<?php

declare(strict_types = 1);
// {{{ License
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
// }}}

namespace Plugin\StoreRemoteMedia;

use App\Core\DB;
use App\Core\Event;
use App\Core\GSFile;
use App\Core\HTTPClient;
use function App\Core\I18n\_m;
use App\Core\Log;
use App\Core\Modules\Plugin;
use App\Entity\Note;
use App\Util\Common;
use App\Util\Exception\DuplicateFoundException;
use App\Util\Exception\ServerException;
use App\Util\Exception\TemporaryFileException;
use App\Util\TemporaryFile;
use Component\Attachment\Entity\AttachmentThumbnail;
use Component\Attachment\Entity\AttachmentToLink;
use Component\Attachment\Entity\AttachmentToNote;
use Component\Link\Entity\Link;
use EventResult;
use Symfony\Contracts\HttpClient\Exception\ClientExceptionInterface;
use Symfony\Contracts\HttpClient\Exception\RedirectionExceptionInterface;
use Symfony\Contracts\HttpClient\Exception\ServerExceptionInterface;
use Symfony\Contracts\HttpClient\Exception\TransportExceptionInterface;

/**
 * The StoreRemoteMedia plugin downloads remotely attached files to local server.
 *
 * @package   GNUsocial
 *
 * @author    Mikael Nordfeldth
 * @author    Stephen Paul Weber
 * @author    Mikael Nordfeldth
 * @author    Miguel Dantas
 * @author    Diogo Peralta Cordeiro
 * @copyright 2015-2016, 2019-2021 Free Software Foundation, Inc http://www.fsf.org
 * @license   https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
 */
class StoreRemoteMedia extends Plugin
{
    public static function version(): string
    {
        return '3.0.0';
    }

    /**
     *  Settings which can be set in social.local.yaml
     *  WARNING, these are _regexps_ (slashes added later). Always escape your dots and end ('$') your strings
     */
    public bool $check_whitelist   = false;
    public bool $check_blacklist   = false;
    public array $domain_whitelist = [
        // hostname
        '.*', // Default to allowing any host
    ];
    public array $domain_blacklist = [];

    // Whether to maintain a copy of the original media or only a thumbnail of it
    private function getStoreOriginal(): bool
    {
        return Common::config('plugin_store_remote_media', 'store_original');
    }

    private function getMaxFileSize(): int
    {
        return min(Common::config('plugin_store_remote_media', 'max_file_size'), Common::config('attachments', 'file_quota'));
    }

    private function getSmartCrop(): bool
    {
        return Common::config('plugin_store_remote_media', 'smart_crop');
    }

    /**
     * @throws DuplicateFoundException
     * @throws ServerException
     * @throws TemporaryFileException
     */
    public function onNewLinkFromNote(Link $link, Note $note): EventResult
    {
        // Embed is the plugin to handle these
        if ($link->getMimetypeMajor() === 'text') {
            return Event::next;
        }

        // Is this URL trusted?
        if (!$this->allowedLink($link->getUrl())) {
            Log::info("Blocked URL ({$link->getUrl()}) in StoreRemoteMedia->onNewLinkFromNote.");
            return Event::next;
        }

        // Have we handled it already?
        $attachment_to_link = DB::find(
            'attachment_to_link',
            ['link_id' => $link->getId()],
        );

        // If it was handled already
        // XXX: Maybe it would be interesting to have retroactive application of $this->getOriginal here
        if (!\is_null($attachment_to_link)) {
            // Relate the note with the existing attachment
            DB::persist(AttachmentToNote::create([
                'attachment_id' => $attachment_to_link->getAttachmentId(),
                'note_id'       => $note->getId(),
            ]));
            DB::flush();
            return Event::stop;
        } else {
            // Validate if the URL really does point to a remote image
            $head = HTTPClient::head($link->getUrl());
            try {
                $headers = $head->getHeaders();
            } catch (ClientExceptionInterface|RedirectionExceptionInterface|ServerExceptionInterface|TransportExceptionInterface $e) {
                Log::debug('StoreRemoteMedia->onNewLinkFromNote@HTTPHead->getHeaders: ' . $e->getMessage(), [$e]);
                return Event::next;
            }

