pragma solidity 0.4.18;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  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 ERC20 {
  function totalSupply()public view returns (uint total_Supply);
  function balanceOf(address _owner)public view returns (uint256 balance);
  function allowance(address _owner, address _spender)public view returns (uint remaining);
  function transferFrom(address _from, address _to, uint _amount)public returns (bool ok);
  function approve(address _spender, uint _amount)public returns (bool ok);
  function transfer(address _to, uint _amount)public returns (bool ok);
  event Transfer(address indexed _from, address indexed _to, uint _amount);
  event Approval(address indexed _owner, address indexed _spender, uint _amount);
}

contract jioCoin is ERC20
{
    using SafeMath for uint256;
    string public constant symbol = "JIO";
    string public constant name = "JIO Coin";
    uint8 public constant decimals = 4;
    // 100 million total supply // muliplies dues to decimal precision
    uint256 public _totalSupply = 500000000000 * 10 **4;   // 500 billion            
    // Balances for each account
    mapping(address => uint256) balances;   
    // Owner of this contract
    address public owner;
    

    mapping (address => mapping (address => uint)) allowed;
    
    event Transfer(address indexed _from, address indexed _to, uint _value);
    event Approval(address indexed _owner, address indexed _spender, uint _value);

    modifier onlyOwner() {
      if (msg.sender != owner) {
            revert();
        }
        _;
        }
        
    
    function jioCoin() public
    {
        owner = msg.sender;
        balances[owner] = _totalSupply; // 500 billion token with company/owner

    }


    
    // total supply of the tokens
    function totalSupply() public view returns (uint256 total_Supply) {
         total_Supply = _totalSupply;
     }
  
     //  balance of a particular account
     function balanceOf(address _owner)public view returns (uint256 balance) {
         return balances[_owner];
     }
  
     // Transfer the balance from owner's account to another account
     function transfer(address _to, uint256 _amount)public returns (bool success) {
         require( _to != 0x0);
         require(balances[msg.sender] >= _amount 
             && _amount >= 0
             && balances[_to] + _amount >= balances[_to]);
             balances[msg.sender] = balances[msg.sender].sub(_amount);
             balances[_to] = balances[_to].add(_amount);
             Transfer(msg.sender, _to, _amount);
             return true;
     }
  
     // Send _value amount of tokens from address _from to address _to
     // The transferFrom method is used for a withdraw workflow, allowing contracts to send
     // tokens on your behalf, for example to "deposit" to a contract address and/or to charge
     // fees in sub-currencies; the command should fail unless the _from account has
     // deliberately authorized the sender of the message via some mechanism; we propose
     // these standardized APIs for approval:
     function transferFrom(
         address _from,
         address _to,
         uint256 _amount
     )public returns (bool success) {
        require(_to != 0x0); 
         require(balances[_from] >= _amount
             && allowed[_from][msg.sender] >= _amount
             && _amount >= 0
             && balances[_to] + _amount >= balances[_to]);
             balances[_from] = balances[_from].sub(_amount);
             allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_amount);
             balances[_to] = balances[_to].add(_amount);
             Transfer(_from, _to, _amount);
             return true;
             }
 
     // Allow _spender to withdraw from your account, multiple times, up to the _value amount.
     // If this function is called again it overwrites the current allowance with _value.
     function approve(address _spender, uint256 _amount)public returns (bool success) {
         allowed[msg.sender][_spender] = _amount;
         Approval(msg.sender, _spender, _amount);
         return true;
     }
  
     function allowance(address _owner, address _spender)public view returns (uint256 remaining) {
         return allowed[_owner][_spender];
   }

	// drain ether called by only owner
	function drain() external onlyOwner {
        owner.transfer(this.balance);
    }
    
}