Master index.php Architecture: Complete Code & A-to-Z Guide

<?php
declare(strict_types=1);

/**
 * ══════════════════════════════════════════════════════════════════════════════
 * Botlify Cloud — Master Production Telegram Bot Engine
 * Version: 4.0 (Official Native Runtime Standard, Complete FSM & Admin Suite)
 *
 * Designed exclusively for the Botlify Cloud Serverless PHP 8.2+ Runtime.
 * Features:
 *   • Auto-loads credentials from Botlify .env file (BOT_TOKEN, ADMIN_CHAT_ID, BOT_USERNAME)
 *   • Direct SQLite 3 (database.db) with WAL mode & 32MB RAM caching
 *   • Self-Healing Database Migrations (ensureColumn) preventing crashes on update
 *   • In-Database Finite State Machine (FSM) with /cancel support
 *   • Full In-Telegram Interactive /admin Panel with Live Stats & copyMessage Broadcast
 *   • 20ms High-speed persistent cURL HTTP/2 socket (bot() helper)
 *   • Strict Error Logging to __DIR__ . '/error.log'
 *   • Immediate callback query answer to dismiss button loading spinners
 * ══════════════════════════════════════════════════════════════════════════════
 */

// ── 0. ERROR LOGGING & PLATFORM RUNTIME CONFIG ───────────────────────────────
@ini_set('log_errors', '1');
@ini_set('error_log', __DIR__ . '/error.log');
@ini_set('display_errors', '0');

// ── 1. CREDENTIALS & ENVIRONMENT AUTO-LOADER ────────────────────────────────
$envFile = __DIR__ . '/.env';
$ENV = [];
if (is_file($envFile)) {
    foreach (file($envFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) as $line) {
        $line = trim($line);
        if ($line !== '' && $line[0] !== '#' && str_contains($line, '=')) {
            [$k, $v] = explode('=', $line, 2);
            $ENV[trim($k)] = trim(trim($v), "'\"");
        }
    }
}

// Bot credentials (auto-injected by Botlify Cloud in .env)
define('BOT_TOKEN', $ENV['BOT_TOKEN'] ?? (getenv('BOT_TOKEN') ?: ''));
define('ADMIN_CHAT_ID', (string)($ENV['ADMIN_CHAT_ID'] ?? (getenv('ADMIN_CHAT_ID') ?: '')));
define('BOT_USERNAME', (string)($ENV['BOT_USERNAME'] ?? (getenv('BOT_USERNAME') ?: '')));
define('DB_FILE', __DIR__ . '/database.db');

// CLI or Health Check Guard
if (BOT_TOKEN === '') {
    if (php_sapi_name() === 'cli' || empty($_SERVER['REQUEST_METHOD'])) {
        echo "Botlify Bot Engine loaded. Please configure BOT_TOKEN in .env or Botlify Studio.\n";
    }
    exit;
}

// ── 2. DATABASE: HIGH-CONCURRENCY SQLITE WAL & SELF-HEALING ENGINE ───────────
function db(): PDO {
    static $pdo = null;
    if ($pdo === null) {
        $pdo = new PDO('sqlite:' . DB_FILE, null, null, [
            PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_TIMEOUT            => 5
        ]);

        // Production-tuned SQLite Pragmas for maximum concurrency
        $pdo->exec('PRAGMA journal_mode = WAL;');
        $pdo->exec('PRAGMA synchronous = NORMAL;');
        $pdo->exec('PRAGMA busy_timeout = 5000;');
        $pdo->exec('PRAGMA cache_size = -32000;'); // 32MB RAM Cache
        $pdo->exec('PRAGMA temp_store = MEMORY;');

        // Initialize Core Schema
        $pdo->exec('CREATE TABLE IF NOT EXISTS users (
            user_id INTEGER PRIMARY KEY,
            username TEXT,
            first_name TEXT,
            is_banned INTEGER DEFAULT 0,
            ban_reason TEXT,
            created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
            last_active DATETIME DEFAULT CURRENT_TIMESTAMP
        );');

