 0.8.25;

interface ILisaSettings {
    /// @notice Protocol admin address that would be able to perform protocol fee claim
    function protocolAdmin() external view returns (address);

    /// @notice The treasury wallet of LISA protocol that will receive protocol fees
    function protocolArtTreasuryAddress() external view returns (address);

    /// @notice Lisa Protocol commission for each sale taken from the total supply of Art Tokens (AT)
    /// It is taken from the total supply of AT after the successful sale. Defined in basis points. E.g. 1.23% = 123 BPS.
    function protocolATFeeBps() external view returns (uint256);

    /// @notice Lisa Protocol commission for each sale taken from the total sale price in base tokens (BT).
    /// It is taken from the proceeds after the successful sale. Defined in basis points. E.g. 1.23% = 123 BPS.
    function protocolBTFeeBps() external view returns (uint256);

    /// @notice The duration of the buyout period in seconds.
    function buyoutDurationSeconds() external returns (uint256);

    /// @notice The maximum amount of the seller's retained tokens in basis points. E.g. 1.23% = 123 BPS.
    function maxSellerRetainedBps() external returns (uint256);

    /// @notice The trusted meta-transactions forwarder contract address.
    function trustedForwarder() external returns (address);

    /// @notice Stores the logic contract address for a given contract key.
    function setLogic(bytes32 contractId, address contractAddress) external;

    /// @notice Returns the logic contract address by key. All subsequent deployments of protocol contracts will use this function to get the most recent version of logic contracts.
    function getLogic(bytes32 contractId) external view returns (address);
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.25;

import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "./Interfaces/ICrowdsale.sol";
import "./ERC2771Context.sol";

/**
 * @title An abstract class to implement base crowdsale functionality.
 * @notice Crowdsale is a contract for managing a token crowdsale for selling ArtToken (AT) tokens
 * for BaseToken (BT). USDC can be used as a base token. Deployer can specify start and end dates of the crowdsale,
 * along with the limits of purchase amount per transaction and total purchase amount per buyer.
 */
abstract contract LisaCrowdsaleBase is
    ICrowdsale,
    ERC2771Context,
    ReentrancyGuard
{
    using SafeERC20 for IERC20;

    // @notice The ArtToken token being sold
    IERC20 internal tokenAT;

    // @notice The token used as a base currency (e.g. USDC)
    IERC20 public tokenBT;

    // @notice Address of the seller where funds are collected
    address public seller;

    // @notice Amount AT available for sale
    uint256 public amountLeftAT;

    // @notice Total amount of AT units a buyer gets per one BT unit
    uint256 public rate;

    // @notice UNIX timestamp of crowdsale start datetime in seconds
    uint256 public startTimestamp;

    // @notice UNIX timestamp of crowdsale end datetime in seconds
    uint256 public endTimestamp;

    // @notice UNIX timestamp of the original crowdsale end datetime in seconds
    uint256 internal _originalEndTimestamp;

    // @notice Minimum amount of BT per a single purchase transaction
    uint256 public minPurchaseBT;

    // @notice Total amount of BT tokens that were collected during the crowdsale
    uint256 public collectedBT;

    // @notice Total amount of BT tokens that each buyer can spend with one or multiple transactions
    uint256 public maxPurchaseBT;

    // @notice Total price of the crowdsale in BT
    uint256 public totalPriceBT;

    // @notice Total amount of AT tokens allocated for this crowdsale
    uint256 public totalForSaleAT;

    // @notice Total amount of base tokens contributed by each address
    mapping(address => uint256) internal allocationsBT;

    // @notice Flag to indicate if the protocol fee was claimed
    bool public protocolFeeClaimed = false;

    // @notice Amount of AT tokens allocated for the protocol fee, taken from the totalForSaleAT
    uint256 public protocolFeeAT;

    // @notice Amount of BT tokens allocated for the protocol fee, taken from the totalPriceBT
    uint256 public protocolFeeBT;

    // @notice LisaSettings contract to access protocol settings
    ILisaSettings internal settings;

    // @notice Amount of BT tokens that should pe collected by participants (excluding seller allocation)
    uint256 public targetSaleProceedsBT;

    /// @notice the URI of the sales agreement stored in permanent storage
    string public salesAgreementURI;

    modifier onlySeller() {
        require(_msgSender() == seller, "Only seller can call this function.");
        _;
    }

    // -------------------  EXTERNAL, VIEW  -------------------

    /**
     * @notice  The amount of AT tokens available for a given buyer, taking into account their current allocation.
     * @dev     Does not take into account the total amount of AT tokens available for sale.
     * @param   buyer  Address of the buyer.
     * @return  uint256  Amount of AT tokens available for a given buyer.
     */
    function remainingToBuyAT(
        address buyer
    ) public view virtual returns (uint256) {
        return getTokenAmount(maxPurchaseBT) - getAllocationFor(buyer);
    }

