AJAX/TP3/php/chat.php

<?php
ini_set('display_errors', 1);
error_reporting(E_ALL);

include('./database.php');

$pdo = dbConnect();

if(isset($_GET['request']) && $_GET['request'] == 'channels'){
    $channels = dbGetChannels($pdo);
    if($channels){
        $formattedChannels = [];
        $id = 1;
        foreach($channels as $channel){
            $formattedChannels[] = ['id' => $id, 'name' => $channel['name']];
            $id++;
        }
        echo json_encode($formattedChannels);
    }
    else{
        echo json_encode('No channels found');
    }
}

if(isset($_GET['request']) && $_GET['request'] == 'messages'){
    if(isset($_GET['channel_id'])){
        header('Content-Type: application/json');
        $channel_id = intval($_GET['channel_id']);
        $messages = dbGetMessages($pdo, $channel_id);
        if($messages){
            echo json_encode($messages);
        }
        else{
            echo json_encode([]);
        }
    }
    else{
        if(isset($_POST['channel_id']) && $_POST['userlogin'] && $_POST['message']){
            header('Content-Type: application/json');
            $channel_id = intval($_POST['channel_id']);
            $userlogin = $_POST['userlogin'];
            $message = $_POST['message'];
            $result = dbAddMessage($pdo, $userlogin, $channel_id, $message);
            if($result){
                echo json_encode(array("status" => "success", "message" => "Message added"));
            } else {
                echo json_encode(array("status" => "error", "message" => "Message not added"));
            }
        }
        else{
            echo json_encode(array("status" => "error", "message" => "Invalid request"));
        }
    }

}