From e792f722fa7b128969e0e63494745727e9f532d2 Mon Sep 17 00:00:00 2001
From: Radu Ursache <radu@ursache.ro>
Date: Fri, 12 Jun 2026 20:07:35 +0300
Subject: [PATCH] Fix 2FA code paste and macOS autofill in PIN code input

Replace the six independently focused NSTextFields with a single
invisible input field (contentType = .oneTimeCode) overlaying
display-only digit boxes. All input now lands in one field, so
pasting a full code works from any state and the system one-time
code autofill from Messages/Mail inserts the whole code instead
of breaking after the first digit when focus jumped between
fields.

Fixes XcodesOrg#587, fixes XcodesOrg#788
---
 Xcodes/Frontend/SignIn/PinCodeTextView.swift | 307 +++++++++++--------
 1 file changed, 175 insertions(+), 132 deletions(-)

diff --git a/Xcodes/Frontend/SignIn/PinCodeTextView.swift b/Xcodes/Frontend/SignIn/PinCodeTextView.swift
index 6140cdd1..062a689b 100644
--- a/Xcodes/Frontend/SignIn/PinCodeTextView.swift
+++ b/Xcodes/Frontend/SignIn/PinCodeTextView.swift
@@ -14,16 +14,9 @@ struct PinCodeTextField: NSViewRepresentable {
         view.codeDidComplete = { complete($0) }
         return view
     }
-    
+
     func updateNSView(_ nsView: NSViewType, context: Context) {
-        nsView.code = (0..<numberOfDigits).map { index in
-            if index < code.count {
-                let codeIndex = code.index(code.startIndex, offsetBy: index)
-                return code[codeIndex]
-            } else {
-                return nil
-            }
-        }
+        nsView.setCode(code)
     }
 }
 
@@ -46,31 +39,22 @@ struct PinCodeTextField_Previews: PreviewProvider {
 
 // MARK: - PinCodeTextView
 
-class PinCodeTextView: NSControl, NSTextFieldDelegate {    
-    var code: [Character?] = [] {
-        didSet {
-            guard code != oldValue else { return }
-
-            if let handler = codeDidChange {
-                handler(String(code.compactMap { $0 }))
-            }
-            updateText()
-            
-            if code.compactMap({ $0 }).count == numberOfDigits,
-               let handler = codeDidComplete {
-                handler(String(code.compactMap { $0 }))
-            }
-        }
-    }
+/// A single hidden text field receives all input (so pasting and macOS one-time-code
+/// autofill insert the whole code at once) while the per-digit boxes are display-only
+class PinCodeTextView: NSControl, NSTextFieldDelegate {
     var codeDidChange: ((String) -> Void)? = nil
     var codeDidComplete: ((String) -> Void)? = nil
 
+    private(set) var currentCode = ""
+
     private let numberOfDigits: Int
     private let stackView: NSStackView = .init(frame: .zero)
-    private var characterViews: [PinCodeCharacterTextField] = []
+    private var characterBoxes: [PinCodeCharacterBox] = []
+    private let inputField = PinCodeInputField()
+    private var firstResponderObservation: NSKeyValueObservation?
 