        $pdo->exec('CREATE TABLE IF NOT EXISTS user_states (
            chat_id TEXT PRIMARY KEY,
            state TEXT NOT NULL,
            state_data TEXT,
            updated_at INTEGER NOT NULL
        );');

        $pdo->exec('CREATE TABLE IF NOT EXISTS broadcast_logs (
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            admin_id TEXT NOT NULL,
            sent_count INTEGER NOT NULL,
            failed_count INTEGER NOT NULL,
            message_text TEXT,
            created_at DATETIME DEFAULT CURRENT_TIMESTAMP
        );');

        // Self-Healing Column Migrations: ensures columns exist even on old databases
        ensureColumn($pdo, 'users', 'is_banned', 'INTEGER DEFAULT 0');
        ensureColumn($pdo, 'users', 'ban_reason', 'TEXT');
        ensureColumn($pdo, 'users', 'last_active', 'DATETIME');
    }
    return $pdo;
}

function ensureColumn(PDO $pdo, string $table, string $column, string $type = 'TEXT'): void {
    try {
        $cols = $pdo->query("PRAGMA table_info({$table})")->fetchAll(PDO::FETCH_COLUMN, 1);
        if (!in_array($column, $cols, true)) {
            $pdo->exec("ALTER TABLE {$table} ADD COLUMN {$column} {$type}");
        }
    } catch (Throwable $e) {}
}

// ── 3. FINITE STATE MACHINE (FSM) HELPERS ────────────────────────────────────
function getState(int|string $chatId): array {
    $st = db()->prepare("SELECT state, state_data FROM user_states WHERE chat_id = ? LIMIT 1");
    $st->execute([(string)$chatId]);
    $row = $st->fetch();
    if ($row) {
        return ['state' => (string)$row['state'], 'data' => json_decode((string)$row['state_data'], true) ?: []];
    }
    return ['state' => '', 'data' => []];
}

function setState(int|string $chatId, string $state, array $data = []): void {
    $st = db()->prepare("INSERT INTO user_states (chat_id, state, state_data, updated_at) VALUES (?, ?, ?, ?)
        ON CONFLICT(chat_id) DO UPDATE SET state = excluded.state, state_data = excluded.state_data, updated_at = excluded.updated_at");
    $st->execute([(string)$chatId, $state, json_encode($data), time()]);
}

function clearState(int|string $chatId): void {
    $st = db()->prepare("DELETE FROM user_states WHERE chat_id = ?");
    $st->execute([(string)$chatId]);
}

// ── 4. TELEGRAM API ENGINE: 20ms PERSISTENT cURL ─────────────────────────────
function bot(string $method, array $params = []): array {
    if (!defined('BOT_TOKEN') || BOT_TOKEN === '') {
        return ['ok' => false];
    }
    static $ch = null;
    if ($ch === null || !($ch instanceof \CurlHandle || is_resource($ch))) {
        $ch = curl_init();
    }
    $opts = [
        CURLOPT_URL               => 'https://api.telegram.org/bot' . BOT_TOKEN . '/' . $method,
        CURLOPT_RETURNTRANSFER    => true,
        CURLOPT_POST              => true,
        CURLOPT_POSTFIELDS        => json_encode($params, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
        CURLOPT_HTTPHEADER        => ['Content-Type: application/json; charset=utf-8'],
        CURLOPT_CONNECTTIMEOUT    => 8,
        CURLOPT_TIMEOUT           => 15,
        CURLOPT_IPRESOLVE         => CURL_IPRESOLVE_V4,
        CURLOPT_TCP_NODELAY       => true,
        CURLOPT_DNS_CACHE_TIMEOUT => 3600,
        CURLOPT_SSL_VERIFYPEER    => false,
        CURLOPT_SSL_VERIFYHOST    => false
    ];
    if (defined('CURL_HTTP_VERSION_2TLS')) {
        $opts[CURLOPT_HTTP_VERSION] = CURL_HTTP_VERSION_2TLS;
    }
    curl_setopt_array($ch, $opts);
    $res = curl_exec($ch);
    return json_decode((string)$res, true) ?: ['ok' => false];
}

