<?php

/**
 * XHTML diff renderer.
 *
 * This class renders diffs in XHTML format.
 *
 * $Horde: framework/Text_Diff/Diff/Renderer/inline.php,v 1.16 2006/01/08 00:06:57 jan Exp $
 *
 * @author  Ciprian Popovici
 * @author  Dan Fuhry
 * @package Text_Diff
 */
class Text_Diff_Renderer_xhtml extends Text_Diff_Renderer {

    /**
     * Number of leading context "lines" to preserve.
     */
    var $_leading_context_lines = 5;

    /**
     * Number of trailing context "lines" to preserve.
     */
    var $_trailing_context_lines = 3;

    /**
     * Prefix for inserted text.
     */
    var $_ins_prefix = "<!-- Start added text -->\n<tr><td style='width: 0px;'>+</td><td class=\"diff-added\" style='width: 100%;'>";

    /**
     * Suffix for inserted text.
     */
    var $_ins_suffix = "</td></tr>\n<!-- End added text -->\n\n";

    /**
     * Prefix for deleted text.
     */
    var $_del_prefix = "<!-- Start deleted text -->\n<tr><td style='width: 0px;'>-</td><td class=\"diff-deleted\" style='width: 100%;'>";

    /**
     * Suffix for deleted text.
     */
    var $_del_suffix = "</td></tr>\n<!-- End deleted text -->\n\n";

    /**
     * Header for each change block.
     */
    var $_block_header = '';

    /**
     * What are we currently splitting on? Used to recurse to show word-level
     * changes.
     */
    var $_split_level = 'lines';
    
    function _blockHeader($xbeg, $xlen, $ybeg, $ylen)
    {
      return "<!-- Start block -->\n<tr><td colspan='2' class='diff-block'>Line $xbeg: {$this->_block_header}</td></tr>";
    }

    function _startBlock($header)
    {
        return $header;
    }

    function _lines($lines, $prefix = ' ', $encode = true)
    {
        if ($encode) {
            array_walk($lines, array(&$this, '_encode'));
        }

        if ($this->_split_level == 'words') {
            return implode('', $lines);
        } else {
            return implode("<br />", $lines) . "\n";
        }
    }

    function _added($lines)
    {
        array_walk($lines, array(&$this, '_encode'));
        $lines[0] = $this->_ins_prefix . $lines[0];
        $lines[count($lines) - 1] .= $this->_ins_suffix;
        return $this->_lines($lines, ' ', false);
    }

    function _deleted($lines, $words = false)
    {
        array_walk($lines, array(&$this, '_encode'));
        $lines[0] = $this->_del_prefix . $lines[0];
        $lines[count($lines) - 1] .= $this->_del_suffix;
        return $this->_lines($lines, ' ', false);
    }
    
    function _context($lines)
    {
        return "<!-- Start context -->\n<tr><td></td><td class=\"diff-context\">".$this->_lines($lines).'</td></tr>'."\n<!-- End context -->\n\n";
    }

    function _changed($orig, $final)
    {
        /* If we've already split on words, don't try to do so again - just display. */ 
        if ($this->_split_level == 'words') {
            $prefix = '';
            while ($orig[0] !== false && $final[0] !== false &&
                   substr($orig[0], 0, 1) == ' ' &&
                   substr($final[0], 0, 1) == ' ') {
                $prefix .= substr($orig[0], 0, 1);
                $orig[0] = substr($orig[0], 1);
                $final[0] = substr($final[0], 1);
            }
            $ret = $prefix . $this->_deleted($orig) . $this->_added($final) . "\n";
            //echo 'DEBUG:<pre>'.htmlspecialchars($ret).'</pre>';
            return $ret;
        }

        $text1 = implode("\n", $orig);
        $text2 = implode("\n", $final);

        /* Non-printing newline marker. */
        $nl = "\0";

        /* We want to split on word boundaries, but we need to
         * preserve whitespace as well. Therefore we split on words,
         * but include all blocks of whitespace in the wordlist. */
        $diff = &new Text_Diff($this->_splitOnWords($text1, $nl),
                               $this->_splitOnWords($text2, $nl));

