// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract ERC20 is IERC20 {
    mapping (address => uint256) private _balances;
    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor (string memory name_, string memory symbol_, uint8 decimals_, uint256 initialSupply_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
        _mint(msg.sender, initialSupply_);
    }

     function name() public view virtual returns (string memory) {
        return _name;
    }

    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual returns (uint8) {
        return _decimals;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][msg.sender];
        _approve(sender, msg.sender, currentAllowance - amount);
        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}

contract TienShinhan is ERC20 {
    mapping (address => bool) public isExempt;
    mapping (address => uint256) public purchaseTime;

    address private _owner;

    constructor (
        string memory name_, 
        string memory symbol_, 
        uint8 decimals_, 
        uint256 initialSupply_,
        address[] memory exemptAddresses // This is the list of initial exempt addresses
    ) 
        ERC20(name_, symbol_, decimals_, initialSupply_ * 10 ** decimals_) { // Multiplying by 10**decimals to correctly handle decimal places
        _owner = msg.sender;

        // Setting the contract creator as exempt
        isExempt[_owner] = true;

        // Setting exempt status for each initial exempt address
        for (uint i = 0; i < exemptAddresses.length; i++) {
            isExempt[exemptAddresses[i]] = true;
        }
    }

    function renounceOwnership() public {
        require(msg.sender == _owner, "Only the contract owner can renounce ownership");
        _owner = address(0);
    }

    function setExemptStatus(address account, bool _isExempt) public {
        require(account != address(0), "Invalid address");
        require(msg.sender == _owner, "Only the contract creator can use this function");
        isExempt[account] = _isExempt;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual override {
        if (!isExempt[sender] && block.timestamp < purchaseTime[sender] + 15 days) {
            revert("Tokens are locked for the first 15 days after purchase");
        }

        if (purchaseTime[recipient] == 0 && !isExempt[recipient]) {
            purchaseTime[recipient] = block.timestamp;
        }

        super._transfer(sender, recipient, amount);
    }
}