<?php

namespace App\Services;

use App\Models\Album;
use App\Models\Artist;
use App\Models\Song;
use App\Repositories\SongRepository;
use Exception;
use getID3;
use getid3_lib;
use Illuminate\Contracts\Cache\Repository as Cache;
use InvalidArgumentException;
use SplFileInfo;
use Symfony\Component\Finder\Finder;

class FileSynchronizer
{
    const SYNC_RESULT_SUCCESS = 1;
    const SYNC_RESULT_BAD_FILE = 2;
    const SYNC_RESULT_UNMODIFIED = 3;

    private $getID3;
    private $mediaMetadataService;
    private $helperService;
    private $songRepository;
    private $cache;
    private $finder;

    /**
     * @var SplFileInfo
     */
    private $splFileInfo;

    /**
     * @var int
     */
    private $fileModifiedTime;

    /**
     * @var string
     */
    private $filePath;

    /**
     * A (MD5) hash of the file's path.
     * This value is unique, and can be used to query a Song record.
     *
     * @var string
     */
    private $fileHash;

    /**
     * The song model that's associated with the current file.
     *
     * @var Song|null
     */
    private $song;

    /**
     * @var string|null
     */
    private $syncError;

    public function __construct(
        getID3 $getID3,
        MediaMetadataService $mediaMetadataService,
        HelperService $helperService,
        SongRepository $songRepository,
        Cache $cache,
        Finder $finder
    ) {
        $this->getID3 = $getID3;
        $this->mediaMetadataService = $mediaMetadataService;
        $this->helperService = $helperService;
        $this->songRepository = $songRepository;
        $this->cache = $cache;
        $this->finder = $finder;
    }

    /**
     * @param string|SplFileInfo $path
     */
    public function setFile($path): self
    {
        $this->splFileInfo = $path instanceof SplFileInfo ? $path : new SplFileInfo($path);

        // Workaround for #344, where getMTime() fails for certain files with Unicode names on Windows.
        try {
            $this->fileModifiedTime = $this->splFileInfo->getMTime();
        } catch (Exception $e) {
            // Not worth logging the error. Just use current stamp for mtime.
            $this->fileModifiedTime = time();
        }

        $this->filePath = $this->splFileInfo->getPathname();
        $this->fileHash = $this->helperService->getFileHash($this->filePath);
        $this->song = $this->songRepository->getOneById($this->fileHash);
        $this->syncError = null;

        return $this;
    }

    /**
     * Get all applicable info from the file.
     */
    public function getFileInfo(): array
    {
        $info = $this->getID3->analyze($this->filePath);

        if (isset($info['error']) || !isset($info['playtime_seconds'])) {
            $this->syncError = isset($info['error']) ? $info['error'][0] : 'No playtime found';

            return [];
        }

        // Copy the available tags over to comment.
        // This is a helper from getID3, though it doesn't really work well.
        // We'll still prefer getting ID3v2 tags directly later.
        getid3_lib::CopyTagsToComments($info);

        $track = $this->getTrackNumberFromInfo($info);

        $props = [
            'artist' => '',
            'album' => '',
            'compilation' => false,
            'title' => basename($this->filePath, '.'.pathinfo($this->filePath, PATHINFO_EXTENSION)), // default to be file name
            'length' => $info['playtime_seconds'],
            'track' => (int) $track,
            'disc' => (int) array_get($info, 'comments.part_of_a_set.0', 1),
            'lyrics' => '',
            'cover' => array_get($info, 'comments.picture', [null])[0],
            'path' => $this->filePath,
            'mtime' => $this->fileModifiedTime,
        ];

        if (!$comments = array_get($info, 'comments_html')) {
            return $props;
        }

        $this->gatherPropsFromTags($info, $comments, $props);
        $props['compilation'] = (bool) $props['compilation'] || $this->isCompilation($props);

        return $props;
    }

    /**
     * Sync the song with all available media info against the database.
     *
     * @param string[] $tags  The (selective) tags to sync (if the song exists)
     * @param bool     $force Whether to force syncing, even if the file is unchanged
     */
    public function sync(array $tags, bool $force = false): int
    {
        if (!$this->isFileNewOrChanged() && !$force) {
            return self::SYNC_RESULT_UNMODIFIED;
        }

        if (!$info = $this->getFileInfo()) {
            return self::SYNC_RESULT_BAD_FILE;
        }

        // Fixes #366. If the file is new, we use all tags by simply setting $force to false.
        if ($this->isFileNew()) {
            $force = false;
        }

        if ($this->isFileChanged() || $force) {
            // This is a changed file, or the user is forcing updates.
            // In such a case, the user must have specified a list of tags to sync.
            // A sample command could be: ./artisan koel:sync --force --tags=artist,album,lyrics
            // We cater for these tags by removing those not specified.

