feat: add better support for selection

Author: gtokman

Example/Example/DetailViewController.swift

@@ -5,6 +5,7 @@
 //  Created by Gary Tokman on 3/26/26.
 //
 
+import Litext
 import MarkdownParser
 import MarkdownView
 import UIKit
@@ -13,6 +14,8 @@ class DetailViewController: UIViewController {
 
     private let example: DiffExample
     private let markdownView = MarkdownTextView()
+    private let commentButton = UIButton(type: .system)
+    private var currentSelectionInfo: LineSelectionInfo?
 
     init(example: DiffExample) {
         self.example = example
@@ -29,7 +32,33 @@ class DetailViewController: UIViewController {
         title = example.title
         view.backgroundColor = .systemBackground
 
-        // Custom menu items
+        switch example.selectionMode {
+        case .textSelection:
+            setupTextSelection()
+        case .lineSelection:
+            setupLineSelection()
+        }
+
+        view.addSubview(markdownView)
+        markdownView.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            markdownView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 16),
+            markdownView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
+            markdownView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
+        ])
+
+        let parser = MarkdownParser()
+        let result = parser.parse(example.markdown)
+        let content = MarkdownTextView.PreprocessedContent(
+            parserResult: result,
+            theme: .default
+        )
+        markdownView.setMarkdown(content)
+    }
+
+    // MARK: - Text Selection
+
+    private func setupTextSelection() {
         markdownView.textView.customMenuItems = [
             LTXCustomMenuItem(
                 title: "Explain",
@@ -50,21 +79,225 @@ class DetailViewController: UIViewController {
                 print("Reject: \"\(context.text)\" (lines \(context.startLine)-\(context.endLine))")
             },
         ]
+    }
 
