<?php
/**
 * @copyright Copyright (c) 2018 Bjoern Schiessle <bjoern@schiessle.org>
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program 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.
 *
 * 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

require_once 'Mastodon_api.php';
require_once '../../mastodon.feed/config.php';

class CollectMastodonData {

    /** @var \Mastodon_api */
    private $api;

    /** @var string url of the mastodon instance */
    private $mastodonUrl = 'https://mastodon.social';

    /** @var string token to authenticate at the mastodon instance */
    private $bearerToken;

    /** @var int keep cache at least 600 seconds = 10 minutes */
    private $threshold = 600;

    /** @var string uid on the mastodon instance */
    private $uid;

    /** @var array cached comments from previous searches */
    private $commentCache = [];

    private $cacheFile = 'myCommentsCache.json';

    public function __construct($config) {
        $this->mastodonUrl = $config['mastodon-instance'];
        $this->bearerToken = $config['token'];
        $this->uid = $config['user-id'];

        $this->api = new Mastodon_api();

        $this->api->set_url($this->mastodonUrl);
        $this->api->set_token($this->bearerToken, 'bearer');
    }

    private function filterComments($descendants, $root, &$result) {
        foreach ($descendants as $d) {
            $result['comments'][$d['id']] = [
                'author' => [
                    'display_name' => $d['account']['display_name'] ? $d['account']['display_name'] : $d['account']['username'],
                    'avatar' => $d['account']['avatar_static'],
                    'url' => $d['account']['url']
                ],
                'toot' => $d['content'],
                'date' => $d['created_at'],
                'url' => $d['uri'],
                'reply_to' => $d['in_reply_to_id'],
                'root' => $root,
            ];
        }

        return $result;
    }

    private function filterStats($stats) {
        $result = [
            'reblogs' => (int)$stats['reblogs_count'],
            'favs' => (int)$stats['favourites_count'],
            'replies' => (int)$stats['replies_count'],
            'url' => $stats['url']
        ];
        return $result;
    }

    private function filterSearchResults($searchResult) {
        $result = [];
        if (isset($searchResult['html']['statuses'])) {
            foreach ($searchResult['html']['statuses'] as $status) {
                if ($status['in_reply_to_id'] === null) {
                    $result[] = $status['id'];
                }
            }
        }

	sort($result);
        return $result;
    }

    /**
     * find all toots for a given blog post and return the corresponding IDs
     *
     * @param string $search
     * @return array
     */
    public function findToots($search) {
        $result = $this->api->search(['q' => $search]);
        return $this->filterSearchResults($result);
    }

    public function getComments($id, &$result) {
        $raw = file_get_contents("https://mastodon.social/api/v1/statuses/$id/context");
        $json = json_decode($raw, true);
        $this->filterComments($json['descendants'], $id, $result);
    }

    public function getStatistics($id, &$result) {
        $raw = file_get_contents("https://mastodon.social/api/v1/statuses/$id");
        $json = json_decode($raw, true);
        $newStats = $this->filterStats($json);
        $result['stats']['reblogs'] += $newStats['reblogs'];
        $result['stats']['favs'] += $newStats['favs'];
        $result['stats']['replies'] += $newStats['replies'];
        if (empty($result['stats']['url'])) {
            $result['stats']['url'] = $newStats['url'];
        }
    }

    public function storeCollection($id, $comments) {
        $timestamp = time();
        $comments['timestamp'] = $timestamp;
        $this->commentCache[$id] = $comments;
        file_put_contents($this->cacheFile, json_encode($this->commentCache));
    }

    public function getCachedCollection($search) {
        if (file_exists($this->cacheFile)) {
            $cachedComments = file_get_contents($this->cacheFile);
            $cachedCommentsArray = json_decode($cachedComments, true);
            if (is_array($cachedCommentsArray)) {
                $this->commentCache = $cachedCommentsArray;
                $currentTimestamp = time();
                if (isset($cachedCommentsArray[$search])) {
                    if ((int)$cachedCommentsArray[$search]['timestamp'] + $this->threshold > $currentTimestamp) {
                        unset($cachedCommentsArray[$search]['timestamp']);
                        return $cachedCommentsArray[$search];
                    }
                }
            }
        }

        return [];
    }
}

$result = ['comments' => [], 'stats' => ['reblogs' => 0, 'favs' => 0, 'replies' => 0, 'url' => '', 'root' => 0]];

$search = isset($_GET['search']) ? $_GET['search'] : '';
$collector = new CollectMastodonData($config);
$ids = [];
if (!empty($search)) {
    $oldCollection = $collector->getCachedCollection($search);
    if (empty($oldCollection)) {
        $ids = $collector->findToots($search);
        $result['stats']['root'] = isset($ids[0]) ? $ids[0] : 0;
        foreach ($ids as $id) {
            // get comments
            $newComments = $collector->getComments($id, $result);
            // get statistics (likes, replies, boosts,...)
            $collector->getStatistics($id, $result);
            // FIXME: At the moment the API doesn't return the correct replies count so I count it manually
            $result['stats']['replies'] = count($result['comments']);
        }
        $collector->storeCollection($search, $result);
    } else {
        $result = $oldCollection;
    }
}

// headers for not caching the results
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');

// headers to tell that result is JSON
header('Content-type: application/json');

// send the result now
echo json_encode($result);