[fabric] Support selection of Paragraph component text content

Summary: Override the hitTest and mouseDown handler in `RCTParagraphComponentView` to forward mouse drag events to the underlying NSTextView to get text selection support in Fabric with correct rendering.

Test Plan:
- Run Zeratul with Fabric enabled.
- Select text
 https://pxl.cl/3q3b3

Reviewers: shawndempsey, chpurrer, #rn-desktop

Reviewed By: shawndempsey

Differential Revision: https://phabricator.intern.facebook.com/D49465174

Tasks: T163838519

Author: Nick Lefever

packages/react-native/React/Fabric/Mounting/ComponentViews/Text/RCTParagraphComponentView.mm

@@ -10,7 +10,9 @@
 
 #if !TARGET_OS_OSX // [macOS]
 #import <MobileCoreServices/UTCoreTypes.h>
-#endif // [macOS]
+#else // [macOS
+#import <React/RCTSurfaceTouchHandler.h>
+#endif // macOS]
 
 #import <react/renderer/components/text/ParagraphComponentDescriptor.h>
 #import <react/renderer/components/text/ParagraphProps.h>
@@ -43,10 +45,10 @@ @interface RCTParagraphTextView : NSTextView // [macOS]
 @property (nonatomic) ParagraphAttributes paragraphAttributes;
 @property (nonatomic) LayoutMetrics layoutMetrics;
 
-#if TARGET_OS_OSX // [macOS]
+#if TARGET_OS_OSX // [macOS
 /// UIKit compatibility shim that simply calls `[self setNeedsDisplay:YES]`
 - (void)setNeedsDisplay;
-#endif
+#endif // macOS]
 
 @end
 
@@ -55,6 +57,9 @@ @interface RCTParagraphComponentView () <UIEditMenuInteractionDelegate>
 
 @property (nonatomic, nullable) UIEditMenuInteraction *editMenuInteraction API_AVAILABLE(ios(16.0));
 
+@end
+#else // [macOS
+@interface RCTParagraphComponentView () <NSTextViewDelegate>
 @end
 #endif // [macOS]
 
@@ -83,9 +88,8 @@ - (instancetype)initWithFrame:(CGRect)frame
     self.accessibilityRole = NSAccessibilityStaticTextRole;
     // Fix blurry text on non-retina displays.
     self.canDrawSubviewsIntoLayer = YES;
-    // The NSTextView is responsible for drawing text and managing selection.
     _textView = [[RCTParagraphTextView alloc] initWithFrame:self.bounds];
-    // The RCTParagraphComponentUnfocusableTextView is only used for rendering and should not appear in the a11y hierarchy.
+    _textView.delegate = self;
     _textView.accessibilityElement = NO;
     _textView.usesFontPanel = NO;
     _textView.drawsBackground = NO;
@@ -325,14 +329,89 @@ - (void)handleLongPress:(UILongPressGestureRecognizer *)gesture
     [menuController showMenuFromView:self rect:self.bounds];
   }
 }
-#endif // [macOS]
+#else // [macOS
+- (NSView *)hitTest:(NSPoint)point
+{
+  // We will forward mouse click events to the NSTextView ourselves to prevent NSTextView from swallowing events that may be handled in JS (e.g. long press).
+  NSView *hitView = [super hitTest:point];
+  
+  NSEventType eventType = NSApp.currentEvent.type;
+  BOOL isMouseClickEvent = NSEvent.pressedMouseButtons > 0;
+  BOOL isMouseMoveEventType = eventType == NSEventTypeMouseMoved || eventType == NSEventTypeMouseEntered || eventType == NSEventTypeMouseExited || eventType == NSEventTypeCursorUpdate;
+  BOOL isMouseMoveEvent = !isMouseClickEvent && isMouseMoveEventType;
+  BOOL isTextViewClick = (hitView && hitView == _textView) && !isMouseMoveEvent;
+  
+  return isTextViewClick ? self : hitView;
+}
+
+- (void)mouseDown:(NSEvent *)event
+{
+  if (!_textView.selectable) {
+    [super mouseDown:event];
+    return;
+  }
+
+  // Double/triple-clicks should be forwarded to the NSTextView.
+  BOOL shouldForward = event.clickCount > 1;
+
+  if (!shouldForward) {
+    // Peek at next event to know if a selection should begin.
+    NSEvent *nextEvent = [self.window nextEventMatchingMask:NSEventMaskLeftMouseUp | NSEventMaskLeftMouseDragged
+                                                  untilDate:[NSDate distantFuture]
+                                                     inMode:NSEventTrackingRunLoopMode
+                                                    dequeue:NO];
+    shouldForward = nextEvent.type == NSEventTypeLeftMouseDragged;
+  }
+
+  if (shouldForward) {
+    NSView *contentView = self.window.contentView;
+    // -[NSView hitTest:] takes coordinates in a view's superview coordinate system.
+    NSPoint point = [contentView.superview convertPoint:event.locationInWindow fromView:nil];
+
+    // Start selection if we're still selectable and hit-testable.
+    if (_textView.selectable && [contentView hitTest:point] == self) {
+      [[RCTSurfaceTouchHandler surfaceTouchHandlerForView:self] cancelTouchWithEvent:event];
+      [self.window makeFirstResponder:_textView];
+      [_textView mouseDown:event];
+    }
+  } else {
+    // Clear selection for single clicks.
+    _textView.selectedRange = NSMakeRange(NSNotFound, 0);
+  }
+}
 
+#pragma mark - Selection
+
+- (void)textDidEndEditing:(NSNotification *)notification
+{
+  _textView.selectedRange = NSMakeRange(NSNotFound, 0);
+}
+
+#endif // macOS]
+
+#if !TARGET_OS_OSX // [macOS]
 - (BOOL)canBecomeFirstResponder
 {
   const auto &paragraphProps = static_cast<const ParagraphProps &>(*_props);
   return paragraphProps.isSelectable;
 }
+#else
+- (BOOL)becomeFirstResponder
+{
+  if (![super becomeFirstResponder]) {
+    return NO;
+  }
+
+  return YES;
+}
 
+- (BOOL)canBecomeFirstResponder
+{
+  return self.focusable;
+}
+#endif // macOS]
+
+#if !TARGET_OS_OSX // [macOS]
 - (BOOL)canPerformAction:(SEL)action withSender:(id)sender
 {
   const auto &paragraphProps = static_cast<const ParagraphProps &>(*_props);
@@ -347,6 +426,7 @@ - (BOOL)canPerformAction:(SEL)action withSender:(id)sender
   return NO;
 #endif // macOS]
 }
+#endif // [macOS]
 
 - (void)copy:(id)sender
 {