<?php
class IPBBridge extends FeedExpander {

	const NAME = 'IPB Bridge';
	const URI = 'https://www.invisionpower.com';
	const DESCRIPTION = 'Returns feeds for forums powered by IPB';
	const MAINTAINER = 'logmanoriginal';
	const PARAMETERS = array(
		array(
			'uri' => array(
				'name' => 'URI',
				'type' => 'text',
				'required' => true,
				'title' => 'Insert forum, subforum or topic URI',
				'exampleValue' => 'https://invisioncommunity.com/forums/forum/499-feedback-and-ideas/'
			),
			'limit' => array(
				'name' => 'Limit',
				'type' => 'number',
				'required' => false,
				'title' => 'Specifies the number of items to return on each request (-1: all)',
				'defaultValue' => 10
			)
		)
	);
	const CACHE_TIMEOUT = 3600;

	// Constants for internal use
	const FORUM_TYPE_LIST_FILTER = '.cForumTopicTable';
	const FORUM_TYPE_TABLE_FILTER = '#forum_table';

	const TOPIC_TYPE_ARTICLE = 'article';
	const TOPIC_TYPE_DIV = 'div.post_block';

	public function getURI(){
		return $this->getInput('uri') ?: parent::getURI();
	}

	public function collectData(){
		// The URI cannot be the mainpage (or anything related)
		switch(parse_url($this->getInput('uri'), PHP_URL_PATH)) {
			case null:
			case '/index.php':
				returnClientError('Provided URI is invalid!');
				break;
			default:
				break;
		}

		// Sanitize the URI (because else it won't work)
		$uri = rtrim($this->getInput('uri'), '/'); // No trailing slashes!

		// Forums might provide feeds, though that's optional *facepalm*
		// Let's check if there is a valid feed available
		$headers = get_headers($uri . '.xml');

		if($headers[0] === 'HTTP/1.1 200 OK') { // Heureka! It's a valid feed!
			return $this->collectExpandableDatas($uri);
		}

		// No valid feed, so do it the hard way
		$html = getSimpleHTMLDOM($uri);

		$limit = $this->getInput('limit');

		// Determine if this is a topic or a forum
		switch(true) {
			case $this->isTopic($html):
				$this->collectTopic($html, $limit);
				break;
			case $this->isForum($html);
				$this->collectForum($html);
				break;
			default:
				returnClientError('Unknown type!');
				break;
		}
	}

	private function isForum($html){
		return !is_null($html->find('div[data-controller*=forums.front.forum.forumPage]', 0))
		|| !is_null($html->find(static::FORUM_TYPE_TABLE_FILTER, 0));
	}

	private function isTopic($html){
		return !is_null($html->find('div[data-controller*=core.front.core.commentFeed]', 0))
		|| !is_null($html->find(static::TOPIC_TYPE_DIV, 0));
	}

	private function collectForum($html){
		// There are multiple forum designs in use (depends on version?)
		// 1 - Uses an ordered list (based on https://invisioncommunity.com/forums)
		// 2 - Uses a table (based on https://onehallyu.com)

		switch(true) {
			case !is_null($html->find(static::FORUM_TYPE_LIST_FILTER, 0)):
				$this->collectForumList($html);
				break;
			case !is_null($html->find(static::FORUM_TYPE_TABLE_FILTER, 0)):
				$this->collectForumTable($html);
				break;
			default:
				returnClientError('Unknown forum format!');
				break;
		}
	}

	private function collectForumList($html){
		foreach($html->find(static::FORUM_TYPE_LIST_FILTER, 0)->children() as $row) {
			// Columns: Title, Statistics, Last modified
			$item = array();

			$item['uri'] = $row->find('a', 0)->href;
			$item['title'] = $row->find('a', 0)->title;
			$item['author'] = $row->find('a', 1)->innertext;
			$item['timestamp'] = strtotime($row->find('time', 0)->getAttribute('datetime'));

			$this->items[] = $item;
		}
	}

	private function collectForumTable($html){
		foreach($html->find(static::FORUM_TYPE_TABLE_FILTER, 0)->children() as $row) {
			// Columns: Icon, Content, Preview, Statistics, Last modified
			$item = array();

			// Skip header row
			if(!is_null($row->find('th', 0))) continue;

			$item['uri'] = $row->find('a', 0)->href;
			$item['title'] = $row->find('.title', 0)->plaintext;
			$item['timestamp'] = strtotime($row->find('[itemprop=dateCreated]', 0)->plaintext);

			$this->items[] = $item;
		}
	}

	private function collectTopic($html, $limit){
		// There are multiple topic designs in use (depends on version?)
		// 1 - Uses articles (based on https://invisioncommunity.com/forums)
		// 2 - Uses divs (based on https://onehallyu.com)

		switch(true) {
			case !is_null($html->find(static::TOPIC_TYPE_ARTICLE, 0)):
				$this->collectTopicHistory($html, $limit, 'collectTopicArticle');
				break;
			case !is_null($html->find(static::TOPIC_TYPE_DIV, 0)):
				$this->collectTopicHistory($html, $limit, 'collectTopicDiv');
				break;
			default:
				returnClientError('Unknown topic format!');
				break;
		}
	}

	private function collectTopicHistory($html, $limit, $callback){
		// Make sure the callback is valid!
		if(!method_exists($this, $callback))
			returnServerError('Unknown function (\'' . $callback . '\')!');

