/**
 * @title Metanopoly Finance
 * @dev Metanopoly Finance (MeFI), the core token of the Metanopoly ecosystem.
 */

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract MeFI {
    // Token metadata
    string public constant name = "Metanopoly Finance";
    string public constant symbol = "MeFI";
    uint8 public constant decimals = 18;
    uint256 private _totalSupply;

    // Balances and allowances mappings
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    // Owner of the contract
    address public immutable owner;

    // Events
    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);

    // Modifiers
    modifier onlyOwner() {
        require(msg.sender == owner, "Caller is not the owner");
        _;
    }

    /**
     * @dev Constructor that initializes the contract, minting the entire supply to the deployer.
     */
    constructor() {
        owner = msg.sender;
        uint256 initialSupply = 1_000_000_000 * 10 ** uint256(decimals); // 1 Billion tokens
        _totalSupply = initialSupply;
        _balances[msg.sender] = initialSupply;
        emit Transfer(address(0), msg.sender, initialSupply);
    }

    /**
     * @dev Returns the total token supply.
     */
    function totalSupply() external view returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev Returns the balance of a specific address.
     * @param account The address to query.
     */
    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev Transfers tokens to a specified address.
     * @param recipient The recipient address.
     * @param amount The amount to transfer.
     */
    function transfer(address recipient, uint256 amount) external returns (bool) {
        require(recipient != address(0), "Transfer to the zero address");
        require(_balances[msg.sender] >= amount, "Insufficient balance");

        _balances[msg.sender] -= amount;
        _balances[recipient] += amount;

        emit Transfer(msg.sender, recipient, amount);
        return true;
    }

    /**
     * @dev Approves a spender to use a specified amount on behalf of the caller.
     * @param spender The address authorized to spend.
     * @param amount The amount to authorize.
     */
    function approve(address spender, uint256 amount) external returns (bool) {
        require(spender != address(0), "Approve to the zero address");

        _allowances[msg.sender][spender] = amount;

        emit Approval(msg.sender, spender, amount);
        return true;
    }

    /**
     * @dev Transfers tokens on behalf of an owner.
     * @param sender The address of the token owner.
     * @param recipient The recipient address.
     * @param amount The amount to transfer.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool) {
        require(sender != address(0), "Transfer from the zero address");
        require(recipient != address(0), "Transfer to the zero address");
        require(_balances[sender] >= amount, "Insufficient balance");
        require(_allowances[sender][msg.sender] >= amount, "Allowance exceeded");

        _balances[sender] -= amount;
        _balances[recipient] += amount;
        _allowances[sender][msg.sender] -= amount;

        emit Transfer(sender, recipient, amount);
        return true;
    }

    /**
     * @dev Returns the allowance of a spender for a specific owner.
     * @param owner_ The address of the token owner.
     * @param spender The address of the spender.
     */
    function allowance(address owner_, address spender) external view returns (uint256) {
        return _allowances[owner_][spender];
    }

    /**
     * @dev Burns a specified amount of tokens from the caller's account.
     * @param amount The amount to burn.
     */
    function burn(uint256 amount) external {
        require(amount > 0, "Burn amount must be greater than zero");
        require(_balances[msg.sender] >= amount, "Burn amount exceeds balance");

        _balances[msg.sender] -= amount;
        _totalSupply -= amount;

        emit Burn(msg.sender, amount);
        emit Transfer(msg.sender, address(0), amount);
    }
}

{
  "compilationTarget": {
    "MeFI.sol": "MeFI"
  },
  "evmVersion": "istanbul",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}