signup.php

<?php
/**
* Copyright 2015, Google, Inc.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
**/

include "constants.php";
require __DIR__ . '/vendor/autoload.php';
$recaptcha = new \ReCaptcha\ReCaptcha(SECRET);

$email = $_POST['email'];
$gRecaptchaResponse = $_POST['g-recaptcha-response'];
$remoteIp = $_SERVER['REMOTE_ADDR'];

$out = Array();
$out["ok"] = false;


$resp = $recaptcha->verify($gRecaptchaResponse, $remoteIp);

if ($resp->isSuccess()) {

  if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {

    $out["message"] = "Invalid Email";
  } else {

    $slackInviteUrl = 'https://'.SUBDOMAIN.'.slack.com/api/users.admin.invite?t='.time();

    // add fileds
    $fields .= "email=".urlencode($email)."&";
    $fields .= "token=".TOKEN."&";
    $fields .= "set_active=true&";
    $fields .= "_attempts=1";

    // open connection
    $ch = curl_init();

    // set the url, number of POST vars, POST data
    curl_setopt($ch, CURLOPT_URL, $slackInviteUrl);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POST, 4);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $fields);

    // send the request to Slack
    $reply = json_decode(curl_exec($ch), true);
    curl_close($ch);

    // output
    if ($reply['ok'] == false) {
      // error sending invite
      if($reply['error'] == "already_in_team") {
        $out["message"] = "You have already joined this Slack!";
      } elseif($reply['error'] == "already_invited") {
        $out["message"] = "Your invite has already been sent!";
      } else {
        $out["message"] = "Error Code: ".$reply['error'];
      }
    } else {
      // invitation was sent sucessfully
      $out["message"] = "Invitation sent!";
      $out["ok"] = true;
    }
  }
  //send JSON response back
  echo (json_encode($out, JSON_PRETTY_PRINT));
} else {
  $out["message"] = "ReCAPTCHA Error. Refresh and try again!";
  echo (json_encode($out, JSON_PRETTY_PRINT));
}