// 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/security/Pausable.sol



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

pragma solidity ^0.8.0;

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

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

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

    bool private _paused;

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

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

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

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

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

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

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;

/**
 * @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;

    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() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

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

        _;

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

// 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/token/ERC20/extensions/draft-IERC20Permit.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/draft-IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @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.
 */
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].
     */
    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);
}

// File: @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/draft-IERC20Permit.sol";
import "../../../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;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @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, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

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



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

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal 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
                /// @solidity memory-safe-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
// 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/Presale.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "./interfaces/IPresale.sol";
import "./interfaces/IAggregator.sol";

contract Presale is IPresale, Pausable, Ownable, ReentrancyGuard {
    using SafeERC20 for IERC20;

    address public immutable saleToken;

    uint256 public totalTokensSold;
    uint256 public startTime;
    uint256 public endTime;
    uint256 public claimStart;
    uint256 public currentStep;

    uint256[9] public token_amount;
    uint256[9] public token_price;
    uint8 constant maxStepIndex = 8;

    IERC20 public USDTInterface;
    IAggregator public aggregatorInterface;

    mapping(address => uint256) _userDeposits;
    mapping(address => bool) public hasClaimed;
    mapping(address => bool) public blacklist;

    modifier checkSaleState(uint256 amount) {
        require(
            block.timestamp >= startTime && block.timestamp <= endTime,
            "Invalid time for buying"
        );
        require(amount > 0, "Invalid sale amount");
        require(
            amount + totalTokensSold <= token_amount[maxStepIndex],
            "Insufficient funds"
        );
        _;
    }

    modifier notBlacklisted() {
        require(!blacklist[_msgSender()], "You are in blacklist");
        _;
    }

    /**
     * @dev Creates the contract
     * @param _owner                - Address of owner
     * @param _saleToken start      - Address of Metacade token
     * @param _aggregatorInterface  - Address of Chainlink ETH/USD price feed
     * @param _USDTInterface        - Address of USDT token
     * @param _token_amount         - Array of prices for each presale step
     * @param _token_price          - Array of totalTokenSold limit for each step
     * @param _startTime            - Sale start time
     * @param _endTime              - Sale end time
     */
    constructor(
        address _owner,
        address _saleToken,
        address _aggregatorInterface,
        address _USDTInterface,
        uint256[9] memory _token_amount,
        uint256[9] memory _token_price,
        uint256 _startTime,
        uint256 _endTime
    ) {
        _transferOwnership(_owner);

        require(_aggregatorInterface != address(0), "Zero aggregator address");
        require(_USDTInterface != address(0), "Zero USDT address");
        require(_saleToken != address(0), "Zero sale token address");
        require(_endTime > _startTime, "Invalid time");
        saleToken = _saleToken;
        aggregatorInterface = IAggregator(_aggregatorInterface);
        USDTInterface = IERC20(_USDTInterface);
        token_amount = _token_amount;
        token_price = _token_price;
        startTime = _startTime;
        endTime = _endTime;

        emit SaleTimeSet(_startTime, _endTime, block.timestamp);
    }

    /**
     * @dev To pause the presale
     */
    function pause() external onlyOwner {
        _pause();
    }

    /**
     * @dev To unpause the presale
     */
    function unpause() external onlyOwner {
        _unpause();
    }

    /**
     * @dev To update the sale times
     * @param _startTime - New sales start time
     * @param _endTime   - New sales end time
     */
    function changeSaleTimes(
        uint256 _startTime,
        uint256 _endTime
    ) external onlyOwner {
        if (startTime != _startTime) startTime = _startTime;
        if (endTime != _endTime) endTime = _endTime;
        emit SaleTimeSet(_startTime, _endTime, block.timestamp);
    }

    /**
     * @dev To set the claim
     * @param _claimStart - claim start time
     * @notice Function also makes sure that presale have enough sale token balance
     */
    function configureClaim(
        uint256 _claimStart
    ) external onlyOwner returns (bool) {
        require(
            IERC20(saleToken).balanceOf(address(this)) >=
                totalTokensSold * 1e18,
            "Not enough balance"
        );
        claimStart = _claimStart;
        return true;
    }