// ── 5. UTILITY & SECURITY HELPERS ───────────────────────────────────────────
function clean(string $text): string {
    return htmlspecialchars($text, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
}

function isAdmin(int|string $userId): bool {
    return ADMIN_CHAT_ID !== '' && (string)$userId === (string)ADMIN_CHAT_ID;
}

function getAdminDashboardMarkup(): array {
    return [
        'inline_keyboard' => [
            [
                ['text' => '📊 Live Analytics', 'callback_data' => 'admin_stats', 'style' => 'primary'],
                ['text' => '📢 Mass Broadcast', 'callback_data' => 'admin_broadcast', 'style' => 'success']
            ],
            [
                ['text' => '👥 User Management', 'callback_data' => 'admin_users'],
                ['text' => '🧹 Clear Error Log', 'callback_data' => 'admin_clear_logs']
            ],
            [
                ['text' => '❌ Close Admin Panel', 'callback_data' => 'admin_close', 'style' => 'danger']
            ]
        ]
    ];
}

function registerOrUpdateUser(int $userId, string $username, string $firstName): array {
    $db = db();
    try {
        $stmt = $db->prepare('INSERT INTO users (user_id, username, first_name) VALUES (?, ?, ?)
            ON CONFLICT(user_id) DO UPDATE SET
                username = excluded.username,
                first_name = excluded.first_name,
                last_active = CURRENT_TIMESTAMP');
        $stmt->execute([$userId, $username, $firstName]);
    } catch (Throwable $e) {
        $stmt = $db->prepare('INSERT OR IGNORE INTO users (user_id, username, first_name) VALUES (?, ?, ?)');
        $stmt->execute([$userId, $username, $firstName]);
    }

    $st = $db->prepare('SELECT * FROM users WHERE user_id = ? LIMIT 1');
    $st->execute([$userId]);
    return $st->fetch() ?: [];
}

// ── 6. MAIN WEBHOOK DISPATCHER ───────────────────────────────────────────────
try {
    $raw = file_get_contents('php://input');
    if (!$raw && isset($GLOBALS['FBH_RAW_INPUT'])) {
        $raw = $GLOBALS['FBH_RAW_INPUT'];
    }
    $update = json_decode((string)$raw, true);

    if (!is_array($update)) {
        http_response_code(200);
        exit('OK');
    }

    // A. Handle Callback Queries (Inline Keyboard Buttons)
    if (isset($update['callback_query'])) {
        $cb        = $update['callback_query'];
        $cbId      = (string)$cb['id'];
        $chatId    = $cb['message']['chat']['id'] ?? 0;
        $messageId = $cb['message']['message_id'] ?? 0;
        $cbUserId  = (int)($cb['from']['id'] ?? 0);
        $data      = (string)($cb['data'] ?? '');

        // Immediately dismiss the loading spinner on user's Telegram client
        bot('answerCallbackQuery', ['callback_query_id' => $cbId]);

        // ── Admin-Only Callback Suite ──
        if (str_starts_with($data, 'admin_')) {
            if (!isAdmin($cbUserId)) {
                bot('answerCallbackQuery', [
                    'callback_query_id' => $cbId,
                    'text'              => '⛔ Unauthorized: Restricted to bot administrator.',
                    'show_alert'        => true
                ]);
                http_response_code(200);
                exit('OK');
            }

            if ($data === 'admin_home') {
                clearState($chatId);
                $totalUsers = (int)db()->query('SELECT COUNT(*) FROM users')->fetchColumn();
                $dbSize = is_file(DB_FILE) ? round(filesize(DB_FILE) / 1024, 2) : 0;
                bot('editMessageText', [
                    'chat_id'      => $chatId,
                    'message_id'   => $messageId,
                    'text'         => "👑 <b>Bot Admin Control Suite</b>\n\n• <b>Total Users:</b> {$totalUsers}\n• <b>Database Size:</b> {$dbSize} KB\n• <b>Engine:</b> SQLite WAL (20ms cURL)\n\nSelect an administrative tool below:",
                    'parse_mode'   => 'HTML',
                    'reply_markup' => getAdminDashboardMarkup()
                ]);
            } elseif ($data === 'admin_stats') {
                $total = (int)db()->query('SELECT COUNT(*) FROM users')->fetchColumn();
                $banned = (int)db()->query('SELECT COUNT(*) FROM users WHERE is_banned = 1')->fetchColumn();
                $dbSize = is_file(DB_FILE) ? round(filesize(DB_FILE) / 1024, 2) : 0;
                $logSize = is_file(__DIR__ . '/error.log') ? round(filesize(__DIR__ . '/error.log') / 1024, 2) : 0;