            // There's a special case with 'album' though.
            // If 'compilation' tag is specified, 'album' must be counted in as well.
            // But if 'album' isn't specified, we don't want to update normal albums.
            // This variable is to keep track of this state.
            $changeCompilationAlbumOnly = false;

            if (in_array('compilation', $tags, true) && !in_array('album', $tags, true)) {
                $tags[] = 'album';
                $changeCompilationAlbumOnly = true;
            }

            $info = array_intersect_key($info, array_flip($tags));

            // If the "artist" tag is specified, use it.
            // Otherwise, re-use the existing model value.
            $artist = isset($info['artist']) ? Artist::get($info['artist']) : $this->song->album->artist;

            // If the "album" tag is specified, use it.
            // Otherwise, re-use the existing model value.
            if (isset($info['album'])) {
                $album = $changeCompilationAlbumOnly
                    ? $this->song->album
                    : Album::get($artist, $info['album'], array_get($info, 'compilation'));
            } else {
                $album = $this->song->album;
            }
        } else {
            // The file is newly added.
            $artist = Artist::get($info['artist']);
            $album = Album::get($artist, $info['album'], array_get($info, 'compilation'));
        }

        if (!$album->has_cover) {
            $this->generateAlbumCover($album, array_get($info, 'cover'));
        }

        $data = array_except($info, ['artist', 'albumartist', 'album', 'cover', 'compilation']);
        $data['album_id'] = $album->id;
        $data['artist_id'] = $artist->id;
        $this->song = Song::updateOrCreate(['id' => $this->fileHash], $data);

        return self::SYNC_RESULT_SUCCESS;
    }

    /**
     * Try to generate a cover for an album based on extracted data, or use the cover file under the directory.
     *
     * @param mixed[]|null $coverData
     */
    private function generateAlbumCover(Album $album, ?array $coverData): void
    {
        // If the album has no cover, we try to get the cover image from existing tag data
        if ($coverData) {
            $extension = explode('/', $coverData['image_mime']);
            $extension = empty($extension[1]) ? 'png' : $extension[1];

            $this->mediaMetadataService->writeAlbumCover($album, $coverData['data'], $extension);

            return;
        }

        // Or, if there's a cover image under the same directory, use it.
        if ($cover = $this->getCoverFileUnderSameDirectory()) {
            $this->mediaMetadataService->copyAlbumCover($album, $cover);
        }
    }

    /**
     * Issue #380.
     * Some albums have its own cover image under the same directory as cover|folder.jpg/png.
     * We'll check if such a cover file is found, and use it if positive.
     *
     * @throws InvalidArgumentException
     */
    private function getCoverFileUnderSameDirectory(): ?string
    {
        // As directory scanning can be expensive, we cache and reuse the result.
        return $this->cache->remember(md5($this->filePath.'_cover'), 24 * 60, function (): ?string {
            $matches = array_keys(iterator_to_array(
                $this->finder->create()
                    ->depth(0)
                    ->ignoreUnreadableDirs()
                    ->files()
                    ->followLinks()
                    ->name('/(cov|fold)er\.(jpe?g|png)$/i')
                    ->in(dirname($this->filePath))
                )
            );

            $cover = $matches ? $matches[0] : null;

            return $cover && $this->isImage($cover) ? $cover : null;
        });
    }

    private function isImage(string $path): bool
    {
        try {
            return (bool) exif_imagetype($path);
        } catch (Exception $e) {
            return false;
        }
    }

    /**
     * Determine if the file is new (its Song record can't be found in the database).
     */
    public function isFileNew(): bool
    {
        return !$this->song;
    }

    /**
     * Determine if the file is changed (its Song record is found, but the timestamp is different).
     */
    public function isFileChanged(): bool
    {
        return !$this->isFileNew() && $this->song->mtime !== $this->fileModifiedTime;
    }

    public function isFileNewOrChanged(): bool
    {
        return $this->isFileNew() || $this->isFileChanged();
    }

    public function getSyncError(): ?string
    {
        return $this->syncError;
    }

    private function getTrackNumberFromInfo(array $info): int
    {
        $track = 0;

        // Apparently track numbers can be stored with different indices as the following.
        $trackIndices = [
            'comments.track',
            'comments.tracknumber',
            'comments.track_number',
        ];

        for ($i = 0; $i < count($trackIndices) && $track === 0; $i++) {
            $track = (int) array_get($info, $trackIndices[$i], [0])[0];
        }

        return $track;
    }

    private function gatherPropsFromTags(array $info, array $comments, array &$props): void
    {
        $propertyMap = [
            'artist' => 'artist',
            'albumartist' => 'band',
            'album' => 'album',
            'title' => 'title',
            'lyrics' => 'unsynchronised_lyric',
            'compilation' => 'part_of_a_compilation',
        ];

        foreach ($propertyMap as $name => $tag) {
            $props[$name] = array_get($info, "tags.id3v2.$tag", [null])[0] ?: array_get($comments, $tag, [''])[0];

            // Fixes #323, where tag names can be htmlentities()'ed
            if (is_string($props[$name]) && $props[$name]) {
                $props[$name] = trim(html_entity_decode($props[$name]));
            }
        }
    }

    private function isCompilation(array $props): bool
    {
        // A "compilation" property can be determined by:
        // - "part_of_a_compilation" tag (used by iTunes), or
        // - "albumartist" (used by non-retarded applications).
        // Also, the latter is only valid if the value is NOT the same as "artist".
        return $props['albumartist'] && $props['artist'] !== $props['albumartist'];
    }
}