<?php

require_once '/var/www/src/bootstrap.php';

const EPG_WORK_DIR = '/var/www/epg/work';
const EPG_TARGET = '/var/www/epg/guide.xml';
const EPG_CACHE = '/var/www/cache/guide.json';
const EPG_LOCK_FILE = '/var/www/epg/update.lock';
const EPG_LOG_FILE = '/var/www/logs/epg-update.log';

function logMessage(string $message, bool $error = false): void
{
    $line = sprintf(
        "[%s] %s\n",
        date('Y-m-d H:i:s'),
        $message
    );

    echo $line;

    if ($error) {
        fwrite(STDERR, $line);
    }

    $logDirectory = dirname(EPG_LOG_FILE);

    if (!is_dir($logDirectory)) {
        mkdir($logDirectory, 0775, true);
    }

    file_put_contents(
        EPG_LOG_FILE,
        $line,
        FILE_APPEND | LOCK_EX
    );
}

function downloadFile(string $url, string $target): bool
{
    $context = stream_context_create([
        'http' => [
            'timeout' => 120,
            'follow_location' => 1,
            'max_redirects' => 5,
            'user_agent' => 'TVGuide EPG Updater/1.0',
        ],
        'https' => [
            'timeout' => 120,
            'follow_location' => 1,
            'max_redirects' => 5,
            'user_agent' => 'TVGuide EPG Updater/1.0',
        ],
    ]);

    $input = @fopen($url, 'rb', false, $context);

    if ($input === false) {
        return false;
    }

    $output = @fopen($target, 'wb');

    if ($output === false) {
        fclose($input);
        return false;
    }

    $bytes = stream_copy_to_stream($input, $output);

    fclose($input);
    fclose($output);

    return $bytes !== false && $bytes > 0;
}

function detectCompression(string $url, string $file): string
{
    $path = strtolower(
        parse_url($url, PHP_URL_PATH) ?? ''
    );

    if (str_ends_with($path, '.xz')) {
        return 'xz';
    }

    if (
        str_ends_with($path, '.gz') ||
        str_ends_with($path, '.gzip')
    ) {
        return 'gz';
    }

    $handle = fopen($file, 'rb');
    $header = $handle ? fread($handle, 6) : '';
    if ($handle) {
        fclose($handle);
    }

    if (str_starts_with($header, "\xFD\x37\x7A\x58\x5A\x00")) {
        return 'xz';
    }

    if (str_starts_with($header, "\x1F\x8B")) {
        return 'gz';
    }

    return 'xml';
}

function unpackFile(
    string $source,
    string $target,
    string $compression
): bool {
    if ($compression === 'xml') {
        return copy($source, $target);
    }

    $command = match ($compression) {
        'xz' => sprintf(
            'xz -dc %s > %s 2>&1',
            escapeshellarg($source),
            escapeshellarg($target)
        ),

        'gz' => sprintf(
            'gzip -dc %s > %s 2>&1',
            escapeshellarg($source),
            escapeshellarg($target)
        ),

        default => null,
    };

    if ($command === null) {
        return false;
    }

    exec($command, $output, $status);

    return
        $status === 0 &&
        file_exists($target) &&
        filesize($target) > 0;
}

function isValidXmlTv(string $file): bool
{
    if (!file_exists($file) || filesize($file) === 0) {
        return false;
    }

    libxml_use_internal_errors(true);

    $xml = simplexml_load_file($file);

    libxml_clear_errors();

    if (!$xml) {
        return false;
    }

    return $xml->getName() === 'tv';
}

function removeOldWorkFiles(): void
{
    foreach (glob(EPG_WORK_DIR . '/*') ?: [] as $file) {
        if (is_file($file)) {
            @unlink($file);
        }
    }
}

$lockHandle = fopen(EPG_LOCK_FILE, 'c');

if ($lockHandle === false) {
    logMessage('Lock-Datei konnte nicht geöffnet werden.', true);
    exit(1);
}

if (!flock($lockHandle, LOCK_EX | LOCK_NB)) {
    logMessage(
        'Ein EPG-Update läuft bereits. Dieser Lauf wird beendet.'
    );
    fclose($lockHandle);
    exit(0);
}

