<?php
/*
 *      Copyright 2012-2016 Daniel Kraus <bovender@bovender.de> ('bovender')
 *      
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *      
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *      
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *      MA 02110-1301, USA.
 */
/// @file
namespace LinkTitles;

/// Helper function for development and debugging.
/// @param $var Any variable. Raw content will be dumped to stderr.
/// @return undefined
function dump($var) {
		error_log(print_r($var, TRUE) . "\n", 3, 'php://stderr');
};

/// Central class of the extension. Sets up parser hooks.
/// This class contains only static functions; do not instantiate.
class Extension {
	/// A Title object for the page that is being parsed.
	private static $currentTitle;

	/// A Title object for the target page currently being examined.
	private static $targetTitle;

  // The TitleValue object of the target page
  private static $targetTitleValue;

	/// The content object for the currently processed target page.
	/// This variable is necessary to be able to prevent loading the target 
	/// content twice.
	private static $targetContent;

	/// Holds the page title of the currently processed target page
	/// as a string.
	private static $targetTitleText;

	/// Delimiter used in a regexp split operation to seperate those parts
	/// of the page that should be parsed from those that should not be
	/// parsed (e.g. inside pre-existing links etc.).
	private static $delimiter;

	private static $wordStartDelim;
	private static $wordEndDelim;

	public static $ltConsoleOutput;
	public static $ltConsoleOutputDebug;

	/// Setup method
	public static function setup() {
		self::BuildDelimiters();
	}

	/// Event handler that is hooked to the PageContentSave event.
	public static function onPageContentSave( &$wikiPage, &$user, &$content, &$summary,
			$isMinor, $isWatch, $section, &$flags, &$status ) {
		global $wgLinkTitlesParseOnEdit;
		global $wgLinkTitlesNamespaces;
		if ( !$wgLinkTitlesParseOnEdit ) return true;

		if ( !$isMinor ) {
			$title = $wikiPage->getTitle();

			// Only process if page is in one of our namespaces we want to link
			// Fixes ugly autolinking of sidebar pages 
			if ( in_array( $title->getNamespace(), $wgLinkTitlesNamespaces )) {
					$text = $content->getContentHandler()->serializeContent( $content );
					if ( !\MagicWord::get( 'MAG_LINKTITLES_NOAUTOLINKS' )->match( $text ) ) {
						$newText = self::parseContent( $title, $text );
						if ( $newText != $text ) {
								$content = $content->getContentHandler()->unserializeContent( $newText );
						}
					}
			}
		};
		return true;
	}

	/// Event handler that is hooked to the InternalParseBeforeLinks event.
	/// @param Parser $parser Parser that raised the event.
	/// @param $text          Preprocessed text of the page.
	public static function onInternalParseBeforeLinks( \Parser &$parser, &$text ) {
		global $wgLinkTitlesParseOnRender;
		if (!$wgLinkTitlesParseOnRender) return true;
		global $wgLinkTitlesNamespaces;
		$title = $parser->getTitle();

		// If the page contains the magic word '__NOAUTOLINKS__', do not parse it.
		// Only process if page is in one of our namespaces we want to link
		if ( !isset( $parser->mDoubleUnderScores[$text] ) && in_array( $title->getNamespace(), $wgLinkTitlesNamespaces ) ) {
			$text = self::parseContent( $title, $text );
		}
		return true;
	}

	/// Core function of the extension, performs the actual parsing of the content.
	/// @param Parser $parser Parser instance for the current page
	/// @param $text          String that holds the article content
	/// @returns string: parsed text with links added if needed
	private static function parseContent( $title, &$text ) {

		// Configuration variables need to be defined here as globals.
		global $wgLinkTitlesPreferShortTitles;
		global $wgLinkTitlesMinimumTitleLength;
		global $wgLinkTitlesBlackList;
		global $wgLinkTitlesFirstOnly;
		global $wgLinkTitlesSmartMode;
		global $wgCapitalLinks;
		global $wgLinkTitlesNamespaces;

