<?php
/**
 * This bridge generates feeds for threads from forums running XenForo version 2
 *
 * Examples:
 * - https://xenforo.com/community/
 * - http://www.ign.com/boards/
 *
 * Notice: XenForo does provide RSS feeds for forums. For example:
 * - https://xenforo.com/community/forums/-/index.rss
 *
 * For more information on XenForo, visit
 * - https://xenforo.com/
 * - https://en.wikipedia.org/wiki/XenForo
 */
class XenForoBridge extends BridgeAbstract {

	// Bridge specific constants
	const CONTEXT_THREAD = 'Thread';
	const XENFORO_VERSION_1 = '1.0';
	const XENFORO_VERSION_2 = '2.0';

	// RSS-Bridge constants
	const NAME = 'XenForo Bridge';
	const URI = 'https://xenforo.com/';
	const DESCRIPTION = 'Generates feeds for threads in forums powered by XenForo';
	const MAINTAINER = 'logmanoriginal';
	const PARAMETERS = array(
		self::CONTEXT_THREAD => array(
			'url' => array(
				'name' => 'Thread URL',
				'type' => 'text',
				'required' => true,
				'title' => 'Insert URL to the thread for which the feed should be generated',
				'exampleValue' => 'https://xenforo.com/community/threads/guide-to-suggestions.2285/'
			)
		),
		'global' => array(
			'limit' => array(
				'name' => 'Limit',
				'type' => 'number',
				'required' => false,
				'title' => 'Specify maximum number of elements to return in the feed',
				'defaultValue' => 10
			)
		)
	);
	const CACHE_TIMEOUT = 7200; // 10 minutes

	private $title = '';
	private $threadurl = '';
	private $version; // Holds the XenForo version

	public function getName() {

		switch($this->queriedContext) {
			case self::CONTEXT_THREAD: return $this->title . ' - ' . static::NAME;
		}

		return parent::getName();

	}

	public function getURI() {

		switch($this->queriedContext) {
			case self::CONTEXT_THREAD: return $this->threadurl;
		}

		return parent::getURI();

	}

	public function collectData() {

		$this->threadurl = filter_var(
			$this->getInput('url'),
			FILTER_VALIDATE_URL,
			FILTER_FLAG_SCHEME_REQUIRED |
			FILTER_FLAG_HOST_REQUIRED |
			FILTER_FLAG_PATH_REQUIRED);

		if($this->threadurl === false) {
			returnClientError('The URL you provided is invalid!');
		}

		$urlparts = parse_url($this->threadurl, PHP_URL_SCHEME);

		// Scheme must be "http" or "https"
		if(preg_match('/http[s]{0,1}/', parse_url($this->threadurl, PHP_URL_SCHEME)) == false) {
			returnClientError('The URL you provided doesn\'t specify a valid scheme (http or https)!');
		}

		// Path cannot be root (../)
		if(parse_url($this->threadurl, PHP_URL_PATH) === '/') {
			returnClientError('The URL you provided doesn\'t link to a valid thread (root path)!');
		}

		// XenForo adds a thread ID to the URL, like "...-thread.454934283". It must be present
		if(preg_match('/.+\.\d+[\/]{0,1}/', parse_URL($this->threadurl, PHP_URL_PATH)) == false) {
			returnClientError('The URL you provided doesn\'t link to a valid thread (ID missing)!');
		}

		// We want to start at the first page in the thread. XenForo uses "../page-n" syntax
		// to identify pages (except for the first page).
		// Notice: XenForo uses the concept of "sentinels" to find and replace parts in the
		// URL. Technically forum hosts can change the syntax!
		if(preg_match('/.+\/(page-\d+.*)$/', $this->threadurl, $matches) != false) {

			// before: https://xenforo.com/community/threads/guide-to-suggestions.2285/page-5
			// after : https://xenforo.com/community/threads/guide-to-suggestions.2285/
			$this->threadurl = str_replace($matches[1], '', $this->threadurl);

		}

		$html = getSimpleHTMLDOMCached($this->threadurl)
			or returnServerError('Failed loading data from "' . $this->threadurl . '"!');

		$html = defaultLinkTo($html, $this->threadurl);

		// Notice: The DOM structure changes depending on the XenForo version used
		if($mainContent = $html->find('div.mainContent', 0)) {
			$this->version = self::XENFORO_VERSION_1;
		} elseif ($mainContent = $html->find('div[class="p-body"]', 0)) {
			$this->version = self::XENFORO_VERSION_2;
		} else {
			returnServerError('This forum is currently not supported!');
		}

		switch($this->version) {
			case self::XENFORO_VERSION_1:

