<?php
// index.php
// Gère génération du cache, redirection classique et gestion des bangs (!code)

// Constantes
define('CACHE_DIR', __DIR__ . '/cache');
define('INSTANCES_JSON', CACHE_DIR . '/instances.json');
define('URLS_TXT',      CACHE_DIR . '/urls.txt');
define('INSTANCES_URL', 'https://searx.space/data/instances.json');
define('CACHE_MAX_AGE', 3600); // 1 heure

// Headers de sécurité
header('X-Frame-Options: SAMEORIGIN');
header('X-Content-Type-Options: nosniff');
header('Referrer-Policy: no-referrer-when-downgrade');
header("Content-Security-Policy: default-src 'none'; frame-ancestors 'none'; sandbox");

// Création dossier cache si nécessaire
if (!is_dir(CACHE_DIR) && !mkdir(CACHE_DIR, 0755, true)) {
    error_log('Erreur création dossier cache');
    http_response_code(500);
    exit('Erreur interne');
}

// Mise à jour du cache si trop vieux ou absent
if (cache_expired()) {
    if (!download_instances_json() || !extract_valid_urls()) {
        error_log('Erreur lors de la génération du cache');
        http_response_code(500);
        exit('Erreur interne');
    }
}

// Récupérer la requête
$query = $_GET['q'] ?? null;

if ($query !== null) {
    if (!is_valid_query($query)) {
        http_response_code(400);
        exit('Paramètre q invalide');
    }

    // Gestion bang : si retourne true, redirection faite et script termine
    if (!try_redirect_bang($query)) {
        redirect_search($query);
    }
} else {
    redirect_random_url();
}

// — Fonctions — //

function cache_expired(): bool
{
    if (!file_exists(URLS_TXT)) {
        return true;
    }
    $age = time() - filemtime(URLS_TXT);
    return $age > CACHE_MAX_AGE;
}

function download_instances_json(): bool
{
    $ch = curl_init(INSTANCES_URL);
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER    => true,
        CURLOPT_FOLLOWLOCATION    => true,
        CURLOPT_TIMEOUT           => 10,
        CURLOPT_SSL_VERIFYPEER    => true,
    ]);
    $data = curl_exec($ch);
    $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    if ($data === false) {
        error_log('curl_exec failed: ' . curl_error($ch));
    }
    curl_close($ch);

    if ($code === 200 && $data !== false) {
        return safe_file_put_contents(INSTANCES_JSON, $data);
    }
    error_log("Erreur téléchargement instances.json, HTTP $code");
    return false;
}

function extract_valid_urls(): bool
{
    if (!file_exists(INSTANCES_JSON)) {
        error_log("instances.json introuvable");
        return false;
    }

    $content = file_get_contents(INSTANCES_JSON);
    if ($content === false) {
        error_log("Impossible de lire instances.json");
        return false;
    }

    $j = json_decode($content, true);
    if (!isset($j['instances']) || !is_array($j['instances'])) {
        error_log("JSON mal formé");
        return false;
    }

    $valid = [];
    foreach ($j['instances'] as $url => $data) {
        if (
            ($data['network_type'] ?? '') === 'normal'
            && ($data['http']['status_code'] ?? 0) === 200
            && ($data['timing']['search']['success_percentage'] ?? 0) === 100.0
            && ($data['timing']['initial']['success_percentage'] ?? 0) === 100.0
            && filter_var($url, FILTER_VALIDATE_URL)
            && in_array(parse_url($url, PHP_URL_SCHEME), ['http', 'https'], true)
        ) {
            $valid[] = rtrim($url, '/');
        }
    }

    if (empty($valid)) {
        error_log("Aucune URL valide");
        return false;
    }

    return safe_file_put_contents(URLS_TXT, implode("\n", $valid));
}

function safe_file_put_contents(string $filename, string $data): bool
{
    $fp = fopen($filename, 'c');
    if (!$fp) {
        error_log("Impossible d'ouvrir $filename en écriture");
        return false;
    }
    if (!flock($fp, LOCK_EX)) {
        fclose($fp);
        error_log("Impossible de verrouiller $filename");
        return false;
    }
    ftruncate($fp, 0);
    $written = fwrite($fp, $data);
    fflush($fp);
    flock($fp, LOCK_UN);
    fclose($fp);

    return $written === strlen($data);
}

function get_all_urls(): array
{
    if (!file_exists(URLS_TXT)) {
        return [];
    }