		( $wgLinkTitlesPreferShortTitles ) ? $sort_order = 'ASC' : $sort_order = 'DESC';
		( $wgLinkTitlesFirstOnly ) ? $limit = 1 : $limit = -1;
		$limitReached = false;

		self::$currentTitle = $title;
		$newText = $text;

		// Build a blacklist of pages that are not supposed to be link 
		// targets. This includes the current page.
		$blackList = str_replace( ' ', '_',
			'("' . implode( '","',$wgLinkTitlesBlackList ) . '","' .
			addslashes( self::$currentTitle->getDbKey() ) . '")' );

		$currentNamespace[] = $title->getNamespace();

		// Build our weight list. Make sure current namespace is first element
		$namespaces = array_diff($wgLinkTitlesNamespaces, $currentNamespace);
		array_unshift($namespaces,  $currentNamespace[0] );

		// No need for sanitiy check. we are sure that we have at least one element in the array
		$weightSelect = "CASE page_namespace ";
		$currentWeight = 0;
		foreach ($namespaces as &$namspacevalue) {
				$currentWeight = $currentWeight + 100;
				$weightSelect = $weightSelect . " WHEN " . $namspacevalue . " THEN " . $currentWeight . PHP_EOL;
		}
		$weightSelect = $weightSelect . " END ";
		$namespacesClause = '(' . implode( ', ', $namespaces ) . ')';

		// Build an SQL query and fetch all page titles ordered by length from 
		// shortest to longest. Only titles from 'normal' pages (namespace uid 
		// = 0) are returned. Since the db may be sqlite, we need a try..catch 
		// structure because sqlite does not support the CHAR_LENGTH function.
		$dbr = wfGetDB( DB_SLAVE );
		try {
			$res = $dbr->select( 
				'page', 
				array( 'page_title', 'page_namespace' , "weight" => $weightSelect),
				array( 
					'page_namespace IN ' . $namespacesClause, 
					'CHAR_LENGTH(page_title) >= ' . $wgLinkTitlesMinimumTitleLength,
					'page_title NOT IN ' . $blackList,
				), 
				__METHOD__, 
				array( 'ORDER BY' => 'CHAR_LENGTH(page_title) ' . $sort_order )
			);
		} catch (Exception $e) {
			$res = $dbr->select( 
				'page', 
				array( 'page_title', 'page_namespace' , "weight" => $weightSelect ),
				array( 
					'page_namespace IN ' . $namespacesClause, 
					'LENGTH(page_title) >= ' . $wgLinkTitlesMinimumTitleLength,
					'page_title NOT IN ' . $blackList,
				), 
				__METHOD__, 
				array( 'ORDER BY' => 'LENGTH(page_title) ' . $sort_order )
			);
		}

		// Iterate through the page titles
		foreach( $res as $row ) {
			self::newTarget( $row->page_namespace, $row->page_title );

			// split the page content by [[...]] groups
			// credits to inhan @ StackOverflow for suggesting preg_split
			// see http://stackoverflow.com/questions/10672286
			$arr = preg_split( self::$delimiter, $newText, -1, PREG_SPLIT_DELIM_CAPTURE );

			// Escape certain special characters in the page title to prevent
			// regexp compilation errors
			self::$targetTitleText = self::$targetTitle->getText();
			$quotedTitle = preg_quote(self::$targetTitleText, '/');

      self::ltDebugLog('TargetTitle='. self::$targetTitleText,"private");
      self::ltDebugLog('TargetTitleQuoted='. $quotedTitle,"private");

			// Depending on the global configuration setting $wgCapitalLinks,
			// the title has to be searched for either in a strictly case-sensitive
			// way, or in a 'fuzzy' way where the first letter of the title may
			// be either case.
			if ( $wgCapitalLinks && ( $quotedTitle[0] != '\\' )) {
				$searchTerm = '((?i)' . $quotedTitle[0] . '(?-i)' . 
					substr($quotedTitle, 1) . ')';
			}	else {
				$searchTerm = '(' . $quotedTitle . ')';
			}