				$titleBar = $mainContent->find('div.titleBar h1', 0)
					or returnServerError('Error finding title bar!');

				$this->title = $titleBar->plaintext;

				// Store items from current page (we'll use $this->items as LIFO buffer)
				$this->extractThreadPostsV1($html, $this->threadurl);
				$this->extractPagesV1($html);

				break;

			case self::XENFORO_VERSION_2:

				$titleBar = $mainContent->find('div[class="p-title"] h1', 0)
					or returnServerError('Error finding title bar!');

				$this->title = $titleBar->plaintext;
				$this->extractThreadPostsV2($html, $this->threadurl);
				$this->extractPagesV2($html);

				break;
		}

		while(count($this->items) > $this->getInput('limit')) {
			array_shift($this->items);
		}

	}

	/**
	 * Extracts thread posts
	 * @param $html A simplehtmldom object
	 * @param $url The url from which $html was loaded
	 */
	private function extractThreadPostsV1($html, $url) {

		$lang = $html->find('html', 0)->lang;

		// Posts are contained in an "ol"
		$messageList = $html->find('#messageList li')
			or returnServerError('Error finding message list!');

		foreach($messageList as $post) {

			if(!isset($post->attr['id'])) { // Skip ads
				continue;
			}

			$item = array();

			$item['uri'] = $url . '#' . $post->getAttribute('id');

			$content = $post->find('.messageContent article', 0);

			// Add some style to quotes
			foreach($content->find('.bbCodeQuote') as $quote) {
				$quote->style = '
					color: #495566;
					background-color: rgb(248,251,253);
					border: 1px solid rgb(111, 140, 180);
					border-color: rgb(111, 140, 180);
					font-style: italic;';
			}

			// Remove script tags
			foreach($content->find('script') as $script) {
				$script->outertext = '';
			}

			$item['content'] = $content->innertext;

			// Remove quotes (for the title)
			foreach($content->find('.bbCodeQuote') as $quote) {
				$quote->innertext = '';
			}

			$title = trim($content->plaintext);

			if(strlen($title) > 70) {
				$item['title'] = substr($title, 0, strpos($title, ' ', 70)) . '...';
			} else {
				$item['title'] = $title;
			}

			/**
			 * Timestamps are presented in two forms:
			 *
			 * 1) short version (for older posts?)
			 * <span
			 * 	class="DateTime"
			 * 	title="22 Oct. 2018 at 23:47"
			 * >22 Oct. 2018</span>
			 *
			 * This form has to be interpreted depending on the current language.
			 *
			 * 2) long version (for newer posts?)
			 * <abbr
			 * 	class="DateTime"
			 * 	data-time="1541008785"
			 * 	data-diff="310694"
			 * 	data-datestring="31 Oct. 2018"
			 * 	data-timestring="18:59"
			 * 	title="31 Oct. 2018 at 18:59"
			 * >Wednesday at 18:59</abbr>
			 *
			 * This form has the timestamp embedded (data-time)
			 */
			if($timestamp = $post->find('abbr.DateTime', 0)) { // long version (preffered)
				$item['timestamp'] = $timestamp->{'data-time'};
			} elseif($timestamp = $post->find('span.DateTime', 0)) { // short version
				$item['timestamp'] = $this->fixDate($timestamp->title, $lang);
			}

			$item['author'] = $post->getAttribute('data-author');

			// Bridge specific properties
			$item['id'] = $post->getAttribute('id');

			$this->items[] = $item;

		}

	}

	private function extractThreadPostsV2($html, $url) {

		$lang = $html->find('html', 0)->lang;

		$messageList = $html->find('div[class="block-body"] article')
			or returnServerError('Error finding message list!');

		foreach($messageList as $post) {

			if(!isset($post->attr['id'])) { // Skip ads
				continue;
			}

			$item = array();

			$item['uri'] = $url . '#' . $post->getAttribute('id');

			$title = $post->find('div[class="message-content"] article', 0)->plaintext;
			$end = strpos($title, ' ', 70);
			$item['title'] = substr($title, 0, $end);

			$item['timestamp'] = $this->fixDate($post->find('time', 0)->title, $lang);
			$item['author'] = $post->getAttribute('data-author');
			$item['content'] = $post->find('div[class="message-content"] article', 0);

			// Bridge specific properties
			$item['id'] = $post->getAttribute('id');

			$this->items[] = $item;

