<?php
/* Copyright (c)
 * - 2006-2013, Ivan Sagalaev (maniac@softwaremaniacs.org), highlight.js
 *              (original author)
 * - 2013-2015, Geert Bergman (geert@scrivo.nl), highlight.php
 * - 2014,      Daniel Lynge, highlight.php (contributor)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of "highlight.js", "highlight.php", nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

namespace Highlight;

class Highlighter
{
    private $modeBuffer = "";
    private $result = "";
    private $top = null;
    private $language = null;
    private $keywordCount = 0;
    private $relevance = 0;
    private $ignoreIllegals = false;

    private static $classMap = array();
    private static $languages = null;
    private static $aliases = null;

    private $tabReplace = null;
    private $classPrefix = "hljs-";

    private $autodetectSet = array(
        "xml", "json", "javascript", "css", "php", "http"
    );

    public function __construct()
    {
        $this->registerLanguages();
    }

    private function registerLanguages() {

        // Languages that take precedence in the classMap array.
        foreach(Array("xml", "django", "javascript", "matlab", "cpp") as $l) {
            $this->createLanguage($l);
        }
        

        $d = dir(__DIR__.DIRECTORY_SEPARATOR."languages");
        while (false !== ($entry = $d->read())) {
            if ($entry[0] !== ".") {
                $lng = substr($entry, 0, -5);
                $this->createLanguage($lng);
            }
        }
        $d->close();

        self::$languages = array_keys(self::$classMap);
    }

    private function createLanguage($languageId)
    {
        if (!isset(self::$classMap[$languageId])) {
            $lang = new Language($languageId);
            self::$classMap[$languageId] = $lang;
            if (isset($lang->mode->aliases)) {
                foreach ($lang->mode->aliases as $alias) {
                    self::$aliases[$alias] = $languageId;
                }
            }
        }
        return self::$classMap[$languageId];
    }

    private function testRe($re, $lexeme)
    {
        if (!$re) {
            return false;
        }
        $test = preg_match($re, $lexeme, $match, PREG_OFFSET_CAPTURE); 
        if ($test === false) {
            throw new \Exception("Invalid regexp: " .
                var_export($re, true));
        }
        return count($match) && ($match[0][1] == 0);
    }

    private function subMode($lexeme, $mode)
    {
        for ($i=0; $i<count($mode->contains); $i++) {
            if ($this->testRe($mode->contains[$i]->beginRe, $lexeme)) {
                return $mode->contains[$i];
            }
        }
    }

    private function endOfMode($mode, $lexeme)
    {
        if ($this->testRe($mode->endRe, $lexeme)) {
            while ($mode->endsParent && $mode->parent) {
                $mode = $mode->parent;
            }
            return $mode;
        }
        if ($mode->endsWithParent) {
            return $this->endOfMode($mode->parent, $lexeme);
        }
    }

    private function isIllegal($lexeme, $mode)
    {
        return
            !$this->ignoreIllegals && $this->testRe($mode->illegalRe, $lexeme);
    }

    private function keywordMatch($mode, $match)
    {
        $kwd = $this->language->caseInsensitive
            ? mb_strtolower($match[0], "UTF-8") : $match[0];

        return isset($mode->keywords[$kwd]) ? $mode->keywords[$kwd] : null;
    }

    private function buildSpan(
            $classname, $insideSpan, $leaveOpen=false, $noPrefix=false)
    {
        $classPrefix = $noPrefix ? "" : $this->classPrefix;
        $openSpan = "<span class=\"" . $classPrefix;
        $closeSpan = $leaveOpen ? "" : "</span>";

        $openSpan .= $classname . "\">";

        return $openSpan . $insideSpan . $closeSpan;
    }

    private function escape($value) {
        return htmlspecialchars($value, ENT_NOQUOTES);
    }

    private function processKeywords()
    {
        if (empty($this->top->keywords)) {
            return $this->escape($this->modeBuffer);
        }

        $result = "";
        $lastIndex = 0;

        /* TODO: when using the crystal language file on django and twigs code
         * the values of $this->top->lexemesRe can become "" (empty). Check
         * if this behaviour is consistent with highlight.js.  
         */
        if ($this->top->lexemesRe) {
            while (preg_match($this->top->lexemesRe, $this->modeBuffer, $match,
                    PREG_OFFSET_CAPTURE, $lastIndex)) {
    