			$regex = '/(?<![\:\.\@\/\?\&])' . self::$wordStartDelim . 
				$searchTerm . self::$wordEndDelim . '/S';
			for ( $i = 0; $i < count( $arr ); $i+=2 ) {
				// even indexes will point to text that is not enclosed by brackets
				$arr[$i] = preg_replace_callback( $regex,
					'LinkTitles\Extension::simpleModeCallback', $arr[$i], $limit, $count );
				if ( $wgLinkTitlesFirstOnly && ( $count > 0 ) ) {
					$limitReached = true;
					break; 
				};
			};
			$newText = implode( '', $arr );

			// If smart mode is turned on, the extension will perform a second
			// pass on the page and add links with aliases where the case does
			// not match.
			if ( $wgLinkTitlesSmartMode && !$limitReached ) {
				$arr = preg_split( self::$delimiter, $newText, -1, PREG_SPLIT_DELIM_CAPTURE );

				for ( $i = 0; $i < count( $arr ); $i+=2 ) {
					// even indexes will point to text that is not enclosed by brackets
					$arr[$i] = preg_replace_callback( '/(?<![\:\.\@\/\?\&])' .
						self::$wordStartDelim . '(' . $quotedTitle . ')' . 
						self::$wordEndDelim . '/iS', 'LinkTitles\Extension::smartModeCallback',
						$arr[$i], $limit, $count );
					if ( $wgLinkTitlesFirstOnly && ( $count > 0  )) {
						break; 
					};
				};
				$newText = implode( '', $arr );
			} // $wgLinkTitlesSmartMode
		}; // foreach $res as $row
		return $newText;
	}

	/// Automatically processes a single page, given a $title Title object.
	/// This function is called by the SpecialLinkTitles class and the 
	/// LinkTitlesJob class.
	/// @param Title 					$title            Title object.
	/// @param RequestContext $context					Current request context. 
	///                  If in doubt, call MediaWiki's `RequestContext::getMain()`
	///                  to obtain such an object.
	/// @returns boolean True if the page exists, false if the page does not exist
	public static function processPage( \Title $title, \RequestContext $context ) {
		self::ltLog('Processing '. $title->getPrefixedText());
		$page = \WikiPage::factory($title);
		$content = $page->getContent();
		if ( $content != null ) {
			$text = $content->getContentHandler()->serializeContent($content);
			$newText = self::parseContent($title, $text);
			if ( $text != $newText ) {
				$content = $content->getContentHandler()->unserializeContent( $newText );
				$page->doQuickEditContent(
					$content,
					$context->getUser(),
					"Links to existing pages added by LinkTitles bot.", // TODO: i18n
					true // minor modification
				);
			};
			return true;
		}
		else {
			return false;
		}
	}

	/// Adds the two magic words defined by this extension to the list of 
	/// 'double-underscore' terms that are automatically removed before a 
	/// page is displayed.
	/// @param $doubleUnderscoreIDs Array of magic word IDs.
	/// @return true
	public static function onGetDoubleUnderscoreIDs( array &$doubleUnderscoreIDs ) {
		$doubleUnderscoreIDs[] = 'MAG_LINKTITLES_NOTARGET';
		$doubleUnderscoreIDs[] = 'MAG_LINKTITLES_NOAUTOLINKS';
		return true;
	}

	// Build an anonymous callback function to be used in simple mode.
	private static function simpleModeCallback( array $matches ) {
		if ( self::checkTargetPage() ) {
			self::ltLog( "Linking '$matches[0]' to '" . self::$targetTitle . "'" );
			return '[[' . $matches[0] . ']]';
		}
		else
		{
			return $matches[0];
		}
	}

