Cleanup GameController barcode parser implementation

Author: staskus

Modules/Sources/Experiments/DefaultFeatureFlagService.swift

@@ -90,8 +90,6 @@ public struct DefaultFeatureFlagService: FeatureFlagService {
             return true
         case .pointOfSaleBarcodeScanningi1:
             return true
-        case .pointOfSaleBarcodeScanningi2:
-            return buildConfig == .localDeveloper || buildConfig == .alpha
         case .showPointOfSaleBarcodeSimulator:
             // Enables a simulated barcode scanner in dev builds for testing. Do not ship this one!
             return false

Modules/Sources/Experiments/FeatureFlag.swift

@@ -188,10 +188,6 @@ public enum FeatureFlag: Int {
     ///
     case pointOfSaleBarcodeScanningi1
 
-    /// Enables further improvements to barcode scanning with an external scanner in POS
-    ///
-    case pointOfSaleBarcodeScanningi2
-
     /// Enables a simulated barcode scanner for testing in POS. Do not ship this one!
     ///
     case showPointOfSaleBarcodeSimulator

WooCommerce/Classes/POS/Presentation/Barcode Scanning/BarcodeScannerContainer.swift

@@ -40,90 +40,15 @@ struct BarcodeScannerContainerRepresentable: UIViewControllerRepresentable {
     let onScan: (Result<String, Error>) -> Void
 
     func makeUIViewController(context: Context) -> UIViewController {
-        let featureFlagService = ServiceLocator.featureFlagService
-
-        if featureFlagService.isFeatureFlagEnabled(.pointOfSaleBarcodeScanningi2) {
-            return GameControllerBarcodeScannerHostingController(
-                configuration: configuration,
-                onScan: onScan
-            )
-        } else {
-            return BarcodeScannerHostingController(
-                configuration: configuration,
-                onScan: onScan
-            )
-        }
+        return GameControllerBarcodeScannerHostingController(
+            configuration: configuration,
+            onScan: onScan
+        )
     }
 
     func updateUIViewController(_ uiViewController: UIViewController, context: Context) {}
 }
 
-/// A UIHostingController that handles keyboard input events for barcode scanning.
-/// This controller captures keyboard input and interprets it as barcode data when a terminating
-/// character is detected.
-class BarcodeScannerHostingController: UIHostingController<EmptyView> {
-    private let configuration: HIDBarcodeParserConfiguration
-    private let scanner: HIDBarcodeParser
-
-    init(
-        configuration: HIDBarcodeParserConfiguration,
-        onScan: @escaping (Result<String, Error>) -> Void
-    ) {
-        self.configuration = configuration
-        self.scanner = HIDBarcodeParser(configuration: configuration,
-                                        onScan: onScan)
-        super.init(rootView: EmptyView())
-    }
-
-    @MainActor required dynamic init?(coder aDecoder: NSCoder) {
-        fatalError("init(coder:) has not been implemented")
-    }
-
-    override var canBecomeFirstResponder: Bool { true }
-
-    override func viewDidAppear(_ animated: Bool) {
-        super.viewDidAppear(animated)
-        becomeFirstResponder()
-    }
-
-    override func viewDidDisappear(_ animated: Bool) {
-        super.viewDidDisappear(animated)
-        resignFirstResponder()
-    }
-
-    override func pressesBegan(_ presses: Set<UIPress>, with event: UIPressesEvent?) {
-        /// We don't call super here because it helps prevent the system from hiding the software keyboard when
-        /// a textfield is next used.
-    }
-
-    /// Handles the end of keyboard press events, interpreting them as barcode input.
-    /// When a terminating character is detected, the accumulated buffer is treated as a complete
-    /// barcode and passed to the onScan callback.
-    /// We don't call `super` here because we don't other responder chain items to handle our barcode as well,
-    /// as this could cause unexpected behavior.
-    override func pressesEnded(_ presses: Set<UIPress>, with event: UIPressesEvent?) {
-        /// While a scanner should just "press" each key once, in theory it's possible for presses to be cancelled
-        /// or change between the `began` call and the `ended` call.
-        /// It's better practice for barcode scanning to only consider the presses when they end.
-        for press in presses {
-            guard let key = press.key else { continue }
-            scanner.processKeyPress(key)
-        }
-    }
-
-    override func pressesChanged(_ presses: Set<UIPress>, with event: UIPressesEvent?) {
-        super.pressesChanged(presses, with: event)
-    }
-
-    /// `pressesCancelled` is rarely called, but Apple's documentation suggests it's possible and that crashes may occur if it's not handled.
-    /// It makes sense to clear the buffer when this happens.
-    /// We call super in case other presses are handled elsewhere in the responder chain.
-    override func pressesCancelled(_ presses: Set<UIPress>, with event: UIPressesEvent?) {
-        scanner.cancel()
-        super.pressesCancelled(presses, with: event)
-    }
-}
-
 /// A UIHostingController that handles GameController keyboard input events for barcode scanning.
 /// This controller uses GameController framework exclusively for language-independent barcode scanning.
 final class GameControllerBarcodeScannerHostingController: UIHostingController<EmptyView> {

WooCommerce/Classes/POS/Presentation/Barcode Scanning/GameControllerBarcodeParser.swift

@@ -46,15 +46,7 @@ final class GameControllerBarcodeParser {
     }
 
     private func shouldRecogniseAsScanKeystroke(_ keyCode: GCKeyCode, isShiftPressed: Bool) -> Bool {
-        guard let character = characterForKeyCode(keyCode, isShiftPressed: isShiftPressed) else {
-            // This prevents a double-trigger-pull on a Star scanner from adding an error row –
-            // Star use this as a shortcut to switch to the software keyboard. They send keycode 174 0xAE, which is
-            // undefined and reserved in UIKeyboardHIDUsage. The scanner doesn't send a character with the code.
-            // There seems to be no reason to handle empty input when considering scans.
-            return false
-        }
-
-        guard character.isNotEmpty else {
+        guard let character = characterForKeyCode(keyCode, isShiftPressed: isShiftPressed), character.isNotEmpty else {
             // This prevents a double-trigger-pull on a Star scanner from adding an error row –
             // Star use this as a shortcut to switch to the software keyboard. They send keycode 174 0xAE, which is
             // undefined and reserved in UIKeyboardHIDUsage. The scanner doesn't send a character with the code.
@@ -195,3 +187,28 @@ final class GameControllerBarcodeParser {
         resetScan()
     }
 }
+
+/// Configuration options for the HID barcode parser
+struct HIDBarcodeParserConfiguration {
+    /// Strings that indicate the end of a barcode scan
+    let terminatingStrings: Set<String>
+
+    /// Minimum length to consider scanned input complete
+    let minimumBarcodeLength: Int
+
+    /// Maximum time between scanned keystrokes
+    /// After this time elapses, any further keystrokes result in the scan being rejected
+    let maximumInterCharacterTime: TimeInterval
+
+    /// Default configuration suitable for most barcode scanners
+    static let `default` = HIDBarcodeParserConfiguration(
+        terminatingStrings: ["\r", "\n"],
+        minimumBarcodeLength: 6,
+        maximumInterCharacterTime: 0.2
+    )
+}
+
+enum HIDBarcodeParserError: Error {
+    case scanTooShort(barcode: String)
+    case timedOut(barcode: String)
+}