<?php
declare(strict_types=1);

require_once __DIR__ . '/../db/schema.php';
require_once __DIR__ . '/../ai/LocalAIApi.php';

function sendTelegramMessage(int|string $chatId, string $text, string $token): bool
{
    $url = "https://api.telegram.org/bot{$token}/sendMessage";
    $data = [
        'chat_id' => $chatId,
        'text' => $text,
    ];

    $options = [
        'http' => [
            'header'  => "Content-type: application/x-www-form-urlencoded
",
            'method'  => 'POST',
            'content' => http_build_query($data),
            'timeout' => 20,
        ],
    ];

    $context = stream_context_create($options);
    $result = @file_get_contents($url, false, $context);

    return $result !== false;
}

function findFaqReply(array $faqs, string $message): string
{
    $normalizedMessage = function_exists('mb_strtolower')
        ? mb_strtolower($message, 'UTF-8')
        : strtolower($message);

    foreach ($faqs as $faq) {
        $keywords = isset($faq['keywords']) && is_string($faq['keywords'])
            ? preg_split('/\s*,\s*/', $faq['keywords'])
            : [];

        foreach ($keywords as $keyword) {
            if (!is_string($keyword) || $keyword === '') {
                continue;
            }

            $needle = function_exists('mb_strtolower')
                ? mb_strtolower($keyword, 'UTF-8')
                : strtolower($keyword);

            $found = function_exists('mb_strpos')
                ? mb_strpos($normalizedMessage, $needle, 0, 'UTF-8') !== false
                : strpos($normalizedMessage, $needle) !== false;

            if ($needle !== '' && $found) {
                return (string) ($faq['answer'] ?? '');
            }
        }
    }

    return '';
}

$content = file_get_contents('php://input');
$update = json_decode($content ?: '', true);

if (!is_array($update) || !isset($update['message']) || !is_array($update['message'])) {
    exit;
}

$message = $update['message'];
$chatId = $message['chat']['id'] ?? null;
$text = isset($message['text']) && is_string($message['text']) ? trim($message['text']) : '';

if ($chatId === null || $text === '') {
    exit;
}

try {
    ensureSupportSchema();

    $stmt = db()->prepare('SELECT setting_value FROM settings WHERE setting_key = :setting_key LIMIT 1');
    $stmt->bindValue(':setting_key', 'telegram_token');
    $stmt->execute();
    $token = (string) ($stmt->fetchColumn() ?: '');

    if ($token === '') {
        error_log('Telegram Error: No bot token found in settings.');
        exit;
    }

    $faqs = [];
    try {
        $stmt = db()->query('SELECT keywords, answer FROM faqs ORDER BY id ASC');
        $faqs = $stmt->fetchAll(PDO::FETCH_ASSOC) ?: [];
    } catch (Throwable $faqError) {
        error_log('Telegram FAQ Load Error: ' . $faqError->getMessage());
    }

    $faqReply = findFaqReply($faqs, $text);
    if ($faqReply !== '') {
        try {
            $stmt = db()->prepare('INSERT INTO messages (user_message, ai_response) VALUES (:user_message, :ai_response)');
            $stmt->bindValue(':user_message', '[Telegram] ' . $text);
            $stmt->bindValue(':ai_response', $faqReply);
            $stmt->execute();
        } catch (Throwable $saveError) {
            error_log('Telegram Save Error: ' . $saveError->getMessage());
        }

        sendTelegramMessage($chatId, $faqReply, $token);
        exit;
    }

    $knowledgeBase = "Berikut knowledge base website ini:

";
    if ($faqs === []) {
        $knowledgeBase .= "- Belum ada FAQ khusus yang dikonfigurasi.
";
    } else {
        foreach ($faqs as $faq) {
            $knowledgeBase .= 'Q: ' . ($faq['keywords'] ?? '') . "
";
            $knowledgeBase .= 'A: ' . ($faq['answer'] ?? '') . "
---
";
        }
    }

    $systemPrompt = "Anda adalah asisten AI Telegram untuk website ini. "
        . "Gunakan knowledge base bila relevan. "
        . "Jawab ringkas, jelas, dan profesional dalam Bahasa Indonesia.

"
        . $knowledgeBase;

    $response = LocalAIApi::createResponse(
        [
            'input' => [
                ['role' => 'system', 'content' => $systemPrompt],
                ['role' => 'user', 'content' => $text],
            ],
        ],
        [
            'poll_interval' => 2,
            'poll_timeout' => 45,
        ]
    );

    if (!empty($response['success'])) {
        $aiReply = LocalAIApi::extractText($response);
        if ($aiReply === '') {
            $decoded = LocalAIApi::decodeJsonFromResponse($response);
            if ($decoded) {
                $aiReply = json_encode($decoded, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
            }
        }
        if ($aiReply === '') {
            $aiReply = 'Pesan Anda sudah diterima, tetapi balasan otomatis belum tersedia saat ini.';
        }

        try {
            $stmt = db()->prepare('INSERT INTO messages (user_message, ai_response) VALUES (:user_message, :ai_response)');
            $stmt->bindValue(':user_message', '[Telegram] ' . $text);
            $stmt->bindValue(':ai_response', $aiReply);
            $stmt->execute();
        } catch (Throwable $saveError) {
            error_log('Telegram Save Error: ' . $saveError->getMessage());
        }

        sendTelegramMessage($chatId, $aiReply, $token);
        exit;
    }

    error_log('Telegram AI Error: ' . ($response['error'] ?? 'Unknown'));
    sendTelegramMessage($chatId, 'Maaf, saya belum bisa memproses permintaan Anda saat ini.', $token);
} catch (Throwable $error) {
    error_log('Telegram Webhook Error: ' . $error->getMessage());
}