    $fp = fopen(URLS_TXT, 'r');
    if (!$fp) {
        error_log("Impossible d'ouvrir urls.txt");
        return [];
    }

    if (!flock($fp, LOCK_SH)) {
        fclose($fp);
        error_log("Impossible de verrouiller urls.txt en lecture");
        return [];
    }

    $urls = [];
    while (($line = fgets($fp)) !== false) {
        $line = trim($line);
        if ($line !== '' && filter_var($line, FILTER_VALIDATE_URL)) {
            $urls[] = $line;
        }
    }
    flock($fp, LOCK_UN);
    fclose($fp);

    return $urls;
}

function redirect_random_url(): void
{
    $urls = get_all_urls();
    if (empty($urls)) {
        http_response_code(500);
        exit('Instances indisponibles');
    }
    $target = $urls[array_rand($urls)];
    header("Location: $target");
    exit;
}

function redirect_search(string $query): void
{
    $urls = get_all_urls();
    if (empty($urls)) {
        http_response_code(500);
        exit('Instances indisponibles pour recherche');
    }
    $base = $urls[array_rand($urls)];

    $parsed = parse_url($base);
    if ($parsed === false) {
        error_log("Base URL invalide dans urls.txt");
        http_response_code(500);
        exit('Erreur interne');
    }

    $path = $parsed['path'] ?? '';
    $path = rtrim($path, '/') . '/search';

    $query_string = http_build_query(['q' => $query]);

    $target = $parsed['scheme'] . '://' . $parsed['host'];
    if (isset($parsed['port'])) {
        $target .= ':' . $parsed['port'];
    }
    $target .= $path . '?' . $query_string;

    header("Location: $target");
    exit;
}

function is_valid_query(string $query): bool
{
    $query = trim($query);
    if ($query === '') {
        return false;
    }
    if (mb_strlen($query) > 200) {
        return false;
    }

    // Vérifier que la chaîne est en UTF-8 valide
    if (!mb_check_encoding($query, 'UTF-8')) {
        return false;
    }

    return preg_match('/^[^\x00-\x1F\x7F]+$/u', $query) === 1;
}

// --- Gestion bangs --- //

function load_bangs(): array
{
    $file = __DIR__ . '/bang.json';
    if (!file_exists($file)) {
        error_log("bang.json introuvable");
        return [];
    }
    $content = file_get_contents($file);
    if ($content === false) {
        error_log("Impossible de lire bang.json");
        return [];
    }
    $bangs = json_decode($content, true);
    if (!is_array($bangs)) {
        error_log("bang.json mal formé");
        return [];
    }
    return $bangs;
}

function try_redirect_bang(string $query): bool
{
    if (substr($query, 0, 1) !== '!') {
        return false;
    }

    if (!preg_match('/^!(\w+)\s?(.*)$/u', $query, $matches)) {
        return false;
    }
    $bang_code = $matches[1];
    $search_term = trim($matches[2]);

    if ($search_term === '') {
        return false;
    }

    $bangs = load_bangs();
    if (empty($bangs)) {
        return false;
    }

    foreach ($bangs as $bang) {
        if (($bang['bang'] ?? '') === $bang_code) {
            $base_url = rtrim($bang['url'], '/');
            $search_url = $base_url . '?q=' . rawurlencode($search_term);
            header("Location: $search_url");
            exit;
        }
    }
    return false;
}