<?php
/**
 * Contain everything related to <math> </math> parsing
 */

class MathRenderer {
	
	//shell programs:
	var $LATEX_PATH = "/usr/bin/latex";
	var $DVIPS_PATH = "/usr/bin/dvips";
	var $CONVERT_PATH = "/usr/bin/convert";
	
	//image url stuff
 	var $URL_PATH = "http://www.mymcat.com/testing/cache";

	var $tex = '';
	var $inputhash = '';
	var $hash = '';
	var $html = '';

	//right now we have NO params, but it might be worth keeping...
	function __construct( $tex, $params=array() ) {
		$this->tex = $tex;
		$this->params = $params;
 	}

	function render() {
		global $wgTmpDirectory;
		$fname = 'MathRenderer::render';

		if( !$this->_recall() ) {
			# Ensure that the temp and output directories are available before continuing...
			if( !file_exists( $wgTmpDirectory ) ) {
				if( !@mkdir( $wgTmpDirectory ) ) {
					return $this->_error( "wgTmpDirectory: $wgTmpDirectory does not exist! " );
				}
			} elseif( !is_dir( $wgTmpDirectory ) || !is_writable( $wgTmpDirectory ) ) {
				return $this->_error( "wgTmpDirectory: $wgTmpDirectory is not accessible!" );
			}

			if( function_exists( 'is_executable' ) && !is_executable( $this->LATEX_PATH ) ) {
				return $this->_error( "latex not found..." );
			}
			if( function_exists( 'is_executable' ) && !is_executable( $this->DVIPS_PATH ) ) {                                
                                return $this->_error( "dvips not found" );      
                        }	
			if( function_exists( 'is_executable' ) && !is_executable( $this->CONVERT_PATH ) ) {                                
                                return $this->_error( "convert (imagemagick) not found" );   
                        }


			//wrap the math text with the generic latex requirements
			//in the future, this wrapper should be modifyable by the parameters
			$thunk = $this->_wrap($this->tex);
			
			//begin working...
			$hash = md5($this->tex);
			$this->hash = $hash;
			wfDebug( "Math: hash is: $this->hash\n" );

			//get to the tmp dir:
			$current_dir = getcwd();
			chdir( $wgTmpDirectory );
			
			// create temporary LaTeX file
			$fp = fopen( "$hash.tex", "w+");
			fputs($fp, $thunk);
			fclose($fp);

			//run latex:
			$command = $this->LATEX_PATH . " --interaction=nonstopmode " . $hash . ".tex";
 			exec($command);
			wfDebug( "Math: latex command, $command\n" );

			//run dvips:
			$command = $this->DVIPS_PATH . " -E $hash" . ".dvi -o " .  "$hash.ps";
 			exec($command);
			wfDebug( "Math: dvips command, $command\n" );


			//run ps through imageMagick:
		 	$command = $this->CONVERT_PATH . " -density 120 $hash.ps $hash.png";
 			exec($command);
			wfDebug( "Math: convert command, $command\n" );

  	//		copy("$hash.png", $this->CACHE_DIR . "/$hash.png");
			chdir($current_dir);

			if (!preg_match("/^[a-f0-9]{32}$/", $this->hash)) {
				return $this->_error( "could not match the hash anywhere" );
			}

			if( !file_exists( "$wgTmpDirectory/{$this->hash}.png" ) ) {
				return $this->_error( 'math_image_error' . " $wgTmpDirectory/{$this->hash}.png  , $dirandhash , " . getcwd() );
			}

			$hashpath = $this->_getHashPath();
			if( !file_exists( $hashpath ) ) {
				if( !@wfMkdirParents( $hashpath, 0755 ) ) {
					return $this->_error( "hashpath error type one: $hashpath" );
				}
			} elseif( !is_dir( $hashpath ) || !is_writable( $hashpath ) ) {
				return $this->_error( 'hashpath error type two' );
			}

			if( !rename( "$wgTmpDirectory/{$this->hash}.png", "$hashpath/{$this->hash}.png" ) ) {
				return $this->_error( "hashpath rename failed" );
			}

			# Now save it back to the DB:
			if ( !wfReadOnly() ) {
				$outmd5_sql = pack('H32', $this->hash);

				$md5_sql = pack('H32', $this->md5); # Binary packed, not hex

				$dbw = wfGetDB( DB_MASTER );
				$dbw->replace( 'math', array( 'math_inputhash' ),
				  array(
					'math_inputhash' => $dbw->encodeBlob($md5_sql),
					'math_outputhash' => $dbw->encodeBlob($outmd5_sql),
					'math_html_conservativeness' => "",
					'math_html' => $this->html,
					'math_mathml' => "",
				  ), $fname, array( 'IGNORE' )
				);
			}
			
