http/output_filter.php

   1 <?php
   2 // Hoplite
   3 // Copyright (c) 2011 Blue Static
   4 //
   5 // This program is free software: you can redistribute it and/or modify it
   6 // under the terms of the GNU General Public License as published by the Free
   7 // Software Foundation, either version 3 of the License, or any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful, but WITHOUT
  10 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 // more details.
  13 //
  14 // You should have received a copy of the GNU General Public License along with
  15 // this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 namespace hoplite\http;
  18
  19 require_once HOPLITE_ROOT . '/http/response_code.php';
  20
  21 /*!
  22   The OutputFilter is executed after all Actions have been processed. The
  23   primary function is to generate the actual HTTP response body from the model
  24   data contained within the http\Response. Depending on how the Request was
  25   sent, this
  26 */
  27 class OutputFilter
  28 {
  29   /*! @var RootController */
  30   private $controller;
  31
  32   /*! @const The key in Response#context that indicates which type of output to
  33              produce, regardless of the request type.
  34   */
  35   const RESPONSE_TYPE = 'response_type';
  36
  37   /*!
  38     Constructor that takes a reference to the RootController.
  39   */
  40   public function __construct(RootController $controller)
  41   {
  42     $this->controller = $controller;
  43   }
  44
  45   /*! Accessor for the RootController. */
  46   public function controller() { return $this->controller; }
  47
  48   /*! @brief Main entry point for output filtering
  49     This is called from the RootController to begin processing the output and
  50     generating the response.
  51   */
  52   public function FilterOutput(Request $request, Response $response)
  53   {
  54     // If there was an error during the processing of an action, allow hooking
  55     // custom logic.
  56     if ($response->response_code != ResponseCode::OK)
  57       if (!$this->_ContinueHandlingResponseForCode($request, $response))
  58         return;
  59
  60     // If there's already raw data for the body, just output that.
  61     if ($response->body)
  62       return;
  63
  64     // Otherwise, construct the body based on how the Request was received and
  65     // any other information in the response.
  66     $this->_CreateBodyForResponse($request, $response);
  67
  68     // Now just output the response.
  69     header("Status: {$response->response_code}", true, $response->response_code);
  70     foreach ($response->headers as $header => $value)
  71       header("$header: $value");
  72     print $response->body;
  73   }
  74
  75   /*!
  76     If the request did not generate an 200 response code, the filter gives the
  77     client an opportunity to override the normal output control flow and perform
  78     some other task. If you want the control flow to continue executing as
  79     normal, return TRUE; otherwise, return FALSE to exit from ::FilterOutput().
  80     @return boolean
  81   */
  82   protected function _ContinueHandlingResponseForCode(Request $request,
  83                                                       Response $response)
  84   {
  85     return TRUE;
  86   }
  87
  88   /*!
  89     Fills out the Response#data field. This could be an evaluated HTML template,
  90     a JSON payload, XML, or any other type of response for the client.
  91   */
  92   protected function _CreateBodyForResponse(Request $request,
  93                                             Response $response)
  94   {
  95     $type = NULL;
  96
  97     // See if the HTTP request contains the desired output format.
  98     if (isset($request->data['format'])) {
  99       if ($request->data['format'] == 'xml')
 100         $type = 'xml';
 101       else if ($request->data['format'] == 'json')
 102         $type = 'json';
 103     }
 104
 105     // If the request didn't specify a type, try and figure it out using
 106     // heuristics.
 107
 108     // If this was from an XHR, assume JSON.
 109     if (!$type && isset($request->data['_SERVER']['X_REQUESTED_WITH']))
 110       $type = 'json';
 111
 112     // Check if an Action specified an overriding response type.
 113     if (isset($response->context[self::RESPONSE_TYPE]))
 114       $type = $response->context[self::RESPONSE_TYPE];
 115
 116     // If no type has been determined, just assume HTML.
 117     if (!$type)
 118       $type = 'html';
 119
 120     if ($type == 'json') {
 121       $response->headers['Content-Type'] = 'application/json';
 122       $response->body = json_encode($response->data);
 123     } else if ($type == 'xml') {
 124       $response->headers['Content-Type'] = 'application/xml';
 125       $response->body = $this->_EncodeXML($response->data);
 126     } else if ($type == 'html') {
 127       $response->headers['Content-Type'] = 'text/html';
 128     }
 129   }
 130
 131   /*!
 132     Creates an XML tree from an array. Equivalent to json_encode.
 133   */
 134   protected function _EncodeXML($data)
 135   {
 136     $response = new \SimpleXMLElement('<response/>');
 137
 138     $writer = function($elm, $parent) use (&$writer) {
 139       foreach ($elm as $key => $value) {
 140         if (is_scalar($value)) {
 141           $parent->AddChild($key, $value);
 142         } else {
 143           $new_parent = $parent->AddChild($key);
 144           $writer($value, $new_parent);
 145         }
 146       }
 147     };
 148
 149     $writer($data, $response);
 150     return $response->AsXML();
 151   }
 152 }