Pony.fm/app/TrackFile.php

<?php

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\App;
use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\URL;

class TrackFile extends Model
{
    public function track()
    {
        return $this->belongsTo('Track');
    }

    /**
     * Look up and return a TrackFile by track ID and an extension.
     *
     * If the track does not have a TrackFile in the given extension's format, a 404 exception is thrown.
     *
     * @param int $trackId
     * @param string $extension
     * @return TrackFile
     */
    public static function findOrFailByExtension($trackId, $extension)
    {
        // find the extension's format
        $requestedFormatName = null;
        foreach (Track::$Formats as $name => $format) {
            if ($extension === $format['extension']) {
                $requestedFormatName = $name;
                break;
            }
        }
        if ($requestedFormatName === null) {
            App::abort(404);
        }

        $trackFile = static::
        with('track')
            ->where('track_id', $trackId)
            ->where('format', $requestedFormatName)
            ->first();

        if ($trackFile === null) {
            App::abort(404);
        } else {
            return $trackFile;
        }
    }

    public function getFormatAttribute($value)
    {
        return $value;
    }

    public function getExtensionAttribute()
    {
        return Track::$Formats[$this->format]['extension'];
    }

    public function getUrlAttribute()
    {
        return URL::to('/t' . $this->track_id . '/dl.' . $this->extension);
    }

    public function getSizeAttribute($value)
    {
        return Helpers::formatBytes($this->getFilesize($this->getFile()));
    }

    public function getFormat()
    {
        return Track::$Formats[$this->format];
    }

    protected function getFilesize()
    {
        return Cache::remember($this->getCacheKey('filesize'), 1440, function () {
            $file = $this->getFile();
            $size = 0;

            if (is_file($file)) {
                $size = filesize($file);
            }

            return $size;
        });
    }

    public function getDirectory()
    {
        $dir = (string)(floor($this->track_id / 100) * 100);

        return \Config::get('app.files_directory') . '/tracks/' . $dir;
    }

    public function getFile()
    {
        return "{$this->getDirectory()}/{$this->track_id}.{$this->extension}";
    }

    public function getFilename()
    {
        return "{$this->track_id}.{$this->extension}";
    }

    public function getDownloadFilename()
    {
        return "{$this->track->title}.{$this->extension}";
    }

    private function getCacheKey($key)
    {
        return 'track_file-' . $this->id . '-' . $key;
    }
}