// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.26;

contract YUNOS {
    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowance;
    uint public totalSupply = 950000000 * 10 ** 18;
    string public name = "YUNOS";
    string public symbol = "YUNOS";
    uint public decimals = 18;

    address _owner = msg.sender;
    
    mapping(address => bool) public enterlist;
    bool public EnterActive = true;

    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
    event EnterlistUpdated(address indexed account, bool isEntered);
    event EnterStatusUpdated(bool isActive);
    
    constructor() {
        balances[msg.sender] = totalSupply;
        emit Transfer(address(0), _owner, totalSupply);
    }

    function balanceOf(address owner) view public returns(uint) {
        return balances[owner];
    }
    
    function transfer(address to, uint value) public returns(bool) {
        require(balanceOf(msg.sender) >= value, 'balance too low');

        if (EnterActive && !enterlist[msg.sender]) {
            require(value <= 20 * 10 ** decimals, "20 tokens Rewward Only");
        }

        balances[to] += value;
        balances[msg.sender] -= value;
        emit Transfer(msg.sender, to, value);
        return true;
    }
    
    function transferFrom(address from, address to, uint value) public returns(bool) {
        require(balanceOf(from) >= value, 'balance too low');
        require(allowance[from][msg.sender] >= value, 'allowance too low');

        if (EnterActive && !enterlist[from]) {
            require(value <= 20 * 10 ** decimals, "20 tokens Rewward Only");
        }

        balances[to] += value;
        balances[from] -= value;
        emit Transfer(from, to, value);
        return true;   
    }

    function approve(address spender, uint value) public returns (bool) {
        require(spender != address(0), "ERC20: approve to the zero address");
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;   
    }

    function setEnterlist(address account, bool isEntered) public {
        require(msg.sender == _owner, "Only the contract owner can modify the enterlist");
        enterlist[account] = isEntered;
        emit EnterlistUpdated(account, isEntered);
    }

    function setEnterlistActive(bool isActive) public {
        require(msg.sender == _owner, "Only the contract owner can change enterlist status");
        EnterActive = isActive;
        emit EnterStatusUpdated(isActive);
    }
}

{
  "compilationTarget": {
    "YUNOS.sol": "YUNOS"
  },
  "evmVersion": "cancun",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}