DevToken

// SPDX-License-Identifier: MIT
pragma solidity ^0.4.26;

// ========== SafeMath Library (Required for 0.4.26) ==========
library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        assert(c / a == b);
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b > 0);
        return a / b;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        assert(b <= a);
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        assert(c >= a);
        return c;
    }
}

// ========== Ownable Contract ==========
contract Ownable {
    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    function Ownable() public {
        owner = msg.sender;
    }

    modifier onlyOwner() {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}

// ========== Pausable Contract ==========
contract Pausable is Ownable {
    bool public paused;

    event Paused(address account);
    event Unpaused(address account);

    modifier whenNotPaused() {
        require(!paused);
        _;
    }

    modifier whenPaused() {
        require(paused);
        _;
    }

    function pause() public onlyOwner whenNotPaused {
        paused = true;
        emit Paused(msg.sender);
    }

    function unpause() public onlyOwner whenPaused {
        paused = false;
        emit Unpaused(msg.sender);
    }
}

// ========== Main DevToken Contract ==========
contract DevToken is Pausable {
    using SafeMath for uint256;

    string public name;
    string public symbol;
    uint8 public decimals = 18;
    uint256 public totalSupply;

    uint256 public constant MAX_SUPPLY = 1000000 * 10**18; // 1M tokens (18 decimals)

    mapping(address => uint256) private balances;
    mapping(address => mapping(address => uint256)) private allowed;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event Mint(address indexed to, uint256 amount);
    event Burn(address indexed from, uint256 amount);

    // ========== Constructor (0.4.26 Syntax) ==========
    function DevToken(
        string _name,
        string _symbol,
        uint256 _initialSupply
    ) public {
        require(_initialSupply <= MAX_SUPPLY);

        name = _name;
        symbol = _symbol;
        totalSupply = _initialSupply;
        balances[msg.sender] = _initialSupply;
        emit Transfer(address(0), msg.sender, _initialSupply);
        emit Mint(msg.sender, _initialSupply);
    }

    // ========== ERC-20 Standard Functions ==========
    function transfer(address _to, uint256 _value) public whenNotPaused returns (bool) {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    function transferFrom(
        address _from,
        address _to,
        uint256 _value
    ) public whenNotPaused returns (bool) {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    function balanceOf(address _owner) public view returns (uint256) {
        return balances[_owner];
    }

    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) public view returns (uint256) {
        return allowed[_owner][_spender];
    }

    // ========== Minting (Owner Only) ==========
    function mint(address _to, uint256 _amount) public onlyOwner whenNotPaused returns (bool) {
        require(_to != address(0));
        require(totalSupply.add(_amount) <= MAX_SUPPLY);

        totalSupply = totalSupply.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        emit Transfer(address(0), _to, _amount);
        emit Mint(_to, _amount);
        return true;
    }

    // ========== Burning ==========
    function burn(uint256 _amount) public whenNotPaused returns (bool) {
        require(_amount <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_amount);
        totalSupply = totalSupply.sub(_amount);
        emit Transfer(msg.sender, address(0), _amount);
        emit Burn(msg.sender, _amount);
        return true;
    }

    // ========== View Functions ==========
    function getMaxSupply() public pure returns (uint256) {
        return MAX_SUPPLY;
    }

    function getRemainingSupply() public view returns (uint256) {
        return MAX_SUPPLY.sub(totalSupply);
    }
}