<?php
// DEFINES
define('DB_SERVER', 'localhost');
define('DB_USERNAME', '');
define('DB_PASSWORD', '');
define('DB_DATABASE', '');

// Core of Platform
class Core{

	public $db;

	/*** for construction process ***/
	public function __construct(){
		$this->db = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_DATABASE);

		if(mysqli_connect_errno()) {
			echo "Error: Could not connect to database.";
		        exit;
		}
	}

	/*** for registration process ***/
	public function register($username,$password,$email){

		$password = md5($password);
		$sql="SELECT * FROM users WHERE username='$username' OR email='$email'";

		//checking if the username or email is available in db
		$check =  $this->db->query($sql) ;
		$count_row = $check->num_rows;

		//if the username is not in db then insert to the table
		if ($count_row == 0){
			$sql1="INSERT INTO users SET username='$username', password='$password', email='$email'";
			$result = mysqli_query($this->db,$sql1) or die(mysqli_connect_errno()."Data cannot inserted");
        	return $result;
		}
		else {
			return false;
		}
	}

	/*** for login process ***/
	public function login($username, $password){

        $password = md5($password);
		$sql2="SELECT user_id from users WHERE username='$username' and password='$password'";

		//checking if the username is available in the table
        $result = mysqli_query($this->db,$sql2);
        $user_data = mysqli_fetch_array($result);
        $count_row = $result->num_rows;

	    if ($count_row == 1) {
	        // this login var will use for the session thing
	        $_SESSION['login'] = true;
	        $_SESSION['uid'] = $user_data['user_id'];
	        return true;
	    }
	    else{
		    return false;
		}
    }

   	/*** return user's data ***/
   	public function get_user_data($user_id, $query){
   		$result = mysqli_query($this->db,"SELECT * FROM users WHERE user_id = $user_id");
   		$user_data = mysqli_fetch_array($result);
   		echo $user_data[$query];
   	}

   	/*** starting the session ***/
    public function get_session(){
        return $_SESSION['login'];
        echo $_SESSION['login'];
    }

    /*** loging out ***/
    public function user_logout() {
        $_SESSION['login'] = FALSE;
        session_destroy();
    }
}

?>