pragma solidity 0.5.2;

contract EAO {

    string public name = "EasyOption.io Assets Ownership";// token name
    string public symbol = "EAO";// token symbol
    uint256 public decimals = 8;// token digit
    uint256 constant MAX_SUPPLY = 4800000000000000;// max supply

    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    uint256 public totalSupply = 0;
    bool public stopped = false;
    address owner = address(0);

    modifier isOwner {
        assert(owner == msg.sender);
        _;
    }

    modifier isRunning {
        assert (!stopped);
        _;
    }

    modifier validAddress {
        assert(address(0) != msg.sender);
        _;
    }

    constructor() public {
        owner = msg.sender;
        totalSupply = MAX_SUPPLY;
        balanceOf[msg.sender] = MAX_SUPPLY;
        emit Transfer(address(0), msg.sender, MAX_SUPPLY);
    }

    function transfer(address _to, uint256 _value) public isRunning validAddress returns (bool success) {
        require(balanceOf[msg.sender] >= _value);
        require(balanceOf[_to] + _value >= balanceOf[_to]);
        balanceOf[msg.sender] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public isRunning validAddress returns (bool success) {
        require(allowance[_from][msg.sender] >= _value);
        require(balanceOf[_from] >= _value);
        require(balanceOf[_to] + _value >= balanceOf[_to]);
        allowance[_from][msg.sender] -= _value;
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
        return true;
    }

    function approve(address _spender, uint256 _value) public isRunning validAddress returns (bool success) {
        require(_value == 0 || allowance[msg.sender][_spender] == 0);
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function stop() public isOwner {
        stopped = true;
    }

    function start() public isOwner {
        stopped = false;
    }

    function setName(string memory _name) public isOwner {
        name = _name;
    }

    function setSymbol(string memory _symbol) public isOwner {
        symbol = _symbol;
    }

    function burn(uint256 _value) public {
        require(balanceOf[msg.sender] >= _value);
        balanceOf[msg.sender] -= _value;
        balanceOf[address(0)] += _value;
        emit Transfer(msg.sender, address(0), _value);
    }

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}