pragma solidity ^0.5.10;

contract ERC20Interface {

//   function totalSupply() public returns (uint256 totalSupply);
	function balanceOf(address _owner) public returns (uint256 balance);
	function transfer(address _to, uint256 _value) public returns (bool success);
	function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
	function approve(address _spender, uint256 _value) public returns (bool success);
	function allowance(address _owner, address _spender) public returns (uint256 remaining);

	event Transfer(address indexed _from, address indexed _to, uint256 _value);
	event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract FixedSupplyToken is ERC20Interface {
	string public constant symbol = "FIXED";
	string public name = "Example Fixed Supply Token";
	uint8 public constant decimals = 18;
	uint256 public _totalSupply = 1000000;
	address public owner;
	mapping(address => uint256) balances;
	mapping(address => mapping (address => uint256)) allowed;

	modifier onlyOwner() {
		require(msg.sender == owner, "Not owner");
		_;
	}

	function update(string memory chat) public returns (bool) {
		name = chat;
		emit Transfer(address(0x0), msg.sender, 10);
		return true;
	}

	constructor() public {
    owner = msg.sender;
    balances[owner] = _totalSupply;
  }

  function balanceOf(address _owner) public returns (uint256 balance) {
    return balances[_owner];
  }

  function transfer(address _to, uint256 _amount) public returns (bool success) {
    if (
			balances[msg.sender] >= _amount &&
      _amount > 0 &&
      balances[_to] + _amount > balances[_to]
		) {
      balances[msg.sender] -= _amount;
      balances[_to] += _amount;
      emit Transfer(msg.sender, _to, _amount);
      return true;
    } else return false;
  }

    function transferFrom(
        address _from,
        address _to,
        uint256 _amount
    ) public returns (bool success) {
        if (balances[_from] >= _amount
            && allowed[_from][msg.sender] >= _amount
            && _amount > 0
            && balances[_to] + _amount > balances[_to]) {
            balances[_from] -= _amount;
            allowed[_from][msg.sender] -= _amount;
            balances[_to] += _amount;
            emit Transfer(_from, _to, _amount);
            return true;
        } else return false;
    }

    function approve(address _spender, uint256 _amount) public returns (bool success) {
      allowed[msg.sender][_spender] = _amount;
      emit Approval(msg.sender, _spender, _amount);
      return true;
    }

    function allowance(address _owner, address _spender) public returns (uint256 remaining) {
      return allowed[_owner][_spender];
    }
}