api.php

<?php
  ini_set('always_populate_raw_post_data', -1);
  ini_set('display_errors', 0);

  error_reporting(0);

  require_once('config.php');

  // get the HTTP method, path and body of the request
  $method = $_SERVER['REQUEST_METHOD'];
  $request = explode('/', $_SERVER['PATH_INFO']);
  $input = json_decode(file_get_contents('php://input'), true);

  // connect to the mysql database
  $link = mysqli_connect($host, $user, $pass, $dbname);
  mysqli_set_charset($link, 'utf8');

  /**
   * Set response status code and print an JS Object with error's info
   * 
   * @param Integer $status_code  Status code
   * @param String  $message      Error's info
   */
  function error_response($status_code, $message) {
    echo(json_encode(array('error' => $message)));
    http_response_code($status_code);
    exit();
  }

  /**
   * Token validation
   * 
   * @param String  $token Token to validate
   * @return Boolean Return true if there is a user with this token 
   *
   */
  function check_token() {
    global $link;
    if(isset(getallheaders()["Authorization"])) {
      $token_check = mysqli_query(
        $link,
        "SELECT COUNT(username) as res
          FROM user 
          WHERE token = '" . getallheaders()["Authorization"] ."'"
      );
      if(mysqli_fetch_object($token_check)->res == 1) {
        return true;
      }
      else {
        error_response(403, 'Invalid Token!');
        return false;
      }
    }
    else {
      error_response(403, 'Unauthorized!');
      return false;
    }
  }

  // var_dump($request);

  switch (count($request)) {
    
    case 2:
    case 3:
      // echo("NO RELAZIONE");
      require_once('./core/single_table.php');
      break;
    case 4:
    case 5:
      require_once('./core/multi_table.php');
      break;
    default:
      echo(json_encode(array('error' => 'Welcome on Uni-API!')));
      break;
  }

  // close mysql connection
  mysqli_close($link);