how to see last message of the chat in laravel?

Please, say me how can i see the last message of each dialog on the single page, named dialogs.

i have two tables: users and chats.

users - standart table with standart meanings.

chats - have fields: user_id, friend_id, chat. user_id and friend_id - there are users who have a conversation, chat - one message from one of them:

id|---user_id---|---friend_id---|---chat---
1 |---1---------|---2-----------|--this is the first message
2 |---2---------|---1-----------|--this is the second message

This part of controller ChatController

public function index()
{

    $users = User::all();

    $user = Auth::user();

    $last_message = Chat::select(['chat'])->where('user_id', $user->id)->orWhere('friend_id', $user->id)->orderBy('id', 'desc')->first(); - //this code not corrected, it display the message from either user



    $search_string = Input::get('search-tag');

    $search_result = null;
    if(!empty($search_string)){
        $search_result = User::where('name', 'like', '%' . $search_string . '%')
            ->orWhere('name', 'like', '%' . strtolower($search_string) . '%')
            ->orWhere('name', 'like', '%' . strtoupper($search_string) . '%')
            ->orWhere('id', strtoupper($search_string))->get();
    }

    $friends = Auth::user()->friends();

    return view('chat.index')
        ->with('user', $user)
        ->with('friends', $friends)
        ->with('search_result', $search_result)
        ->with('last_message', $last_message)
              ->with('users', $users);
}

This is the model of chat:

 <?php

class Chat extends Model
{
    protected $dispatchesEvents = [
        'created' => BroadcastChat::class
    ];

    protected $fillable = ['user_id', 'friend_id', 'chat'];

    public function user(){
        return $this->belongsTo(User::class);
    }

    public function friend(){
        return $this->belongsTo(User::class);
    }

}

I need in correct declaration user_id and friend_id to output a message between these specific users to the variable $last_message and display it in the chats.index

via Chebli Mohamed