Contract Address Details

// SPDX-License-Identifier: MIT

// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.8.0

// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity 0.8.19;

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

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

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

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

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

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

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

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

// File @openzeppelin/contracts/utils/Context.sol@v4.8.0

// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File @openzeppelin/contracts/access/Ownable.sol@v4.8.0

// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.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);
    }
}

/**
 * @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() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // 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;
    }
}

contract Presale is Ownable, ReentrancyGuard {
    uint256 public tokenPrice = 7777 ether; // price of each token in ETH
    uint256 public hardCap = 49772800 ether; // hard cap in ETH
    // uint256 public hardCap = 23331 ether; // hard cap in ETH
    uint256 public filled = 0; // hard cap in ETH
    address public tokenAddress; // address of the token contract
    mapping(address => uint256) public tokenBalances; // keep track of the number of tokens each address holds
    mapping(address => uint256) public invested; // keep track of the amount of ETH each address has invested
    mapping(address => bool) public is_buyer; // mapping for checking if an address has bought tokens
    mapping(address => bool) public claimed; // mapping for checking if an address has claimed tokens

    event TokenPurchase(address indexed buyer, uint256 amount); // emit an event when tokens are purchased
    event Claim(address indexed buyer, uint256 amount); // emit an event when tokens are claimed

    constructor(address _tokenAddress) {
        tokenAddress = _tokenAddress;
    }

    receive() external payable {}

    function setTokenPrice(uint256 _tokenPrice) public onlyOwner {
        tokenPrice = _tokenPrice;
    }

    function setTokenAddress(address _tokenAddress) public onlyOwner {
        tokenAddress = _tokenAddress;
    }

    function buyTokens() public payable nonReentrant {
        require(
            is_buyer[msg.sender] == false,
            "You have already bought tokens"
        );
        require(msg.value == 7777 ether, "Wrong amount of ETH sent");
        require(filled <= hardCap, "Presale is already filled");

        uint256 amount = (msg.value / tokenPrice) * 10 ** 18;
        tokenBalances[msg.sender] += amount;
        invested[msg.sender] += msg.value;
        is_buyer[msg.sender] = true;
        filled += msg.value;
        emit TokenPurchase(msg.sender, amount);
    }

    function isClaimEnabled() public view returns (bool) {
        return filled >= hardCap;
    }

    function claimTokens() external nonReentrant {
        require(filled >= hardCap, "Claim is not yet enabled");

        uint256 amount = tokenBalances[msg.sender];
        require(amount > 0, "not have tokens to claim");

        tokenBalances[msg.sender] = 0;
        claimed[msg.sender] = true;

        IERC20(tokenAddress).transfer(msg.sender, amount);

        emit Claim(msg.sender, amount);
    }

    // function to withdraw ETH from the contract
    function withdraw() public onlyOwner {
        (bool success, ) = payable(owner()).call{value: address(this).balance}(
            ""
        );
        require(success, "Transfer failed.");
    }

    // function to withdraw ERC20 tokens from the contract
    function withdrawToken() public onlyOwner {
        IERC20 token = IERC20(tokenAddress);
        uint256 balance = token.balanceOf(address(this));
        token.transfer(owner(), balance);
    }
}