<?php
    defined('BASEPATH') OR exit('No direct script access allowed');

    class PostsModel extends CI_Model
    {
        public function __construct()
        {
            parent::__construct();
            $this->load->model('UserModel', '', TRUE);
            $this->load->model('NotificationModel', '', TRUE);
        }

        function addPost($userID, $content)
        {
            return $this->addReply($userID, $content, NULL);
        }

        public function addReply($userID, $content, $replyToUUID)
        {
            $content = $this->preparePostContent($content);
            $uuid = $this->generatePostUUID($userID, $content);
            $replyTo = NULL;
            if ($replyToUUID !== NULL) {
                $replyToID = $this->db->query('SELECT ID FROM user_posts WHERE uuid = ?', [$replyToUUID])->result_array();
                $replyTo = !empty($replyToID) ? $replyToID[0]['ID'] : NULL;
            }
            $this->db->query('INSERT INTO user_posts (user_id, content, uuid, reply_to) VALUES (?, ?, ?, ?)', [$userID, $content, $uuid, $replyTo]);


            $insertedPost = $this->db->query('SELECT ID, user_id FROM user_posts WHERE uuid = ?', [$uuid])->result_array();
            $this->addPostMentions($insertedPost[0]['ID'], $content, $uuid);
            $this->addPostHashtags($insertedPost[0]['ID'], $content);

            // Send notification to user whose post was replied to
            if ($userID != $insertedPost[0]['user_id']) {
                $this->NotificationModel->userNotificationPostReply($userID, $insertedPost[0]['user_id'], $insertedPost[0]['ID'], $uuid);
            }

            return $insertedPost[0]['ID'];
        }

        public function deletePost($userID, $uuid) {
            $postID = $this->db->query('SELECT ID FROM user_posts WHERE user_id = ? AND uuid = ?', [$userID, $uuid])->result_array()[0]['ID'];
            $this->db->query('DELETE FROM user_posts WHERE user_id = ? AND uuid = ?', [$userID, $uuid]);
            $this->db->query('DELETE FROM user_posts_hashtags WHERE postID = ?', [$postID]);
            $this->db->query('DELETE FROM user_posts_mentions WHERE postID = ?', [$postID]);
            $this->db->query('DELETE FROM user_posts_likes WHERE postID = ?', [$postID]);
            $this->db->query('DELETE FROM user_posts_media WHERE postID = ?', [$postID]);
        }

        public function addImageToPost($postID, $imageUrl) {
            $this->db->query('INSERT INTO user_posts_media (postID, mediaType, mediaUrl) VALUES (?, ?, ?)', [$postID, 'image', $imageUrl]);
        }

        public function preparePostContent($content)
        {
            if ($this->endsWith($content, '<br>&nbsp;')) {
                $content = substr($content, 0, strlen($content) - 10);
            }
            $content = htmlspecialchars($content);
            return $content;
        }

        function endsWith($haystack, $needle)
        {
            $length = strlen($needle);

            return $length === 0 ||
                (substr($haystack, -$length) === $needle);
        }

        function generatePostUUID($userID, $content)
        {
            return md5($userID . $content . date("Y-m-d H:i:s"));
        }

        public function addPostMentions($postID, $content, $postUUID)
        {
            preg_match_all('/@([A-Za-z0-9._]+)/', $content, $mentions, PREG_OFFSET_CAPTURE);
            foreach ($mentions[1] as $mention) {
                $mentionedUser = $this->UserModel->getUserIDByUsername(strtolower($mention[0]));
                if ($mentionedUser == null) {
                    continue;
                }
                $mentionedUser = $mentionedUser[0];
                $this->addMention($postID, $_SESSION['user']['ID'], $mentionedUser['ID'], $mention[1], $postUUID);
            }
        }

        public function addMention($postID, $userID, $mentionedUserID, $position, $postUUID)
        {
            $this->db->query('INSERT INTO user_posts_mentions (userID, postID, mentionedUserID, position) VALUES (?, ?, ?, ?)', [$userID, $postID, $mentionedUserID, $position]);

