[gh-124] Add a input filter that allows the embedding of content from nodes...

[gh-124] Add a input filter that allows the embedding of content from nodes inside of nodes by using tags.
[gh-124] Add support for the <!--#include virtual="some/path"--> SSI directive as a filter.

sites/all/modules/unl/unl.module

@@ -1513,3 +1513,130 @@ function unl_query_alter(QueryAlterableInterface $query) {
     }
   }
 }
+
+/**
+ * Implementation of hook_filter_info()
+ */
+function unl_filter_info()
+{
+  return array(
+    'unl_embed' => array(
+      'title' => 'UNL Node Embed',
+      'description' => "Allow a node's body to be embedded into another node by using tags.",
+      'process callback' => 'unl_filter_embed_process',
+      'cache' => FALSE,
+    ),
+    'unl_ssi' => array(
+      'title' => 'UNL SSI',
+      'description' => 'Implements the <!--#include virtual="some/path"--> Server Side Include directive.',
+      'process callback' => 'unl_filter_ssi_process',
+      'cache' => FALSE,
+    ),
+  );
+}
+
+/**
+ * Implementation of hook_filter_FILTER_process pseudo-hook
+ * 
+ * Replace any instances of [[node:X]] in the $text with the content of node X's body. 
+ */
+function unl_filter_embed_process($text, $filter, $format, $langcode, $cache, $cache_id)
+{
+  static $processed_hashes = array();
+  
+  $text_hash = hash('sha256', $text);
+  if (in_array($text_hash, array_keys($processed_hashes))) {
+    // Possible recursion detected, return the cache result.
+    return $processed_hashes[$text_hash];
+  }
+  
+  // In case of recursion, set the cached result to this until we have the real result.
+  $processed_hashes[$text_hash] = 'Error: Cannot embed a node in itself..';
+  
+  $matches = NULL;
+  preg_match_all('/\[\[node:([0-9]+)\]\]/', $text, $matches);
+  $node_ids = $matches[1];
+  $nodes = entity_load('node', $node_ids);
+  $replace_array = array();
+  foreach ($node_ids as $node_id) {
+    $content = node_view($nodes[$node_id]);
+    $replace_array["[[node:$node_id]]"] = PHP_EOL . "<!-- Node $node_id start -->" . PHP_EOL
+    									. render($content['body'])
+    									. PHP_EOL . "<!-- Node $node_id end -->" . PHP_EOL;
+  }
+  $text = strtr($text, $replace_array);
+  // Set the cached result to the real result.
+  $processed_hashes[$text_hash] = $text;
+  return $text;
+}
+
+/**
+ * Implementation of hook_filter_FILTER_process pseudo-hook
+ * 
+ * Replace any instances of <!--#include virtual="url"--> with the content 
+ * found at that URL.  If the url is in the unl.edu domain, format=partial
+ * will be added to the query string.
+ */
+function unl_filter_ssi_process($text, $filter, $format, $langcode, $cache, $cache_id) {
+  $matches = NULL;
+  preg_match_all('/<!-- *#include +virtual=((".*")|(\'.*\')) *-->/', $text, $matches);
+  
+  $replacements = array();
+  
+  foreach ($matches[1] as $match_index => $match) {
+    $full_match = $matches[0][$match_index];
+    
+    // Break down the URL target then rebuild it as absolute.
+    $url = substr($match, 1, -1);
+    $parts = parse_url($url);
+    if (!isset($parts['scheme'])) {
+      $parts['scheme'] = $_SERVER['HTTPS'] ? 'https' : 'http';
+    }
+    if (!isset($parts['host'])) {
+      $parts['host'] = $_SERVER['HTTP_HOST'];
+    }
+    if (isset($parts['path']) && substr($parts['path'], 0, 1) != '/') {
+      if (variable_get('unl_use_base_tag')) {
+        $parts['path'] = $GLOBALS['base_path'] . $parts['path'];
+      } else {
+        $parts['path'] = $GLOBALS['base_path'] . request_path() . '/' . $parts['path'];
+      }
+    }
+    if (!isset($parts['path'])) {
+      $parts['path'] = '/';
+    }
+    $url = $parts['scheme'] . '://' . $parts['host'] . $parts['path'];
+    
+    
+    // If this is a request to another UNL site, add format=partial to the query.
+    if (substr($parts['host'], -7) == 'unl.edu') {
+      if (isset($parts['query']) && $parts['query']) {
+        $parts['query'] .= '&';
+      } else {
+        $parts['query'] = '';
+      }
+      $parts['query'] .= 'format=partial';
+    }
+  
+    // Finish rebuilding the URL.
+    if (isset($parts['query'])) {
+      $url .= '?' . $parts['query'];
+    }
+    if (isset($parts['fragment'])) {
+      $url .= '#' . $parts['fragment'];
+    }
+    
+    $content = file_get_contents($url);
+    $replacements[$full_match] = PHP_EOL
+                               . '<!-- Begin content from ' . $url . ' -->' . PHP_EOL
+                               . $content . PHP_EOL
+                               . '<!-- End content from ' . $url . ' -->' . PHP_EOL;
+  }
+  
+  foreach ($replacements as $from => $to) {
+    $text = str_replace($from, $to, $text);
+  }
+  
+  return $text;
+}
+