<?php

/**

 * A class to render Diffs in different formats.

 *

 * This class renders the diff in classic diff format. It is intended that

 * this class be customized via inheritance, to obtain fancier outputs.

 *

 * Copyright 2004-2010 The Horde Project (http://www.horde.org/)

 *

 * See the enclosed file COPYING for license information (LGPL). If you did

 * not receive this file, see http://opensource.org/licenses/lgpl-license.php.

 *

 * @package Text_Diff

 */

class Text_Diff_Renderer {

    /**

     * Number of leading context "lines" to preserve.

     *

     * This should be left at zero for this class, but subclasses may want to

     * set this to other values.

     */

    var $_leading_context_lines = 0;

    /**

     * Number of trailing context "lines" to preserve.

     *

     * This should be left at zero for this class, but subclasses may want to

     * set this to other values.

     */

    var $_trailing_context_lines = 0;

    /**

     * Constructor.

     */

    {

        foreach ($params as $param => $value) {

            $v = '_' . $param;

            if (isset($this->$v)) {

                $this->$v = $value;

            }

        }

    }

    /**

     * Get any renderer parameters.

     *

     * @return array  All parameters of this renderer object.

     */

    function getParams()

    {

        $params = array();

        foreach (get_object_vars($this) as $k => $v) {

            if ($k[0] == '_') {

                $params[substr($k, 1)] = $v;

            }

        }

        return $params;

    }

    /**

     * 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 these are unchanged (copied) lines, and we want to keep

             * leading or trailing context lines, extract them from the copy

             * block. */

            if (is_a($edit, 'Text_Diff_Op_copy')) {

                /* Do we have any diff blocks yet? */

                if (is_array($block)) {

                    /* How many lines to keep as context from the copy

                     * block. */

                    $keep = $i == count($diffs) - 1 ? $ntrail : $nlead + $ntrail;

                    if (count($edit->orig) <= $keep) {

                        /* We have less lines in the block than we want for

                         * context => keep the whole block. */

                        $block[] = $edit;

                    } else {

                        if ($ntrail) {

                            /* Create a new block with as many lines as we need

                             * for the trailing context. */

                            $context = array_slice($edit->orig, 0, $ntrail);

                            $block[] = new Text_Diff_Op_copy($context);

                        }

                        /* @todo */

                        $output .= $this->_block($x0, $ntrail + $xi - $x0,

                                                 $y0, $ntrail + $yi - $y0,

                                                 $block);

                        $block = false;

                    }

                }

                /* Keep the copy block as the context for the next block. */

                $context = $edit->orig;

            } else {

                /* Don't we have any diff blocks yet? */

                if (!is_array($block)) {

                    /* Extract context lines from the preceding copy 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)) {

            $output .= $this->_block($x0, $xi - $x0,

                                     $y0, $yi - $y0,

                                     $block);

        }

        return $output . $this->_endDiff();

    }

    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();

    }

    function _startDiff()

    {

        return '';

    }

    function _endDiff()

    {

        return '';

    }

    function _blockHeader($xbeg, $xlen, $ybeg, $ylen)

    {

        if ($xlen > 1) {

            $xbeg .= ',' . ($xbeg + $xlen - 1);

        }

        if ($ylen > 1) {

            $ybeg .= ',' . ($ybeg + $ylen - 1);

        }

        // this matches the GNU Diff behaviour

        if ($xlen && !$ylen) {

            $ybeg--;

        } elseif (!$xlen) {

            $xbeg--;

        }

        return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;

    }

    function _startBlock($header)

    {

        return $header . "\n";

    }

    function _endBlock()

    {

        return '';

    }

    function _lines($lines, $prefix = ' ')

    {

        return $prefix . implode("\n$prefix", $lines) . "\n";

    }

    function _context($lines)

    {

        return $this->_lines($lines, '  ');

    }

    function _added($lines)

    {

        return $this->_lines($lines, '> ');

    }

    function _deleted($lines)

    {

        return $this->_lines($lines, '< ');

    }

    function _changed($orig, $final)

    {

        return $this->_deleted($orig) . "---\n" . $this->_added($final);

    }

}