            // Send notification
            $this->NotificationModel->userNotificationPostMentioned($userID, $mentionedUserID, $postID, $postUUID);
        }

        public function addPostHashtags($postID, $content)
        {
            preg_match_all('/#([A-Za-z0-9]+)/', $content, $hashtags, PREG_OFFSET_CAPTURE);
            foreach ($hashtags[1] as $hashtag) {
                $this->addHashtag($postID, $_SESSION['user']['ID'], $hashtag[0], $hashtag[1]);
            }
        }

        public function addHashtag($postID, $userID, $hashtag, $position)
        {
            $this->db->query('INSERT INTO user_posts_hashtags (userID, postID, hashtag, position) VALUES (?, ?, ?, ?)', [$userID, $postID, $hashtag, $position]);
        }

        function getUserPosts($id, $count, $offset, $maxLength = 250)
        {
            $this->db->cache_off();
            $posts = $this->db->query('SELECT * FROM user_posts p WHERE user_id = ? ORDER BY date DESC LIMIT ? OFFSET ?', [$id, $count, $offset])->result_array();
            $this->db->cache_on();

            $posts = $this->preparePostList($posts, $maxLength);

            return $posts;
        }

        public function preparePostList($postList, $maxLength = 250)
        {
            foreach ($postList as $i => $post) {
                $post = $this->mergePostUserData($post);

                $post['replyCount'] = $this->getPostReplyCountByID($post['ID']);
                $post['likeCount'] = $this->getPostLikeCountByID($post['ID']);
                if ($maxLength > 0) {
                    $post['content'] = strlen($post['content']) > $maxLength ? substr($post['content'], 0, $maxLength) . '...' : $post['content'];
                }
                $post['content'] = $this->mergePostMentionsHashtags($post['ID'], $post['content']);
                $post['media'] = $this->getPostMedia($post['ID']);

                if (isset($_SESSION['user']) && !empty($_SESSION['user'])) {
                    $post = $this->mergeUserHasLiked($post, $_SESSION['user']['ID']);
                }

                if($post['reply_to'] != NULL) {
                    $post = $this->mergeReplyData($post);
                }

                $postList[$i] = $post;
            }

            $postList = $this->UserModel->setDefaultImages($postList);

            return $postList;
        }

        public function getPostMedia($postID) {
            $result = $this->db->query('SELECT * FROM user_posts_media WHERE postID = ?', [$postID])->result_array();
            return $result;
        }

        private function mergePostUserData($post)
        {
            $user = $this->UserModel->getUserByID($post['user_id']);
            $user = $user[0];

            $post['username'] = $user['username'];
            $post['displayname'] = $user['displayname'];
            $post['profile_picture'] = $user['profile_picture'];
            return $post;
        }

        public function getPostReplyCountByID($postID)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT count(*) replyCount FROM user_posts WHERE reply_to = ?', [$postID])->result_array();
            $this->db->cache_on();

            return $data[0]['replyCount'];
        }

        public function getPostLikeCountByID($id)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT count(*) likeCount FROM user_posts_likes WHERE postID = ?', [$id])->result_array();
            $this->db->cache_on();
            return $data[0]['likeCount'];
        }

        private function mergePostMentionsHashtags($postID, $content)
        {
            $mentions = $this->db->query('SELECT m.*, u.username, u.displayname FROM user_posts_mentions m LEFT JOIN users u ON m.mentionedUserID = u.ID WHERE postID = ?', [$postID])->result_array();
            $hashtags = $this->db->query('SELECT * FROM user_posts_hashtags WHERE postID = ?', [$postID])->result_array();

            $links = array_merge($mentions, $hashtags);
            usort($links, function ($a, $b) {
                return $a['position'] - $b['position'];
            });

