/**
* From Ethereum Gold initial
* copyleft 2019
*
*/

pragma solidity >=0.4.22 <0.6.0;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  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;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  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;
  }

  /**
  * @dev Substracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

/**
 * The owned contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of user permissions.
 */
contract owned {
    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor() public {
        owner = msg.sender;
    }

    /**
     * Throws if called by any account other than the owner.
     */
    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    /**
     * Allows the current owner to transfer control of the contract to a newOwner.
     * NewOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) onlyOwner public {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}

/**
* Interface provided to external calls.
*/
interface tokenRecipient {
    function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; 
}

contract TokenERC20 {

   //Multi-trans need to be added

	using SafeMath for uint256;
		
    // Public variables of the token
    string public name;
    string public symbol;
    uint8 public decimals = 8;
    // 18 decimals is the strongly suggested default, avoid changing it
    
    uint256 public totalSupply;

    // Contract generation time
    uint public timeBegin;

    // This creates an array with all balances
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    // This generates a public event on the blockchain that will notify clients
    event Transfer(address indexed from, address indexed to, uint256 value);
    
    // This generates a public event on the blockchain that will notify clients
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    /**
     * Initializes contract with initial supply tokens to the creator of the contract.
     */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        string memory tokenSymbol
    ) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                    // Give the creator all initial tokens
        name = tokenName;                                       // Set the name for display purposes
        symbol = tokenSymbol;                                   // Set the symbol for display purposes
    }

    /**
     * Internal transfer, only can be called by this contract.
     */
    function _transfer(address _from, address _to, uint256 _value) internal {
        // Prevent transfer to 0x0 address. Use burn() instead
        require(_to != address(0x0));
        // Check if the sender has enough
        require(balanceOf[_from] >= _value);
        // Check for overflows
        require(balanceOf[_to] + _value > balanceOf[_to]);
        // Save this for an assertion in the future
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
        // Asserts are used to use static analysis to find bugs in your code. They should never fail
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    /**
     * Transfer tokens
     * Send `_value` tokens to `_to` from your account.
     */
    function transfer(address _to, uint256 _value) public returns (bool success) {
        _transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * Transfer tokens from other address
     * Send `_value` tokens to `_to` in behalf of `_from`.
     */
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _to, _value);
        return true;
    }

    /**
     * Set allowance for other address
     * Allows `_spender` to spend no more than `_value` tokens in your behalf.
     */
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * Set allowance for other address and notify
     * Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it.
     */
    function approveAndCall(address _spender, uint256 _value, bytes memory _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, address(this), _extraData);
            return true;
        }
    }

    /**
     * Allows callers to bulk transfer tokens.
     */
    function batch(address []toAddr, uint256 []value) public returns (bool){
        require(toAddr.length == value.length && toAddr.length >= 1);
        for(uint256 i = 0 ; i < toAddr.length; i++){
            transfer(toAddr[i], value[i]);
        }
    }

}