class.html-to-wiki.php

<?php

/**
 * Created by PhpStorm.
 * User: Sicz-Mesziár János
 * Date: 2015.11.10.
 * Time: 21:43
 */
class HtmlToWiki {

    //@formatter:off
    private static $inline = array(
        '<i>'       => "''",        // italic
        '</i>'      => "''",
        '<b>'       => " '''",       // bold
        '</b>'      => "''' ",
        '<strong>'  => " '''",
        '</strong>' => "''' ",
        '<span>'    => "",          // span
        '</span>'   => "",
        '&nbsp;'    => " "
    );

    private static $block = array(
        '<div>'     => "",          // div
        '</div>'    => "\n",
        '<p>'       => "\n",        // p
        '</p>'      => "\n",
        '<ul>'      => "\n",        // ul
        '</ul>'     => "\n",
        '<ol>'      => "\n",        // ol
        '</ol>'     => "\n",
        '<li>'      => "* ",        // li
        '</li>'     => "\n"
    );

    private static $heading = array(
        '<h1>'      => "\n= ",
        '</h1>'     => " =\n",
        '<h2>'      => "\n== ",
        '</h2>'     => " ==\n",
        '<h3>'      => "\n=== ",
        '</h3>'     => " ===\n",
        '<h4>'      => "\n==== ",
        '</h4>'     => " ====\n",
        '<h5>'      => "\n===== ",
        '</h5>'     => " =====\n",
        '<h6>'      => "\n====== ",
        '</h6>'     => " ======\n",
    );

    private static $separator = array(
        '<br>'      => "\n",
        '<br/>'     => "\n",
        '<hr>'      => "---\n",
        '<hr/>'     => "---\n"
    );

    private static $bullets_and_hyphens = array(
        // BULLETS
        "•",    // \x{2022} --> BULLET
        "∙",    // \x{2219} --> BULLET OPERATOR
        "◦",    // \x{25E6} --> WHITE BULLET
        "◘",   // \x{25D8} --> INVERSE BULLET
        "⦿",   // \x{29BF} --> CIRCLED BULLET
        "‣",    // \x{2023} --> TRIANGULAR BULLET
        "⁃",    // \x{2043} --> HYPHEN BULLET
        "·",    // \x{00B7} --> MIDDLE DOT

        // HYPHENS
        "-",     // \x{002D} --> HYPHEN-MINUS
        "⁻",     // \x{207B} --> SUPERSCRIPT MINUS
        "₋",     // \x{208B} --> SUBSCRIPT MINUS
        "﹣",    // \x{FE63} --> SMALL HYPHEN-MINUS
        "－"     // \x{FF0D} --> FULLWIDTH HYPHEN-MINUS
    );
    //@formatter:on


    /**
     * @param $html String
     * @return String
     */
    public function toWiki($html) {
        // TRIM --------------------------------
        $result = trim($html);

        // CONVERSION --------------------------
        // 1. Get the payload
        $result = $this->parseHTMLBody($result);
        // 2. Make single line to prevent new-lines problems
        $result = $this->removeNewLines($result);
        // 3. Parse elements (that depend attributes like <a href...>)
        $result = $this->replaceHTMLLinks($result);
        // 4. Clean unnecessary HTML attributes
        $result = $this->removeHTMLArguments($result);
        // 5. Parse elements
        $result = $this->replaceHTMLInlineElements($result);
        $result = $this->replaceHTMLBlockElements($result);
        $result = $this->replaceHTMLHeadingElements($result);
        $result = $this->replaceHTMLSeparatorElements($result);
        // 6. Clean Wiki
        $result = $this->trimLines($result);
        $result = $this->removeWhitespaces($result);
        $result = $this->removeBlankLines($result);
        $result = $this->removeHTMLElements($result);
        // 7. Fix Wiki content
        $result = $this->fixWiki($result);

        return trim($result);
    }


    // HTML CLEANING & CONVERTER FUNCTIONS ----------------------------------------------
    public function parseHTMLBody($html) {
        preg_match('/<body[^>]*>(.*?)<\/body>/s', $html, $matches);
        return !empty($matches) ? trim($matches[1]) : trim($html);
    }