            $finalContent = '';
            $prevPos = 0;
            foreach ($links as $link) {
                $finalContent .= substr($content, $prevPos, $link['position'] - $prevPos - 1);

                if (isset($link['username'])) { // Is link a mention?
                    $finalContent .= '<a href="' . base_url('user/' . $link['username']) . '">@' . $link['displayname'] . '</a>';
                    $prevPos = $link['position'] + strlen($link['username']);
                } else { // Link is a hashtag
                    $finalContent .= '<a href="' . base_url('posts/search?q=%23' . $link['hashtag'] . '&type=type-posts') . '">#' . $link['hashtag'] . '</a>';
                    $prevPos = $link['position'] + strlen($link['hashtag']);
                }

                if ($prevPos > strlen($content)) {
                    break;
                }

            }
            $finalContent .= substr($content, $prevPos, strlen($content) - $prevPos);

            return $finalContent;
        }

        private function mergeUserHasLiked($post, $userID)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts_likes WHERE postID = (SELECT ID FROM user_posts WHERE uuid = ?) AND likerUserID = ?', [$post['uuid'], $userID])->result_array();
            $this->db->cache_on();

            if (empty($data)) {
                $post['userHasLiked'] = FALSE;
            } else {
                $post['userHasLiked'] = TRUE;
            }
            return $post;
        }

        private function mergeReplyData($post) {
            $data = $this->db->query('SELECT uuid, username, displayname FROM user_posts LEFT JOIN users ON users.ID = user_posts.user_id WHERE user_posts.ID = ?', [$post['reply_to']])->result_array();
            $post['replyToUuid'] = $data[0]['uuid'];
            $post['replyToUsername'] = $data[0]['username'];
            $post['replyToDisplayname'] = $data[0]['displayname'];

            return $post;
        }

        public function getNewestPosts($count, $maxLength = 250)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts ORDER BY date DESC LIMIT ?', [$count])->result_array();
            $this->db->cache_on();

            $data = $this->preparePostList($data, $maxLength);

            return $data;
        }

        public function getFeedPosts($userID, $amount, $offset)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts WHERE user_id IN (SELECT followedUserID FROM user_followers WHERE followerUserID = ?) OR ID IN(SELECT postID FROM user_posts_mentions WHERE mentionedUserID = ?) OR ID IN (SELECT postID FROM user_posts_likes WHERE likedUserID = ?) OR user_id = ? ORDER BY date DESC LIMIT ? OFFSET ?', [$userID, $userID, $userID, $userID, $amount, $offset])->result_array();
            $this->db->cache_on();

            $data = $this->preparePostList($data);

            return $data;
        }

        public function getPopularPosts($amount, $offset)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts p ORDER BY ((SELECT count(*) FROM user_posts_likes WHERE postID = p.ID) + (SELECT count(*) FROM user_posts WHERE reply_to = p.ID)) DESC, date DESC LIMIT ? OFFSET ?', [$amount, $offset])->result_array();
            $this->db->cache_on();

            $data = $this->preparePostList($data);

            return $data;
        }

        public function getPostDetails($userID, $uuid)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts WHERE user_id = ? AND uuid = ?', [$userID, $uuid])->result_array();
            $this->db->cache_on();

            $data = $this->preparePostList($data, -1);

            return $data;
        }

        public function getPostReplies($postID)
        {
            $this->db->cache_off();
            $replies = $this->db->query('SELECT * FROM user_posts WHERE reply_to = ? ORDER BY date', [$postID])->result_array();
            $this->db->cache_on();

            $replies = $this->preparePostList($replies);

            return $replies;
        }

        public function getPostByUUID($uuid) {
            $this->db->cache_off();
            $result = $this->db->query('SELECT * FROM user_posts WHERE uuid = ?', [$uuid])->result_array();
            $this->db->cache_on();
            return $result;
        }

        public function addPostLikeByUUID($uuid, $userID)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT * FROM user_posts_likes WHERE postID = (SELECT ID FROM user_posts WHERE uuid = ?) AND likerUserID = ?', [$uuid, $userID])->result_array();
            $this->db->cache_on();

