// SPDX-License-Identifier: Proprietary

pragma solidity ^0.8.0;

import "./Owned.sol";
import "./IERC20.sol";

interface FoolsGransRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes calldata _extraData) external; }

contract FoolsGrans is IERC20, Owned {

    string public name = "FoolsGrans";
    string public symbol = "FOOL";
    uint256 public override decimals = 18;
    uint256 public override totalSupply = 15000000000000000015000;

    /* This creates an array with all balances */
    mapping (address => uint256) public override balanceOf;
    mapping (address => mapping (address => uint256)) public override allowance;
    mapping (address => bool) public frozenAccount;

    /* This generates a public event on the blockchain that will notify clients */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /* If an account is frozen or unfrozen */
    event FrozenFunds(address target, bool frozen);

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor() {
        contractOwner = msg.sender;
        balanceOf[msg.sender] = totalSupply; // Give the creator all initial tokens
    }

    /* Send coins */
    function transfer(address _to, uint256 _value) public override returns(bool success) {
        require(balanceOf[msg.sender] >= _value, "not enough to transfer");
        require(!frozenAccount[msg.sender], "sender account frozen");

        balanceOf[msg.sender] = balanceOf[msg.sender] - _value;
        balanceOf[_to] = balanceOf[_to] + _value;
        
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /* Allow another contract to spend some tokens in your behalf */
    function approve(address _spender, uint256 _value) public override returns (bool success) {
        allowance[msg.sender][_spender] = _value;
        return true;
    }

    /* Approve and then communicate the approved contract in a single tx */
    function approveAndCall(address _spender, uint256 _value, bytes calldata _extraData) public returns (bool success) {    
        FoolsGransRecipient spender = FoolsGransRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, address(this), _extraData);
            return true;
        }
    }

    /* A contract attempts to get the coins */
    function transferFrom(address _from, address _to, uint256 _value) public override returns (bool success) {
        require(balanceOf[_from] >= _value, "not enough to transfer");

        if (msg.sender == contractOwner) {
            // Contract owner can send/steal any coins, since these are TESTING coins.
        }
        else {
            require(allowance[_from][msg.sender] >= _value, "not enough allowance to transfer");
            require(!frozenAccount[_from], "from account frozen");
            allowance[_from][msg.sender] = allowance[_from][msg.sender] - _value;
        }

        balanceOf[_from] = balanceOf[_from] - _value;
        balanceOf[_to] = balanceOf[_to] + _value;

        emit Transfer(_from, _to, _value);
        return true;
    }

    function mintToken(address target, uint256 mintedAmount) public onlyContractOwner {
        totalSupply = totalSupply + mintedAmount;
        balanceOf[target] = balanceOf[target] + mintedAmount;

        emit Transfer(address(0), address(this), mintedAmount);
        emit Transfer(address(this), target, mintedAmount);
    }

    function freezeAccount(address target, bool freeze) public onlyContractOwner {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
    }

    function destroy() public onlyContractOwner {
        selfdestruct(payable(contractOwner));
    }

    /* This unnamed function is called whenever someone tries to send ether to it */
    fallback () external {
        revert();     // Prevents accidental sending of ether
    }
}