<?php
/**
 * MediaWiki math extension
 *
 * (c) 2002-2012 Tomasz Wegrzanowski, Brion Vibber, Moritz Schubotz, and other MediaWiki contributors
 * GPLv2 license; info in main package.
 *
 * @file
 */

/**
 * Abstract base class with static methods for rendering the <math> tags using 
 * different technologies. These static methods create a new instance of the 
 * extending classes and render the math tags based on the mode setting of the user.
 * Furthermore this class handles the caching of the rendered output and provides
 *  debug information,
 * if run in mathdebug mode.
 *
 * @author Tomasz Wegrzanowski
 * @author Brion Vibber
 * @author Moritz Schubotz
 */
abstract class MathRenderer {
	/**
	 *  The following variables should made private, as soon it can be verified
	 *  that they are not being directly accessed by other extensions.
	 */
	var $mode = MW_MATH_PNG;
	var $tex = '';
	/**
	 * is calculated by texvc.
	 * @var string
	 */
	var $hash = '';
	var $html = '';
	var $mathml = '';
	var $conservativeness = 0;
	var $params = '';
	var $changed = false;
	protected $recall;

	/**
	 * Constructs a base MathRenderer
	 *
	 * @param string $tex (optional) LaTeX markup
	 * @param array $params (optional) HTML attributes
	 */
	public function __construct( $tex='', $params = array() ) {
		$this->tex = $tex;
		$this->params = $params;
	}

	/**
	 * Static method for rendering math tag
	 *
	 * @param string $tex LaTeX markup
	 * @param array $params HTML attributes
	 * @param int $mode constant indicating rendering mode
	 * @return string HTML for math tag
	 */
	public static function renderMath( $tex, $params = array(), $mode = MW_MATH_PNG ) {
		$renderer = self::getRenderer( $tex, $params, $mode );
		return $renderer->render();
	}

	/**
	 * Static factory method for getting a renderer based on mode
	 *
	 * @param string $tex LaTeX markup
	 * @param array $params HTML attributes
	 * @param int $mode constant indicating rendering mode
	 * @return MathRenderer appropriate renderer for mode
	 */
	public static function getRenderer( $tex, $params = array(),  $mode = MW_MATH_PNG ) {
		global $wgDefaultUserOptions;
		$validModes = array( MW_MATH_PNG, MW_MATH_SOURCE, MW_MATH_MATHJAX );
		if ( !in_array( $mode, $validModes ) )
			$mode = $wgDefaultUserOptions['math'];
		switch ( $mode ) {
			case MW_MATH_SOURCE:
				$renderer = new MathSource( $tex, $params );
				break;
			case MW_MATH_MATHJAX:
				$renderer = new MathMathJax( $tex, $params );
				break;
			case MW_MATH_PNG:
			default:
				$renderer = new MathTexvc( $tex, $params );
		}
		wfDebugLog ( "Math", 'start rendering $' . $renderer->tex . '$' );
		return $renderer;
	}

	/**
	 * Performs the rendering and returns the rendered element that needs to be embedded.
	 *
	 * @return string of rendered HTML
	 */
	abstract public function render();


	/**
	 * texvc error messages
	 * TODO: update to MathML
	 * Returns an internationalized HTML error string
	 *
	 * @param string $msg message key for specific error
	 * @param string $append string to append after error
	 * @return string HTML error string
	 */
	protected function getError( $msg, $append = '' ) {
		$mf = wfMessage( 'math_failure' )->inContentLanguage()->escaped();
		$errmsg = wfMessage( $msg )->inContentLanguage()->escaped();
		$source = htmlspecialchars( str_replace( "\n", ' ', $this->tex ) );
		return "<strong class='error'>$mf ($errmsg$append): $source</strong>\n";
	}

	/**
	 * Return hash of input
	 *
	 * @return string hash
	 */
	public function getInputHash() {
		// TODO: What happens if $tex is empty?
		$dbr = wfGetDB( DB_SLAVE );
		return $dbr->encodeBlob( pack( "H32", md5( $this->tex ) ) ); # Binary packed, not hex
	}

	/**
	 * Reads rendering data from database
	 *
	 * @return boolean true if read successfully, false otherwise
	 */
	public function readFromDatabase() {
		$dbr = wfGetDB( DB_SLAVE );
		$rpage = $dbr->selectRow(
			'math',
			array(
				'math_outputhash', 'math_html_conservativeness', 'math_html',
				'math_mathml'
			),
			array(
				'math_inputhash' => $this->getInputHash()
			),
			__METHOD__
		);
		if ( $rpage !== false ) {
			# Trailing 0x20s can get dropped by the database, add it back on if necessary:
			$xhash = unpack( 'H32md5', $dbr->decodeBlob( $rpage->math_outputhash ) . "                " );
			$this->hash = $xhash['md5'];
			$this->conservativeness = $rpage->math_html_conservativeness;
			$this->html = $rpage->math_html;
			$this->mathml = $rpage->math_mathml;
			$this->recall = true;
			return true;
		}