     // MARK: - Initializers
-    
+
     init(
         numberOfDigits: Int,
         itemSpacing: CGFloat
@@ -91,158 +75,217 @@ class PinCodeTextView: NSControl, NSTextFieldDelegate {
             stackView.trailingAnchor.constraint(greaterThanOrEqualTo: self.trailingAnchor),
             stackView.centerXAnchor.constraint(equalTo: self.centerXAnchor),
         ])
-        
-        self.code = (0..<numberOfDigits).map { _ in nil }
-        self.characterViews = (0..<numberOfDigits).map { _ in
-            let view = PinCodeCharacterTextField()
+
+        self.characterBoxes = (0..<numberOfDigits).map { _ in
+            let view = PinCodeCharacterBox()
             view.translatesAutoresizingMaskIntoConstraints = false
-            view.delegate = self
             return view
         }
-        characterViews.forEach { 
-            stackView.addArrangedSubview($0) 
-            stackView.heightAnchor.constraint(equalTo: $0.heightAnchor).isActive = true            
+        characterBoxes.forEach {
+            stackView.addArrangedSubview($0)
+            stackView.heightAnchor.constraint(equalTo: $0.heightAnchor).isActive = true
         }
+
+        // The invisible input field sits on top of the boxes so it gets all
+        // clicks and keyboard input, and anchors the system autofill suggestion
+        inputField.translatesAutoresizingMaskIntoConstraints = false
+        inputField.delegate = self
+        addSubview(inputField)
+        NSLayoutConstraint.activate([
+            inputField.topAnchor.constraint(equalTo: self.topAnchor),
+            inputField.bottomAnchor.constraint(equalTo: self.bottomAnchor),
+            inputField.leadingAnchor.constraint(equalTo: self.leadingAnchor),
+            inputField.trailingAnchor.constraint(equalTo: self.trailingAnchor),
+        ])
+
+        updateBoxes()
     }
-    
+
     required init?(coder aDecoder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }
-    
-    private func updateText() {
-        characterViews.enumerated().forEach { (index, item) in
-            if (0..<code.count).contains(index) {
-                let _index = code.index(code.startIndex, offsetBy: index)
-                item.character = code[_index]
-            } else {
-                item.character = nil
-            }
+
+    func setCode(_ newCode: String) {
+        let sanitized = sanitize(newCode)
+        guard sanitized != currentCode else { return }
+        currentCode = sanitized
+        if inputField.stringValue != sanitized {
+            inputField.stringValue = sanitized
         }
+        updateBoxes()
     }
-    
-    // MARK: NSTextFieldDelegate
-    
-    func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
-        if commandSelector == #selector(deleteBackward(_:)) {
-            // If empty, move to previous or first character view
-            if textView.string.isEmpty {
-                if let lastFieldIndexWithCharacter = code.lastIndex(where: { $0 != nil }) {
-                    window?.makeFirstResponder(characterViews[lastFieldIndexWithCharacter])
-                } else {
-                    window?.makeFirstResponder(characterViews[0])
-                }
-
-                return true
-            }
+
+    private func sanitize(_ string: String) -> String {
+        String(string.filter { $0.isLetter || $0.isNumber }.prefix(numberOfDigits))
+    }
+
+    private func updateBoxes() {
+        let characters = Array(currentCode)
+        let activeIndex = isInputFocused ? min(characters.count, numberOfDigits - 1) : nil
+        characterBoxes.enumerated().forEach { (index, box) in
+            box.character = index < characters.count ? characters[index] : nil
+            box.isActive = index == activeIndex
         }
-        
-        // Perform default behaviour
+    }
+
+    private var isInputFocused: Bool {
+        guard let responder = window?.firstResponder else { return false }
+        if responder === inputField { return true }
+        if let editor = responder as? NSTextView, editor.delegate === inputField { return true }
         return false
     }
-    
-    func controlTextDidChange(_ obj: Notification) {
-        guard
-            let field = obj.object as? NSTextField,
-            isEnabled,
-            let fieldIndex = characterViews.firstIndex(where: { $0 === field })
-        else { return } 
-        
-        let newFieldText = field.stringValue
-        
-        // Handle pasting multiple characters (e.g., pasting "123456" from clipboard)
-        if newFieldText.count > 1 {
-            // Filter to alphanumeric characters only
-            let validCharacters = newFieldText.filter { $0.isLetter || $0.isNumber }
-            
-            // Always start from the first field and clear previous content
-            var newCode = Array(repeating: Character?.none, count: numberOfDigits)
-            for (offset, character) in validCharacters.enumerated() {
-                if offset < numberOfDigits {
-                    newCode[offset] = character
-                }
-            }
-            
-            // Update all fields at once to avoid triggering didSet multiple times
-            code = newCode
-            
-            // Move focus to next empty field or the last field if all are filled
-            let nextEmptyIndex = code.firstIndex(where: { $0 == nil }) ?? numberOfDigits - 1
-            if nextEmptyIndex < characterViews.count {
-                window?.makeFirstResponder(characterViews[nextEmptyIndex])
-            } else {
-                resignFirstResponder()
+
+    override func viewDidMoveToWindow() {
+        super.viewDidMoveToWindow()
+        firstResponderObservation = window?.observe(\.firstResponder) { [weak self] _, _ in
+            DispatchQueue.main.async { self?.updateBoxes() }
+        }
+        // Focus immediately so the system one-time-code suggestion can appear
+        DispatchQueue.main.async { [weak self] in
+            guard let self, let window = self.window else { return }
+            if window.firstResponder === window {
+                window.makeFirstResponder(self.inputField)
             }
-            
-            return
         }
-        
-        // Handle single character input
-        let lastCharacter: Character?
-        if newFieldText.isEmpty {
-            lastCharacter = nil
-        } else {
-            lastCharacter = newFieldText[newFieldText.index(before: newFieldText.endIndex)]
+    }
+
+    // Returns the contiguous run of characters added between old and new,
+    // assuming a single insertion (typing, paste or autofill)
+    private func insertedText(from old: String, to new: String) -> String? {
+        guard new.count > old.count else { return nil }
+        let oldChars = Array(old)
+        let newChars = Array(new)
+        var prefix = 0
+        while prefix < oldChars.count, oldChars[prefix] == newChars[prefix] {
+            prefix += 1
+        }
+        var suffix = 0
+        while suffix < oldChars.count - prefix,
+              oldChars[oldChars.count - 1 - suffix] == newChars[newChars.count - 1 - suffix] {
+            suffix += 1
         }
+        return String(newChars[prefix..<(newChars.count - suffix)])
+    }
 