                $result .= $this->escape(substr(
                    $this->modeBuffer, $lastIndex, $match[0][1] - $lastIndex));
                $keyword_match = $this->keywordMatch($this->top, $match[0]);
    
                if ($keyword_match) {
                    $this->relevance += $keyword_match[1];
                    $result .= $this->buildSpan(
                        $keyword_match[0], $this->escape($match[0][0]));
                } else {
                    $result .= $this->escape($match[0][0]);
                }
    
                $lastIndex = strlen($match[0][0]) + $match[0][1];
            }
        }

        return $result . $this->escape(substr($this->modeBuffer, $lastIndex));
    }

    private function processSubLanguage()
    {
        try {
            $hl = new Highlighter();
            $hl->autodetectSet = $this->autodetectSet;

            $explicit = is_string($this->top->subLanguage);
            if ($explicit && !isset(
                    array_flip(self::$languages)[$this->top->subLanguage])) {
                return $this->escape($this->modeBuffer);
            }

            if ($explicit) {
                $res = $hl->highlight($this->top->subLanguage,
                    $this->modeBuffer, true,
                    isset($this->continuations[$this->top->subLanguage])
                    ? $this->continuations[$this->top->subLanguage] : null);
            } else {
                $res = $hl->highlightAuto($this->modeBuffer,
                    count($this->top->subLanguage) ? $this->top->subLanguage 
                    : null);
            }
            // Counting embedded language score towards the host language may
            // be disabled with zeroing the containing mode relevance. Usecase
            // in point is Markdown that allows XML everywhere and makes every
            // XML snippet to have a much larger Markdown score.
            if ($this->top->relevance > 0) {
                $this->relevance += $res->relevance;
            }
            if ($explicit) {
                $this->continuations[$this->top->subLanguage] = $res->top;
            }
            return $this->buildSpan($res->language, $res->value, false, true);

        } catch (\Exception $e) {
            error_log("TODO, is this a relevant catch?");
            error_log($e);
            return $this->escape($this->modeBuffer);
        }
    }

    private function processBuffer()
    {
        return !is_null($this->top->subLanguage)
            ? $this->processSubLanguage() : $this->processKeywords();
    }

    private function startNewMode($mode, $lexeme)
    {
        $markup = $mode->className
            ? $this->buildSpan($mode->className, "", true) : "";

        if ($mode->returnBegin) {
            $this->result .= $markup;
            $this->modeBuffer = "";
        } elseif ($mode->excludeBegin) {
            $this->result .= $this->escape($lexeme) . $markup;
            $this->modeBuffer = "";
        } else {
            $this->result .= $markup;
            $this->modeBuffer = $lexeme;
        }

        $t = clone $mode;
        $t->parent = $this->top;
        $this->top = $t;
    }

    private function processLexeme($buffer, $lexeme=null)
    {
        $this->modeBuffer .= $buffer;

        if (null === $lexeme) {
            $this->result .= $this->processBuffer();
            return 0;
        }

        $new_mode = $this->subMode($lexeme, $this->top);
        if ($new_mode) {
            $this->result .= $this->processBuffer();
            $this->startNewMode($new_mode, $lexeme);
            return $new_mode->returnBegin ? 0 : strlen($lexeme);
        }

        $end_mode = $this->endOfMode($this->top, $lexeme);
        if ($end_mode) {
            $origin = $this->top;
            if (!($origin->returnEnd || $origin->excludeEnd)) {
                $this->modeBuffer .= $lexeme;
            }
            $this->result .= $this->processBuffer();
            do {
                if ($this->top->className) {
                    $this->result .= "</span>";
                }
                $this->relevance += $this->top->relevance;
                $this->top = $this->top->parent;
            } while ($this->top != $end_mode->parent);
            if ($origin->excludeEnd) {
                $this->result .= $this->escape($lexeme);
            }
            $this->modeBuffer = "";
            if ($end_mode->starts) {
                $this->startNewMode($end_mode->starts, "");
            }
            return $origin->returnEnd ? 0 : strlen($lexeme);
        }

        if ($this->isIllegal($lexeme, $this->top)) {
            $className = $this->top->className
                ? $this->top->className : "unnamed";
            $err = "Illegal lexeme \"{$lexeme}\" for mode \"{$className}\"";
            throw new \Exception($err);
        }

        // Parser should not reach this point as all types of lexemes should
        // be caught earlier, but if it does due to some bug make sure it
        // advances at least one character forward to prevent infinite looping.