                bot('editMessageText', [
                    'chat_id'      => $chatId,
                    'message_id'   => $messageId,
                    'text'         => "📊 <b>Live Platform Analytics</b>\n━━━━━━━━━━━━━━━━━━━━━\n"
                                    . "• <b>Total Users:</b> " . number_format($total) . "\n"
                                    . "• <b>Active Users:</b> " . number_format($total - $banned) . "\n"
                                    . "• <b>Suspended/Banned:</b> {$banned}\n"
                                    . "• <b>Database (database.db):</b> {$dbSize} KB\n"
                                    . "• <b>Error Log (error.log):</b> {$logSize} KB\n"
                                    . "• <b>Speed:</b> ~20ms Persistent cURL",
                    'parse_mode'   => 'HTML',
                    'reply_markup' => [
                        'inline_keyboard' => [
                            [['text' => '« Back to Admin Panel', 'callback_data' => 'admin_home']]
                        ]
                    ]
                ]);
            } elseif ($data === 'admin_broadcast') {
                setState($chatId, 'admin_awaiting_broadcast');
                bot('editMessageText', [
                    'chat_id'      => $chatId,
                    'message_id'   => $messageId,
                    'text'         => "📢 <b>Universal Multi-Media Broadcast Mode</b>\n━━━━━━━━━━━━━━━━━━━━━\n"
                                    . "Send or forward the message you want to broadcast.\n\n"
                                    . "✅ <i>Supports: Text, Photos, Videos, Documents, Audio, Voice, and Stickers!</i>\n\n"
                                    . "Send <code>/cancel</code> to abort anytime.",
                    'parse_mode'   => 'HTML',
                    'reply_markup' => [
                        'inline_keyboard' => [
                            [['text' => '❌ Cancel Broadcast', 'callback_data' => 'admin_home', 'style' => 'danger']]
                        ]
                    ]
                ]);
            } elseif ($data === 'admin_users') {
                $recent = db()->query('SELECT user_id, username, first_name, is_banned FROM users ORDER BY rowid DESC LIMIT 5')->fetchAll();
                $list = "👥 <b>Recent Users & Management</b>\n━━━━━━━━━━━━━━━━━━━━━\n";
                foreach ($recent as $r) {
                    $uName = !empty($r['username']) ? '@' . clean($r['username']) : 'No @';
                    $status = !empty($r['is_banned']) ? '🔴 BANNED' : '🟢 ACTIVE';
                    $list .= "• <code>{$r['user_id']}</code> | {$uName} | {$status}\n";
                }
                $list .= "\n<b>Quick Actions:</b>\n• Ban: <code>/ban &lt;user_id&gt; &lt;reason&gt;</code>\n• Unban: <code>/unban &lt;user_id&gt;</code>";

                bot('editMessageText', [
                    'chat_id'      => $chatId,
                    'message_id'   => $messageId,
                    'text'         => $list,
                    'parse_mode'   => 'HTML',
                    'reply_markup' => [
                        'inline_keyboard' => [
                            [['text' => '« Back to Admin Panel', 'callback_data' => 'admin_home']]
                        ]
                    ]
                ]);
            } elseif ($data === 'admin_clear_logs') {
                if (is_file(__DIR__ . '/error.log')) {
                    @file_put_contents(__DIR__ . '/error.log', '');
                }
                bot('answerCallbackQuery', [
                    'callback_query_id' => $cbId,
                    'text'              => '🧹 error.log has been cleared!',
                    'show_alert'        => false
                ]);
                bot('editMessageText', [
                    'chat_id'      => $chatId,
                    'message_id'   => $messageId,
                    'text'         => "🧹 <b>Logs Cleared</b>\n\n<code>error.log</code> is now empty (0 KB).",
                    'parse_mode'   => 'HTML',
                    'reply_markup' => [
                        'inline_keyboard' => [
                            [['text' => '« Back to Admin Panel', 'callback_data' => 'admin_home']]
                        ]
                    ]
                ]);
            } elseif ($data === 'admin_close') {
                clearState($chatId);
                bot('deleteMessage', ['chat_id' => $chatId, 'message_id' => $messageId]);
            }

