<?php

declare(strict_types=1);

namespace App\Libraries\Pipeline;

use App\Libraries\Process;
use App\Libraries\UrlGuard;

/**
 * YouTube driver.
 *
 * Always available (no external service): thumbnail download, oEmbed
 * metadata, URL analysis. Downloading video/audio requires yt-dlp AND
 * the operator feature flag — when disabled the driver throws a clear
 * user-facing message and tool pages show an honest notice up-front.
 */
final class Youtube implements DriverInterface
{
    private const ID_PATTERN = '(?:[A-Za-z0-9_-]{11})';

    /** @return string|null 11-char video id from any public URL form */
    public static function extractId(string $url): ?string
    {
        $url = trim($url);
        if (preg_match('/^' . self::ID_PATTERN . '$/', $url) === 1) {
            return $url; // bare id
        }

        $host = strtolower(parse_url($url, PHP_URL_HOST) ?? '');
        if (! preg_match('/(^|\.)(youtube\.com|youtu\.be|youtube-nocookie\.com)$/', $host)) {
            return null;
        }

        if ($host === 'youtu.be') {
            $id = trim(parse_url($url, PHP_URL_PATH) ?? '', '/');

            return preg_match('/^' . self::ID_PATTERN . '$/', $id) === 1 ? $id : null;
        }

        parse_str(parse_url($url, PHP_URL_QUERY) ?? '', $query);
        if (! empty($query['v']) && preg_match('/^' . self::ID_PATTERN . '$/', (string) $query['v'])) {
            return (string) $query['v'];
        }
        if (preg_match('#/(?:embed|shorts|live|v)/(' . self::ID_PATTERN . ')#', $url, $m)) {
            return $m[1];
        }

        return null;
    }

    public function handle(array $job, array $tool, callable $update): array
    {
        $params = json_decode($job['params'] ?? '{}', true) ?: [];
        $videoId = self::extractId((string) ($params['url'] ?? ''));
        if ($videoId === null) {
            throw new \RuntimeException('Invalid YouTube URL.');
        }
        $update(10, 'fetching');

        return match ($job['operation']) {
            'yt_thumbnails' => $this->thumbnails($job, $videoId),
            default         => $this->withYtDlp($job, $params, $update),
        };
    }

    /**
     * Thumbnail pack: maxres/sd/hq/mq/default as a zip. Fetched only
     * from Google-owned image hosts through the allowlist.
     */
    private function thumbnails(array $job, string $videoId): array
    {
        $guard = new UrlGuard();
        if (! $guard->isAllowedMediaHost('i.ytimg.com')) {
            throw new \RuntimeException('Thumbnails are not fetchable on this server.');
        }

        $qualities = [
            'maxresdefault' => 'Max resolution (1280x720+)',
            'sddefault'     => 'Standard definition (640x480)',
            'hqdefault'     => 'High quality (480x360)',
            'mqdefault'     => 'Medium quality (320x180)',
            'default'       => 'Thumbnail (120x90)',
        ];

        $tmpDir = sys_get_temp_dir() . '/tv_thumb_' . $job['id'];
        if (! is_dir($tmpDir)) { mkdir($tmpDir, 0700, true); }
        $found = 0;

        foreach ($qualities as $key => $_label) {
            $target = rtrim($tmpDir, '/') . "/{$key}.jpg";
            $data   = $this->httpGet("https://i.ytimg.com/vi/{$videoId}/{$key}.jpg");
            if ($data !== null && strlen($data) > 1000) {
                file_put_contents($target, $data);
                ++$found;
            }
        }

        // webp variants too
        foreach (['maxresdefault', 'hq720', 'sddefault', 'hqdefault'] as $key) {
            $webpName = str_replace('.jpg', '.webp', $key) === $key ? $key . '.webp' : $key;
            $data     = $this->httpGet("https://i.ytimg.com/vi_webp/{$videoId}/{$webpName}");
            if ($data !== null && strlen($data) > 1000) {
                file_put_contents(rtrim($tmpDir, '/') . '/' . basename($webpName), $data);
                ++$found;
            }
        }

        if ($found === 0) {
            throw new \RuntimeException('No thumbnails were found for this video.');
        }

        [$zipFile, $zipPath] = [\App\Libraries\Pipeline::safeName($job['id'], 'zip'), \App\Libraries\Pipeline::storageDir() . '/' . \App\Libraries\Pipeline::safeName($job['id'], 'zip')];
        $zip = new \ZipArchive();
        $zip->open($zipPath, \ZipArchive::CREATE | \ZipArchive::OVERWRITE);
        foreach (glob(rtrim($tmpDir, '/') . '/*') ?: [] as $f) {
            $zip->addFile($f, basename($f));
        }
        $zip->close();
        array_map('unlink', glob(rtrim($tmpDir, '/') . '/*') ?: []);
        @rmdir($tmpDir);

        return ['file' => basename($zipPath), 'name' => "thumbnails_{$videoId}.zip", 'ext' => 'zip'];
    }