            // IDs needed for handling notifications later
            $postUser = $this->db->query('SELECT ID FROM users WHERE ID = (SELECT user_id FROM user_posts WHERE uuid = ?)', [$uuid])->result_array();
            $postID = $this->db->query('SELECT ID FROM user_posts WHERE uuid = ?', [$uuid])->result_array();
            if (empty($data)) {
                $this->db->query('INSERT INTO user_posts_likes (postID, likedUserID, likerUserID) VALUES ((SELECT ID FROM user_posts WHERE uuid = ?), (SELECT user_id FROM user_posts WHERE uuid = ?), ?)', [$uuid, $uuid, $userID]);

                // Send like notification
                if ($postUser[0]['ID'] != $userID) {
                    $this->NotificationModel->userNotificationPostLike($userID, $postUser[0]['ID'], $postID[0]['ID'], $uuid);
                }

                return true;
            } else {
                $this->db->query('DELETE FROM user_posts_likes WHERE postID = (SELECT ID FROM user_posts WHERE uuid = ?) AND likerUserID = ?', [$uuid, $userID]);

                // Remove existing notification
                $this->NotificationModel->removeNotification($userID, $postUser[0]['ID'], $postID[0]['ID'], 'users.likedPost');

                return false;
            }

        }

        public function getPostLikeCountByUUID($uuid)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT count(*) likeCount FROM user_posts_likes WHERE postID = (SELECT ID FROM user_posts WHERE uuid = ?)', [$uuid])->result_array();
            $this->db->cache_on();
            return $data[0]['likeCount'];
        }

        public function isUUIDValid($uuid)
        {
            $this->db->cache_off();
            $data = $this->db->query('SELECT ID FROM user_posts WHERE uuid = ?', [$uuid])->result_array();
            $this->db->cache_on();
            return !empty($data);
        }

        public function closeTags($html)
        {
            preg_match_all('#<(?!meta|img|br|hr|input\b)\b([a-z]+)(?: .*)?(?<![/|/ ])>#iU', $html, $result);
            $openedtags = $result[1];
            preg_match_all('#</([a-z]+)>#iU', $html, $result);
            $closedtags = $result[1];
            $len_opened = count($openedtags);
            if (count($closedtags) == $len_opened) {
                return $html;
            }
            $openedtags = array_reverse($openedtags);
            for ($i = 0; $i < $len_opened; $i++) {
                if (!in_array($openedtags[$i], $closedtags)) {
                    $html .= '</' . $openedtags[$i] . '>';
                } else {
                    unset($closedtags[array_search($openedtags[$i], $closedtags)]);
                }
            }
            return $html;
        }

        public function searchPosts($query, $limit = 20, $offset = 0)
        {
            $this->db->cache_off();
            $results = $this->db->query('SELECT * FROM user_posts WHERE content RLIKE ? OR (SELECT username FROM users WHERE ID = user_id) RLIKE ? ORDER BY (SELECT count(*) FROM user_posts_likes WHERE postID = ID) DESC, (SELECT count(*) FROM user_posts WHERE user_posts.reply_to = ID) DESC, date DESC LIMIT ? OFFSET ?', [$query, $query, $limit, $offset])->result_array();
            $this->db->cache_on();

            $results = $this->preparePostList($results);

            return $results;
        }

        public function reportPost($uuid, $reason, $reasonText) {
            $this->db->query('INSERT INTO user_posts_reports (postID, reason, reasonText) VALUES ((SELECT ID FROM user_posts WHERE uuid = ?), ?, ?)', [$uuid, $reason, $reasonText]);
            $this->db->cache_delete('admin', 'reports');

            // Send notification
            $postID = $this->db->query('SELECT ID FROM user_posts WHERE uuid = ?', [$uuid])->result_array();
            $this->NotificationModel->rankNotificationPostReport(
                isset($_SESSION['user']) ? $_SESSION['user']['ID'] : -1,
                8, $postID[0]['ID'], $uuid);
        }
    }