            http_response_code(200);
            exit('OK');
        }

        // ── Public User Callbacks ──
        if ($data === 'nav_help') {
            bot('sendMessage', [
                'chat_id'    => $chatId,
                'text'       => "📖 <b>Botlify Cloud Documentation & Help</b>\n\nThis bot is running on the <b>Botlify Native PHP 8.2+ Runtime</b> with SQLite WAL mode.\n\nUse /start to return to the main dashboard.",
                'parse_mode' => 'HTML'
            ]);
        } elseif ($data === 'nav_stats') {
            $userCount = db()->query('SELECT COUNT(*) FROM users')->fetchColumn();
            bot('sendMessage', [
                'chat_id'    => $chatId,
                'text'       => "📊 <b>Live Platform Statistics</b>\n\n• Total Registered Users: <b>" . number_format((int)$userCount) . "</b>\n• Database Engine: <b>SQLite 3 (database.db)</b>\n• Execution Speed: <b>~20ms cURL</b>",
                'parse_mode' => 'HTML'
            ]);
        }

        http_response_code(200);
        exit('OK');
    }

    // B. Handle Incoming Messages
    if (isset($update['message'])) {
        $msg       = $update['message'];
        $chatId    = $msg['chat']['id'] ?? 0;
        $userId    = (int)($msg['from']['id'] ?? 0);
        $firstName = (string)($msg['from']['first_name'] ?? 'User');
        $username  = (string)($msg['from']['username'] ?? '');
        $text      = trim((string)($msg['text'] ?? ''));

        if (!$chatId || !$userId) {
            http_response_code(200);
            exit('OK');
        }

        // Register or refresh user in database.db
        $user = registerOrUpdateUser($userId, $username, $firstName);

        // Ban Firewall: Intercepts banned users
        if (!empty($user['is_banned'])) {
            $reason = !empty($user['ban_reason']) ? clean((string)$user['ban_reason']) : 'Violation of bot terms';
            bot('sendMessage', [
                'chat_id'      => $chatId,
                'text'         => "⛔ <b>Access Denied: Your Account is Suspended</b>\n\n⚠️ <b>Reason:</b> <i>{$reason}</i>",
                'parse_mode'   => 'HTML',
                'reply_markup' => ['remove_keyboard' => true]
            ]);
            http_response_code(200);
            exit('OK');
        }

        // Global /cancel command
        if ($text === '/cancel') {
            clearState($chatId);
            bot('sendMessage', [
                'chat_id'      => $chatId,
                'text'         => '❌ <i>Operation cancelled.</i>',
                'parse_mode'   => 'HTML',
                'reply_markup' => ['remove_keyboard' => true]
            ]);
            http_response_code(200);
            exit('OK');
        }

        // ── Active FSM Interceptor ──
        $userState = getState($chatId);
        if ($userState['state'] === 'admin_awaiting_broadcast' && isAdmin($userId)) {
            clearState($chatId);
            $msgId = (int)($msg['message_id'] ?? 0);
            bot('sendChatAction', ['chat_id' => $chatId, 'action' => 'typing']);

            $stmt = db()->query('SELECT user_id FROM users WHERE is_banned = 0');
            $allUsers = $stmt->fetchAll(PDO::FETCH_COLUMN);

            $sent = 0;
            $failed = 0;
            foreach ($allUsers as $targetUid) {
                // Universal copyMessage: clones text, photos, videos, stickers, voice with zero re-upload!
                $res = bot('copyMessage', [
                    'chat_id'      => $targetUid,
                    'from_chat_id' => $chatId,
                    'message_id'   => $msgId
                ]);
                if (!empty($res['ok'])) {
                    $sent++;
                } else {
                    $failed++;
                }
                usleep(38000); // 38ms safe sleep (~26 msg/sec anti-flood)
            }

