// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface ERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address who) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function approveAndCall(address spender, uint tokens, bytes memory data) external returns (bool success);
    function transferFrom(address from, address to, uint256 value) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event Burn(address indexed burner, uint256 value);
}

interface ApproveAndCallFallBack {
    function receiveApproval(address from, uint256 tokens, address token, bytes memory data) external;
}

contract BosSCoin is ERC20 {
  mapping (address => uint256) private balances;
  mapping (address => mapping (address => uint256)) private allowed;
  string public constant name  = "BosS Coin";
  string public constant symbol = "BOSS";
  uint8 public constant decimals = 18;
  
  address owner = msg.sender;

  uint256 _totalSupply = 1000000000000 * (10 ** 18); // 1 trillion supply

    constructor() {
        balances[msg.sender] = _totalSupply;
        emit Transfer(address(0), msg.sender, _totalSupply);
    }

    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address player) public view override returns (uint256) {
        return balances[player];
    }

    function allowance(address player, address spender) public view override returns (uint256) {
        return allowed[player][spender];
    }

    function transfer(address to, uint256 value) public override returns (bool) {
        require(value <= balances[msg.sender]);
        require(to != address(0));

        balances[msg.sender] -= value;
        balances[to] += value;

        emit Transfer(msg.sender, to, value);
        return true;
    }

    function approve(address spender, uint256 value) public override returns (bool) {
        require(spender != address(0));
        allowed[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    function approveAndCall(address spender, uint256 tokens, bytes memory data) external override returns (bool) {
        allowed[msg.sender][spender] = tokens;
        emit Approval(msg.sender, spender, tokens);
        ApproveAndCallFallBack(spender).receiveApproval(msg.sender, tokens, address(this), data);
        return true;
    }

    function transferFrom(address from, address to, uint256 value) public override returns (bool) {
        require(value <= balances[from]);
        require(value <= allowed[from][msg.sender]);
        require(to != address(0));
        
        balances[from] -= value;
        balances[to] += value;
        
        allowed[from][msg.sender] -= value;
        
        emit Transfer(from, to, value);
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        require(spender != address(0));
        allowed[msg.sender][spender] = allowed[msg.sender][spender] + addedValue;
        emit Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        require(spender != address(0));
        allowed[msg.sender][spender] = allowed[msg.sender][spender] - subtractedValue;
        emit Approval(msg.sender, spender, allowed[msg.sender][spender]);
        return true;
    }

    function burn(uint256 amount) external {
        require(amount != 0);
        require(amount <= balances[msg.sender]);
        _totalSupply -= amount;
        balances[msg.sender] -= amount;
        emit Burn(msg.sender, amount);
        emit Transfer(msg.sender, address(0), amount);
    }
}




library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    require(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a / b;
    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);
    return c;
  }

  function ceil(uint256 a, uint256 m) internal pure returns (uint256) {
    uint256 c = add(a,m);
    uint256 d = sub(c,1);
    return mul(div(d,m),m);
  }
}