<?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.
 *
 * $Horde: framework/Text_Diff/Diff/Renderer.php,v 1.12 2005/12/16 11:07:33 jan Exp $
 *
 * @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.
 		*/
		function Text_Diff_Renderer($params = array())
		{
				foreach ($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 => $edit) {
						if (is_a($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);
												}
												$output .= $this->_block($x0, $ntrail + $xi - $x0,
 																								$y0, $ntrail + $yi - $y0,
 																								$block);
												$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)) {
						$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);
				}

				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);
		}

}