		}

	}

	private function extractPagesV1($html) {

		// A navigation bar becomes available if the number of posts grows too
		// high. When this happens we need to load further pages (from last backwards)
		if(($pageNav = $html->find('div.PageNav', 0)) !== false) {

			$lastpage = $pageNav->{'data-last'};
			$baseurl  = $pageNav->{'data-baseurl'};
			$sentinel = $pageNav->{'data-sentinel'};

			$hosturl  = parse_url($this->threadurl, PHP_URL_SCHEME)
			. '://'
			. parse_url($this->threadurl, PHP_URL_HOST)
			. '/';

			$page = $lastpage;

			// Load at least the last page
			do {

				$pageurl = $hosturl . str_replace($sentinel, $lastpage, $baseurl);

				// We can optimize performance by caching all but the last page
				if($page != $lastpage) {
					$html = getSimpleHTMLDOMCached($pageurl)
						or returnServerError('Error loading contents from ' . $pageurl . '!');
				} else {
					$html = getSimpleHTMLDOM($pageurl)
						or returnServerError('Error loading contents from ' . $pageurl . '!');
				}

				$html = defaultLinkTo($html, $hosturl);

				$this->extractThreadPostsV1($html, $pageurl);

				$page--;

			} while (count($this->items) < $this->getInput('limit') && $page != 1);

		}

	}

	private function extractPagesV2($html) {

		// A navigation bar becomes available if the number of posts grows too
		// high. When this happens we need to load further pages (from last backwards)
		if(($pageNav = $html->find('div.pageNav', 0)) !== false) {

			foreach($pageNav->find('li') as $nav) {
				$lastpage = $nav->plaintext;
			}

			// Manually extract baseurl and inject sentinel
			$baseurl = $pageNav->find('li a', -1)->href;
			$baseurl = str_replace('page-' . $lastpage, 'page-{{sentinel}}', $baseurl);

			$sentinel = '{{sentinel}}';

			$hosturl  = parse_url($this->threadurl, PHP_URL_SCHEME)
			. '://'
			. parse_url($this->threadurl, PHP_URL_HOST);

			$page = $lastpage;

			// Load at least the last page
			do {

				$pageurl = $hosturl . str_replace($sentinel, $lastpage, $baseurl);

				// We can optimize performance by caching all but the last page
				if($page != $lastpage) {
					$html = getSimpleHTMLDOMCached($pageurl)
						or returnServerError('Error loading contents from ' . $pageurl . '!');
				} else {
					$html = getSimpleHTMLDOM($pageurl)
						or returnServerError('Error loading contents from ' . $pageurl . '!');
				}

				$html = defaultLinkTo($html, $this->hosturl);

				$this->extractThreadPostsV2($html, $this->pageurl);

				$page--;

			} while (count($this->items) < $this->getInput('limit') && $page != 1);

		}

	}

	/**
	 * Fixes dates depending on the choosen language:
	 *
	 * de : dd.mm.yy
	 * en : dd.mm.yy
	 * it : dd/mm/yy
	 *
	 * Basically strtotime doesn't convert dates correctly due to formats
	 * being hard to interpret. So we use the DateTime object.
	 *
	 * We don't know the timezone, so just assume +00:00 (or whatever
	 * DateTime chooses)
	 */
	private function fixDate($date, $lang = 'en-US') {

		$mnamesen = [
			'January',
			'Feburary',
			'March',
			'April',
			'May',
			'June',
			'July',
			'August',
			'September',
			'October',
			'November',
			'December'
		];

		switch($lang) {
			case 'en-US': // example: Jun 9, 2018 at 11:46 PM

				$df = date_create_from_format('M d, Y \a\t H:i A', $date);
				break;

			case 'de-DE': // example: 19 Juli 2018 um 19:27 Uhr

				$mnamesde = [
					'Januar',
					'Februar',
					'März',
					'April',
					'Mai',
					'Juni',
					'Juli',
					'August',
					'September',
					'Oktober',
					'November',
					'Dezember'
				];

				$mnamesdeshort = [
					'Jan.',
					'Feb.',
					'Mär.',
					'Apr.',
					'Mai',
					'Juni',
					'Juli',
					'Aug.',
					'Sep.',
					'Okt.',
					'Nov.',
					'Dez.'
				];

				$date = str_ireplace($mnamesde, $mnamesen, $date);
				$date = str_ireplace($mnamesdeshort, $mnamesen, $date);

				$df = date_create_from_format('d M Y \u\m H:i \U\h\r', $date);
				break;

		}

		// debugMessage(date_format($df, 'U'));

		return date_format($df, 'U');

	}

}