<?php

declare(strict_types=1);

/**
 * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
 *
 * Copyright (C) 2019 Jan Böhmer (https://github.com/jbtronics)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

namespace App\Services\Attachments;

use App\Entity\Attachments\Attachment;
use SplFileInfo;
use function strlen;

/**
 * This service contains basic commonly used functions to work with attachments.
 * Especially this services gives you important infos about attachments, that can not be retrieved via the entities
 * (like filesize or if a file is existing).
 *
 * Special operations like getting attachment urls or handling file uploading/downloading are in their own services.
 */
class AttachmentManager
{
    protected $pathResolver;

    public function __construct(AttachmentPathResolver $pathResolver)
    {
        $this->pathResolver = $pathResolver;
    }

    /**
     * Gets an SPLFileInfo object representing the file associated with the attachment.
     *
     * @param Attachment $attachment The attachment for which the file should be generated
     *
     * @return SplFileInfo|null The fileinfo for the attachment file. Null, if the attachment is external or has
     *                          invalid file.
     */
    public function attachmentToFile(Attachment $attachment): ?SplFileInfo
    {
        if ($attachment->isExternal() || ! $this->isFileExisting($attachment)) {
            return null;
        }

        return new SplFileInfo($this->toAbsoluteFilePath($attachment));
    }

    /**
     * Returns the absolute filepath of the attachment. Null is returned, if the attachment is externally saved,
     * or is not existing.
     *
     * @param Attachment $attachment The attachment for which the filepath should be determined
     */
    public function toAbsoluteFilePath(Attachment $attachment): ?string
    {
        if (empty($attachment->getPath())) {
            return null;
        }

        if ($attachment->isExternal()) {
            return null;
        }

        $path = $this->pathResolver->placeholderToRealPath($attachment->getPath());

        //realpath does not work with null as argument
        if (null === $path) {
            return null;
        }

        $tmp = realpath($path);
        //If path is not existing realpath returns false.
        if (false === $tmp) {
            return null;
        }

        return $tmp;
    }

    /**
     * Checks if the file in this attachement is existing. This works for files on the HDD, and for URLs
     * (it's not checked if the ressource behind the URL is really existing, so for every external attachment true is returned).
     *
     * @param Attachment $attachment The attachment for which the existence should be checked
     *
     * @return bool true if the file is existing
     */
    public function isFileExisting(Attachment $attachment): bool
    {
        if (empty($attachment->getPath())) {
            return false;
        }

        $absolute_path = $this->toAbsoluteFilePath($attachment);

        if (null === $absolute_path) {
            return false;
        }

        return file_exists($absolute_path) || $attachment->isExternal();
    }

    /**
     * Returns the filesize of the attachments in bytes.
     * For external attachments or not existing attachments, null is returned.
     *
     * @param Attachment $attachment the filesize for which the filesize should be calculated
     */
    public function getFileSize(Attachment $attachment): ?int
    {
        if ($attachment->isExternal()) {
            return null;
        }

        if (! $this->isFileExisting($attachment)) {
            return null;
        }

        $tmp = filesize($this->toAbsoluteFilePath($attachment));

        return  false !== $tmp ? $tmp : null;
    }

    /**
     * Returns a human readable version of the attachment file size.
     * For external attachments, null is returned.
     *
     * @param int $decimals The number of decimals numbers that should be printed
     *
     * @return string|null A string like 1.3M
     */
    public function getHumanFileSize(Attachment $attachment, $decimals = 2): ?string
    {
        $bytes = $this->getFileSize($attachment);

        if (null === $bytes) {
            return null;
        }

        //Format filesize for human reading
        //Taken from: https://www.php.net/manual/de/function.filesize.php#106569 and slightly modified

        $sz = 'BKMGTP';
        $factor = (int) floor((strlen($bytes) - 1) / 3);

        return sprintf("%.{$decimals}f", $bytes / 1024 ** $factor).@$sz[$factor];
    }
}