<?php

declare(strict_types=1);

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

if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    http_response_code(405);
    echo json_encode([
        'status' => 'error',
        'message' => 'Method not allowed',
    ], JSON_UNESCAPED_UNICODE);
    exit;
}

$config = require __DIR__ . '/../config/menu.php';
$languages = is_array($config['languages'] ?? null) ? $config['languages'] : [];
$lang = strtolower(trim((string) ($_GET['lang'] ?? 'pl')));

if ($lang === '' || !isset($languages[$lang])) {
    http_response_code(422);
    echo json_encode([
        'status' => 'error',
        'message' => 'Unsupported language',
        'allowed' => array_keys($languages),
    ], JSON_UNESCAPED_UNICODE);
    exit;
}

$langConfig = $languages[$lang];
$source = (string) ($langConfig['source'] ?? 'upstream');
$ttl = max(60, (int) ($config['ttl_seconds'] ?? 1800));
$timeout = max(3, (int) ($config['timeout_seconds'] ?? 12));
$cacheDir = __DIR__ . '/cache';
$cacheFile = $cacheDir . '/menu_' . $lang . '.json';

if (!is_dir($cacheDir)) {
    @mkdir($cacheDir, 0755, true);
}

function readMenuCache(string $cacheFile): ?array
{
    if (!is_file($cacheFile)) {
        return null;
    }

    $raw = file_get_contents($cacheFile);
    if ($raw === false || $raw === '') {
        return null;
    }

    $decoded = json_decode($raw, true);
    return is_array($decoded) ? $decoded : null;
}

function writeMenuCache(string $cacheFile, array $payload): void
{
    file_put_contents(
        $cacheFile,
        json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
        LOCK_EX
    );
}

function fetchUpstreamMenu(string $url, int $timeout): ?array
{
    $body = false;
    $httpCode = 0;

    if (function_exists('curl_init')) {
        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_TIMEOUT => $timeout,
            CURLOPT_HTTPHEADER => ['Accept: application/json'],
        ]);
        $body = curl_exec($ch);
        $errno = curl_errno($ch);
        $httpCode = (int) curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);
        if ($errno !== 0) {
            $body = false;
        }
    } else {
        $context = stream_context_create([
            'http' => [
                'method' => 'GET',
                'timeout' => $timeout,
                'header' => "Accept: application/json\r\n",
                'ignore_errors' => true,
            ],
        ]);
        $body = @file_get_contents($url, false, $context);
        if (isset($http_response_header[0]) && preg_match('/\s(\d{3})\s/', $http_response_header[0], $m)) {
            $httpCode = (int) $m[1];
        }
    }

    if ($body === false || ($httpCode > 0 && ($httpCode < 200 || $httpCode >= 300))) {
        return null;
    }

    $decoded = json_decode($body, true);
    return is_array($decoded) ? $decoded : null;
}

function mapUpstreamMenu(array $raw, string $lang, string $source): array
{
    $categories = [];
    foreach ($raw['categories'] ?? [] as $cat) {
        if (!is_array($cat)) {
            continue;
        }
        $id = trim((string) ($cat['id'] ?? ''));
        $name = trim((string) ($cat['name'] ?? ''));
        if ($id === '' || $name === '') {
            continue;
        }
        $categories[] = ['id' => $id, 'name' => $name];
    }

    $sections = [];
    foreach ($raw['tables'] ?? [] as $table) {
        if (!is_array($table)) {
            continue;
        }
        $sectionName = trim((string) ($table['name'] ?? ''));
        if ($sectionName === '') {
            continue;
        }

        $items = [];
        foreach ($table['items'] ?? [] as $item) {
            if (!is_array($item)) {
                continue;
            }
            $items[] = [
                'position' => (string) ($item['id'] ?? ''),
                'categoryId' => (string) ($item['category'] ?? ''),
                'tag' => '',
                'image' => (string) ($item['image'] ?? ''),
                'title' => trim((string) ($item['name'] ?? '')),
                'description' => trim((string) ($item['name_extra'] ?? '')),
                'price' => (string) ($item['price'] ?? ''),
            ];
        }

        $sections[] = [
            'categoryName' => $sectionName,
            'items' => $items,
        ];
    }

    return [
        'status' => 'success',
        'lang' => $lang,
        'source' => $source,
        'cachedAt' => gmdate('c'),
        'categories' => $categories,
        'sections' => $sections,
    ];
}

$cached = readMenuCache($cacheFile);
$now = time();
$cachedAtTs = 0;
if ($cached && !empty($cached['cachedAt'])) {
    $cachedAtTs = strtotime((string) $cached['cachedAt']) ?: 0;
}
$isFresh = $cached && $cachedAtTs > 0 && ($now - $cachedAtTs) < $ttl;

if ($isFresh) {
    echo json_encode($cached, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

if ($source === 'ai') {
    if ($cached) {
        echo json_encode($cached, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        exit;
    }
    http_response_code(503);
    echo json_encode([
        'status' => 'error',
        'message' => 'AI menu not available yet',
        'lang' => $lang,
    ], JSON_UNESCAPED_UNICODE);
    exit;
}

$base = rtrim((string) ($config['upstream_base'] ?? ''), '/');
$url = $base . '/' . rawurlencode($lang);
$raw = fetchUpstreamMenu($url, $timeout);

if ($raw === null) {
    if ($cached) {
        echo json_encode($cached, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
        exit;
    }
    http_response_code(502);
    echo json_encode([
        'status' => 'error',
        'message' => 'Failed to fetch menu',
        'lang' => $lang,
    ], JSON_UNESCAPED_UNICODE);
    exit;
}

$mapped = mapUpstreamMenu($raw, $lang, 'upstream');
writeMenuCache($cacheFile, $mapped);

echo json_encode($mapped, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);