    /**
     * @notice  Returns the crowdsale status at the moment of the call.
     * @return  CrowdsaleStatus enum value.
     */
    function status() public view virtual returns (CrowdsaleStatus);

    /**
     * @notice  Returns AT allocation for a given buyer (or seller if they want to retain some AT tokens).
     * @param   buyer Buyer's address that participated in this crowdsale.
     * @return  uint256 Amount of AT tokens allocated for a given buyer.
     */
    function getAllocationFor(
        address buyer
    ) public view virtual returns (uint256);

    /**
     * @notice Returns the number of AT that can be purchased with the specified amountBT
     * @param amountBT Value in baseTokens (e.g. USDC)
     * @return Number of AT that will be purchased with the specified amountBT
     */
    function getTokenAmount(
        uint256 amountBT
    ) public view virtual returns (uint256) {
        return amountBT * rate;
    }

    /**
     * @notice Returns the number of BT that the user should pay for a given number of AT.
     * @param amountAT Value in ArtTokens (refer to tokenAT)
     * @return The number of BT that the user should pay for a given number of AT.
     * For example if BT=USDC, costBT(1 * 10 ^ 18) should return the the cost of 1 AT token in USDC
     */
    function costBT(uint256 amountAT) public view returns (uint256) {
        require(
            amountAT == 0 || amountAT >= rate,
            "Crowdsale: amountAT should not be less than the rate"
        );
        return amountAT / rate;
    }

    /**
     * @notice  Returns the address of the token being sold.
     */
    function token() external view returns (address) {
        return address(tokenAT);
    }

    // -------------------  EXTERNAL, MUTATING  -------------------

    function buyTokens(uint256 amountBT) public virtual override;

    function buyTokensFor(
        address buyer,
        uint256 amountBT
    ) public virtual override returns (uint256, uint256);

    /**
     * @notice Buy tokens with ERC20 permit allowing approvals to be made via signatures, as defined in
     * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
     * @param amountBT amount of purchase in base tokens
     * @param deadline deadline for the permit
     * @param v signature v
     * @param r signature r
     * @param s signature s
     */
    function buyTokensWithPermit(
        uint256 amountBT,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        IERC20Permit(address(tokenBT)).permit(
            _msgSender(),
            address(this),
            amountBT,
            deadline,
            v,
            r,
            s
        );
        buyTokens(amountBT);
    }

    /**
     * @notice Buy tokens with ERC20 permit allowing approvals to be made via signatures, as defined in
     * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
     * If there is not enough AT tokens left, the purchase will be partial
     * @param buyer address of the buyer who receives AT and BT tokens
     * @param amountBT amount of purchase in base tokens
     * @param deadline deadline for the permit
     * @param v signature v
     * @param r signature r
     * @param s signature s
     */
    function buyTokensForWithPermit(
        address buyer,
        uint256 amountBT,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        IERC20Permit(address(tokenBT)).permit(
            _msgSender(),
            address(this),
            amountBT,
            deadline,
            v,
            r,
            s
        );
        buyTokensFor(buyer, amountBT);
    }

    /**
     * @notice  Claim the protocol fee. Can only be called once by the LISA protocol admin
     * when the crowdsale is successful.
     * Transfers the protocol fee amount to the protocol fee wallet.
     */
    function claimProtocolFee() external {
        require(
            _msgSender() == settings.protocolAdmin(),
            "Only Admin can claim"
        );
        require(!protocolFeeClaimed, "Lisa fee already claimed");
        _claimProtocolFee();
    }

    /**
     * @notice  Claim the sale proceeds. Can only be called once by the seller when the crowdsale is successful.
     * Transfers the sale proceeds BT tokens to the caller.
     */
    function claimSaleProceeds() external virtual returns (uint256);

    /**
     * @notice  Request a refund. Can only be called by a participant after the crowdsale is unsuccessful.
     * Transfers the BT tokens to the caller.
     */
    function refund() public virtual nonReentrant returns (uint256) {
        require(
            status() == CrowdsaleStatus.UNSUCCESSFUL,
            "Crowdsale should be unsuccessful to claim tokens"
        );
        require(
            _msgSender() != seller,
            "Crowdsale: Seller cannot request refund"
        );
        uint256 refundBT = allocationsBT[_msgSender()];
        if (refundBT > 0) {
            allocationsBT[_msgSender()] = 0;
            emit TokensRefunded(_msgSender(), refundBT);
            IERC20(tokenBT).safeTransfer(_msgSender(), refundBT);
        }
        return refundBT;
    }