        /* Get the diff in inline format. */
        $renderer = &new Text_Diff_Renderer_inline(array_merge($this->getParams(),
                                                               array('split_level' => 'words')));

        /* Run the diff and get the output. */
        $ret = str_replace($nl, "<br />", $renderer->render($diff));
        //echo 'DEBUG:<pre>'.htmlspecialchars($ret).'</pre>';
        return $ret . "\n";
    }

    function _splitOnWords($string, $newlineEscape = "<br />")
    {
        $words = array();
        $length = strlen($string);
        $pos = 0;

        while ($pos < $length) {
            // Eat a word with any preceding whitespace.
            $spaces = strspn(substr($string, $pos), " \n");
            $nextpos = strcspn(substr($string, $pos + $spaces), " \n");
            $words[] = str_replace("\n", $newlineEscape, substr($string, $pos, $spaces + $nextpos));
            $pos += $spaces + $nextpos;
        }

        return $words;
    }

    function _encode(&$string)
    {
        $string = htmlspecialchars($string);
    }
    
    /**
     * Renders a diff.
     *
     * @param Text_Diff $diff  A Text_Diff object.
     *
     * @return string  The formatted output.
     */
    
    function render($diff)
    {
        $xi = $yi = 1;
        $block = false;
        $context = array();

        $nlead = $this->_leading_context_lines;
        $ntrail = $this->_trailing_context_lines;

        $output = $this->_startDiff();

        $diffs = $diff->getDiff();
        foreach ($diffs as $i => $edit) {
            if (is_a($edit, 'Text_Diff_Op_copy')) {
                if (is_array($block)) {
                    $keep = $i == count($diffs) - 1 ? $ntrail : $nlead + $ntrail;
                    if (count($edit->orig) <= $keep) {
                        $block[] = $edit;
                    } else {
                        if ($ntrail) {
                            $context = array_slice($edit->orig, 0, $ntrail);
                            $block[] = &new Text_Diff_Op_copy($context);
                        }
                        $bk = $this->_block($x0, $ntrail + $xi - $x0,
                                            $y0, $ntrail + $yi - $y0,
                                            $block);
                        $output .= $bk;
                        $block = false;
                    }
                }
                $context = $edit->orig;
            } else {
                if (!is_array($block)) {
                    $context = array_slice($context, count($context) - $nlead);
                    $x0 = $xi - count($context);
                    $y0 = $yi - count($context);
                    $block = array();
                    if ($context) {
                        $block[] = &new Text_Diff_Op_copy($context);
                    }
                }
                $block[] = $edit;
            }

            if ($edit->orig) {
                $xi += count($edit->orig);
            }
            if ($edit->final) {
                $yi += count($edit->final);
            }
        }

        if (is_array($block)) {
            $bk = $this->_block($x0, $xi - $x0,
                                $y0, $yi - $y0,
                                $block);
            $output .= $bk;
        }

        $final = $output . $this->_endDiff();
        if ($final == '') $final = '<tr><td class="diff-block">No differences.</td></tr>';
        //$final = preg_replace('#('.preg_quote($this->_ins_suffix).'|'.preg_quote($this->_del_suffix).')(.+?)('.preg_quote($this->_ins_prefix).'|'.preg_quote($this->_ins_suffix).')#', '\\1<tr><td></td><td class="diff-context>\\2</td></tr>\\3', $final);
        return '<table class="diff">'.$final.'</table>'."\n\n";
    }
    
    function _block($xbeg, $xlen, $ybeg, $ylen, &$edits)
    {
        $output = $this->_startBlock($this->_blockHeader($xbeg, $xlen, $ybeg, $ylen));

        foreach ($edits as $edit) {
            switch (strtolower(get_class($edit))) {
            case 'text_diff_op_copy':
                $output .= $this->_context($edit->orig);
                break;

            case 'text_diff_op_add':
                $output .= $this->_added($edit->final);
                break;

            case 'text_diff_op_delete':
                $output .= $this->_deleted($edit->orig);
                break;

            case 'text_diff_op_change':
                $output .= $this->_changed($edit->orig, $edit->final);
                break;
            }
        }

        return $output . $this->_endBlock();
    }

}