            // Does it respect the file quota?
            $file_size = $headers['content-length'][0] ?? null;
            $max_size  = $this->getMaxFileSize();
            if (\is_null($file_size) || $file_size > $max_size) {
                Log::debug("Went to download remote media of size {$file_size} but the plugin's filesize limit is {$max_size} so we aborted in StoreRemoteMedia->onNewLinkFromNote.");
                return Event::next;
            }

            // Retrieve media
            $get_response = HTTPClient::get($link->getUrl());
            $media        = $get_response->getContent();
            $mimetype     = $get_response->getHeaders()['content-type'][0] ?? null;
            unset($get_response);

            // TODO: Add functionality to specify allowed content types to retrieve here

            // Ensure we still want to handle it
            if ($mimetype != $link->getMimetype()) {
                $link->setMimetype($mimetype);
                DB::persist($link);
                DB::flush();
                if ($link->getMimetypeMajor() === 'text') {
                    return Event::next;
                }
            }

            // We can ignore empty files safely, the user can guess them (:
            if (!empty($media)) {
                // Create an attachment for this
                $temp_file = new TemporaryFile();
                $temp_file->write($media);
                $attachment = GSFile::storeFileAsAttachment($temp_file);

                // Relate the link with the attachment
                // TODO: Create a function that gets the title from content disposition or URL when such header isn't available
                DB::persist(AttachmentToLink::create([
                    'link_id'       => $link->getId(),
                    'attachment_id' => $attachment->getId(),
                ]));

                // Relate the note with the attachment
                DB::persist(AttachmentToNote::create([
                    'attachment_id' => $attachment->getId(),
                    'note_id'       => $note->getId(),
                ]));

                DB::flush();

                // Should we create a thumb and delete the original file?
                if (!$this->getStoreOriginal()) {
                    $thumbnail = AttachmentThumbnail::getOrCreate(
                        attachment: $attachment,
                        size: 'medium',
                        crop: $this->getSmartCrop(),
                    );
                    $attachment->deleteStorage();
                }
            }

            return Event::stop;
        }
    }

    /**
     * @return bool true if allowed by the lists, false otherwise
     */
    private function allowedLink(string $url): bool
    {
        $passed_whitelist = !$this->check_whitelist;
        $passed_blacklist = !$this->check_blacklist;

        if ($this->check_whitelist) {
            $passed_whitelist = false; // don't trust be default
            $host             = parse_url($url, \PHP_URL_HOST);
            foreach ($this->domain_whitelist as $regex => $provider) {
                if (preg_match("/{$regex}/", $host)) {
                    $passed_whitelist = true; // we trust this source
                }
            }
        }

        if ($this->check_blacklist) {
            // assume it passed by default
            $host = parse_url($url, \PHP_URL_HOST);
            foreach ($this->domain_blacklist as $regex => $provider) {
                if (preg_match("/{$regex}/", $host)) {
                    $passed_blacklist = false; // we blocked this source
                }
            }
        }

        return $passed_whitelist && $passed_blacklist;
    }

    /**
     * Event raised when GNU social polls the plugin for information about it.
     * Adds this plugin's version information to $versions array
     *
     * @param array $versions inherited from parent
     *
     * @return bool true hook value
     */
    public function onPluginVersion(array &$versions): EventResult
    {
        $versions[] = [
            'name'     => 'StoreRemoteMedia',
            'version'  => $this->version(),
            'author'   => 'Mikael Nordfeldth, Diogo Peralta Cordeiro',
            'homepage' => GNUSOCIAL_PROJECT_URL,
            'description', // TRANS: Plugin description. => _m('Plugin for downloading remotely attached files to local server.'),
        ];
        return Event::next;
    }
}