        $this->modeBuffer .= $lexeme;
        $l = strlen($lexeme);
        return $l ? $l : 1;
    }

    /**
     * Replace tabs for something more usable.
     */
    private function replaceTabs($code) {
        if ($this->tabReplace !== null) {
            return str_replace("\t", $this->tabReplace, $code);
        }
        return $code;
    }

    /**
     * Set the set of languages used for autodetection. When using
     * autodetection the code to highlight will be probed for every language
     * in this set. Limiting this set to only the languages you want to use
     * will greatly improve highlighting speed.
     *
     * @param array $set
     *      An array of language games to use for autodetection. This defaults
     *      to a typical set Web development languages.
     */
    public function setAutodetectLanguages(array $set)
    {
        $this->autodetectSet = array_unique($set);
        $this->registerLanguages();
    }

    /**
     * Get the tab replacement string.
     *
     * @return string
     *      The tab replacement string.
     */
    public function getTabReplace()
    {
        return $this->tabReplace;
    }

    /**
     * Set the tab replacement string. This defaults to NULL: no tabs
     * will be replaced.
     *
     * @param string $tabReplace
     *      The tab replacement string.
     */
    public function setTabReplace($tabReplace)
    {
        $this->tabReplace = $tabReplace;
    }

    /**
     * @throws
     *      A DomainException if the requested language was not in this 
     *      Highlighter's language set. 
     */
    private function getLanguage($name) {
        if (isset(self::$classMap[$name])) {
            return self::$classMap[$name];
        } elseif (isset(self::$aliases[$name]) && 
                isset(self::$classMap[self::$aliases[$name]])) {
            return self::$classMap[self::$aliases[$name]];
        }
        throw new \DomainException("Unknown language: $name");
    }

    /**
     * Core highlighting function. Accepts a language name, or an alias, and a
     * string with the code to highlight. Returns an object with the following
     * properties:
     * - relevance (int)
     * - value (an HTML string with highlighting markup)
     * @throws
     *      A DomainException if the requested language was not in this 
     *      Highlighter's language set. 
     */
    public function highlight(
            $language, $code, $ignoreIllegals=true, $continuation=null)
    {
        $this->language = $this->getLanguage($language);
        $this->language->compile();
        $this->top = $continuation ? $continuation : $this->language->mode;
        $this->continuations = array();
        $this->result = "";

        for ($current = $this->top; $current != $this->language->mode;
                $current = $current->parent) {
            if ($current->className) {
                $this->result =
                    $this->buildSpan($current->className, '', true) .
                    $this->result;
            }
        }

        $this->modeBuffer = "";
        $this->relevance = 0;
        $this->ignoreIllegals = $ignoreIllegals;

        $res = new \stdClass;
        $res->relevance = 0;
        $res->value = "";
        $res->language = "";

        try {
            $match = null;
            $count = 0;
            $index = 0;

            while ($this->top && $this->top->terminators) {
                $test = preg_match($this->top->terminators, $code, $match,
                        PREG_OFFSET_CAPTURE, $index);
                if ($test === false) {
                     throw new \Exception("Invalid regExp ".
                         var_export($this->top->terminators, true));
                } else if ($test === 0) {
                    break;
                }
                $count = $this->processLexeme(
                    substr($code, $index, $match[0][1] - $index), $match[0][0]);
                $index = $match[0][1] + $count;
            }
            $this->processLexeme(substr($code, $index));

            for ($current = $this->top; $current != $this->language->mode;
                    $current = $current->parent) {
                if ($current->className) {
                    $this->result .= "</span>";
                }
            }

            $res->relevance = $this->relevance;
            $res->value = $this->replaceTabs($this->result);
            $res->language = $this->language->name;
            $res->top = $this->top;

            return $res;

        } catch (\Exception $e) {

            if (strpos($e->getMessage(), "Illegal") !== false) {
                $res->value = $this->escape($code);
                return $res;
            } else {
                throw $e;
            }
        }
    }

    public function highlightAuto($code, $languageSubset = null)
    {
        $res = new \stdClass;
        $res->relevance = 0;
        $res->value = $this->escape($code);
        $res->language = "";
        $scnd = clone $res;

        $tmp = $languageSubset ? $languageSubset : $this->autodetectSet;

        foreach ($tmp as $l) {
            $current = $this->highlight($l, $code, false);
            if ($current->relevance > $scnd->relevance) {
                $scnd = $current;
            }
            if ($current->relevance > $res->relevance) {
                $scnd = $res;
                $res = $current;
            }
        }

        if ($scnd->language) {
            $res->secondBest = $scnd;
        }

        return $res;
    }

    /**
     * Return a list of all supported languages. Using this list in
     * setAutodetectLanguages will turn on autodetection for all supported
     * languages.
     *
     * @return array
     *      An array of language names (strings).
     */
    public function listLanguages()
    {
        return self::$languages;
    }

}