PreSaleMint.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.8.0 <0.9.0;

contract PreSaleMint {
    address public immutable           _owner;
    mapping(address => uint256) public addressMintedBalance;    // # of NFTs minted by every address
    address[] public                   whitelistedAddresses;    // Dynamic array version of the whitelist
    mapping(address => bool) public    whitelistedAddressesMap; // Mapping version of the whitelist
    
    modifier onlyOwner() {
        require(msg.sender == _owner, "Caller is not the owner of the contract.");
        _;
    }
    
    constructor() {
        _owner = msg.sender;
    }

    function isWhitelisted(address _user) public view returns (bool) {
        for(uint i = 0; i < whitelistedAddresses.length; i++) {
            if(whitelistedAddresses[i] == _user) 
                return true;
        }
        
        return false;
    }
    
    function whitelistUsers(address[] calldata _users) public onlyOwner {
        delete whitelistedAddresses;
        whitelistedAddresses = _users;
    }

    function whitelistUsersMap(address[] calldata _users) public onlyOwner {
        for(uint i = 0; i < _users.length; i++) {
            whitelistedAddressesMap[_users[i]] = true;
        }
    }

    function preSaleMintCarMan(uint256 _mintAmount) public {
        require(isWhitelisted(msg.sender), "User is not in the whitelist.");

        for (uint256 i = 1; i <= _mintAmount; i++) { 
            addressMintedBalance[msg.sender]++;
            //_safeMint();
        }
    }

    function preSaleMintModify(uint256 _mintAmount) public {
        require(whitelistedAddressesMap[msg.sender], "User is not in the whitelist.");
        
        for(uint256 i = 1; i <= _mintAmount; i++) {
            addressMintedBalance[msg.sender]++;
            //_safeMint();
        }
    }
}