// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;

contract Token{
    mapping(address => uint) public balances;
    mapping(address => mapping(address => uint)) public allowance;
    uint public totalSupply = 20000000 * 10 ** 18;
    string public name = "Trilogy";
    string public symbol = "TGY";
    uint public decimals = 18;
    
    event Transfer (address indexed from, address indexed to, uint value);
    event Approval (address indexed owner, address indexed spender, uint value);
    
    constructor() {
       balances[msg.sender] = totalSupply; 
    }
    
    function balanceOf(address owner) public view returns(uint){
        
        
        return balances[owner];
    }
    
    function transfer(address to, uint value)public returns(bool){
        require(balanceOf(msg.sender) >= value , 'Balance too low');
        balances[to] +=  value;
        balances[msg.sender] -= value;
        emit Transfer(msg.sender, to, value);
        return true;
    }
    
    function transferFrom(address from, address to, uint value) public returns(bool){
        require (balanceOf(from) >= value , "Balance too low");
        require (allowance[from][msg.sender] >= value, "Allowance too low");
        balances[to] +=  value;
        balances[from] -= value;
        emit Transfer(from, to , value);
        return true;
    }
    
    function approve(address spender, uint value)public returns(bool){
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender,spender,value);
        return true;
    }
}