[FacebookBridge] Add context for public Facebook groups (#739)

The previous context is now labeled 'User', while the new context is
labeled 'Group'. The existing code was not changed, instead new group*
functions were implemented to handle groups.

The general principle of capturing groups is the same as done for users
with adjustments to account for different HTML structures.

Captcha responses are currently not supported for groups! There doesn't
seem to be a way to trigger them consistently, which makes it hard to
handle them properly.

Features of the group context:

- The feed title is based on the group name
- The group URI used for capturing is returned for the feed URI
- Author names and timestamps are reproduced from the source
- Post titles are reproduced from the source if they exist, otherwise
the title is build manually from the author name and the content
- Original contents are included with the feed
- All images are attached as enclosures as well

Closes #

bridges/FacebookBridge.php

@@ -1,41 +1,257 @@
 <?php
 class FacebookBridge extends BridgeAbstract {
 
-	const MAINTAINER = 'teromene';
+	const MAINTAINER = 'teromene, logmanoriginal';
 	const NAME = 'Facebook';
 	const URI = 'https://www.facebook.com/';
 	const CACHE_TIMEOUT = 300; // 5min
 	const DESCRIPTION = 'Input a page title or a profile log. For a profile log,
  please insert the parameter as follow : myExamplePage/132621766841117';
 
-	const PARAMETERS = array( array(
-		'u' => array(
-			'name' => 'Username',
-			'required' => true
-		),
-		'media_type' => array(
-			'name' => 'Media type',
-			'type' => 'list',
-			'required' => false,
-			'values' => array(
-				'All' => 'all',
-				'Video' => 'video',
-				'No Video' => 'novideo'
+	const PARAMETERS = array(
+		'User' => array(
+			'u' => array(
+				'name' => 'Username',
+				'required' => true
+			),
+			'media_type' => array(
+				'name' => 'Media type',
+				'type' => 'list',
+				'required' => false,
+				'values' => array(
+					'All' => 'all',
+					'Video' => 'video',
+					'No Video' => 'novideo'
+				),
+				'defaultValue' => 'all'
 			),
-			'defaultValue' => 'all'
+			'skip_reviews' => array(
+				'name' => 'Skip reviews',
+				'type' => 'checkbox',
+				'required' => false,
+				'defaultValue' => false,
+				'title' => 'Feed includes reviews when checked'
+			)
 		),
-		'skip_reviews' => array(
-			'name' => 'Skip reviews',
-			'type' => 'checkbox',
-			'required' => false,
-			'defaultValue' => false,
-			'title' => 'Feed includes reviews when checked'
+		'Group' => array(
+			'g' => array(
+				'name' => 'Group',
+				'type' => 'text',
+				'required' => true,
+				'exampleValue' => 'https://www.facebook.com/groups/743149642484225',
+				'title' => 'Insert group name or facebook group URL'
+			)
 		)
-	));
+	);
 
 	private $authorName = '';
+	private $groupName = '';
+
+	public function getURI() {
+		$uri = self::URI;
+
+		switch($this->queriedContext) {
+
+			case 'Group':
+				$uri .= 'groups/' . $this->sanitizeGroup(filter_var($this->getInput('g'), FILTER_SANITIZE_URL));
+				break;
+
+		}
+
+		return $uri .= '?_fb_noscript=1';
+	}
+
+	public function collectData() {
+
+		switch($this->queriedContext) {
+
+			case 'Group':
+				$this->collectGroupData();
+				break;
+
+			case 'User':
+				$this->collectUserData();
+				break;
+
+			default:
+				returnClientError('Unknown context: "' . $this->queriedContext . '"!');
+
+		}
+
+	}
+
+	#region Group
+
+	private function collectGroupData() {
+
+		$header = array('Accept-Language: ' . getEnv('HTTP_ACCEPT_LANGUAGE') . "\r\n");
+
+		$html = getSimpleHTMLDOM($this->getURI(), $header)
+			or returnServerError('Failed loading facebook page: ' . $this->getURI());
+
+		if(!$this->isPublicGroup($html)) {
+			returnClientError('This group is not public! RSS-Bridge only supports public groups!');
+		}
+
+		defaultLinkTo($html, substr(self::URI, 0, strlen(self::URI) - 1));
+
+		$this->groupName = $this->extractGroupName($html);
+
+		$posts = $html->find('div.userContentWrapper')
+			or returnServerError('Failed finding posts!');
+
+		foreach($posts as $post) {
+
+			$item = array();
+
+			$item['uri'] = $this->extractGroupURI($post);
+			$item['title'] = $this->extractGroupTitle($post);
+			$item['author'] = $this->extractGroupAuthor($post);
+			$item['content'] = $this->extractGroupContent($post);
+			$item['timestamp'] = $this->extractGroupTimestamp($post);
+			$item['enclosures'] = $this->extractGroupEnclosures($post);
+
+			$this->items[] = $item;
+
+		}
+
+	}
+
+	private function sanitizeGroup($group) {
+
+		if(filter_var(
+			$group,
+			FILTER_VALIDATE_URL,
+			FILTER_FLAG_HOST_REQUIRED | FILTER_FLAG_PATH_REQUIRED)) {
+			// User provided a URL
+
+			$urlparts = parse_url($group);
+
+			if($urlparts['host'] !== parse_url(self::URI)['host']
+			&& 'www.' . $urlparts['host'] !== parse_url(self::URI)['host']) {
+
+				returnClientError('The host you provided is invalid! Received "'
+				. $urlparts['host']
+				. '", expected "'
+				. parse_url(self::URI)['host']
+				. '"!');
+
+			}
+
+			return explode('/', $urlparts['path'])[2];
+
+		} elseif(strpos($group, '/') !== false) {
+			returnClientError('The group you provided is invalid: ' . $group);
+		} else {
+			return $group;
+		}
+
+	}
+
+	private function isPublicGroup($html) {
+
+		// Facebook redirects to the groups about page for non-public groups
+		$about = $html->find('#pagelet_group_about', 0);
+
+		return !($about);
+
+	}
+
+	private function extractGroupName($html) {
+
+		$ogtitle = $html->find('meta[property="og:title"]', 0)
+			or returnServerError('Unable to find group title!');
 