    /** Gated yt-dlp execution (audio/video download + conversion). */
    private function withYtDlp(array $job, array $params, callable $update): array
    {
        $pipeline = service('pipeline');
        if (! $pipeline->youtubeEnabled()) {
            throw new \RuntimeException(
                'Downloading from YouTube is currently disabled on this server. Please review the platform terms of use before enabling this capability.'
            );
        }

        $format = strtolower((string) ($params['format'] ?? 'mp3'));
        $url    = 'https://www.youtube.com/watch?v=' . urlencode((string) self::extractId((string) ($params['url'] ?? '')));

        $update(15, 'fetching');
        $outTemplate = rtrim(\App\Libraries\Pipeline::incomingDir(), '/') . '/' . $job['id'] . '.%(ext)s';

        $args = ['-f', 'bestaudio/best', '-o', $outTemplate, '--no-playlist', '--no-warnings', '--socket-timeout', '30'];
        if (in_array($format, ['mp3', 'wav', 'm4a', 'aac', 'flac', 'ogg'], true)) {
            $codecMap = ['mp3' => 'mp3', 'wav' => 'wav', 'm4a' => 'aac', 'aac' => 'aac', 'flac' => 'flac', 'ogg' => 'vorbis'];
            $args[]   = '-x';
            $args[]   = '--audio-format';
            $args[]   = $codecMap[$format];
            $ext      = $format;
        } else {
            // best mp4-compatible stream
            $args[] = '-f';
            $args[] = 'bv*[ext=mp4]+ba[ext=m4a]/b[ext=mp4]/b';
            $args[] = '--merge-output-format';
            $args[] = 'mp4';
            $ext    = 'mp4';
        }
        $args[] = $url;

        $proc = Process::binary('yt-dlp', $args, config('Site')->maxProcessingSeconds);
        if (! $proc->run()) {
            throw new \RuntimeException('This video could not be downloaded. It may be private, region-locked or unavailable.');
        }
        $update(75, 'converting');

        // find produced file
        $produced = glob(rtrim(\App\Libraries\Pipeline::incomingDir(), '/') . '/' . $job['id'] . '.*') ?: [];
        $produced = array_values(array_filter($produced, static fn ($f) => ! str_ends_with((string) $f, '.part')));
        if ($produced === []) {
            throw new \RuntimeException('The download did not produce a file.');
        }
        $source = $produced[0];

        $outPath = \App\Libraries\Pipeline::storageDir() . '/' . \App\Libraries\Pipeline::safeName($job['id'], $ext);
        if (pathinfo($source, PATHINFO_EXTENSION) === $ext) {
            rename($source, $outPath);
        } else {
            $conv = Process::binary('ffmpeg', ['-y', '-i', $source, $outPath], config('Site')->maxProcessingSeconds);
            @unlink($source);
            if (! $conv->run()) {
                throw new \RuntimeException('Conversion failed after download.');
            }
        }

        return ['file' => basename($outPath), 'name' => 'download.' . $ext, 'ext' => $ext];
    }

    /**
     * oEmbed metadata lookup — no API key, official public endpoint,
     * SSRF-guarded host allowlist.
     *
     * @return array|null title/author/thumb or null
     */
    public static function fetchInfo(string $videoId): ?array
    {
        $endpoint = 'https://www.youtube.com/oembed?url=' . rawurlencode('https://www.youtube.com/watch?v=' . $videoId) . '&format=json';

        $ch = curl_init($endpoint);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => 8,
            CURLOPT_CONNECTTIMEOUT => 4,
            CURLOPT_FOLLOWLOCATION => false,
            CURLOPT_USERAGENT      => config('Site')->name . '/1.0',
        ]);
        $body   = curl_exec($ch);
        $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        curl_close($ch);

        if ($status !== 200 || ! is_string($body)) {
            return null;
        }
        $data = json_decode($body, true);
        if (! is_array($data) || empty($data['title'])) {
            return null;
        }

        return [
            'id'           => $videoId,
            'title'        => (string) $data['title'],
            'author'       => (string) ($data['author_name'] ?? ''),
            'author_url'   => (string) ($data['author_url'] ?? ''),
            'thumbnail'    => (string) ($data['thumbnail_url'] ?? ('https://i.ytimg.com/vi/' . $videoId . '/hqdefault.jpg')),
            'duration'     => null, // oEmbed doesn't expose duration
            'width'        => (int) ($data['width'] ?? 0),
            'height'       => (int) ($data['height'] ?? 0),
        ];
    }

    private function httpGet(string $url): ?string
    {
        try {
            (new UrlGuard())->check($url);
        } catch (\InvalidArgumentException) {
            return null;
        }
        $ch = curl_init($url);
        curl_setopt_array($ch, [
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_TIMEOUT        => 10,
            CURLOPT_FOLLOWLOCATION => false,
            CURLOPT_USERAGENT      => config('Site')->name . '/1.0',
        ]);
        $body   = curl_exec($ch);
        $status = curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
        curl_close($ch);

        return $status === 200 && is_string($body) ? $body : null;
    }
}