	// Callback function for use with preg_replace_callback.
	// This essentially performs a case-sensitive comparison of the 
	// current page title and the occurrence found on the page; if 
	// the cases do not match, it builds an aliased (piped) link.
	// If $wgCapitalLinks is set to true, the case of the first 
	// letter is ignored by MediaWiki and we don't need to build a 
	// piped link if only the case of the first letter is different.
	private static function smartModeCallback( array $matches ) {
		global $wgCapitalLinks;

		if ( $wgCapitalLinks ) {
			// With $wgCapitalLinks set to true we have a slightly more 
			// complicated version of the callback than if it were false; 
			// we need to ignore the first letter of the page titles, as 
			// it does not matter for linking.
			if ( self::checkTargetPage() ) {
				self::ltLog( "Linking (smart) '$matches[0]' to '" . self::$targetTitle . "'" );
				if ( strcmp(substr(self::$targetTitleText, 1), substr($matches[0], 1)) == 0 ) {
					// Case-sensitive match: no need to bulid piped link.
					return '[[' . $matches[0] . ']]';
				} else  {
					// Case-insensitive match: build piped link.
					return '[[' . self::$targetTitleText . '|' . $matches[0] . ']]';
				}
			}
			else
			{
				return $matches[0];
			}
		} else {
			// If $wgCapitalLinks is false, we can use the simple variant 
			// of the callback function.
			if ( self::checkTargetPage() ) {
				self::ltLog( "Linking (smart) '$matches[0]' to '" . self::$targetTitle . "'" );
				if ( strcmp(self::$targetTitleText, $matches[0]) == 0 ) {
					// Case-sensitive match: no need to bulid piped link.
					return '[[' . $matches[0] . ']]';
				} else  {
					// Case-insensitive match: build piped link.
					return '[[' . self::$targetTitleText . '|' . $matches[0] . ']]';
				}
			}
			else
			{
				return $matches[0];
			}
		}
	}

	/// Sets member variables for the current target page.
	private static function newTarget( $ns, $title ) {
		self::$targetTitle = \Title::makeTitleSafe( $ns, $title );
		self::ltDebugLog( 'newtarget='.  self::$targetTitle->getText(), "private" );
		self::$targetTitleValue = self::$targetTitle->getTitleValue();
		self::ltDebugLog( 'altTarget='. self::$targetTitleValue->getText(), "private" );
		self::$targetContent = null;
	}

	/// Returns the content of the current target page.
	/// This function serves to be used in preg_replace_callback callback 
	/// functions, in order to load the target page content from the 
	/// database only when needed.
	/// @note It is absolutely necessary that the newTarget() 
	/// function is called for every new page.
	private static function getTargetContent() {
		if ( ! isset( $targetContent ) ) {
			self::$targetContent = \WikiPage::factory(
				self::$targetTitle)->getContent();
		};
		return self::$targetContent;
	}

	/// Examines the current target page. Returns true if it may be linked; 
	/// false if not. This depends on the settings 
	/// $wgLinkTitlesCheckRedirect and $wgLinkTitlesEnableNoTargetMagicWord 
	/// and whether the target page is a redirect or contains the 
	/// __NOAUTOLINKTARGET__ magic word.
	/// @returns boolean
	private static function checkTargetPage() {
		global $wgLinkTitlesEnableNoTargetMagicWord;
		global $wgLinkTitlesCheckRedirect;

		// If checking for redirects is enabled and the target page does 
		// indeed redirect to the current page, return the page title as-is 
		// (unlinked).
		if ( $wgLinkTitlesCheckRedirect ) {
			$redirectTitle = self::getTargetContent()->getUltimateRedirectTarget();
			if ( $redirectTitle && $redirectTitle->equals(self::$currentTitle) ) {
				return false;
			}
		};

		// If the magic word __NOAUTOLINKTARGET__ is enabled and the target 
		// page does indeed contain this magic word, return the page title 
		// as-is (unlinked).
		if ( $wgLinkTitlesEnableNoTargetMagicWord ) {
			if ( self::getTargetContent()->matchMagicWord(
					\MagicWord::get('MAG_LINKTITLES_NOTARGET') ) ) {
				return false;
			}
		};
		return true;
	}