-        code[fieldIndex] = lastCharacter
-        
-        if lastCharacter != nil {
-            if fieldIndex >= characterViews.count - 1 {
-                resignFirstResponder()
-            } else {
-                window?.makeFirstResponder(characterViews[fieldIndex + 1])
-            }
+    // MARK: NSTextFieldDelegate
+
+    func controlTextDidChange(_ obj: Notification) {
+        guard isEnabled else { return }
+
+        let rawText = inputField.stringValue
+        let sanitized: String
+
+        // If a full code was pasted or autofilled while digits were already
+        // entered, the pasted code wins over the leftover digits
+        if let inserted = insertedText(from: currentCode, to: rawText),
+           inserted.count > 1,
+           sanitize(inserted).count == numberOfDigits {
+            sanitized = sanitize(inserted)
         } else {
-            if let lastFieldIndexWithCharacter = code.lastIndex(where: { $0 != nil }) {
-                window?.makeFirstResponder(characterViews[lastFieldIndexWithCharacter])
-            } else {
-                window?.makeFirstResponder(characterViews[0])
-            }
+            sanitized = sanitize(rawText)
+        }
+
+        if inputField.stringValue != sanitized {
+            inputField.stringValue = sanitized
+        }
+
+        guard sanitized != currentCode else { return }
+        currentCode = sanitized
+        updateBoxes()
+
+        codeDidChange?(sanitized)
+        if sanitized.count == numberOfDigits {
+            codeDidComplete?(sanitized)
         }
     }
-    
+
     // MARK: NSResponder
-    
+
     override var acceptsFirstResponder: Bool {
         true
     }
-    
+
     override func becomeFirstResponder() -> Bool {
-        characterViews.first?.becomeFirstResponder() ?? false
+        inputField.becomeFirstResponder()
+    }
+
+    override var isEnabled: Bool {
+        didSet { inputField.isEnabled = isEnabled }
     }
 }
 
-// MARK: - PinCodeCharacterTextField
+// MARK: - PinCodeInputField
+
+/// Invisible single-line field that owns the actual text input.
+/// `.oneTimeCode` lets macOS offer 2FA codes from Messages/Mail
+private class PinCodeInputField: NSTextField {
+    init() {
+        super.init(frame: .zero)
+
+        isBordered = false
+        drawsBackground = false
+        focusRingType = .none
+        textColor = .clear
+        usesSingleLineMode = true
+        cell?.isScrollable = true
+        contentType = .oneTimeCode
+    }
 
-class PinCodeCharacterTextField: NSTextField {
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+
+    override func becomeFirstResponder() -> Bool {
+        let didBecome = super.becomeFirstResponder()
+        if didBecome, let editor = currentEditor() as? NSTextView {
+            // Hide the field editor's caret and selection, the digit boxes
+            // underneath are the visible representation
+            editor.insertionPointColor = .clear
+            editor.selectedTextAttributes = [
+                .backgroundColor: NSColor.clear,
+                .foregroundColor: NSColor.clear,
+            ]
+        }
+        return didBecome
+    }
+}
+
+// MARK: - PinCodeCharacterBox
+
+/// Display-only box for a single digit
+private class PinCodeCharacterBox: NSTextField {
     var character: Character? = nil {
         didSet {
             stringValue = character.map(String.init) ?? ""
         }
     }
-    private var lastSize: NSSize?
-    
+
+    var isActive: Bool = false {
+        didSet {
+            layer?.borderWidth = isActive ? 2 : 0
+            layer?.borderColor = NSColor.controlAccentColor.cgColor
+            layer?.cornerRadius = isActive ? 3 : 0
+        }
+    }
+
     init() {
         super.init(frame: .zero)
 
         wantsLayer = true
+        isEditable = false
+        isSelectable = false
         alignment = .center
         maximumNumberOfLines = 1
         font = .boldSystemFont(ofSize: 48)
-        
+
         setContentHuggingPriority(.required, for: .vertical)
         setContentHuggingPriority(.required, for: .horizontal)
     }
-    
+
     required init?(coder aDecoder: NSCoder) {
         fatalError("init(coder:) has not been implemented")
     }
-    
-    override func textDidChange(_ notification: Notification) {
-        super.textDidChange(notification)
-        self.invalidateIntrinsicContentSize()
-    }
-    
+
     // This is kinda cheating
     // Assuming that 0 is the widest and tallest character in 0-9
     override var intrinsicContentSize: NSSize {