Simplify SelectableText state management

This commit simplifies the state management and information flow for SelectableText.

This also fixes issues and inconsistencies with the selected text for a highlight action,
which often appeared in some scenarios with the symptom of a highlight
action showing the incorrect or outdated selected text.

Previously, the state of the selected text and highlight action was
tracked in two independent state/binding variables which caused
re-renders when they were modified, often leading to inconsistencies as
those two independent variables would not be changed atomically across
renders leading to inconsistent, undefined behavior

The commit addresses this by using a single state object instead of two,
and a direct callback interface when the highlight button is pressed,
which eliminates the need of relying on view re-renders to apply.

Signed-off-by: Daniel D’Aquino <daniel@daquino.me>

damus/Components/SelectableText.swift

@@ -13,8 +13,7 @@ struct SelectableText: View {
     let event: NostrEvent?
     let attributedString: AttributedString
     let textAlignment: NSTextAlignment
-    @State private var showHighlightPost = false
-    @State private var selectedText = ""
+    @State private var highlightPostingState: HighlightPostingState = .hide
     @State private var selectedTextHeight: CGFloat = .zero
     @State private var selectedTextWidth: CGFloat = .zero
 
@@ -37,8 +36,9 @@ struct SelectableText: View {
                 fixedWidth: selectedTextWidth,
                 textAlignment: self.textAlignment,
                 enableHighlighting: self.enableHighlighting(),
-                showHighlightPost: $showHighlightPost,
-                selectedText: $selectedText,
+                postHighlight: { selectedText in
+                    self.highlightPostingState = .show_post_view(highlighted_text: selectedText)
+                },
                 height: $selectedTextHeight
             )
             .padding([.leading, .trailing], -1.0)
@@ -53,9 +53,13 @@ struct SelectableText: View {
                 self.selectedTextWidth = newSize.width
             }
         }
-        .sheet(isPresented: $showHighlightPost) {
-            if let event {
-                HighlightPostView(damus_state: damus_state, event: event, selectedText: $selectedText)
+        .sheet(isPresented: Binding(get: {
+            return self.highlightPostingState.show()
+        }, set: { newValue in
+            self.highlightPostingState = newValue ? .show_post_view(highlighted_text: self.highlightPostingState.highlighted_text() ?? "") : .hide
+        })) {
+            if let event, case .show_post_view(let highlighted_text) = self.highlightPostingState {
+                HighlightPostView(damus_state: damus_state, event: event, selectedText: .constant(highlighted_text))
                     .presentationDragIndicator(.visible)
                     .presentationDetents([.height(selectedTextHeight + 150), .medium, .large])
             }
@@ -66,15 +70,34 @@ struct SelectableText: View {
     func enableHighlighting() -> Bool {
         self.event != nil
     }
+    
+    enum HighlightPostingState {
+        case hide
+        case show_post_view(highlighted_text: String)
+        
+        func show() -> Bool {
+            if case .show_post_view(let highlighted_text) = self {
+                return true
+            }
+            return false
+        }
+        
+        func highlighted_text() -> String? {
+            switch self {
+                case .hide:
+                    return nil
+                case .show_post_view(highlighted_text: let highlighted_text):
+                    return highlighted_text
+            }
+        }
+    }
 }
 
 fileprivate class TextView: UITextView {
-    @Binding var showHighlightPost: Bool
-    @Binding var selectedText: String
+    var postHighlight: (String) -> Void
 
-    init(frame: CGRect, textContainer: NSTextContainer?, showHighlightPost: Binding<Bool>, selectedText: Binding<String>) {
-        self._showHighlightPost = showHighlightPost
-        self._selectedText = selectedText
+    init(frame: CGRect, textContainer: NSTextContainer?, postHighlight: @escaping (String) -> Void) {
+        self.postHighlight = postHighlight
         super.init(frame: frame, textContainer: textContainer)
     }
 
@@ -91,8 +114,8 @@ fileprivate class TextView: UITextView {
 
     @objc public func highlightText(_ sender: Any?) {
         guard let selectedRange = self.selectedTextRange else { return }
-        selectedText = self.text(in: selectedRange) ?? ""
-        showHighlightPost.toggle()
+        guard let selectedText = self.text(in: selectedRange) else { return }
+        self.postHighlight(selectedText)
     }
 
 }
@@ -105,12 +128,11 @@ fileprivate class TextView: UITextView {
     let fixedWidth: CGFloat
     let textAlignment: NSTextAlignment
     let enableHighlighting: Bool
-    @Binding var showHighlightPost: Bool
-    @Binding var selectedText: String
+    let postHighlight: (String) -> Void
     @Binding var height: CGFloat
 
     func makeUIView(context: UIViewRepresentableContext<Self>) -> TextView {
-        let view = TextView(frame: .zero, textContainer: nil, showHighlightPost: $showHighlightPost, selectedText: $selectedText)
+        let view = TextView(frame: .zero, textContainer: nil, postHighlight: postHighlight)
         view.isEditable = false
         view.dataDetectorTypes = .all
         view.isSelectable = true