<?php
// Fehlerberichterstattung für Debugging
error_reporting(E_ALL);
ini_set('display_errors', 0); // Keine Ausgabe, nur JSON

header('Content-Type: application/json');
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST');
header('Access-Control-Allow-Headers: Content-Type');

// Fehlerbehandlung
set_error_handler(function($errno, $errstr, $errfile, $errline) {
    throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
});

try {
    // Nur POST-Anfragen erlauben
    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        http_response_code(405);
        echo json_encode(['error' => 'Nur POST-Anfragen erlaubt']);
        exit;
    }

    // Lese JSON-Input
    $rawInput = file_get_contents('php://input');
    $input = json_decode($rawInput, true);

    if (json_last_error() !== JSON_ERROR_NONE) {
        throw new Exception('Ungültiges JSON: ' . json_last_error_msg());
    }

    if (!isset($input['playlistId']) || !isset($input['apiKey'])) {
        http_response_code(400);
        echo json_encode(['error' => 'playlistId und apiKey sind erforderlich']);
        exit;
    }

    $playlistId = $input['playlistId'];
    $apiKey = $input['apiKey'];

    // Validierung
    if (empty($playlistId) || empty($apiKey)) {
        http_response_code(400);
        echo json_encode(['error' => 'playlistId und apiKey dürfen nicht leer sein']);
        exit;
    }

    $videos = [];
    $pageToken = '';
    $maxResults = 50;
    $playlistTitle = '';

    // Prüfe ob cURL verfügbar ist
    if (!function_exists('curl_init')) {
        throw new Exception('cURL ist nicht verfügbar. Bitte aktiviere die cURL-Extension in PHP.');
    }

    // Hole Playlist-Informationen (Titel)
    $playlistInfoUrl = "https://www.googleapis.com/youtube/v3/playlists?part=snippet&id=" . urlencode($playlistId) . "&key=" . urlencode($apiKey);
    $playlistInfoResponse = curlRequest($playlistInfoUrl);

    if ($playlistInfoResponse !== false) {
        $playlistInfoData = json_decode($playlistInfoResponse, true);
        if (isset($playlistInfoData['items'][0]['snippet']['title'])) {
            $playlistTitle = $playlistInfoData['items'][0]['snippet']['title'];
        }
    }

    // Hole alle Videos der Playlist (paginiert)
    do {
        $url = "https://www.googleapis.com/youtube/v3/playlistItems?part=contentDetails&playlistId=" . urlencode($playlistId) . "&maxResults=" . $maxResults . "&pageToken=" . urlencode($pageToken) . "&key=" . urlencode($apiKey);

        $response = curlRequest($url);

        if ($response === false) {
            throw new Exception('API-Anfrage fehlgeschlagen (Netzwerkfehler)');
        }

        $data = json_decode($response, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            throw new Exception('Ungültige JSON-Antwort von YouTube API');
        }

        if (isset($data['error'])) {
            $errorMsg = $data['error']['message'] ?? 'YouTube API Fehler';
            $errorCode = $data['error']['code'] ?? 'unbekannt';
            throw new Exception("YouTube API Fehler ($errorCode): $errorMsg");
        }

        if (!isset($data['items'])) {
            throw new Exception('Ungültige API-Antwort: items fehlt');
        }

        // Sammle Video-IDs
        $videoIds = array_map(function($item) {
            return $item['contentDetails']['videoId'];
        }, $data['items']);

        if (empty($videoIds)) {
            break; // Keine Videos mehr
        }

        // Hole Video-Details (inkl. Upload-Datum und Dauer)
        $videoDetailsUrl = "https://www.googleapis.com/youtube/v3/videos?part=snippet,contentDetails&id=" . implode(',', $videoIds) . "&key=" . urlencode($apiKey);
        $videoResponse = curlRequest($videoDetailsUrl);

        if ($videoResponse === false) {
            throw new Exception('Video-Details konnten nicht geladen werden');
        }

        $videoData = json_decode($videoResponse, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            throw new Exception('Ungültige JSON-Antwort bei Video-Details');
        }

        if (isset($videoData['error'])) {
            $errorMsg = $videoData['error']['message'] ?? 'YouTube API Fehler';
            throw new Exception("YouTube API Fehler bei Video-Details: $errorMsg");
        }

        // Extrahiere Upload-Daten und Dauer
        if (isset($videoData['items'])) {
            foreach ($videoData['items'] as $video) {
                $videos[] = [
                    'publishedAt' => $video['snippet']['publishedAt'] ?? null,
                    'duration' => $video['contentDetails']['duration'] ?? null
                ];
            }
        }

        $pageToken = $data['nextPageToken'] ?? '';
    } while ($pageToken);

    // Berechne Gesamtdauer
    $totalMinutes = 0;
    foreach ($videos as $video) {
        if ($video['duration']) {
            $totalMinutes += parseDuration($video['duration']);
        }
    }

    // Finde ältestes und neuestes Datum
    $dates = array_filter(array_map(function($video) {
        return $video['publishedAt'];
    }, $videos));

    sort($dates);

    $oldestDate = count($dates) > 0 ? substr($dates[0], 0, 10) : null;
    $newestDate = count($dates) > 0 ? substr($dates[count($dates) - 1], 0, 10) : null;

    // Sende Ergebnis
    echo json_encode([
        'playlistTitle' => $playlistTitle,
        'videoCount' => count($videos),
        'totalMinutes' => $totalMinutes,
        'oldestDate' => $oldestDate,
        'newestDate' => $newestDate
    ]);

} catch (Exception $e) {
    http_response_code(500);
    echo json_encode([
        'error' => $e->getMessage(),
        'file' => basename($e->getFile()),
        'line' => $e->getLine()
    ]);
}

/**
 * Macht HTTP-Anfrage mit cURL
 */
function curlRequest($url) {
    $ch = curl_init();

    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
    curl_setopt($ch, CURLOPT_USERAGENT, 'YouTube Playlist Analyzer/1.0');

    $response = curl_exec($ch);
    $error = curl_error($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

    curl_close($ch);

    if ($response === false) {
        throw new Exception('cURL-Fehler: ' . $error);
    }

    return $response;
}

/**
 * Konvertiert ISO 8601 Duration in Minuten
 * Format: PT#H#M#S
 */
function parseDuration($duration) {
    preg_match('/PT(?:(\d+)H)?(?:(\d+)M)?(?:(\d+)S)?/', $duration, $matches);

    $hours = isset($matches[1]) ? (int)$matches[1] : 0;
    $minutes = isset($matches[2]) ? (int)$matches[2] : 0;
    $seconds = isset($matches[3]) ? (int)$matches[3] : 0;

    // Auf volle Minuten aufrunden
    $totalMinutes = $hours * 60 + $minutes + ceil($seconds / 60);

    return $totalMinutes;
}
?>