<?php
declare(strict_types=1);

/**
 * Videos (#402): `data/videos/{folder}/{hash}.mp4`, beside it `{hash}.jpg` (the poster) and
 * `{hash}.meta.json` (size, length, frame rate, sound), all served as they are.
 *
 * Unlike an image or a sound a video is not kept as it came: the upload goes into the VideoQueue,
 * and the worker writes the MP4 when it is done (see VideoFormat). The hash is the one of the
 * uploaded bytes, so the name a project stores is known the moment the upload is in, long before
 * the file exists, and uploading the same file twice converts it once.
 */
final class VideoStore extends HashedFileStore
{
    /**
     * What an upload has to start with to be sent to ffmpeg at all: the ISO family (MP4, MOV, M4V,
     * 3GP), Matroska (MKV, WebM), AVI and MPEG transport streams. ffmpeg has the last word.
     */
    private const SIGNATURE_HINT = 'MP4, MOV, WebM, MKV or AVI';

    private readonly VideoQueue $queue;

    public function __construct(private readonly string $root)
    {
        parent::__construct($root);
        $this->queue = new VideoQueue("{$root}/queue");
    }

    protected static function filePattern(): string
    {
        return '[a-f0-9]{64}\.mp4';
    }

    public function queue(): VideoQueue
    {
        return $this->queue;
    }

    /**
     * Takes an upload: a file already converted answers as it is, anything else waits in the
     * queue, a failed one is tried again.
     *
     * @return array<string,mixed>
     * @throws InvalidVideoException when the bytes cannot be a video
     */
    public function store(string $bytes, string $originalName, string $folder): array
    {
        $in = fopen('php://memory', 'r+b');
        fwrite($in, $bytes);
        rewind($in);
        try {
            return $this->storeStream($in, strlen($bytes), $originalName, $folder);
        } finally {
            fclose($in);
        }
    }

    /**
     * Like store(), straight from the request: the bytes go to disk as they come, and only their
     * first ones and their hash are looked at, so a video of 2 GB needs no 2 GB of memory.
     *
     * @param resource $in
     * @return array<string,mixed>
     * @throws VideoTooLargeException when the stream has more than `$maxBytes`
     * @throws InvalidVideoException when the bytes cannot be a video
     */
    public function storeStream($in, int $maxBytes, string $originalName, string $folder): array
    {
        $upload = $this->queue->receive($in, $maxBytes);
        try {
            if (!self::looksLikeVideo((string) file_get_contents($upload, false, null, 0, 256))) {
                throw new InvalidVideoException('Not a video file – use ' . self::SIGNATURE_HINT);
            }
            if (!preg_match('/^' . UserStore::FOLDER_PATTERN . '$/', $folder)) {
                throw new InvalidArgumentException("Invalid folder: {$folder}");
            }
            $hash = hash_file('sha256', $upload);
            $dir = "{$this->root}/{$folder}";
            if (!is_dir($dir) && !mkdir($dir, 0775, true) && !is_dir($dir)) {
                throw new RuntimeException("Cannot create directory {$dir}");
            }
            OriginalName::write($dir, "{$hash}.mp4", $originalName);
            if (!is_file("{$dir}/{$hash}.mp4")) {
                $job = $this->queue->job($folder, $hash);
                if ($job === null || $job['state'] === VideoQueue::FAILED) {
                    $this->queue->add($folder, $hash, $upload, OriginalName::sanitize($originalName));
                }
            }
            return $this->record("{$folder}/{$hash}.mp4");
        } finally {
            if (is_file($upload)) {
                unlink($upload);
            }
        }
    }

    /**
     * One file as the picker shows it, done or not; null when there is neither file nor job.
     *
     * @return array<string,mixed>|null
     */
    public function record(string $file): ?array
    {
        if (!self::isValidName($file)) {
            return null;
        }
        if (is_file("{$this->root}/{$file}")) {
            $folder = self::folderOf($file);
            $dir = $folder === '' ? $this->root : "{$this->root}/{$folder}";
            return [
                'file' => $file,
                'name' => OriginalName::read($dir, basename($file)),
                ...$this->details("{$this->root}/{$file}"),
                'bytes' => (int) filesize("{$this->root}/{$file}"),
            ];
        }
        $job = $this->jobOf($file);
        return $job === null ? null : $this->pending($job);
    }

