1 files changed, 115 insertions, 0 deletions
diff --git a/Echo/includes/EchoDiffGroup.php b/Echo/includes/EchoDiffGroup.php
new file mode 100644
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+++ b/Echo/includes/EchoDiffGroup.php
@@ -0,0 +1,115 @@
+<?php
+/**
+ * MediaWiki Extension: Echo
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * This program is distributed WITHOUT ANY WARRANTY.
+ */
+
+/**
+ * @file
+ * @ingroup Extensions
+ * @author Erik Bernhardson
+ */
+
+/**
+ * Represents a single set of changes all effecting neighboring lines
+ */
+class EchoDiffGroup {
+	/**
+	 * @var int[] The left and right position this change starts at
+	 */
+	protected $position;
+
+	/**
+	 * @var string[] The lines that have been added
+	 */
+	protected $new = [];
+
+	/**
+	 * @var string[] The lines that have been removed
+	 */
+	protected $old = [];
+
+	/**
+	 * @param int $leftPos The starting line number in the left text
+	 * @param int $rightPos The starting line number in the right text
+	 */
+	public function __construct( $leftPos, $rightPos ) {
+		// +1 due to the origional code use 1 indexing for this result
+		$this->position = [
+			'right-pos' => $rightPos + 1,
+			'left-pos' => $leftPos + 1,
+		];
+	}
+
+	/**
+	 * @param string $line Line in the right text but not in the left
+	 */
+	public function add( $line ) {
+		$this->new[] = $line;
+	}
+
+	/**
+	 * @param string $line Line in the left text but not in the right
+	 */
+	public function subtract( $line ) {
+		$this->old[] = $line;
+	}
+
+	/**
+	 * @return array[] set of changes
+	 * Each change consists of:
+	 * An 'action', one of:
+	 *   - add
+	 *   - subtract
+	 *   - change
+	 * 'content' that was added or removed, or in the case
+	 *    of a change, 'old_content' and 'new_content'
+	 * 'left_pos' and 'right_pos' (in 1-indexed lines) of the change.
+	 */
+	public function getChangeSet() {
+		$old = implode( "\n", $this->old );
+		$new = implode( "\n", $this->new );
+		$position = $this->position;
+		$changeSet = [];
+
+		// The implodes must come first because we consider array( '' ) to also be false
+		// meaning a blank link replaced with content is an addition
+		if ( $old && $new ) {
+			$min = min( count( $this->old ), count( $this->new ) );
+			$changeSet[] = $position + [
+				'action' => 'change',
+				'old_content' => implode( "\n", array_slice( $this->old, 0, $min ) ),
+				'new_content' => implode( "\n", array_slice( $this->new, 0, $min ) ),
+			];
+			$position['left-pos'] += $min;
+			$position['right-pos'] += $min;
+			$old = implode( "\n", array_slice( $this->old, $min ) );
+			$new = implode( "\n", array_slice( $this->new, $min ) );
+		}
+
+		if ( $new ) {
+			$changeSet[] = $position + [
+				'action' => 'add',
+				'content' => $new,
+			];
+		} elseif ( $old ) {
+			$changeSet[] = $position + [
+				'action' => 'subtract',
+				'content' => $old,
+			];
+		}
+
+		return $changeSet;
+	}
+}