/// Builds the delimiter that is used in a regexp to separate
/// text that should be parsed from text that should not be
/// parsed (e.g. inside existing links etc.)
private static function BuildDelimiters() {
		// Configuration variables need to be defined here as globals.
		global $wgLinkTitlesParseHeadings;
		global $wgLinkTitlesSkipTemplates;
		global $wgLinkTitlesWordStartOnly;
		global $wgLinkTitlesWordEndOnly;

		// Use unicode character properties rather than \b escape sequences
		// to detect whole words containing non-ASCII characters as well.
		// Note that this requires a PCRE library that was compiled with 
		// --enable-unicode-properties
		( $wgLinkTitlesWordStartOnly ) ? self::$wordStartDelim = '(?<!\pL)' : self::$wordStartDelim = '';
		( $wgLinkTitlesWordEndOnly ) ? self::$wordEndDelim = '(?!\pL)' : self::$wordEndDelim = '';

		if ( $wgLinkTitlesSkipTemplates )
		{
			$templatesDelimiter = '{{[^}]+}}|';
		} else {
			// Match template names (ignoring any piped [[]] links in them) 
			// along with the trailing pipe and parameter name or closing 
			// braces; also match sequences of '|wordcharacters=' (without 
			// spaces in them) that usually only occur as parameter names in 
			// transclusions (but could also occur as wiki table cell contents).
			// TODO: Find a way to match parameter names in transclusions, but 
			// not in table cells or other sequences involving a pipe character 
			// and equal sign.
			$templatesDelimiter = '{{[^|]*?(?:(?:\[\[[^]]+]])?)[^|]*?(?:\|(?:\w+=)?|(?:}}))|\|\w+=|';
		}

		// Build a regular expression that will capture existing wiki links ("[[...]]"),
		// wiki headings ("= ... =", "== ... ==" etc.),  
		// urls ("http://example.com", "[http://example.com]", "[http://example.com Description]",
		// and email addresses ("mail@example.com").
		// Since there is a user option to skip headings, we make this part of the expression
		// optional. Note that in order to use preg_split(), it is important to have only one
		// capturing subpattern (which precludes the use of conditional subpatterns).
		( $wgLinkTitlesParseHeadings ) ? $delimiter = '' : $delimiter = '=+.+?=+|';
		$urlPattern = '[a-z]+?\:\/\/(?:\S+\.)+\S+(?:\/.*)?';
		self::$delimiter = '/(' .                     // exclude from linking:
			'\[\[.*?\]\]|' .                            // links
			$delimiter .                                // titles (if requested)
			$templatesDelimiter .                       // templates (if requested)
			'^ .+?\n|\n .+?\n|\n .+?$|^ .+?$|' .        // preformatted text
			'<nowiki>.*?<.nowiki>|<code>.*?<\/code>|' . // nowiki/code
			'<pre>.*?<\/pre>|<html>.*?<\/html>|' .      // pre/html
			'<script>.*?<\/script>|' .                  // script
			'<div.+?>|<\/div>|' .                       // attributes of div elements
			'<span.+?>|<\/span>|' .                     // attributes of span elements
			'<file>[^<]*<\/file>|' .                    // stuff inside file elements
			'style=".+?"|class=".+?"|' .                // styles and classes (e.g. of wikitables)
			'\[' . $urlPattern . '\s.+?\]|'. $urlPattern .  '(?=\s|$)|' . // urls
			'(?<=\b)\S+\@(?:\S+\.)+\S+(?=\b)' .        // email addresses
			')/ismS';
		}

    /// Local Debugging output function which can send output to console as well
    public static function ltDebugLog($text) {
        if (self::$ltConsoleOutputDebug)
        {
            print $text . "\n";
        }
        wfDebugLog('LinkTitles', $text , 'private');
    }

    /// Local Logging output function which can send output to console as well
    public static function ltLog($text) {
        if (self::$ltConsoleOutput)
        {
            print $text . "\n";
        }
        wfDebugLog('LinkTitles', $text , 'private');
    }
}

// vim: ts=2:sw=2:noet:comments^=\:///