    /**
     * @dev To add users to blacklist
     * @param _users - Array of addresses to add in blacklist
     */
    function addToBlacklist(address[] calldata _users) external onlyOwner {
        uint256 usersAmount = _users.length;
        uint256 i = 0;
        while (i < usersAmount) blacklist[_users[i++]] = true;
    }

    /**
     * @dev To remove users from blacklist
     * @param _users - Array of addresses to remove from blacklist
     */
    function removeFromBlacklist(address[] calldata _users) external onlyOwner {
        uint256 usersAmount = _users.length;
        uint256 i = 0;
        while (i < usersAmount) blacklist[_users[i++]] = false;
    }

    /**
     * @dev Returns price for current step
     */
    function getCurrentPrice() external view returns (uint256) {
        return token_price[currentStep];
    }

    /**
     * @dev Returns amount of tokens sold on current step
     */
    function getSoldOnCurrentStage()
        external
        view
        returns (uint256 soldOnCurrentStage)
    {
        soldOnCurrentStage =
            totalTokensSold -
            ((currentStep == 0) ? 0 : token_amount[currentStep - 1]);
    }

    /**
     * @dev Returns presale last stage token amount limit
     */
    function getTotalPresaleAmount() external view returns (uint256) {
        return token_amount[maxStepIndex];
    }

    /**
     * @dev Returns total price of sold tokens
     * @notice Value may be inaccurate, since not all tokens were sold on the beta presale
     */
    function totalSoldPrice() external view returns (uint256) {
        return _calculateInternalCost(totalTokensSold, 0, 0);
    }

    /**
     * @dev Returns total price of sold tokens
     * @param _tokenAddress - Address of token to resque
     * @param _amount       - Amount of tokens to resque
     */
    function resqueERC20(
        address _tokenAddress,
        uint256 _amount
    ) external onlyOwner {
        IERC20(_tokenAddress).safeTransfer(_msgSender(), _amount);
    }

    /**
     * @dev Returns tokens purchased by the user
     * @param _user - Address of user
     */
    function userDeposits(address _user) public view returns (uint256) {
        if (hasClaimed[_user]) return 0;
        return _userDeposits[_user];
    }

    /**
     * @dev To buy into a presale using ETH
     * @param _amount - Amount of tokens to buy
     */
    function buyWithEth(
        uint256 _amount
    )
        external
        payable
        checkSaleState(_amount)
        notBlacklisted
        whenNotPaused
        nonReentrant
        returns (bool)
    {
        uint256 ethAmount = ethBuyHelper(_amount);
        require(msg.value >= ethAmount, "Less payment");
        _sendValue(payable(owner()), ethAmount);
        uint256 excess = msg.value - ethAmount;
        if (excess > 0) _sendValue(payable(_msgSender()), excess);
        totalTokensSold += _amount;
        _userDeposits[_msgSender()] += _amount * 1e18;
        uint8 stepAfterPurchase = _getStepByTotalSoldAmount();
        if (stepAfterPurchase > currentStep) currentStep = stepAfterPurchase;
        emit TokensBought(_msgSender(), _amount, ethAmount, block.timestamp);
        return true;
    }

    /**
     * @dev To buy into a presale using USDT
     * @param _amount - Amount of tokens to buy
     */
    function buyWithUSDT(
        uint256 _amount
    )
        external
        checkSaleState(_amount)
        notBlacklisted
        whenNotPaused
        nonReentrant
        returns (bool)
    {
        uint256 usdtPrice = usdtBuyHelper(_amount);
        require(
            usdtPrice <= USDTInterface.allowance(_msgSender(), address(this)),
            "Not enough allowance"
        );
        USDTInterface.safeTransferFrom(_msgSender(), owner(), usdtPrice);
        totalTokensSold += _amount;
        _userDeposits[_msgSender()] += _amount * 1e18;
        uint8 stepAfterPurchase = _getStepByTotalSoldAmount();
        if (stepAfterPurchase > currentStep) currentStep = stepAfterPurchase;
        emit TokensBought(_msgSender(), _amount, usdtPrice, block.timestamp);
        return true;
    }

    /**
     * @dev To claim tokens after claiming starts
     */
    function claim() external whenNotPaused nonReentrant {
        require(
            block.timestamp >= claimStart && claimStart > 0,
            "Claim has not started yet"
        );
        require(!hasClaimed[_msgSender()], "Already claimed");
        uint256 amount = userDeposits(_msgSender());
        require(amount > 0, "Nothing to claim");
        hasClaimed[_msgSender()] = true;
        IERC20(saleToken).safeTransfer(_msgSender(), amount);
        emit TokensClaimed(_msgSender(), amount, block.timestamp);
    }