-        view.addSubview(markdownView)
-        markdownView.translatesAutoresizingMaskIntoConstraints = false
+    // MARK: - Line Selection
+
+    private func setupLineSelection() {
+        markdownView.lineSelectionHandler = { [weak self] info in
+            self?.updateCommentButton(info: info)
+        }
+
+        setupCommentButton()
+    }
+
+    private func setupCommentButton() {
+        commentButton.isHidden = true
+
+        var config = UIButton.Configuration.filled()
+        config.baseBackgroundColor = .systemGray5
+        config.baseForegroundColor = .label
+        config.cornerStyle = .capsule
+        config.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 16, bottom: 10, trailing: 16)
+        config.image = UIImage(systemName: "text.bubble")
+        config.imagePadding = 8
+        config.preferredSymbolConfigurationForImage = UIImage.SymbolConfiguration(pointSize: 14)
+        commentButton.configuration = config
+        commentButton.addTarget(self, action: #selector(commentTapped), for: .touchUpInside)
+
+        view.addSubview(commentButton)
+        commentButton.translatesAutoresizingMaskIntoConstraints = false
         NSLayoutConstraint.activate([
-            markdownView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 16),
-            markdownView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
-            markdownView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
+            commentButton.centerXAnchor.constraint(equalTo: view.centerXAnchor),
+            commentButton.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -16),
         ])
+    }
+
+    private func updateCommentButton(info: LineSelectionInfo?) {
+        currentSelectionInfo = info
+        guard let info else {
+            commentButton.isHidden = true
+            return
+        }
+
+        let range = info.lineRange
+        let title: String
+        if range.lowerBound == range.upperBound {
+            title = "Comment on line \(range.lowerBound)"
+        } else {
+            title = "Comment on lines \(range.lowerBound)-\(range.upperBound)"
+        }
+        commentButton.configuration?.title = title
+        commentButton.isHidden = false
+
+        UIView.animate(withDuration: 0.2) {
+            self.commentButton.transform = CGAffineTransform(scaleX: 1.05, y: 1.05)
+        } completion: { _ in
+            UIView.animate(withDuration: 0.15) {
+                self.commentButton.transform = .identity
+            }
+        }
+    }
+
+    @objc private func commentTapped() {
+        guard let info = currentSelectionInfo else { return }
+        let sheet = CommentSheetViewController(selectionInfo: info, language: example.language)
+        if let pc = sheet.presentationController as? UISheetPresentationController {
+            pc.detents = [.large()]
+        }
+        present(sheet, animated: true)
+    }
+}
+
+// MARK: - Comment Sheet
+
+class CommentSheetViewController: UIViewController {
+
+    private let selectionInfo: LineSelectionInfo
+    private let language: String?
+    private let codeMarkdownView = MarkdownTextView()
+    private let commentTextView = UITextView()
+
+    init(selectionInfo: LineSelectionInfo, language: String?) {
+        self.selectionInfo = selectionInfo
+        self.language = language
+        super.init(nibName: nil, bundle: nil)
+    }
+
+    @available(*, unavailable)
+    required init?(coder: NSCoder) {
+        fatalError()
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        view.backgroundColor = .systemBackground
+        setupNavBar()
+        setupCodePreview()
+        setupCommentTextView()
+    }
+
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        commentTextView.becomeFirstResponder()
+    }
+
+    private func setupNavBar() {
+        let navBar = UINavigationBar()
+        navBar.isTranslucent = false
+        navBar.barTintColor = .systemBackground
+        navBar.shadowImage = UIImage()
+        navBar.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(navBar)
+        NSLayoutConstraint.activate([
+            navBar.topAnchor.constraint(equalTo: view.topAnchor),
+            navBar.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            navBar.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+        ])
+
+        let navItem = UINavigationItem(title: "Add Comment")
+
+        let closeButton = UIBarButtonItem(
+            image: UIImage(systemName: "xmark"),
+            style: .plain,
+            target: self,
+            action: #selector(closeTapped)
+        )
+        closeButton.tintColor = .secondaryLabel
+        navItem.leftBarButtonItem = closeButton
+
+        let commentAction = UIAction(title: "Comment") { [weak self] _ in
+            self?.submitComment()
+        }
+        let commentButton = UIButton(type: .system, primaryAction: commentAction)
+        commentButton.configuration = {
+            var config = UIButton.Configuration.plain()
+            config.title = "Comment"
+            config.baseForegroundColor = .label
+            config.contentInsets = NSDirectionalEdgeInsets(top: 6, leading: 14, bottom: 6, trailing: 14)
+            return config
+        }()
+        navItem.rightBarButtonItem = UIBarButtonItem(customView: commentButton)
+
+        navBar.setItems([navItem], animated: false)
+    }
+
+    private func setupCodePreview() {
+        codeMarkdownView.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(codeMarkdownView)
+        NSLayoutConstraint.activate([
+            codeMarkdownView.topAnchor.constraint(equalTo: view.topAnchor, constant: 56),
+            codeMarkdownView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 16),
+            codeMarkdownView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
+        ])
+
+        let lines = selectionInfo.contents
+        let startLine = selectionInfo.lineRange.lowerBound
+        let lang = language ?? ""
+        let diffBlock = lines.enumerated().map { idx, line in
+            let lineNum = startLine + idx
+            return "\(lineNum) \(line)"
+        }.joined(separator: "\n")
+
+        let markdown = """
+        ```diff \(lang)
+        \(diffBlock)
+        ```
+        """
 