    /** A video is there for deleting while it is converted or failed, too. */
    public function exists(string $file): bool
    {
        return parent::exists($file) || $this->jobOf($file) !== null;
    }

    /** Lists the converted files like every store does, and the ones on their way after them. */
    public function list(string $folder, bool $seesAll, array $owners): array
    {
        $items = parent::list($folder, $seesAll, $owners);
        foreach ($this->queue->jobs() as $job) {
            if ($seesAll || $job['folder'] === $folder) {
                $items[] = $this->pending($job) + [
                    'updatedAt' => (string) $job['createdAt'],
                    'owner' => $owners[$job['folder']] ?? '',
                    'deletable' => true,
                ];
            }
        }
        return $items;
    }

    public function delete(string $file): bool
    {
        if (!self::isValidName($file)) {
            return false;
        }
        $folder = self::folderOf($file);
        $hash = basename($file, '.mp4');
        $removed = $folder !== '' && $this->queue->remove($folder, $hash);
        if (is_file("{$this->root}/{$file}")) {
            $removed = parent::delete($file) || $removed;
            $dir = $folder === '' ? $this->root : "{$this->root}/{$folder}";
            foreach (["{$dir}/{$hash}.jpg", "{$dir}/{$hash}.meta.json"] as $path) {
                if (is_file($path)) {
                    unlink($path);
                }
            }
        } elseif ($removed) {
            OriginalName::delete("{$this->root}/{$folder}", "{$hash}.mp4");
        }
        return $removed;
    }

    /** Called by the worker once the MP4 is in place: what the editor reads instead of probing. */
    public static function writeDetails(string $dir, string $hash, array $details): void
    {
        $json = json_encode($details, JSON_UNESCAPED_SLASHES);
        AtomicFile::write("{$dir}/{$hash}.meta.json", (string) $json, AtomicFile::SERVED, 'video details');
    }

    /** @return array<string,mixed> */
    protected function details(string $path): array
    {
        $meta = substr($path, 0, -strlen('.mp4')) . '.meta.json';
        $raw = is_file($meta) ? file_get_contents($meta) : false;
        $details = $raw === false ? null : json_decode($raw, true);
        $details = is_array($details) ? $details : [];
        $file = substr($path, strlen($this->root) + 1);
        return [
            'status' => 'ready',
            'width' => (int) ($details['width'] ?? 0),
            'height' => (int) ($details['height'] ?? 0),
            'duration' => (float) ($details['duration'] ?? 0),
            'fps' => (float) ($details['fps'] ?? 0),
            'audio' => (bool) ($details['audio'] ?? false),
            'poster' => substr($file, 0, -strlen('.mp4')) . '.jpg',
        ];
    }

    /** @return array<string,mixed>|null */
    private function jobOf(string $file): ?array
    {
        $folder = self::folderOf($file);
        return $folder === '' ? null : $this->queue->job($folder, basename($file, '.mp4'));
    }

    /**
     * @param array<string,mixed> $job
     * @return array<string,mixed>
     */
    private function pending(array $job): array
    {
        return [
            'file' => "{$job['folder']}/{$job['hash']}.mp4",
            'name' => (string) $job['name'],
            'status' => (string) $job['state'],
            'progress' => (float) $job['progress'],
            'error' => (string) $job['error'],
            'bytes' => 0,
        ];
    }

    private static function looksLikeVideo(string $bytes): bool
    {
        if (strlen($bytes) < 16) {
            return false;
        }
        return substr($bytes, 4, 4) === 'ftyp'
            || str_starts_with($bytes, "\x1A\x45\xDF\xA3")
            || (str_starts_with($bytes, 'RIFF') && substr($bytes, 8, 4) === 'AVI ')
            || ($bytes[0] === "\x47" && strlen($bytes) > 188 && $bytes[188] === "\x47");
    }
}

/** Thrown by VideoStore::store when the uploaded bytes cannot be a video. */
final class InvalidVideoException extends RuntimeException
{
}

/** Thrown by VideoQueue::receive when an upload is bigger than the API takes. */
final class VideoTooLargeException extends RuntimeException
{
}