            // Log broadcast
            $logStmt = db()->prepare('INSERT INTO broadcast_logs (admin_id, sent_count, failed_count, message_text) VALUES (?, ?, ?, ?)');
            $logStmt->execute([(string)$userId, $sent, $failed, $text !== '' ? $text : '[Media/Attachment]']);

            bot('sendMessage', [
                'chat_id'      => $chatId,
                'text'         => "✅ <b>Universal Broadcast Complete!</b>\n━━━━━━━━━━━━━━━━━━━━━\n• Successfully Sent: <b>{$sent}</b>\n• Failed / Blocked: <b>{$failed}</b>\n• Total Reached: <b>" . ($sent + $failed) . "</b>",
                'parse_mode'   => 'HTML',
                'reply_markup' => getAdminDashboardMarkup()
            ]);
            http_response_code(200);
            exit('OK');
        }

        // ── Admin Command: /admin ──
        if ($text === '/admin') {
            if (!isAdmin($userId)) {
                bot('sendMessage', [
                    'chat_id'    => $chatId,
                    'text'       => '⛔ <i>Access denied. This command is restricted to the bot administrator.</i>',
                    'parse_mode' => 'HTML'
                ]);
                http_response_code(200);
                exit('OK');
            }

            clearState($chatId);
            $totalUsers = (int)db()->query('SELECT COUNT(*) FROM users')->fetchColumn();
            $dbSize = is_file(DB_FILE) ? round(filesize(DB_FILE) / 1024, 2) : 0;

            bot('sendMessage', [
                'chat_id'      => $chatId,
                'text'         => "👑 <b>Bot Admin Control Suite</b>\n\n• <b>Total Users:</b> {$totalUsers}\n• <b>Database Size:</b> {$dbSize} KB\n• <b>Engine:</b> SQLite WAL (20ms cURL)\n\nSelect an administrative tool below:",
                'parse_mode'   => 'HTML',
                'reply_markup' => getAdminDashboardMarkup()
            ]);
            http_response_code(200);
            exit('OK');
        }

        // ── Admin Command: /ban <user_id> <reason> ──
        if (str_starts_with($text, '/ban') && isAdmin($userId)) {
            $parts = explode(' ', $text, 3);
            $targetUid = (int)($parts[1] ?? 0);
            $banReason = trim($parts[2] ?? 'Banned by administrator');

            if ($targetUid <= 0) {
                bot('sendMessage', ['chat_id' => $chatId, 'text' => "⚠️ <b>Usage:</b> <code>/ban &lt;user_id&gt; &lt;reason&gt;</code>", 'parse_mode' => 'HTML']);
                http_response_code(200);
                exit('OK');
            }

            $st = db()->prepare('UPDATE users SET is_banned = 1, ban_reason = ? WHERE user_id = ?');
            $st->execute([$banReason, $targetUid]);

            bot('sendMessage', [
                'chat_id'    => $chatId,
                'text'       => "🔴 <b>User Banned Successfully</b>\n\n• <b>User ID:</b> <code>{$targetUid}</code>\n• <b>Reason:</b> {$banReason}",
                'parse_mode' => 'HTML'
            ]);
            http_response_code(200);
            exit('OK');
        }

        // ── Admin Command: /unban <user_id> ──
        if (str_starts_with($text, '/unban') && isAdmin($userId)) {
            $parts = explode(' ', $text, 2);
            $targetUid = (int)($parts[1] ?? 0);

            if ($targetUid <= 0) {
                bot('sendMessage', ['chat_id' => $chatId, 'text' => "⚠️ <b>Usage:</b> <code>/unban &lt;user_id&gt;</code>", 'parse_mode' => 'HTML']);
                http_response_code(200);
                exit('OK');
            }

