<?php
declare(strict_types=1);

// -------------------- CONSTANTES --------------------
const CACHE_DIR = '/var/cache/homepage';
const INSTANCES_JSON = CACHE_DIR . '/instances.json';
const URLS_TXT = __DIR__ . '/urls.txt'; // ← Hors du cache, à la racine
const INSTANCES_URL = 'https://searx.space/data/instances.json';
const CACHE_MAX_AGE = 3600; // 1 heure
const BANG_FILE = __DIR__ . '/bang.json';
const USE_SEARX_INSTANCES = true; // false → utilise engines.txt

// -------------------- 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");
header('X-Search-Mode: ' . (USE_SEARX_INSTANCES ? 'searx' : 'engines')); // ← Point 6

// -------------------- CLASSES --------------------

class CacheManager
{
    private array $urlsCache = [];

    public function __construct(private string $cacheDir = CACHE_DIR) {
        if (!is_dir($cacheDir) && !mkdir($cacheDir, 0755, true)) {
            throw new RuntimeException("Impossible de créer le dossier cache");
        }
    }

    public function isExpired(): bool {
        return !file_exists(URLS_TXT) || (time() - filemtime(URLS_TXT)) > CACHE_MAX_AGE;
    }

    public function downloadInstances(): bool {
        $data = file_get_contents(INSTANCES_URL);
        if ($data === false) return false;
        return $this->safeWrite(INSTANCES_JSON, $data);
    }

    public function extractValidUrls(): bool {
        if (!file_exists(INSTANCES_JSON)) return false;

        $json = json_decode(file_get_contents(INSTANCES_JSON), true);
        if (!isset($json['instances']) || !is_array($json['instances'])) return false;

        $valid = array_filter(array_keys($json['instances']), function($url) use ($json) {
            $data = $json['instances'][$url] ?? [];
            return ($data['network_type'] ?? '') === 'normal'
                && ($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);
        });

        if (empty($valid)) return false;

        return $this->safeWrite(URLS_TXT, implode("\n", array_map('rtrim', $valid)));
    }

    private function safeWrite(string $file, string $data): bool {
        $written = file_put_contents($file, $data, LOCK_EX);
        return $written !== false && $written === strlen($data);
    }

    public function loadUrls(): array {
        if (empty($this->urlsCache)) {
            if (!file_exists(URLS_TXT)) return [];
            $urls = file(URLS_TXT, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
            $this->urlsCache = array_filter($urls, fn($url) => filter_var($url, FILTER_VALIDATE_URL));
        }
        return $this->urlsCache;
    }

    public function getRandomUrl(): string {
        $urls = $this->loadUrls();
        if (empty($urls)) throw new RuntimeException("Aucune URL disponible");
        return $urls[array_rand($urls)];
    }
}

class BangManager
{
    private array $bangs = [];

    public function __construct(private string $file = BANG_FILE) {
        $this->loadBangs();
    }

    private function loadBangs(): void {
        if (!file_exists($this->file)) return;
        $data = json_decode(file_get_contents($this->file), true);
        $this->bangs = is_array($data) ? $data : [];
    }

    public function tryRedirect(string $query): bool {
        if (!str_starts_with($query, '!')) return false;
        if (!preg_match('/^!(\w+)\s?(.*)$/u', $query, $matches)) return false;

        [$bangCode, $searchTerm] = [$matches[1], trim($matches[2])];
        if ($searchTerm === '') return false;

        foreach ($this->bangs as $bang) {
            if (($bang['bang'] ?? '') === $bangCode) {
                header("Location: " . rtrim($bang['url'], '/') . '?q=' . rawurlencode($searchTerm));
                exit;
            }
        }
        return false;
    }
}

class EngineManager
{
    private static ?array $cachedEngines = null;
    private array $engines = [];

    public function __construct(private string $file = __DIR__ . '/engines.txt')
    {
        if (self::$cachedEngines === null) {
            $this->loadEngines();
            self::$cachedEngines = $this->engines;
        } else {
            $this->engines = self::$cachedEngines;
        }
    }

    private function loadEngines(): void
    {
        if (!file_exists($this->file)) {
            throw new RuntimeException("Fichier engines.txt introuvable");
        }
        $lines = file($this->file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
        $this->engines = array_filter($lines, fn($line) => !empty(trim($line)));
    }

    public function getRandomEngine(): string
    {
        if (empty($this->engines)) {
            throw new RuntimeException("Aucun moteur de recherche configuré dans engines.txt");
        }
        return $this->engines[array_rand($this->engines)];
    }
}

class SearxHandler
{
    public function __construct(private CacheManager $cache, private BangManager $bang) {}

    public function handle(): void
    {
        $method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
        $query = $_REQUEST['q'] ?? null;

        if ($query !== null && !$this->bang->tryRedirect($query)) {
            $instance = rtrim($this->cache->getRandomUrl(), '/');
            $url = $instance . '/search?' . http_build_query(['q' => $query]);

            if ($method === 'GET') {
                header("Location: $url");
                exit;
            } elseif ($method === 'POST') {
                header("Location: $url"); // Redirige en GET pour simplifier
                exit;
            } else {
                http_response_code(405);
                exit('Méthode non autorisée');
            }
        } elseif ($query === null) {
            $instance = rtrim($this->cache->getRandomUrl(), '/');
            if ($method === 'GET') {
                header("Location: $instance");
                exit;
            } elseif ($method === 'POST') {
                header("Location: $instance");
                exit;
            } else {
                http_response_code(405);
                exit('Méthode non autorisée');
            }
        }
    }
}

class EngineHandler
{
    public function __construct(private EngineManager $engineManager, private BangManager $bang) {}

    public function handle(): void
    {
        $method = $_SERVER['REQUEST_METHOD'] ?? 'GET';
        $query = $_REQUEST['q'] ?? null;

        if ($query !== null && !$this->bang->tryRedirect($query)) {
            $engineTemplate = $this->engineManager->getRandomEngine();
            $url = sprintf($engineTemplate, rawurlencode($query));

            if ($method === 'GET') {
                header("Location: $url");
                exit;
            } elseif ($method === 'POST') {
                header("Location: $url"); // Redirige en GET
                exit;
            } else {
                http_response_code(405);
                exit('Méthode non autorisée');
            }
        } elseif ($query === null) {
            // Rediriger vers la page d'accueil du premier moteur
            $engineTemplate = $this->engineManager->getRandomEngine();
            $homepage = str_replace('?query=%s', '', str_replace('?q=%s', '', $engineTemplate));
            if ($method === 'GET') {
                header("Location: $homepage");
                exit;
            } elseif ($method === 'POST') {
                header("Location: $homepage");
                exit;
            } else {
                http_response_code(405);
                exit('Méthode non autorisée');
            }
        }
    }
}

// -------------------- EXECUTION --------------------
try {
    $bang = new BangManager();
    $engineManager = new EngineManager();

    if (USE_SEARX_INSTANCES) {
        $cache = new CacheManager();
        if ($cache->isExpired()) {
            if (!$cache->downloadInstances() || !$cache->extractValidUrls()) {
                http_response_code(500);
                exit('Erreur interne : veuillez réessayer plus tard.');
            }
        }
        $handler = new SearxHandler($cache, $bang);
    } else {
        $handler = new EngineHandler($engineManager, $bang);
    }

    $handler->handle();

} catch (\Throwable $e) {
    // Ne pas exposer les détails techniques → Point 3
    error_log('Erreur interne : ' . $e->getMessage() . ' | Trace: ' . $e->getTraceAsString());
    http_response_code(500);
    exit('Erreur interne : veuillez réessayer plus tard.');
}