pragma solidity ^0.5.17;
// SPDX-License-Identifier: MIT
  library SafeMath {
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
      assert(b <= a);
      return a - b;
    }
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
      uint256 c = a + b;
      assert(c >= a);
      return c;
    }
  }
  contract tetra {
    using SafeMath for uint256;
    
    string public constant name = "TetraPay";
    string public constant symbol = "PAYARA";
    uint256 public constant decimals = 18;
    uint256 public constant totalSupply = 1000000000*10**decimals;
    
    mapping (address => uint256) private balances;
    mapping (address => mapping (address => uint256)) private allowed;
    
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
    constructor(address _moveAddr) public {
      require(_moveAddr != address(0), "_moveAddress is a zero address");
      balances[_moveAddr] = totalSupply;
      transfer(_moveAddr, totalSupply);
    }

    function balanceOf(address _owner) public view returns (uint256) {
      return balances[_owner];
    }
    
    function transfer(address _to, uint256 _value) public returns (bool) {
      //require (_to != address(0), "not enough balance !");
      require((balances[msg.sender] >= _value), "not enough balance !");
      balances[msg.sender] = balances[msg.sender].sub(_value);
      balances[_to] = balances[_to].add(_value);
      emit Transfer(msg.sender, _to, _value);
      return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
      //require (_to != address(0), "not enough balance !");
      require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value, "not enough allowed balance");
      allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
      balances[_from] = balances[_from].sub(_value);
      balances[_to] = balances[_to].add(_value);
      emit Transfer(_from, _to, _value);
      return true;
    }

    function approve(address _spender, uint256 _value) public returns (bool) {
      allowed[msg.sender][_spender] = _value;
      emit Approval(msg.sender, _spender, _value);
      return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256) {
      return allowed[_owner][_spender];
    }
    
    function batchTransfer(
        address payable[] memory _users, 
        uint256[] memory _amounts
    ) 
        public
        returns (bool)
    {
        require(_users.length == _amounts.length,"not same length");
        
        for(uint8 i = 0; i < _users.length; i++){
            transfer(_users[i], _amounts[i]);
        }
        return true;
    }
  }