From e091c775932f1a102a5373171535bd6221e03711 Mon Sep 17 00:00:00 2001
From: Stegmujo <johannesst@gmx.de>
Date: Mon, 10 Oct 2022 14:00:00 +0000
Subject: [PATCH] Add TexVC with Check functionality

Bug: T312528

Change-Id: Ib66a4603e3c1869d5c197b72b46b098d0df15e34
---
 src/TexVC/TexVC.php | 171 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 171 insertions(+)
 create mode 100644 src/TexVC/TexVC.php

diff --git a/src/TexVC/TexVC.php b/src/TexVC/TexVC.php
new file mode 100644
index 000000000..8a1d15da8
--- /dev/null
+++ b/src/TexVC/TexVC.php
@@ -0,0 +1,171 @@
+<?php
+
+declare( strict_types = 1 );
+
+namespace MediaWiki\Extension\Math\TexVC;
+
+use Exception;
+use MediaWiki\Extension\Math\TexVC\Nodes\TexArray;
+use stdClass;
+
+/**
+ * A TeX/LaTeX validator.
+ * TexVC(PHP) takes user input and validates it while replacing
+ * MediaWiki-specific functions.  It is a PHP port of the JavaScript port of texvc,
+ * which was originally written in Ocaml for the Math extension.
+ *
+ * @author Johannes Stegmüller
+ */
+class TexVC {
+	/** @var Parser */
+	private $parser;
+	/** @var TexUtil */
+	private $tu;
+
+	public function __construct() {
+		$this->parser = new Parser();
+		$this->tu = new TexUtil();
+	}
+
+	private function strStartsWith( $haystack, $needle ): bool {
+		return strpos( $haystack, $needle ) === 0;
+	}
+
+	/**
+	 * Usually this step is done implicitly within the check-method.
+	 * @param string $input tex-string as input for the grammar
+	 * @param null|array $options array options for the grammar.
+	 * @return mixed output of the grammar.
+	 * @throws SyntaxError when SyntaxError in the input
+	 */
+	public function parse( $input, $options = null ) {
+		return $this->parser->parse( $input, $options );
+	}
+
+	/** status is one character:
+	 *  + : success! result is in 'output'
+	 *  E : Lexer exception raised
+	 *  F : TeX function not recognized
+	 *  S : Parsing error
+	 *  - : Generic/Default failure code. Might be an invalid argument,
+	 *      output file already exist, a problem with an external
+	 *      command ...
+	 * @param string|TexArray|stdClass $input tex to be checked as string,
+	 * can also be the output of former parser call
+	 * @param null|array $options array options for settings of the check
+	 * @param array &$warnings reference on warnings occurring during the check
+	 * @return array|string[] output with information status (see above)
+	 * @throws Exception in case of a major problem with the check and activated debug option.
+	 */
+	public function check( $input, $options = null, &$warnings = [] ) {
+		try{
+			$options = ParserUtil::createOptions( $options );
+			if ( is_string( $input ) ) {
+				$input = $this->parser->parse( $input, $options );
+			}
+			$output = $input->render();
+			$result = [
+				'status' => '+',
+				'output' => $output,
+				'warnings' => $warnings,
+				'input' => $input,
+				'success' => true,
+			];
+
+			$pkgs = [ 'ams', 'cancel', 'color', 'euro', 'teubner', 'mhchem', 'mathoid' ];
+
+			foreach ( $pkgs as $pkg ) {
+				$pkg .= '_required';
+				$tuRef = $this->tu->getBaseElements()[$pkg];
+				$result[$pkg] = $input->containsFunc( $tuRef );
+			}
+			if ( !$options['usemhchem'] ) {
+				if ( $result['mhchem_required'] ) {
+					return [
+						'status' => 'C',
+						'details' => 'mhchem package required.'
+					];
+				}
+			}
+			return $result;
+		} catch ( Exception $ex ) {
+			if ( $ex instanceof SyntaxError && !$options['oldtexvc']
+					&& $this->strStartsWith( $ex->getMessage(), 'Deprecation' ) ) {
+
+				$warnings[] = [
+					'type' => 'texvc-deprecation',
+					'details' => $this->handleTexError( $ex, $options )
+				];
+				$options['oldtexvc'] = true;
+				return $this->check( $input, $options, $warnings );
+			}
+
+			if ( $ex instanceof SyntaxError && $options['usemhchem'] && !$options['oldmhchem'] ) {
+				$warnings[] = [
+					'type' => 'mhchem-deprecation',
+					'details' => $this->handleTexError( $ex, $options )
+				];
+				$options['oldmhchem'] = true;
+				return $this->check( $input, $options, $warnings );
+			}
+		}
+		return $this->handleTexError( $ex, $options );
+	}
+
+	private function handleTexError( Exception $e, $options = null ) {
+		if ( $options && $options['debug'] ) {
+			throw $e;
+		}
+		$report = [ 'success' => false, 'warnings' => [] ];
+		if ( $e instanceof SyntaxError ) {
+			if ( $e->getMessage() === 'Illegal TeX function' ) {
+				$report['status'] = 'F';
+				$report['details'] = $e->found;
+				$report += $this->getLocationInfo( $e );
+			} else {
+				$report['status'] = 'S';
+				$report['details'] = $e->getMessage();
+				$report += $this->getLocationInfo( $e );
+			}
+			$report['error'] = [
+				'message' => $e->getMessage(),
+				'expected' => $e->expected,
+				'found' => $e->found,
+				'location' => [
+					/** This currently only has the start location, since end is not noted in SyntaxError in PHP
+					 * this issue is tracked in: https://phabricator.wikimedia.org/T321060
+					 */
+					'offset' => $e->grammarOffset,
+					'line' => $e->grammarLine,
+					'column' => $e->grammarColumn
+				],
+				'name' => $e->name
+			];
+
+		} else {
+			$report['status'] = '-';
+			$report['details'] = $e->getMessage();
+			$report['error'] = $e;
+		}
+		return $report;
+	}
+
+	/**
+	 * Gets the location information of an error object, or returns default error
+	 * location if no location information was specified.
+	 * @param SyntaxError $e error object
+	 * @return array information on the error.
+	 */
+	private function getLocationInfo( SyntaxError $e ) {
+		try {
+			return [
+				'offset'  => $e->grammarOffset,
+				'line' => $e->grammarLine,
+				'column' => $e->grammarColumn
+			];
+		} catch ( Exception $err ) {
+			return [ 'offset' => 0, 'line' => 0, 'column' => 0 ];
+		}
+	}
+
+}