         let parser = MarkdownParser()
-        let result = parser.parse(example.markdown)
+        let result = parser.parse(markdown)
         let content = MarkdownTextView.PreprocessedContent(
             parserResult: result,
             theme: .default
         )
-        markdownView.setMarkdown(content)
+        codeMarkdownView.setMarkdown(content)
+    }
+
+    private func setupCommentTextView() {
+        commentTextView.font = .systemFont(ofSize: 16)
+        commentTextView.textColor = .label
+        commentTextView.backgroundColor = .clear
+        commentTextView.textContainerInset = UIEdgeInsets(top: 12, left: 12, bottom: 12, right: 12)
+        commentTextView.translatesAutoresizingMaskIntoConstraints = false
+
+        let placeholder = UILabel()
+        placeholder.text = "Leave a comment..."
+        placeholder.font = .systemFont(ofSize: 16)
+        placeholder.textColor = .placeholderText
+        placeholder.translatesAutoresizingMaskIntoConstraints = false
+        commentTextView.addSubview(placeholder)
+        NSLayoutConstraint.activate([
+            placeholder.topAnchor.constraint(equalTo: commentTextView.topAnchor, constant: 12),
+            placeholder.leadingAnchor.constraint(equalTo: commentTextView.leadingAnchor, constant: 17),
+        ])
+        self.placeholderLabel = placeholder
+        commentTextView.delegate = self
+
+        view.addSubview(commentTextView)
+        NSLayoutConstraint.activate([
+            commentTextView.topAnchor.constraint(equalTo: codeMarkdownView.bottomAnchor, constant: 8),
+            commentTextView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            commentTextView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            commentTextView.bottomAnchor.constraint(equalTo: view.keyboardLayoutGuide.topAnchor),
+        ])
+    }
+
+    private weak var placeholderLabel: UILabel?
+
+    @objc private func closeTapped() {
+        dismiss(animated: true)
+    }
+
+    private func submitComment() {
+        let text = commentTextView.text ?? ""
+        print("Comment submitted: \"\(text)\" on lines \(selectionInfo.lineRange)")
+        dismiss(animated: true)
+    }
+}
+
+extension CommentSheetViewController: UITextViewDelegate {
+    func textViewDidChange(_ textView: UITextView) {
+        placeholderLabel?.isHidden = !textView.text.isEmpty
     }
 }

Example/Example/DiffExample.swift

@@ -7,16 +7,24 @@
 
 import Foundation
 
+enum SelectionMode {
+    case textSelection
+    case lineSelection
+}
+
 struct DiffExample {
     let title: String
     let subtitle: String
     let markdown: String
+    let selectionMode: SelectionMode
+    var language: String? = nil
 }
 
 let examples: [DiffExample] = [
+    // Line selection examples — tap a line or long-press-drag to select a range
     DiffExample(
         title: "Rename Refactor",
-        subtitle: "Swift class rename",
+        subtitle: "Line selection · Tap or drag lines",
         markdown: """
         ```diff swift
         @@ -1,6 +1,6 @@
@@ -29,11 +37,13 @@ let examples: [DiffExample] = [
              }
          }
         ```
-        """
+        """,
+        selectionMode: .lineSelection,
+        language: "swift"
     ),
     DiffExample(
         title: "Bug Fix",
-        subtitle: "Off-by-one error in Python",
+        subtitle: "Line selection · Tap or drag lines",
         markdown: """
         ```diff python
         @@ -3,7 +3,7 @@
@@ -46,11 +56,15 @@ let examples: [DiffExample] = [
                      return mid
                  elif arr[mid] < target:
         ```
-        """
+        """,
+        selectionMode: .lineSelection,
+        language: "python"
     ),
+
+    // Text selection examples — long-press to select text, custom menu actions
     DiffExample(
         title: "Add Logging",
-        subtitle: "TypeScript API handler",
+        subtitle: "Text selection · Long-press to select",
         markdown: """
         ```diff typescript
         @@ -8,6 +8,8 @@
@@ -63,11 +77,13 @@ let examples: [DiffExample] = [
                  return Response.notFound();
              }
         ```
-        """
+        """,
+        selectionMode: .textSelection,
+        language: "typescript"
     ),
     DiffExample(
         title: "Config Change",
-        subtitle: "JSON configuration update",
+        subtitle: "Text selection · Long-press to select",
         markdown: """
         ```diff json
         @@ -2,5 +2,6 @@
@@ -79,11 +95,13 @@ let examples: [DiffExample] = [
         +    "license": "MIT"
          }
         ```
-        """
+        """,
+        selectionMode: .textSelection,
+        language: "json"
     ),
     DiffExample(
         title: "SQL Migration",
-        subtitle: "Add index and column",
+        subtitle: "Text selection · Long-press to select",
         markdown: """
         ```diff sql
         @@ -1,4 +1,6 @@
@@ -95,6 +113,8 @@ let examples: [DiffExample] = [
         +    created_at TIMESTAMPTZ DEFAULT NOW()
          );
         ```
-        """
+        """,
+        selectionMode: .textSelection,
+        language: "sql"
     ),
 ]