    /**
     * @notice  Update the crowdsale end timestamp. Can only be called by the seller.
     * @param newEndTimestamp New end timestamp in seconds.
     */
    function updateEndTimestamp(uint256 newEndTimestamp) external onlySeller {
        require(
            newEndTimestamp > endTimestamp,
            "Crowdsale: New end timestamp should be greater than the current end timestamp"
        );
        require(
            newEndTimestamp <= _originalEndTimestamp + 30 days,
            "Crowdsale: New end timestamp should not be more than 30 days after original end timestamp"
        );
        require(
            status() == CrowdsaleStatus.IN_PROGRESS ||
                status() == CrowdsaleStatus.NOT_STARTED,
            "Crowdsale: Crowdsale should be in progress or not started to update end timestamp"
        );
        endTimestamp = newEndTimestamp;
    }

    /**
     * @notice  Update the seller retained amount. Can only be called by the seller.
     * The max amount is capped at `settings.maxSellerRetainedBps` of the total supply of AT tokens.
     * @param newAmountAT New seller retained amount in AT.
     */
    function updateSellerRetainedAmount(
        uint256 newAmountAT
    ) external onlySeller {
        require(
            status() == CrowdsaleStatus.IN_PROGRESS ||
                status() == CrowdsaleStatus.NOT_STARTED,
            "Crowdsale: Crowdsale should be in progress or not started to update seller retained amount"
        );
        uint256 curAmountAT = getAllocationFor(seller);
        if (newAmountAT < curAmountAT) {
            _decreaseSellerRetainedAmount(newAmountAT, curAmountAT);
        } else {
            _increaseSellerRetainedAmount(newAmountAT, curAmountAT);
        }
    }

    /**
     * @dev fallback function
     */
    receive() external payable {
        revert("Crowdsale: sending ETH is not supported");
    }

    function updateTrustedForwarder(address forwarder) external onlySeller {
        require(forwarder != address(0), "Crowdsale: forwarder cannot be zero");
        _trustedForwarder = forwarder;
    }

    // -------------------  INTERNAL, MUTATING  -------------------
    /**
     * @dev Executed when a purchase has been validated and is ready to be executed
     * @param buyer Address paying for the tokens
     * @param amountBT Number of baseTokens to be paid
     */
    function _processPurchase(
        address buyer,
        uint256 amountBT
    ) internal virtual {
        tokenBT.safeTransferFrom(buyer, address(this), amountBT);
    }

    function _updatePurchasingState(
        address buyer,
        uint256 amountAT,
        uint256 amountBT
    ) internal virtual;

    function _decreaseSellerRetainedAmount(
        uint256 newSellerRetainedAmountAT,
        uint256 curSellerRetainedAmountAT
    ) internal virtual {
        uint256 diffAT = curSellerRetainedAmountAT - newSellerRetainedAmountAT;
        amountLeftAT += diffAT;
        targetSaleProceedsBT += costBT(diffAT);
        allocationsBT[seller] -= costBT(diffAT);
    }

    function _increaseSellerRetainedAmount(
        uint256 newSellerRetainedAmountAT,
        uint256 curSellerRetainedAmountAT
    ) internal virtual {
        uint256 diffAT = newSellerRetainedAmountAT - curSellerRetainedAmountAT;
        uint maxSellerRetainedAmountAT = (tokenAT.totalSupply() *
            settings.maxSellerRetainedBps()) / 10000;
        diffAT = diffAT + curSellerRetainedAmountAT > maxSellerRetainedAmountAT
            ? maxSellerRetainedAmountAT - curSellerRetainedAmountAT
            : diffAT;
        diffAT = diffAT > amountLeftAT ? amountLeftAT : diffAT;
        amountLeftAT -= diffAT;
        targetSaleProceedsBT -= costBT(diffAT);
        allocationsBT[seller] += costBT(diffAT);
    }

    function _claimProtocolFee() internal {
        require(
            status() == CrowdsaleStatus.SUCCESSFUL,
            "Crowdsale was not successful"
        );
        if (protocolFeeClaimed) {
            return;
        }
        protocolFeeClaimed = true;
        tokenAT.safeTransfer(
            settings.protocolArtTreasuryAddress(),
            protocolFeeAT
        );
        tokenBT.safeTransfer(
            settings.protocolArtTreasuryAddress(),
            protocolFeeBT
        );
    }
}

{
  "optimizer": {
    "enabled": true,
    "runs": 1000,
    "details": {
      "yul": true
    }
  },
  "viaIR": false,
  "evmVersion": "paris",
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "metadata": {
    "useLiteralContent": true
  },
  "libraries": {}
}

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