<?php
  /* Copyright (c) 2009 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.
   *
   * Author: Eric Bidelman <e.bidelman@google.com>
   */
  
  $PRIV_KEY_FILE = '/path/to/your/rsa_private_key.pem';
  
  // OAuth library - http://oauth.googlecode.com/svn/code/php/
  require_once('OAuth.php');
  
  // Google's accepted signature methods
  $hmac_method = new OAuthSignatureMethod_HMAC_SHA1();
  $rsa_method = new OAuthSignatureMethod_RSA_SHA1();
  $SIG_METHODS = array($rsa_method->get_name() => $rsa_method,
                       $hmac_method->get_name() => $hmac_method);
  
  /**
   * Makes an HTTP request to the specified URL
   *
   * @param string $http_method The HTTP method (GET, POST, PUT, DELETE)
   * @param string $url Full URL of the resource to access
   * @param array $extraHeaders (optional) Additional headers to include in each
   *     request. Elements are header/value pair strings ('Host: example.com')
   * @param string $postData (optional) POST/PUT request body
   * @param bool $returnResponseHeaders True if resp. headers should be returned.
   * @return string Response body from the server
   */
  function send_signed_request($http_method, $url, $extraHeaders=null,
                               $postData=null, $returnResponseHeaders=true) {
    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_FAILONERROR, false);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
  
    // Return request headers in the reponse
  //   curl_setopt($curl, CURLINFO_HEADER_OUT, true);
  
    // Return response headers ni the response?
    if ($returnResponseHeaders) {
      curl_setopt($curl, CURLOPT_HEADER, true);
    }
  
    $headers = array();
    //$headers[] = 'GData-Version: 2.0';  // use GData v2 by default
    if (is_array($extraHeaders)) {
      $headers = array_merge($headers, $extraHeaders);
    }
  
    // Setup default curl options for each type of HTTP request.
    // This is also a great place to add additional headers for each request.
    switch($http_method) {
      case 'GET':
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
        break;
      case 'POST':
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($curl, CURLOPT_POST, 1);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $postData);
        break;
      case 'PUT':
        $headers[] = 'If-Match: *';
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($curl, CURLOPT_CUSTOMREQUEST, $http_method);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $postData);
        break;
      case 'DELETE':
        $headers[] = 'If-Match: *';
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
        curl_setopt($curl, CURLOPT_CUSTOMREQUEST, $http_method);
        break;
      default:
        curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);
    }
  
    // Execute the request.  If an error occures, fill the response body with it.
    $response = curl_exec($curl);
    if (!$response) {
      $response = curl_error($curl);
    }
  
    // Add server's response headers to our response body
   $response = curl_getinfo($curl, CURLINFO_HEADER_OUT) . $response;
  
    curl_close($curl);
  
    return $response;
  }
  
  /**
  * Takes XML as a string and returns it nicely indented
  *
  * @param string $xml The xml to beautify
  * @param boolean $html_output True if returned XML should be escaped for HTML.
  * @return string The beautified xml
  */
  function xml_pretty_printer($xml, $html_output=false) {
    $xml_obj = new SimpleXMLElement($xml);
    $level = 2;
  
    // Get an array containing each XML element
    $xml = explode("
  ", preg_replace('/>\s*</', ">
  <", $xml_obj->asXML()));
  
    // Hold current indentation level
    $indent = 0;
  
    $pretty = array();
  
    // Shift off opening XML tag if present
    if (count($xml) && preg_match('/^<\?\s*xml/', $xml[0])) {
      $pretty[] = array_shift($xml);
    }
  
    foreach ($xml as $el) {
      if (preg_match('/^<([\w])+[^>\/]*>$/U', $el)) {
        // opening tag, increase indent
        $pretty[] = str_repeat(' ', $indent) . $el;
        $indent += $level;
      } else {
        if (preg_match('/^<\/.+>$/', $el)) {
          $indent -= $level;  // closing tag, decrease indent
        }
        if ($indent < 0) {
          $indent += $level;
        }
        $pretty[] = str_repeat(' ', $indent) . $el;
      }
    }
  
    $xml = implode("
  ", $pretty);
    return $html_output ? htmlentities($xml) : $xml;
  }
  
  /**
   * Joins key/value pairs by $inner_glue and each pair together by $outer_glue.
   *
   * Example: implode_assoc('=', '&', array('a' => 1, 'b' => 2)) === 'a=1&b=2'
   *
   * @param string $inner_glue What to implode each key/value pair with
   * @param string $outer_glue What to impode each key/value string subset with
   * @param array $array Associative array of query parameters
   * @return string Urlencoded string of query parameters
   */
  function implode_assoc($inner_glue, $outer_glue, $array) {
    $output = array();
    foreach($array as $key => $item) {
      $output[] = $key . $inner_glue . urlencode($item);
    }
    return implode($outer_glue, $output);
  }
  
  /**
   * Explodes a string of key/value url parameters into an associative array.
   * This method performs the compliment operations of implode_assoc().
   *
   * Example: explode_assoc('=', '&', 'a=1&b=2') === array('a' => 1, 'b' => 2)
   *
   * @param string $inner_glue What each key/value pair is joined with
   * @param string $outer_glue What each set of key/value pairs is joined with.
   * @param array $array Associative array of query parameters
   * @return array Urlencoded string of query parameters
   */
  function explode_assoc($inner_glue, $outer_glue, $params) {
    $tempArr = explode($outer_glue, $params);
    foreach($tempArr as $val) {
      $pos = strpos($val, $inner_glue);
      $key = substr($val, 0, $pos);
      $array2[$key] = substr($val, $pos + 1, strlen($val));
    }
    return $array2;
  }
  
  ?>