    public function replaceHTMLLinks($html) {
        // Based on: http://www.the-art-of-web.com/php/parse-links/
        preg_match_all('/<a\s[^>]*href\s*=\s*(\"??)([^\" >]*?)\\1[^>]*>(.*)<\/a>/siU', $html, $matches, PREG_PATTERN_ORDER);
        if (!empty($matches)) {
            for ($i = 0; $i < count($matches[0]); $i++) {
                $match = trim($matches[0][$i]);
                $link = trim($matches[2][$i]);
                $text = $this->removeHTMLElements(trim($matches[3][$i]));
                if (!empty($match) && !empty($link) && !empty($text)) {
                    $wiki_link = '[' . $link . ' ' . $text . ']';
                    $html = str_replace($match, $wiki_link, $html);
                }
            }
        }
        return $html;
    }

    public function removeHTMLArguments($html) {
        return preg_replace('/<([a-z][a-z0-9]*)[^>]*?(\/?)>/i', '<$1$2>', $html);
    }

    public function removeHTMLElements($html) {
        return trim(strip_tags($html));
    }

    public function replaceHTMLInlineElements($html) {
        foreach (self::$inline as $k => $v)
            $html = str_replace($k, $v, $html);
        return $html;
    }

    public function replaceHTMLBlockElements($html) {
        foreach (self::$block as $k => $v)
            $html = str_replace($k, $v, $html);
        return $html;
    }

    public function replaceHTMLHeadingElements($html) {
        foreach (self::$heading as $k => $v)
            $html = str_replace($k, $v, $html);
        return $html;
    }

    public function replaceHTMLSeparatorElements($html) {
        foreach (self::$separator as $k => $v)
            $html = str_replace($k, $v, $html);
        return $html;
    }

    // SIMPLE TEXT CLEANING FUNCTIONS ----------------------------------------------
    public function removeNewLines($text) {
        return trim(preg_replace('/\s+/', ' ', $text));
    }

    public function removeWhitespaces($text) {
        for ($i = 0; $i < 5; $i++)
            $text = str_replace('  ', ' ', $text);
        return $text;
    }

    public function removeBlankLines($text) {
        return preg_replace('/\n(\s*\n)+/', "\n\n", $text);
    }

    public function trimLines($text) {
        return implode("\n", array_map('trim', explode("\n", $text)));
    }


    // CONTENT FIXING -------------------------------------------------------------
    public function fixWiki($wiki) {
        $rows = explode("\n", $wiki);
        for($i=0; $i<count($rows); $i++){
            if(!empty($rows[$i])){
                $rows[$i] = $this -> fixHeadings($rows[$i]);
                $rows[$i] = $this -> fixBulletsAndHyphens($rows[$i]);
                $rows[$i] = $this -> fixRow($rows[$i]);
            }
        }
        $wiki = implode("\n", $rows);
        $wiki = $this -> fixListsEmptyRows($wiki);
        return $wiki;
    }

    public function fixHeadings($row){
        if($this->startsWith($row, "="))
            return preg_replace("/^(=+\s+)'''(.*)'''\s+(=+)$/u", '$1 $2 $3', $row);
        return $row;
    }

    public function fixBulletsAndHyphens($row){
        $end = min(mb_strpos($row, ' '), mb_strlen($row));
        $part = mb_substr($row, 0, $end);
        foreach(self::$bullets_and_hyphens as $bullet)
            $part = str_ireplace($bullet, "*", $part);
        $only_first_match = 1;
        $row = substr_replace($row, $part, 0, $end);
        $row = str_replace("'''* '''", "* ", $row, $only_first_match);
        return $row;
    }

    public function fixRow($row){
        if(trim($row, "'= ") == '') return '';
        return $row;
    }

    public function fixListsEmptyRows($wiki){
        return preg_replace("/\n\n\*/i", "\n*", $wiki);
    }


    // Utils
    private function startsWith($haystack, $needle)
    {
        $length = strlen($needle);
        return (substr($haystack, 0, $length) === $needle);
    }

}