core/app/Helpers/FileManager.php

<?php
namespace App\Helpers;

use App\Models\File;

class FileManager
{
    /**
     * @param File $file
     *
     * @return \Illuminate\Contracts\Routing\UrlGenerator|string
     */
    public static function getPreview(File $file)
    {
        list($type, $subtype) = explode('/', $file->mime_type);

        switch ($type) {
            case 'image':

                // try to check if file have thumbnail
                if (file_exists(config('app.thumbnail_url') . '/' . $file->filename)) {
                    $url = config('app.thumbnail_url') . '/' . $file->filename;
                } else {
                    $url = config('app.upload_url') . '/' . $file->filename;
                }

                return '<img src="' . $url . '" alt="' . $file->description . '" />';
                break;
            case 'text':
                return '<i class="fa fa-file-text-o"></i>';
                break;
            case 'application':
                switch ($subtype) {
                    case 'pdf':
                        return '<i class="fa fa-file-pdf-o"></i>';
                        break;
                    default:
                        return '<i class="fa fa-newspaper-o"></i>';
                        break;
                }
                break;
            default:
                return '<i class="fa fa-question"></i>';
                break;
        }
    }

    /**
     *
     *
     * @param File $file
     *
     * @return string
     */
    public static function getFormattedSize(File $file)
    {
        $bytes = $file->file_size;

        $label = ['B', 'KB', 'MB', 'GB', 'TB', 'PB'];
        for ($i = 0; $bytes >= 1024 && $i < (count($label) - 1); $bytes /= 1024, $i++) {
            ;
        }

        return (round($bytes, 2) . " " . $label[$i]);
    }

    /**
     * Get preview for file detail
     *
     * @param File $file
     *
     * @return \Illuminate\Contracts\Routing\UrlGenerator|string
     */
    public static function getLargePreview(File $file)
    {
        list($type, $subtype) = explode('/', $file->mime_type);

        $url = config('app.upload_url') . '/' . $file->filename;
        $path = config('app.upload_path') . DIRECTORY_SEPARATOR . $file->filename;

        switch ($type) {
            case 'image':
                return '<img src="' . $url . '" alt="' . $file->description . '" />';
                break;
            case 'text':

                $string = '<pre><code>';
                $string .= htmlspecialchars(file_get_contents($path));
                $string .= '</pre></code>';

                return $string;
                break;
            case 'application':
                switch ($subtype) {
                    case 'pdf':
                        return '<i class="fa fa-file-pdf-o"></i>';
                        break;
                    default:
                        return '<i class="fa fa-newspaper-o"></i>';
                        break;
                }
                break;
            default:
                return self::getPreview($file);
                break;
        }
    }

    /**
     * @param File $file
     *
     * @return array
     */
    public static function getAdditionalInfo(File $file)
    {
        list($type, $subtype) = explode('/', $file->mime_type);

        $path = config('app.upload_path') . DIRECTORY_SEPARATOR . $file->filename;

        switch ($type) {
            case 'text':

                return [
                    trans('admin/fileManager.encoding') => mb_detect_encoding(file_get_contents($path))
                ];
                break;

            case 'image':
                list ($width, $height) = getimagesize($path);

                return [
                    trans('admin/fileManager.resolution') => $height . ' x ' . $width,
                ];

                break;
        }

        return [];
    }
}