config.php

<?php
// ==============================
// 📊 DATABASE CONFIGURATION
// ==============================

define("DB_SERVER", "YOUR_DB_SERVER");                  // 🌐 Database host (e.g., 'localhost' or '127.0.0.1')
define("DB_USERNAME", "YOUR_DB_USERNAME");              // 👤 Database username (e.g., 'root')
define("DB_PASSWORD", "YOUR_DB_PASSWORD");              // 🔒 Database password (use a strong password)
define("DB_NAME", "click_payment");                     // 💾 Database name for storing payment data

// ==============================
// 💸 CLICK PAYMENT INTEGRATION
// ==============================

define("MERCHANT_ID", "YOUR_MERCHANT_ID");              // 🏷️ Unique Merchant ID provided by Click
define("SERVICE_ID", "YOUR_SERVICE_ID");                // 💡 Service ID for your specific /service
define("MERCHANT_USER_ID", "YOUR_MERCHANT_USER_ID");    // 👥 Merchant User ID assigned by Click
define("SECRET_KEY", "YOUR_SECRET_KEY");                // 🛡️ Secret key for API authentication (KEEP IT SAFE!)

define("SITE_PATH", $_SERVER['REQUEST_SCHEME'] . "://" . $_SERVER['HTTP_HOST']);
date_default_timezone_set('Etc/GMT-5');

class Database
{
    private $conn;

    public function __construct()
    {
        $this->conn = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_NAME);

        if ($this->conn->connect_error) {
            die("Database connection error: " . $this->conn->connect_error);
        }
    }

    public function __destruct()
    {
        if ($this->conn) {
            $this->conn->close();
        }
    }

    public function executeQuery($sql, $params = [], $types = "")
    {
        $result = $this->conn->prepare($sql);

        if (!$result) {
            return "SQL error: " . $this->conn->error;
        }

        if ($params) {
            $result->bind_param($types, ...$params);
        }

        if (!$result->execute()) {
            return "Execution error: " . $result->error;
        }

        return $result;
    }

    function validate($value)
    {
        return htmlspecialchars(trim(stripslashes($value)), ENT_QUOTES, 'UTF-8');
    }

    public function select($table, $columns = "*", $condition = "", $params = [], $types = "")
    {
        $sql = "SELECT $columns FROM $table" . ($condition ? " WHERE $condition" : "");
        $result = $this->executeQuery($sql, $params, $types);

        if (is_string($result)) {
            return $result;
        }

        return $result->get_result()->fetch_all(MYSQLI_ASSOC);
    }

    public function insert($table, $data)
    {
        $keys = implode(', ', array_keys($data));
        $placeholders = implode(', ', array_fill(0, count($data), '?'));
        $sql = "INSERT INTO $table ($keys) VALUES ($placeholders)";
        $types = str_repeat('s', count($data));

        $result = $this->executeQuery($sql, array_values($data), $types);
        if (is_string($result)) {
            return $result;
        }

        return $this->conn->insert_id;
    }

    public function update($table, $data, $condition = "", $params = [], $types = "")
    {
        $set = implode(", ", array_map(function ($k) {
            return "$k = ?";
        }, array_keys($data)));
        $sql = "UPDATE $table SET $set" . ($condition ? " WHERE $condition" : "");
        $types = str_repeat('s', count($data)) . $types;

        $result = $this->executeQuery($sql, array_merge(array_values($data), $params), $types);
        if (is_string($result)) {
            return $result;
        }

        return $this->conn->affected_rows;
    }

    public function delete($table, $condition = "", $params = [], $types = "")
    {
        $sql = "DELETE FROM $table" . ($condition ? " WHERE $condition" : "");

        $result = $this->executeQuery($sql, $params, $types);
        if (is_string($result)) {
            return $result;
        }

        return $this->conn->affected_rows;
    }

    public function hashPassword($password)
    {
        return hash_hmac('sha256', $password, 'iqbolshoh');
    }

    public function checkUserSession($role)
    {
        if (($_SESSION['loggedin'] ?? false) !== true || ($_SESSION['role'] ?? '') !== $role) {
            header("Location: " . SITE_PATH . "/login/");
            exit;
        }

        if (!$this->select('active_sessions', '*', 'session_token = ?', [session_id()], 's')) {
            header("Location: " . SITE_PATH . "/logout/");
            exit;
        }
    }
}