			$this->_cleanup( $hash );
		}
		
		return $this->_doRender();
	}

	function _error( $msg, $append = '' ) {
		$mf   = htmlspecialchars( wfMsg( 'math_failure' ) );
		$errmsg = htmlspecialchars( $msg );
		$source = htmlspecialchars( str_replace( "\n", ' ', $this->tex ) );
		return "<strong class='error'>$mf ($errmsg$append): $source</strong>\n";
	}

	function _wrap($thunk) {
  		return <<<EOS
    		\documentclass[10pt]{article}

	 	% add additional packages here
		\usepackage{amsmath}
		\usepackage{amsfonts}
		\usepackage{amssymb}
		\usepackage{pst-plot}
		\usepackage{color}

		\pagestyle{empty}
		\begin{document}
		\begin{equation*}
		\large
		$thunk
		\end{equation*}
		\end{document}
EOS;
	}


	function _cleanup($hash) {

		$current_dir = getcwd();
		chdir( $wgTmpDirectory );

		unlink($this->TMP_DIR . "/$hash.tex");
		unlink($this->TMP_DIR . "/$hash.aux");
		unlink($this->TMP_DIR . "/$hash.log");
		unlink($this->TMP_DIR . "/$hash.dvi");
		unlink($this->TMP_DIR . "/$hash.ps");
		unlink($this->TMP_DIR . "/$hash.png");

		chdir($current_dir);
	}

	function _recall() {
		global $wgMathDirectory;
		$fname = 'MathRenderer::_recall';

		$this->md5 = md5( $this->tex );
		$dbr = wfGetDB( DB_SLAVE );
		$rpage = $dbr->selectRow( 'math',
			array( 'math_outputhash','math_html_conservativeness','math_html','math_mathml' ),
			array( 'math_inputhash' => $dbr->encodeBlob(pack("H32", $this->md5))), # Binary packed, not hex
			$fname
		);

		if( $rpage !== false ) {
			# Tailing 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;

			if( file_exists( $this->_getHashPath() . "/{$this->hash}.png" ) ) {
				return true;
			}

			if( file_exists( $wgMathDirectory . "/{$this->hash}.png" ) ) {
				$hashpath = $this->_getHashPath();

				if( !file_exists( $hashpath ) ) {
					if( !@wfMkdirParents( $hashpath, 0755 ) ) {
						return false;
					}
				} elseif( !is_dir( $hashpath ) || !is_writable( $hashpath ) ) {
					return false;
				}
				if ( function_exists( "link" ) ) {
					return link ( $wgMathDirectory . "/{$this->hash}.png",
							$hashpath . "/{$this->hash}.png" );
				} else {
					return rename ( $wgMathDirectory . "/{$this->hash}.png",
							$hashpath . "/{$this->hash}.png" );
				}
			}

		}

		# Missing from the database and/or the render cache
		return false;
	}

	/**
	 * Select among PNG, HTML, or MathML output depending on
	 * THIS ONLY does PNG now...
	 */
	function _doRender() {
		return $this->_linkToMathImage();
	}
	
	function _attribs( $tag, $defaults=array(), $overrides=array() ) {
		$attribs = Sanitizer::validateTagAttributes( $this->params, $tag );
		$attribs = Sanitizer::mergeAttributes( $defaults, $attribs );
		$attribs = Sanitizer::mergeAttributes( $attribs, $overrides );
		return $attribs;
	}

	function _linkToMathImage() {
		global $wgMathPath;
		$url = "$wgMathPath/" . substr($this->hash, 0, 1)
					.'/'. substr($this->hash, 1, 1) .'/'. substr($this->hash, 2, 1)
					. "/{$this->hash}.png";

		return Xml::element( 'img',
			$this->_attribs(
				'img',
				array(
					'class' => 'tex',
					'alt' => $this->tex ),
				array(
					'src' => $url ) ) );
	}

	function _getHashPath() {
		global $wgMathDirectory;
		$path = $wgMathDirectory .'/'. substr($this->hash, 0, 1)
					.'/'. substr($this->hash, 1, 1)
					.'/'. substr($this->hash, 2, 1);
		wfDebug( "TeX: getHashPath, hash is: $this->hash, path is: $path\n" );
		return $path;
	}

	public static function renderMath( $tex, $params=array() ) {
		global $wgUser;
		$math = new MathRenderer( $tex, $params );
	//	$math->setOutputMode( $wgUser->getOption('math'));
		return $math->render();
	}
}