<?php

/**

 * WordPress Diff bastard child of old MediaWiki Diff Formatter.

 *

 * Basically all that remains is the table structure and some method names.

 *

 * @package WordPress

 * @subpackage Diff

 */

if ( !class_exists( 'Text_Diff' ) ) {

	/** Text_Diff class */

	require( dirname(__FILE__).'/Text/Diff.php' );

	/** Text_Diff_Renderer class */

	require( dirname(__FILE__).'/Text/Diff/Renderer.php' );

	/** Text_Diff_Renderer_inline class */

	require( dirname(__FILE__).'/Text/Diff/Renderer/inline.php' );

}

/**

 * Table renderer to display the diff lines.

 *

 * @since 2.6.0

 * @uses Text_Diff_Renderer Extends

 */

class WP_Text_Diff_Renderer_Table extends Text_Diff_Renderer {

	/**

	 * @see Text_Diff_Renderer::_leading_context_lines

	 * @var int

	 * @access protected

	 * @since 2.6.0

	 */

	var $_leading_context_lines  = 10000;

	/**

	 * @see Text_Diff_Renderer::_trailing_context_lines

	 * @var int

	 * @access protected

	 * @since 2.6.0

	 */

	var $_trailing_context_lines = 10000;

	/**

	 * {@internal Missing Description}}

	 *

	 * @var float

	 * @access protected

	 * @since 2.6.0

	 */

	var $_diff_threshold = 0.6;

	/**

	 * Inline display helper object name.

	 *

	 * @var string

	 * @access protected

	 * @since 2.6.0

	 */

	var $inline_diff_renderer = 'WP_Text_Diff_Renderer_inline';

	/**

	 * Constructor - Call parent constructor with params array.

	 *

	 * This will set class properties based on the key value pairs in the array.

	 *

	 * @since 2.6.0

	 *

	 * @param array $params

	 */

	function __construct( $params = array() ) {

		parent::__construct( $params );

	}

	/**

	 * @ignore

	 *

	 * @param string $header

	 * @return string

	 */

	function _startBlock( $header ) {

		return '';

	}

	/**

	 * @ignore

	 *

	 * @param array $lines

	 * @param string $prefix

	 */

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

	}

	/**

	 * @ignore

	 *

	 * @param string $line HTML-escape the value.

	 * @return string

	 */

	function addedLine( $line ) {

		return "<td>+</td><td class='diff-addedline'>{$line}</td>";

	}

	/**

	 * @ignore

	 *

	 * @param string $line HTML-escape the value.

	 * @return string

	 */

	function deletedLine( $line ) {

		return "<td>-</td><td class='diff-deletedline'>{$line}</td>";

	}

	/**

	 * @ignore

	 *

	 * @param string $line HTML-escape the value.

	 * @return string

	 */

	function contextLine( $line ) {

		return "<td> </td><td class='diff-context'>{$line}</td>";

	}

	/**

	 * @ignore

	 *

	 * @return string

	 */

	function emptyLine() {

		return '<td colspan="2">&nbsp;</td>';

	}

	/**

	 * @ignore

	 * @access private

	 *

	 * @param array $lines

	 * @param bool $encode

	 * @return string

	 */

	function _added( $lines, $encode = true ) {

		$r = '';

		foreach ($lines as $line) {

			if ( $encode )

				$line = htmlspecialchars( $line );

			$r .= '<tr>' . $this->emptyLine() . $this->addedLine( $line ) . "</tr>\n";

		}

		return $r;

	}

	/**

	 * @ignore

	 * @access private

	 *

	 * @param array $lines

	 * @param bool $encode

	 * @return string

	 */

	function _deleted( $lines, $encode = true ) {

		$r = '';

		foreach ($lines as $line) {

			if ( $encode )

				$line = htmlspecialchars( $line );

			$r .= '<tr>' . $this->deletedLine( $line ) . $this->emptyLine() . "</tr>\n";

		}

		return $r;

	}

	/**

	 * @ignore

	 * @access private

	 *

	 * @param array $lines

	 * @param bool $encode

	 * @return string

	 */

	function _context( $lines, $encode = true ) {

		$r = '';

		foreach ($lines as $line) {

			if ( $encode )

				$line = htmlspecialchars( $line );

			$r .= '<tr>' .

				$this->contextLine( $line ) . $this->contextLine( $line ) . "</tr>\n";

		}

		return $r;

	}

	/**

	 * Process changed lines to do word-by-word diffs for extra highlighting.

	 *

	 * (TRAC style) sometimes these lines can actually be deleted or added rows.