		$next = null; // Holds the URI of the next page

		while(true) {
			$next = $this->$callback($html, is_null($next));

			if(is_null($next) || ($limit > 0 && count($this->items) >= $limit)) {
				break;
			}

			$html = getSimpleHTMLDOMCached($next);
		}

		// We might have more items than specified, remove excess
		$this->items = array_slice($this->items, 0, $limit);
	}

	private function collectTopicArticle($html, $firstrun = true){
		$title = $html->find('h1.ipsType_pageTitle', 0)->plaintext;

		// Are we on last page?
		if($firstrun && !is_null($html->find('.ipsPagination', 0))) {
			$last = $html->find('.ipsPagination_last a', 0)->{'data-page'};
			$active = $html->find('.ipsPagination_active a', 0)->{'data-page'};

			if($active !== $last) {
				// Load last page into memory (cached)
				$html = getSimpleHTMLDOMCached($html->find('.ipsPagination_last a', 0)->href);
			}
		}

		foreach(array_reverse($html->find(static::TOPIC_TYPE_ARTICLE)) as $article) {
			$item = array();

			$item['uri'] = $article->find('time', 0)->parent()->href;
			$item['author'] = $article->find('aside a', 0)->plaintext;
			$item['title'] = $item['author'] . ' - ' . $title;
			$item['timestamp'] = strtotime($article->find('time', 0)->getAttribute('datetime'));

			$content = $article->find('[data-role=commentContent]', 0);
			$content = $this->scaleImages($content);
			$item['content'] = $this->fixContent($content);
			$item['enclosures'] = $this->findImages($article->find('[data-role=commentContent]', 0)) ?: null;

			$this->items[] = $item;
		}

		// Return whatever page comes next (previous, as we add in inverse order)
		// Do we have a previous page? (inactive means no)
		if(!is_null($html->find('li[class=ipsPagination_prev ipsPagination_inactive]', 0))) {
			return null; // No, or no more
		} elseif(!is_null($html->find('li[class=ipsPagination_prev]', 0))) {
			return $html->find('.ipsPagination_prev a', 0)->href;
		}

		return null;
	}

	private function collectTopicDiv($html, $firstrun = true){
		$title = $html->find('h1.ipsType_pagetitle', 0)->plaintext;

		// Are we on last page?
		if($firstrun && !is_null($html->find('.pagination', 0))) {

			$active = $html->find('li[class=page active]', 0)->plaintext;

			// There are two ways the 'last' page is displayed:
			// - With a distict 'last' button (only if there are enough pages)
			// - With a button for each page (use last button)
			if(!is_null($html->find('li.last', 0))) {
				$last = $html->find('li.last a', 0);
			} else {
				$last = $html->find('li[class=page] a', -1);
			}

			if($active !== $last->plaintext) {
				// Load last page into memory (cached)
				$html = getSimpleHTMLDOMCached($last->href);
			}
		}

		foreach(array_reverse($html->find(static::TOPIC_TYPE_DIV)) as $article) {
			$item = array();

			$item['uri'] = $article->find('a[rel=bookmark]', 0)->href;
			$item['author'] = $article->find('.author', 0)->plaintext;
			$item['title'] = $item['author'] . ' - ' . $title;
			$item['timestamp'] = strtotime($article->find('.published', 0)->getAttribute('title'));

			$content = $article->find('[itemprop=commentText]', 0);
			$content = $this->scaleImages($content);
			$item['content'] = $this->fixContent($content);

			$item['enclosures'] = $this->findImages($article->find('.post_body', 0)) ?: null;

			$this->items[] = $item;
		}

		// Return whatever page comes next (previous, as we add in inverse order)
		// Do we have a previous page?
		if(!is_null($html->find('li.prev', 0))) {
			return $html->find('li.prev a', 0)->href;
		}

		return null;
	}

	/** Returns all images from the provide HTML DOM */
	private function findImages($html){
		$images = array();

		foreach($html->find('img') as $img) {
			$images[] = $img->src;
		}

		return $images;
	}

	/** Sets the maximum width and height for all images */
	private function scaleImages($html, $width = 400, $height = 400){
		foreach($html->find('img') as $img) {
			$img->style = "max-width: {$width}px; max-height: {$height}px;";
		}

		return $html;
	}

	/** Removes all unnecessary tags and adds formatting */
	private function fixContent($html){

		// Restore quote highlighting
		foreach($html->find('blockquote') as $quote) {
			$quote->style = <<<EOD
padding: 0px 15px;
border-width: 1px 1px 1px 2px;
border-style: solid;
border-color: #ededed #e8e8e8 #dbdbdb #666666;
background: #fbfbfb;
EOD;
		}

		// Remove unnecessary tags
		$content = strip_tags(
			$html->innertext,
			'<p><a><img><ol><ul><li><table><tr><th><td><strong><blockquote><br><hr><h>'
		);

		return $content;
	}
}