bot.php

<?php
$ACCESS_TOKEN = 'XXXXXXXXXXXXXXXXXXXXXXX';

// Get POST body content
$content = file_get_contents('php://input');

// Log Webhook POST to console
error_log("Incoming Webhook: " . $content);

// Parse JSON
$events = json_decode($content, true);

$output = [];

// Validate parsed JSON data
if (!is_null($events['events'])) {

 // Loop through each event
 foreach ($events['events'] as $event) {

  // Reply only when message sent is in 'text' format
  if ($event['type'] == 'message' && $event['message']['type'] == 'text') {

   // Get text sent
	 $text = $event['message']['text'];

   // Get replyToken
   $replyToken = $event['replyToken'];

   // Build message to reply back
   $messages = [
    'type' => 'text',
    'text' => $text
   ];

   // Make a POST Request to Messaging API to reply to sender
   $url = 'https://api.line.me/v2/bot/message/reply';
   $data = [
    'replyToken' => $replyToken,
    'messages' => [$messages],
   ];
   $post = json_encode($data);
   $headers = array('Content-Type: application/json', 'Authorization: Bearer ' . $ACCESS_TOKEN);

   $ch = curl_init($url);
   curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
   curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
   curl_setopt($ch, CURLOPT_POSTFIELDS, $post);
   curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
   curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
   $result = curl_exec($ch);
   curl_close($ch);

   $output[] = json_decode($result);
  }
 }
}

echo json_encode($output);