<?php
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');

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

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 '';
}

$rawInput = file_get_contents('php://input');
$input = json_decode($rawInput ?: '', true);
$message = '';

if (is_array($input) && isset($input['message']) && is_string($input['message'])) {
    $message = trim($input['message']);
}

if ($message === '') {
    echo json_encode(['reply' => 'Silakan tulis pertanyaan Anda terlebih dahulu.'], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

try {
    ensureSupportSchema();

    $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('FAQ Load Error: ' . $faqError->getMessage());
    }

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

        echo json_encode(['reply' => $faqReply], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        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 yang ramah untuk website ini. "
        . "Gunakan knowledge base bila jawabannya tersedia. "
        . "Jika pertanyaan tidak ada di knowledge base, bantu secara umum dan jelaskan dengan singkat. "
        . "Jawab singkat, jelas, dan profesional dalam Bahasa Indonesia.

"
        . $knowledgeBase;

    $response = LocalAIApi::createResponse(
        [
            'input' => [
                ['role' => 'system', 'content' => $systemPrompt],
                ['role' => 'user', 'content' => $message],
            ],
        ],
        [
            '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', $message);
            $stmt->bindValue(':ai_response', $aiReply);
            $stmt->execute();
        } catch (Throwable $saveError) {
            error_log('DB Save Error: ' . $saveError->getMessage());
        }

        echo json_encode(['reply' => $aiReply], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        exit;
    }

    error_log('AI Error: ' . ($response['error'] ?? 'Unknown'));
    $fallbackReply = 'Saya belum bisa membalas otomatis saat ini. Silakan coba lagi sebentar lagi.';

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

    echo json_encode(['reply' => $fallbackReply], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
} catch (Throwable $error) {
    error_log('Chat Error: ' . $error->getMessage());
    echo json_encode(['reply' => 'Terjadi kesalahan internal. Silakan coba lagi.'], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
}