	 * We do additional processing to figure that out

	 *

	 * @access private

	 * @since 2.6.0

	 *

	 * @param array $orig

	 * @param array $final

	 * @return string

	 */

	function _changed( $orig, $final ) {

		$r = '';

		// Does the aforementioned additional processing

		// *_matches tell what rows are "the same" in orig and final. Those pairs will be diffed to get word changes

		//	match is numeric: an index in other column

		//	match is 'X': no match. It is a new row

		// *_rows are column vectors for the orig column and the final column.

		//	row >= 0: an indix of the $orig or $final array

		//	row  < 0: a blank row for that column

		list($orig_matches, $final_matches, $orig_rows, $final_rows) = $this->interleave_changed_lines( $orig, $final );

		// These will hold the word changes as determined by an inline diff

		$orig_diffs  = array();

		$final_diffs = array();

		// Compute word diffs for each matched pair using the inline diff

		foreach ( $orig_matches as $o => $f ) {

			if ( is_numeric($o) && is_numeric($f) ) {

				$text_diff = new Text_Diff( 'auto', array( array($orig[$o]), array($final[$f]) ) );

				$renderer = new $this->inline_diff_renderer;

				$diff = $renderer->render( $text_diff );

				// If they're too different, don't include any <ins> or <dels>

				if ( $diff_count = preg_match_all( '!(<ins>.*?</ins>|<del>.*?</del>)!', $diff, $diff_matches ) ) {

					// length of all text between <ins> or <del>

					$stripped_matches = strlen(strip_tags( join(' ', $diff_matches[0]) ));

					// since we count lengith of text between <ins> or <del> (instead of picking just one),

					//	we double the length of chars not in those tags.

					$stripped_diff = strlen(strip_tags( $diff )) * 2 - $stripped_matches;

					$diff_ratio = $stripped_matches / $stripped_diff;

					if ( $diff_ratio > $this->_diff_threshold )

						continue; // Too different. Don't save diffs.

				}

				// Un-inline the diffs by removing del or ins

				$orig_diffs[$o]  = preg_replace( '|<ins>.*?</ins>|', '', $diff );

				$final_diffs[$f] = preg_replace( '|<del>.*?</del>|', '', $diff );

			}

		}

		foreach ( array_keys($orig_rows) as $row ) {

			// Both columns have blanks. Ignore them.

			if ( $orig_rows[$row] < 0 && $final_rows[$row] < 0 )

				continue;

			// If we have a word based diff, use it. Otherwise, use the normal line.

			if ( isset( $orig_diffs[$orig_rows[$row]] ) )

				$orig_line = $orig_diffs[$orig_rows[$row]];

			elseif ( isset( $orig[$orig_rows[$row]] ) )

				$orig_line = htmlspecialchars($orig[$orig_rows[$row]]);

			else

				$orig_line = '';

			if ( isset( $final_diffs[$final_rows[$row]] ) )

				$final_line = $final_diffs[$final_rows[$row]];

			elseif ( isset( $final[$final_rows[$row]] ) )

				$final_line = htmlspecialchars($final[$final_rows[$row]]);

			else

				$final_line = '';

			if ( $orig_rows[$row] < 0 ) { // Orig is blank. This is really an added row.

				$r .= $this->_added( array($final_line), false );

			} elseif ( $final_rows[$row] < 0 ) { // Final is blank. This is really a deleted row.

				$r .= $this->_deleted( array($orig_line), false );

			} else { // A true changed row.

				$r .= '<tr>' . $this->deletedLine( $orig_line ) . $this->addedLine( $final_line ) . "</tr>\n";

			}

		}

		return $r;

	}

	/**

	 * Takes changed blocks and matches which rows in orig turned into which rows in final.

	 *

	 * Returns

	 *	*_matches ( which rows match with which )

	 *	*_rows ( order of rows in each column interleaved with blank rows as

	 *		necessary )

	 *

	 * @since 2.6.0

	 *

	 * @param unknown_type $orig

	 * @param unknown_type $final

	 * @return unknown

	 */

	function interleave_changed_lines( $orig, $final ) {

		// Contains all pairwise string comparisons. Keys are such that this need only be a one dimensional array.

		$matches = array();

		foreach ( array_keys($orig) as $o ) {

			foreach ( array_keys($final) as $f ) {

				$matches["$o,$f"] = $this->compute_string_distance( $orig[$o], $final[$f] );

			}

		}

		asort($matches); // Order by string distance.