    /**
     * @dev To get latest ETH/USD price
     * @notice Return result in 1e18 format
     */
    function getLatestPrice() public view returns (uint256) {
        (, int256 price, , , ) = aggregatorInterface.latestRoundData();
        return uint256(price * 1e10);
    }

    /**
     * @dev Calculate ETH price for given amount
     * @param _amount - Amount of tokens to calculate price
     * @notice Return result in 1e18 format
     */
    function ethBuyHelper(
        uint256 _amount
    ) public view returns (uint256 ethAmount) {
        ethAmount = (calculatePrice(_amount) * 1e18) / getLatestPrice();
    }

    /**
     * @dev Calculate USDT price for given amount
     * @param _amount - Amount of tokens to calculate price
     * @notice Return result in 1e6 format
     */
    function usdtBuyHelper(
        uint256 _amount
    ) public view returns (uint256 usdtPrice) {
        usdtPrice = calculatePrice(_amount) / 1e12;
    }

    /**
     * @dev To calculate the price in USD for given amount of tokens
     * @param _amount - Amount of tokens to calculate price
     * @notice Return result in 1e18 format
     */
    function calculatePrice(uint256 _amount) public view returns (uint256) {
        require(
            _amount + totalTokensSold <= token_amount[maxStepIndex],
            "Insufficient token amount."
        );
        return _calculateInternalCost(_amount, currentStep, totalTokensSold);
    }

    /**
     * @dev For sending ETH from contract
     * @param _recipient - Recipient address
     * @param _weiAmount - Amount of ETH to send in wei
     */
    function _sendValue(
        address payable _recipient,
        uint256 _weiAmount
    ) internal {
        require(address(this).balance >= _weiAmount, "Low balance");
        (bool success, ) = _recipient.call{value: _weiAmount}("");
        require(success, "ETH Payment failed");
    }

    /**
     * @dev Recursively calculate cost for specified conditions
     * @param _amount          - Amount of tokens to calculate price
     * @param _currentStep     - Starting step to calculate price
     * @param _totalTokensSold - Starting total token sold amount to calculate price
     */
    function _calculateInternalCost(
        uint256 _amount,
        uint256 _currentStep,
        uint256 _totalTokensSold
    ) internal view returns (uint256 cost) {
        uint256 currentPrice = token_price[_currentStep];
        uint256 currentAmount = token_amount[_currentStep];
        if (_totalTokensSold + _amount <= currentAmount) {
            cost = _amount * currentPrice;
        } else {
            uint256 currentStageAmount = currentAmount - _totalTokensSold;
            uint256 nextStageAmount = _amount - currentStageAmount;
            cost =
                currentStageAmount *
                currentPrice +
                _calculateInternalCost(
                    nextStageAmount,
                    _currentStep + 1,
                    currentAmount
                );
        }

        return cost;
    }

    /**
     * @dev Calculate current step amount from total tokens sold amount
     */
    function _getStepByTotalSoldAmount() internal view returns (uint8) {
        uint8 stepIndex = maxStepIndex;
        while (stepIndex > 0) {
            if (token_amount[stepIndex - 1] < totalTokensSold) break;
            stepIndex -= 1;
        }
        return stepIndex;
    }
}

// File: contracts/interfaces/IAggregator.sol



// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

interface IAggregator {
    function latestRoundData()
        external
        view
        returns (
            uint80 roundId,
            int256 answer,
            uint256 startedAt,
            uint256 updatedAt,
            uint80 answeredInRound
        );
}

// File: contracts/interfaces/IPresale.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.17;

interface IPresale {
    event SaleTimeSet(uint256 _start, uint256 _end, uint256 timestamp);

    event TokensBought(
        address indexed user,
        uint256 indexed tokensBought,
        uint256 amountPaid,
        uint256 timestamp
    );

    event TokensClaimed(
        address indexed user,
        uint256 amount,
        uint256 timestamp
    );

    event ClaimStartUpdated(
        uint256 prevValue,
        uint256 newValue,
        uint256 timestamp
    );
}