ChatController.php

<?php

class ChatController extends ControllerBase
{
    public function indexAction()
    {
        // Logged User
        $userId = $this->session->get('user')['user_id'];

        // Load conversations
        $conversations = [];
        $convQuery = Message::query()
                            ->columns('MAX(message_id) as message_id, MAX(createdAt) as createdAt')
                            ->where('(from_user_id = :from_user_id: OR to_user_id = :to_user_id:) AND from_user_id IN (SELECT user_id FROM User) AND to_user_id IN (SELECT user_id FROM User)')
                            ->groupBy('conversation_id')
                            ->bind(['from_user_id' => $userId, 'to_user_id' => $userId])
                            ->execute();

        foreach ($convQuery as $res) {
            $message = Message::findFirst($res->message_id);

            $convUser = $message->from_user_id == $userId ? User::findFirst($message->to_user_id):  User::findFirst($message->from_user_id);

            $conversations[] = [
                'message_id'      => $res->message_id,
                'content'         => $message->content,
                'conversation_id' => $message->conversation_id,
                'createdAt'       => $message->createdAt,
                'user'            => $convUser,
            ];
        }

        // Get conversations users
        $conversationsUsersIds = array_map(function($value){
            return $value['user']->user_id;
        }, $conversations);


        // New conversation
        $newChatId = $this->request->getPost('new_chat_id');

        if ($newChatId && in_array($newChatId, $conversationsUsersIds) == false) {
            $newChatUser = User::findFirst($newChatId);

            $this->view->newChat = [
                'conversation_id' => Message::buildConversationId($userId, $newChatUser->user_id),
                'user'            => $newChatUser,
            ];
        }

        $this->view->user = $this->session->get('user');

        usort($conversations, function($a, $b) {
            return $b['message_id'] - $a['message_id'];
        });

        $this->view->conversations = $conversations;

        $this->view->setMainView('pages/chat');
    }

    /**
     * Carregar mensagens de acordo com a conversa
     *
     * @return  json
     */
    public function messagesAction()
    {
        $conversationId = $this->request->getQuery('conversation_id');

        if ($this->isValidConversation($conversationId)) {

            // Order
            $orderBy = $this->request->getQuery('order', null, 'message_id DESC');

            // Limit
            $limit = $this->request->getQuery('limit', null, 10);

            // Binds & Types
            $binds = ['conversationId' => $conversationId];

            // Start Query
            $query = 'conversation_id = :conversationId:';

            // Filter Id Lower Than
            if ($this->request->getQuery('filter_id_lt')) {
                $query .= ' AND message_id < :filter_id_lt:';

                $binds['filter_id_lt'] = $this->request->getQuery('filter_id_lt');
            }

            // Filter Id Higher Than
            if ($this->request->getQuery('filter_id_gt')) {
                $query .= ' AND message_id > :filter_id_gt:';

                $binds['filter_id_gt'] = $this->request->getQuery('filter_id_gt');
            }

            // Load messages
            $messages = Message::query()->where($query, $binds)->orderBy($orderBy)->limit($limit)->execute()->toArray();

            $json['messages'] = [];

            foreach ($messages as $msg) {
                $json['messages'][] = array(
                    'message_id'      => $msg['message_id'],
                    'createdAt'       => $msg['createdAt'],
                    'conversation_id' => $msg['conversation_id'],
                    'from_user'       => \User::findFirst($msg['from_user_id']),
                    'to_user'         => \User::findFirst($msg['to_user_id']),
                    'content'         => $msg['content'],
                );
            }

            $json['success'] = true;
        } else {
            $json['success'] = false;
        }

        $this->response->setStatusCode(200, "OK");
        $this->response->setHeader("Content-Type", "application/json");
        $this->response->setContent(json_encode($json));
        $this->response->send();
    }

    /**
     * Carregar mensagens de acordo com a conversa
     *
     * @return  json
     */
    public function sendMessageAction()
    {
        // Logged User

        $userId = $this->session->get('user')['user_id'];

        $conversationId = $this->request->getPost('conversation_id');

        $toUserId = $this->request->getPost('to_user_id');

        if (empty($this->request->getPost('content')) == false && $this->isValidConversation($conversationId, $toUserId)) {

            // Get conversation
            $conversation = Message::findByConversation_id($conversationId)->getFirst();

            $message = new Message();

            $message->from_user_id = $userId;

            $message->content = $this->request->getPost('content');

            if (empty($conversation) == false) {
                $message->conversation_id = $conversation->conversation_id;

                $message->to_user_id = $conversation->from_user_id == $userId ? $conversation->to_user_id : $conversation->from_user_id;
            } else {
                $message->to_user_id = $toUserId;

                $message->conversation_id = Message::buildConversationId($userId, $toUserId);
            }

            $message->save();

            $json['success'] = true;
            $json['message_id'] = $message->getWriteConnection()->lastInsertId();
        } else {
            $json['success'] = false;
        }

        $this->response->setStatusCode(200, "OK");
        $this->response->setHeader("Content-Type", "application/json");
        $this->response->setContent(json_encode($json));
        $this->response->send();
    }

    /**
     * Check if conversation belongs to user
     *
     * @param   integer  $conversationId  Conversation Id
     * @param   integer  $conversationId  Conversation Id
     * @return  boolean
     */
    private function isValidConversation($conversationId, $toUserId = null)
    {
        // Logged User
        $userId = $this->session->get('user')['user_id'];

        // Get conversation
        $conversation = Message::findByConversation_id($conversationId)->getFirst();

        if (empty($conversation) == false) {
            return in_array($userId, [$conversation->from_user_id, $conversation->to_user_id]);
        }

        // Validate new conversation
        if (empty($conversation) && $toUserId) {
            return Message::buildConversationId($userId, $toUserId) == $conversationId;
        }

        return false;
    }
}