		$orig_matches  = array();

		$final_matches = array();

		foreach ( $matches as $keys => $difference ) {

			list($o, $f) = explode(',', $keys);

			$o = (int) $o;

			$f = (int) $f;

			// Already have better matches for these guys

			if ( isset($orig_matches[$o]) && isset($final_matches[$f]) )

				continue;

			// First match for these guys. Must be best match

			if ( !isset($orig_matches[$o]) && !isset($final_matches[$f]) ) {

				$orig_matches[$o] = $f;

				$final_matches[$f] = $o;

				continue;

			}

			// Best match of this final is already taken?  Must mean this final is a new row.

			if ( isset($orig_matches[$o]) )

				$final_matches[$f] = 'x';

			// Best match of this orig is already taken?  Must mean this orig is a deleted row.

			elseif ( isset($final_matches[$f]) )

				$orig_matches[$o] = 'x';

		}

		// We read the text in this order

		ksort($orig_matches);

		ksort($final_matches);

		// Stores rows and blanks for each column.

		$orig_rows = $orig_rows_copy = array_keys($orig_matches);

		$final_rows = array_keys($final_matches);

		// Interleaves rows with blanks to keep matches aligned.

		// We may end up with some extraneous blank rows, but we'll just ignore them later.

		foreach ( $orig_rows_copy as $orig_row ) {

			$final_pos = array_search($orig_matches[$orig_row], $final_rows, true);

			$orig_pos = (int) array_search($orig_row, $orig_rows, true);

			if ( false === $final_pos ) { // This orig is paired with a blank final.

				array_splice( $final_rows, $orig_pos, 0, -1 );

			} elseif ( $final_pos < $orig_pos ) { // This orig's match is up a ways. Pad final with blank rows.

				$diff_pos = $final_pos - $orig_pos;

				while ( $diff_pos < 0 )

					array_splice( $final_rows, $orig_pos, 0, $diff_pos++ );

			} elseif ( $final_pos > $orig_pos ) { // This orig's match is down a ways. Pad orig with blank rows.

				$diff_pos = $orig_pos - $final_pos;

				while ( $diff_pos < 0 )

					array_splice( $orig_rows, $orig_pos, 0, $diff_pos++ );

			}

		}

		// Pad the ends with blank rows if the columns aren't the same length

		$diff_count = count($orig_rows) - count($final_rows);

		if ( $diff_count < 0 ) {

			while ( $diff_count < 0 )

				array_push($orig_rows, $diff_count++);

		} elseif ( $diff_count > 0 ) {

			$diff_count = -1 * $diff_count;

			while ( $diff_count < 0 )

				array_push($final_rows, $diff_count++);

		}

		return array($orig_matches, $final_matches, $orig_rows, $final_rows);

/*

		// Debug

		echo "\n\n\n\n\n";

		echo "-- DEBUG Matches: Orig -> Final --";

		foreach ( $orig_matches as $o => $f ) {

			echo "\n\n\n\n\n";

			echo "ORIG: $o, FINAL: $f\n";

			var_dump($orig[$o],$final[$f]);

		}

		echo "\n\n\n\n\n";

		echo "-- DEBUG Matches: Final -> Orig --";

		foreach ( $final_matches as $f => $o ) {

			echo "\n\n\n\n\n";

			echo "FINAL: $f, ORIG: $o\n";

			var_dump($final[$f],$orig[$o]);

		}

		echo "\n\n\n\n\n";

		echo "-- DEBUG Rows: Orig -- Final --";

		echo "\n\n\n\n\n";

		foreach ( $orig_rows as $row => $o ) {

			if ( $o < 0 )

				$o = 'X';

			$f = $final_rows[$row];

			if ( $f < 0 )

				$f = 'X';

			echo "$o -- $f\n";

		}

		echo "\n\n\n\n\n";

		echo "-- END DEBUG --";

		echo "\n\n\n\n\n";

		return array($orig_matches, $final_matches, $orig_rows, $final_rows);

*/

	}

	/**

	 * Computes a number that is intended to reflect the "distance" between two strings.

	 *

	 * @since 2.6.0

	 *

	 * @param string $string1

	 * @param string $string2

	 * @return int

	 */

	function compute_string_distance( $string1, $string2 ) {

		// Vectors containing character frequency for all chars in each string

		$chars1 = count_chars($string1);

		$chars2 = count_chars($string2);

		// L1-norm of difference vector.

		// $string1 has zero length? Odd. Give huge penalty by not dividing.

		if ( !$string1 )

			return $difference;

		// Return distance per charcter (of string1)

		return $difference / strlen($string1);

	}