Update IndentLines functions

Author: hi2gage

Sources/CodeEditSourceEditor/Controller/TextViewController+IndentLines.swift

@@ -9,35 +9,111 @@ import AppKit
 import CodeEditTextView
 
 extension TextViewController {
-    /// Handles indentation and unindentation
+    /// Handles indentation and unindentation for selected lines in the text view.
     ///
-    /// Handles the indentation of lines in the text view based on the current indentation option.
+    /// This function modifies the indentation of the selected lines based on the current `indentOption`.
+    /// It handles both indenting (moving text to the right) and unindenting (moving text to the left), with the
+    /// behavior depending on whether `inwards` is `true` or `false`. It processes the `indentOption` to apply the
+    /// correct number of spaces or tabs.
     ///
-    /// This function assumes that the document is formatted according to the current selected indentation option.
-    /// It will not indent a tab character if spaces are selected, and vice versa. Ensure that the document is
-    /// properly formatted before invoking this function.
+    /// The function operates on **one-to-many selections**, where each selection can affect **one-to-many lines**.
+    /// Each of those lines will be modified accordingly.
     ///
-    /// - Parameter inwards: A Boolean flag indicating whether to outdent (default is `false`).
+    /// ```
+    /// +----------------------------+
+    /// | Selection 1                |
+    /// |                            |
+    /// | +------------------------+ |
+    /// | | Line 1 (Modified)      | |
+    /// | +------------------------+ |
+    /// | +------------------------+ |
+    /// | | Line 2 (Modified)      | |
+    /// | +------------------------+ |
+    /// +----------------------------+
+    ///
+    /// +----------------------------+
+    /// | Selection 2                |
+    /// |                            |
+    /// | +------------------------+ |
+    /// | | Line 1 (Modified)      | |
+    /// | +------------------------+ |
+    /// | +------------------------+ |
+    /// | | Line 2 (Modified)      | |
+    /// | +------------------------+ |
+    /// +----------------------------+
+    /// ```
+    ///
+    /// **Selection Updates**:
+    /// The method will not update the selection (and its highlighting) until all lines for the given selection
+    /// have been processed. This ensures that the selection updates are only applied after all indentations
+    /// are completed, preventing issues where the selection might be updated incrementally during the processing
+    /// of multiple lines.
+    ///
+    /// - Parameter inwards: A `Bool` flag indicating whether to outdent (default is `false`).
+    ///   - If `inwards` is `true`, the text will be unindented.
+    ///   - If `inwards` is `false`, the text will be indented.
+    ///
+    /// - Note: This function assumes that the document is formatted according to the selected indentation option.
+    ///   It will not indent a tab character if spaces are selected, and vice versa. Ensure that the document is
+    ///   properly formatted before invoking this function.
+    ///
+    /// - Important: This method operates on the current selections in the `textView`. It performs a reverse iteration
+    ///   over the text selections, ensuring that edits do not affect the later selections.
+
     public func handleIndent(inwards: Bool = false) {
-        let indentationChars: String = indentOption.stringValue
         guard !cursorPositions.isEmpty else { return }
 
         textView.undoManager?.beginUndoGrouping()
-        for cursorPosition in self.cursorPositions.reversed() {
+        var selectionIndex = 0
+        textView.editSelections { textView, selection in
             // get lineindex, i.e line-numbers+1
-            guard let lineIndexes = getHighlightedLines(for: cursorPosition.range) else { continue }
-
-            for lineIndex in lineIndexes {
-                adjustIndentation(
-                    lineIndex: lineIndex,
-                    indentationChars: indentationChars,
-                    inwards: inwards
-                )
-            }
+            guard let lineIndexes = getHighlightedLines(for: selection.range) else { return }
+
+            adjustIndentation(lineIndexes: lineIndexes, inwards: inwards)
+
+            updateSelection(
+                selection: selection,
+                textSelectionCount: textView.selectionManager.textSelections.count,
+                inwards: inwards,
+                lineCount: lineIndexes.count,
+                selectionIndex: selectionIndex
+            )
+
+            selectionIndex += 1
         }
         textView.undoManager?.endUndoGrouping()
     }
 
+    private func updateSelection(
+        selection: TextSelectionManager.TextSelection,
+        textSelectionCount: Int,
+        inwards: Bool,
+        lineCount: Int,
+        selectionIndex: Int
+    ) {
+        let sectionModifier = calculateSelectionIndentationAdjustment(
+            textSelectionCount: textSelectionCount,
+            selectionIndex: selectionIndex,
+            lineCount: lineCount
+        )
+
+        let charCount = indentOption.charCount
+
+        selection.range.location += inwards ? -charCount * sectionModifier : charCount * sectionModifier
+        if lineCount > 1 {
+            let ammount = charCount * (lineCount - 1)
+            selection.range.length += inwards ? -ammount : ammount
+        }
+    }
+
+    private func calculateSelectionIndentationAdjustment(
+        textSelectionCount: Int,
+        selectionIndex: Int,
+        lineCount: Int
+    ) -> Int {
+        return 1 + ((textSelectionCount - selectionIndex) - 1) * lineCount
+    }
+
     /// This method is used to handle tabs appropriately when multiple lines are selected,
     /// allowing normal use of tabs.
     ///
@@ -66,6 +142,17 @@ extension TextViewController {
         return startLineInfo.index...endLineInfo.index
     }
 
+    private func adjustIndentation(lineIndexes: ClosedRange<Int>, inwards: Bool) {
+        let indentationChars: String = indentOption.stringValue
+        for lineIndex in lineIndexes {
+            adjustIndentation(
+                lineIndex: lineIndex,
+                indentationChars: indentationChars,
+                inwards: inwards
+            )
+        }
+    }
+
     private func adjustIndentation(lineIndex: Int, indentationChars: String, inwards: Bool) {
         guard let lineInfo = textView.layoutManager.textLineForIndex(lineIndex) else { return }
 

Sources/CodeEditSourceEditor/Enums/IndentOption.swift

@@ -19,6 +19,16 @@ public enum IndentOption: Equatable, Hashable {
         }
     }
 
+    /// Represents the number of chacters that indent represents
+    var charCount: Int {
+        switch self {
+        case .spaces(let count):
+            count
+        case .tab:
+            1
+        }
+    }
+
     public static func == (lhs: IndentOption, rhs: IndentOption) -> Bool {
         switch (lhs, rhs) {
         case (.tab, .tab):