            $st = db()->prepare('UPDATE users SET is_banned = 0, ban_reason = NULL WHERE user_id = ?');
            $st->execute([$targetUid]);

            bot('sendMessage', [
                'chat_id'    => $chatId,
                'text'       => "🟢 <b>User Unbanned Successfully</b>\n\n• <b>User ID:</b> <code>{$targetUid}</code>",
                'parse_mode' => 'HTML'
            ]);
            http_response_code(200);
            exit('OK');
        }

        // ── General User Command: /start ──
        if ($text === '/start') {
            $welcomeText = "👋 <b>Welcome, " . clean($firstName) . "!</b>\n\n"
                         . "Your high-speed Telegram bot is online and powered by <b>Botlify Cloud</b>.\n\n"
                         . "• <b>Runtime:</b> PHP 8.2+ Serverless\n"
                         . "• <b>Storage:</b> SQLite WAL (<code>database.db</code>)\n"
                         . "• <b>Self-Healing:</b> Auto-migrating database schema\n"
                         . "• <b>Latency:</b> Sub-20ms Persistent cURL";

            bot('sendMessage', [
                'chat_id'           => $chatId,
                'text'              => $welcomeText,
                'parse_mode'        => 'HTML',
                'message_effect_id' => '5104841245755180586', // Full-screen confetti
                'reply_markup'      => [
                    'inline_keyboard' => [
                        [
                            ['text' => '📊 Live Stats', 'callback_data' => 'nav_stats', 'style' => 'primary'],
                            ['text' => '📖 Help Guide', 'callback_data' => 'nav_help']
                        ],
                        [
                            ['text' => '🌐 Botlify Cloud', 'url' => 'https://botlify.cloud']
                        ]
                    ]
                ]
            ]);
            http_response_code(200);
            exit('OK');
        }

        // Fallback response for unhandled text
        bot('sendMessage', [
            'chat_id'    => $chatId,
            'text'       => "🤖 <i>Message received. Use /start to explore the bot dashboard.</i>",
            'parse_mode' => 'HTML'
        ]);
    }

    http_response_code(200);
    echo 'OK';
} catch (Throwable $e) {
    error_log(date('[Y-m-d H:i:s] ') . 'Bot Error: ' . $e->getMessage() . ' in ' . $e->getFile() . ':' . $e->getLine());
    http_response_code(200);
    echo 'OK';
}

function bot(string $method, array $params = []): array {
    static $ch = null; // Reused across calls in the same execution thread
    if ($ch === null) {
        $ch = curl_init();
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_POST           => true,
            CURLOPT_TIMEOUT        => 12,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_HTTPHEADER     => ['Content-Type: application/json']
        ]);
    }
    // ...
}

You are the Senior Telegram Bot Architect for Botlify Cloud (https://botlify.cloud).
When writing or editing Telegram bot PHP code, you MUST follow these non-negotiable platform rules:

1. ARCHITECTURE & SPEED (20ms Engine):
   - Language: Strict PHP 8.2+ without composer dependencies.
   - Database: Local SQLite 3 via PDO ('sqlite:' . __DIR__ . '/database.db') with WAL mode enabled:
     PRAGMA journal_mode = WAL;
     PRAGMA synchronous = NORMAL;
     PRAGMA busy_timeout = 5000;
   - cURL Socket: Always use a static persistent cURL socket inside bot($method, $params) sending json_encode($params) with Content-Type: application/json.
   - Never use file_get_contents() for Telegram API requests.

2. SECURITY SANDBOX COMPLIANCE:
   - Prohibited functions: exec, shell_exec, system, passthru, eval, proc_open, popen, pcntl_*, posix_*, or root path traversal (../).
   - Shell execution backticks (`...`) are strictly blocked.
   - Telegram Markdown backticks inside literal strings (e.g. "`code`") are safe and allowed.

3. IN-TELEGRAM ADMIN SUITE:
   - Gated by numeric ADMIN_CHAT_ID constant.
   - Include /admin with live stats (total users, active 24h, database size).
   - Use usleep(38000) for safe rate pacing (~26 msgs/sec) during mass broadcasts.

4. DELIVERABLE:
   - Return clean, complete, copy-paste ready PHP index.php with self-healing schemas (CREATE TABLE IF NOT EXISTS).
   - Always end scripts with exit('OK'); for webhook efficiency.