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 require_once HOPLITE_ROOT . '/views/template_loader.php';
  21
  22 /*!
  23   The OutputFilter is executed after all Actions have been processed. The
  24   primary function is to generate the actual HTTP response body from the model
  25   data contained within the http\Response. Depending on how the Request was
  26   sent, this
  27 */
  28 class OutputFilter
  29 {
  30   /*! @var RootController */
  31   private $controller;
  32
  33   /*! @const The key in Response#context that indicates which type of output to
  34              produce, regardless of the request type.
  35   */
  36   const RESPONSE_TYPE = 'response_type';
  37
  38   /*! @const A key in Response#context to render a template with the
  39              Response#data when creating a HTML body.
  40   */
  41   const RENDER_TEMPLATE = 'template';
  42
  43   /*!
  44     Constructor that takes a reference to the RootController.
  45   */
  46   public function __construct(RootController $controller)
  47   {
  48     $this->controller = $controller;
  49   }
  50
  51   /*! Accessor for the RootController. */
  52   public function controller() { return $this->controller; }
  53
  54   /*! @brief Main entry point for output filtering
  55     This is called from the RootController to begin processing the output and
  56     generating the response.
  57   */
  58   public function FilterOutput(Request $request, Response $response)
  59   {
  60     // If there was an error during the processing of an action, allow hooking
  61     // custom logic.
  62     if ($response->response_code != ResponseCode::OK)
  63       if (!$this->_ContinueHandlingResponseForCode($request, $response))
  64         return;
  65
  66     // If there's already raw data for the body, just output that. Otherwise,
  67     // construct the body based on how the Request was received and any other
  68     //  information in the response.
  69     if (!$response->body)
  70       $this->_CreateBodyForResponse($request, $response);
  71
  72     // Now just output the response.
  73     header("Status: {$response->response_code}", true, $response->response_code);
  74     foreach ($response->headers as $header => $value)
  75       header("$header: $value");
  76     print $response->body;
  77   }
  78
  79   /*!
  80     If the request did not generate an 200 response code, the filter gives the
  81     client an opportunity to override the normal output control flow and perform
  82     some other task. If you want the control flow to continue executing as
  83     normal, return TRUE; otherwise, return FALSE to exit from ::FilterOutput().
  84     @return boolean
  85   */
  86   protected function _ContinueHandlingResponseForCode(Request $request,
  87                                                       Response $response)
  88   {
  89     return TRUE;
  90   }
  91
  92   /*!
  93     Fills out the Response#data field. This could be an evaluated HTML template,
  94     a JSON payload, XML, or any other type of response for the client.
  95   */
  96   protected function _CreateBodyForResponse(Request $request,
  97                                             Response $response)
  98   {
  99     $type = NULL;
 100
 101     // See if the HTTP request contains the desired output format.
 102     if (isset($request->data['format'])) {
 103       if ($request->data['format'] == 'xml')
 104         $type = 'xml';
 105       else if ($request->data['format'] == 'json')
 106         $type = 'json';
 107     }
 108
 109     // If the request didn't specify a type, try and figure it out using
 110     // heuristics.
 111
 112     // If this was from an XHR, assume JSON.
 113     if (!$type && isset($request->data['_SERVER']['HTTP_X_REQUESTED_WITH']))
 114       $type = 'json';
 115
 116     // Check if an Action specified an overriding response type.
 117     if (isset($response->context[self::RESPONSE_TYPE]))
 118       $type = $response->context[self::RESPONSE_TYPE];
 119
 120     // If no type has been determined, just assume HTML.
 121     if (!$type)
 122       $type = 'html';
 123
 124     if ($type == 'json') {
 125       $response->headers['Content-Type'] = 'application/json';
 126       $response->body = json_encode($response->data, JSON_NUMERIC_CHECK);
 127     } else if ($type == 'xml') {
 128       $response->headers['Content-Type'] = 'application/xml';
 129       $response->body = $this->_EncodeXML($response->data);
 130     } else if ($type == 'html') {
 131       $response->headers['Content-Type'] = 'text/html';
 132       if (isset($response->context[self::RENDER_TEMPLATE])) {
 133         $template = \hoplite\views\TemplateLoader::Fetch($response->context[self::RENDER_TEMPLATE]);
 134         $response->body = $template->Render($response->data);
 135       }
 136     }
 137   }
 138
 139   /*!
 140     Creates an XML tree from an array. Equivalent to json_encode.
 141   */
 142   protected function _EncodeXML($data)
 143   {
 144     $response = new \SimpleXMLElement('<response/>');
 145
 146     $writer = function($elm, $parent) use (&$writer) {
 147       foreach ($elm as $key => $value) {
 148         if (is_scalar($value)) {
 149           $parent->AddChild($key, $value);
 150         } else {
 151           $new_parent = $parent->AddChild($key);
 152           $writer($value, $new_parent);
 153         }
 154       }
 155     };
 156
 157     $writer($data, $response);
 158     return $response->AsXML();
 159   }
 160 }