$startedAt = microtime(true);

try {
    logMessage('EPG-Update gestartet.');

    $config = new Config(
        '/var/www/config/config.json',
        '/var/www/config/channels.json'
    );

    $epg = $config->get('epg', []);
    $urls = $epg['urls'] ?? [];

    if (!$urls && !empty($epg['url'])) {
        $urls = [$epg['url']];
    }

    if (!$urls) {
        throw new RuntimeException(
            'Keine epg.urls in config.json gesetzt.'
        );
    }

    if (!is_dir(EPG_WORK_DIR)) {
        mkdir(EPG_WORK_DIR, 0775, true);
    }

    removeOldWorkFiles();

    $xmlFiles = [];

    foreach (array_values($urls) as $index => $url) {
        $downloadFile =
            EPG_WORK_DIR . "/source-{$index}.download";

        $xmlFile =
            EPG_WORK_DIR . "/source-{$index}.xml";

        logMessage("Lade Quelle " . ($index + 1) . ": {$url}");

        if (!downloadFile($url, $downloadFile)) {
            logMessage(
                "Download fehlgeschlagen oder leer: {$url}",
                true
            );
            continue;
        }

        $compression = detectCompression(
            $url,
            $downloadFile
        );

        logMessage(
            sprintf(
                'Download abgeschlossen: %.2f MB, Format: %s',
                filesize($downloadFile) / 1024 / 1024,
                strtoupper($compression)
            )
        );

        if (!unpackFile(
            $downloadFile,
            $xmlFile,
            $compression
        )) {
            logMessage(
                "Datei konnte nicht entpackt werden: {$url}",
                true
            );
            continue;
        }

        if (!isValidXmlTv($xmlFile)) {
            logMessage(
                "XMLTV-Datei ist ungültig: {$url}",
                true
            );
            continue;
        }

        $xmlFiles[] = $xmlFile;
    }

    if (!$xmlFiles) {
        throw new RuntimeException(
            'Keine gültigen XMLTV-Dateien geladen.'
        );
    }

    /*
     * Zuerst in eine temporäre Datei mergen.
     * Die bestehende guide.xml bleibt bei einem Fehler unangetastet.
     */
    $temporaryTarget =
        EPG_WORK_DIR . '/guide-' . getmypid() . '.xml';

    logMessage(
        count($xmlFiles) . ' gültige Quelle(n), Merge gestartet.'
    );

    $merge = new XmlTvMergeService();
    $merge->merge($xmlFiles, $temporaryTarget);

    if (!isValidXmlTv($temporaryTarget)) {
        throw new RuntimeException(
            'Die zusammengeführte XMLTV-Datei ist ungültig.'
        );
    }

    /*
     * Atomarer Austausch innerhalb desselben Dateisystems.
     */
    if (!rename($temporaryTarget, EPG_TARGET)) {
        throw new RuntimeException(
            'guide.xml konnte nicht atomar ersetzt werden.'
        );
    }

    logMessage(
        sprintf(
            'guide.xml aktualisiert: %.2f MB',
            filesize(EPG_TARGET) / 1024 / 1024
        )
    );

    $cacheService = new XmlTvCacheService(
        EPG_TARGET,
        $config->get('timezone', 'Europe/Vienna'),
        EPG_CACHE
    );

    $cacheData = $cacheService->rebuildCache();

    $channelCount =
        count($cacheData['channels'] ?? []);

    $programmeCount = 0;

    foreach ($cacheData['channels'] ?? [] as $channel) {
        $programmeCount +=
            count($channel['programmes'] ?? []);
    }

    $duration = microtime(true) - $startedAt;

    logMessage(
        sprintf(
            'EPG-Update erfolgreich: %d Sender, %d Sendungen, %.1f Sekunden.',
            $channelCount,
            $programmeCount,
            $duration
        )
    );

    exit(0);
} catch (Throwable $exception) {
    $duration = microtime(true) - $startedAt;

    logMessage(
        sprintf(
            'EPG-Update fehlgeschlagen nach %.1f Sekunden: %s',
            $duration,
            $exception->getMessage()
        ),
        true
    );

    exit(1);
} finally {
    flock($lockHandle, LOCK_UN);
    fclose($lockHandle);
}