-	public function collectData(){
+		return htmlspecialchars_decode($ogtitle->content, ENT_QUOTES);
+
+	}
+
+	private function extractGroupURI($post) {
+
+		$elements = $post->find('a')
+			or returnServerError('Unable to find URI!');
+
+		foreach($elements as $anchor) {
+
+			// Find the one that is a permalink
+			if(strpos($anchor->href, 'permalink') !== false) {
+				return $anchor->href;
+			}
+
+		}
+
+		return null;
+
+	}
+
+	private function extractGroupContent($post) {
+
+		$content = $post->find('div.userContent', 0)
+			or returnServerError('Unable to find user content!');
+
+		return $content->innertext . $content->next_sibling()->innertext;
+
+	}
+
+	private function extractGroupTimestamp($post) {
+
+		$element = $post->find('abbr[data-utime]', 0)
+			or returnServerError('Unable to find timestamp!');
+
+		return $element->getAttribute('data-utime');
+
+	}
+
+	private function extractGroupAuthor($post) {
+
+		$element = $post->find('img', 0)
+			or returnServerError('Unable to find author information!');
+
+		return $element->{'aria-label'};
+
+	}
+
+	private function extractGroupEnclosures($post) {
+
+		$elements = $post->find('div.userContent', 0)->next_sibling()->find('img');
+
+		$enclosures = array();
+
+		foreach($elements as $enclosure) {
+			$enclosures[] = $enclosure->src;
+		}
+
+		return empty($enclosures) ? null : $enclosures;
+
+	}
+
+	private function extractGroupTitle($post) {
+
+		$element = $post->find('h5', 0)
+			or returnServerError('Unable to find title!');
+
+		if(strpos($element->plaintext, 'shared') === false) {
+
+			$content = strip_tags($this->extractGroupContent($post));
+
+			return $this->extractGroupAuthor($post)
+			. ' posted: '
+			. substr(
+					$content,
+					0,
+					strpos(wordwrap($content, 64), "\n")
+				)
+			. '...';
+
+		}
+
+		return $element->plaintext;
+
+	}
+
+	#endregion
+
+	private function collectUserData(){
 
 		//Extract a string using start and end delimiters
 		function extractFromDelimiters($string, $start, $end){
@@ -336,9 +552,22 @@ EOD;
 	}
 
 	public function getName(){
-		if(!empty($this->authorName)) {
-			return isset($this->extraInfos['name']) ? $this->extraInfos['name'] : $this->authorName
-			. ' - Facebook Bridge';
+
+		switch($this->queriedContext) {
+
+			case 'User':
+				if(!empty($this->authorName)) {
+					return isset($this->extraInfos['name']) ? $this->extraInfos['name'] : $this->authorName
+					. ' - Facebook Bridge';
+				}
+				break;
+
+			case 'Group':
+				if(!empty($this->groupName)) {
+					return $this->groupName . ' - Facebook Bridge';
+				}
+				break;
+
 		}
 
 		return parent::getName();