		# Missing from the database and/or the render cache
		$this->recall = false;
		return false;
	}

	/**
	 * Writes rendering entry to database.
	 *
	 * WARNING: Use writeCache() instead of this method to be sure that all
	 * renderer specific (such as squid caching) are taken into account.
	 * This function stores the values that are currently present in the class to the database even if they are empty.
	 *
	 * This function can be seen as protected function.
	 */
	public function writeToDatabase() {
		# Now save it back to the DB:
		if ( !wfReadOnly() ) {
			$dbw = wfGetDB( DB_MASTER );
			if ( $this->hash !== '' ) {
				$outmd5_sql = $dbw->encodeBlob( pack( 'H32', $this->hash ) );
			} else {
				$outmd5_sql = '';
			}
			wfDebugLog( "Math", 'store entry for $' . $this->tex . '$ in database (hash:' . $this->hash . ')\n' );
			$dbw->replace(
				'math',
				array( 'math_inputhash' ),
				array(
					'math_inputhash' => $this->getInputHash(),
					'math_outputhash' => $outmd5_sql ,
					'math_html_conservativeness' => $this->conservativeness,
					'math_html' => $this->html,
					'math_mathml' => $this->mathml,
					),
				__METHOD__
			);
		}
	}

	/**
	 * Returns sanitized attributes
	 *
	 * @param string $tag element name
	 * @param array $defaults default attributes
	 * @param array $overrides attributes to override defaults
	 * @return array HTML attributes
	 */
	protected function getAttributes( $tag, $defaults = array(), $overrides = array() ) {
		$attribs = Sanitizer::validateTagAttributes( $this->params, $tag );
		$attribs = Sanitizer::mergeAttributes( $defaults, $attribs );
		$attribs = Sanitizer::mergeAttributes( $attribs, $overrides );
		return $attribs;
	}
	/**
	 * Writes cache.  Does nothing by default
	 */
	public function writeCache() {
	}

	/**
	 * Determines if this is a cached/recalled render
	 *
	 * @return boolean true if recalled, false otherwise
	 */
	public function isRecall() {
		return $this->recall;
	}

	/**
	 * Gets TeX markup
	 *
	 * @return string TeX markup
	 */
	public function getTex() {
		return $this->tex;
	}

	/**
	 * gets the rendering mode MW_MATH_*
	 *
	 * @return int
	 */
	public function getMode() {
		return $this->mode;
	}

	/**
	 * Sets the TeX code
	 *
	 * @param string $tex
	 */
	public function setTex( $tex ) {
		$this->changed = true;
		$this->tex = $tex;
	}

	/**
	 * Get the hash calculated by texvc
	 * 
	 * @return string hash
	 */
	public function getHash() {
		return $this->hash;
	}

	/**
	 * @param string $hash
	 */
	public function setHash( $hash ) {
		$this->changed = true;
		$this->hash = $hash;
	}

	/**
	 * Returns the html-representation of the mathematical formula.
	 * @return string
	 */
	public function getHtml() {
		return $this->html;
	}

	/**
	 * @param string $html
	 */
	public function setHtml( $html ) {
		$this->changed = true;
		$this->html = $html;
	}

	/**
	 * Gets the MathML XML element
	 * @return string in UTF-8 encoding
	 */
	public function getMathml() {
		return $this->mathml;
	}

	/**
	 * @param string $mathml use UTF-8 encoding
	 */
	public function setMathml( $mathml ) {
		$this->changed = true;
		$this->mathml = $mathml;
	}

	/**
	 * Gets the so called 'conservativeness' calculated by texvc
	 *
	 * @return int
	 */
	public function getConservativeness() {
		return $this->conservativeness;
	}

	/**
	 * @param int $conservativeness
	 */
	public function setConservativeness( $conservativeness ) {
		$this->changed = true;
		$this->conservativeness = $conservativeness;
	}

	/**
	 * Get the attributes of the math tag
	 * 
	 * @return array()
	 */
	public function getParams() {
		return $this->params;
	}

	/**
	 * @param array() $params
	 */
	public function setParams( $params ) {
		//$changed is not set to true here, because the attributes do not affect
		//the rendering in the current implementation.
		//If this behavior will change in the future $this->tex is no longer a 
		//primary key and the input hash cannot be calculate form $this->tex 
		//only. See the discussion 'Tag extensions in Block mode' on wikitech-l.
		$this->params = $params;
	}

	/**
	 * Checks if the instance was modified i.e., because math was rendered
	 *
	 * @return boolean true if something was changed false otherwise
	 */
	public function isChanged() {
		return $this->changed;
	}

}