From 8994a8c6276e01d18a37ad4b99f8babdf7260706 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Tue, 8 Oct 2024 21:54:22 -0700
Subject: [PATCH] macos: implement key sequence UI

---
 macos/Sources/Ghostty/Ghostty.App.swift       | 35 +++++++++++-
 macos/Sources/Ghostty/Ghostty.Config.swift    | 47 +--------------
 macos/Sources/Ghostty/Ghostty.Input.swift     | 57 +++++++++++++++++++
 macos/Sources/Ghostty/Package.swift           |  7 ++-
 macos/Sources/Ghostty/SurfaceView.swift       | 28 +++++++++
 .../Sources/Ghostty/SurfaceView_AppKit.swift  | 23 ++++++++
 6 files changed, 149 insertions(+), 48 deletions(-)

diff --git a/macos/Sources/Ghostty/Ghostty.App.swift b/macos/Sources/Ghostty/Ghostty.App.swift
index 82a08f666..a2ed8903a 100644
--- a/macos/Sources/Ghostty/Ghostty.App.swift
+++ b/macos/Sources/Ghostty/Ghostty.App.swift
@@ -516,7 +516,8 @@ extension Ghostty {
                 toggleVisibility(app, target: target)
 
             case GHOSTTY_ACTION_KEY_SEQUENCE:
-                fallthrough
+                keySequence(app, target: target, v: action.action.key_sequence)
+
             case GHOSTTY_ACTION_CLOSE_ALL_WINDOWS:
                 fallthrough
             case GHOSTTY_ACTION_TOGGLE_TAB_OVERVIEW:
@@ -1073,6 +1074,38 @@ extension Ghostty {
             }
         }
 
+        private static func keySequence(
+            _ app: ghostty_app_t,
+            target: ghostty_target_s,
+            v: ghostty_action_key_sequence_s) {
+            switch (target.tag) {
+            case GHOSTTY_TARGET_APP:
+                Ghostty.logger.warning("key sequence does nothing with an app target")
+                return
+
+            case GHOSTTY_TARGET_SURFACE:
+                guard let surface = target.target.surface else { return }
+                guard let surfaceView = self.surfaceView(from: surface) else { return }
+                if v.active {
+                    NotificationCenter.default.post(
+                        name: Notification.didContinueKeySequence,
+                        object: surfaceView,
+                        userInfo: [
+                            Notification.KeySequenceKey: keyEquivalent(for: v.trigger) as Any
+                        ]
+                    )
+                } else {
+                    NotificationCenter.default.post(
+                        name: Notification.didEndKeySequence,
+                        object: surfaceView
+                    )
+                }
+
+            default:
+                assertionFailure()
+            }
+        }
+
         // MARK: User Notifications
 
         /// Handle a received user notification. This is called when a user notification is clicked or dismissed by the user
diff --git a/macos/Sources/Ghostty/Ghostty.Config.swift b/macos/Sources/Ghostty/Ghostty.Config.swift
index 99e08bf9d..95f8ad734 100644
--- a/macos/Sources/Ghostty/Ghostty.Config.swift
+++ b/macos/Sources/Ghostty/Ghostty.Config.swift
@@ -87,25 +87,6 @@ extension Ghostty {
 #if os(macOS)
         // MARK: - Keybindings
 
-        /// A convenience struct that has the key + modifiers for some keybinding.
-        struct KeyEquivalent: CustomStringConvertible {
-            let key: String
-            let modifiers: NSEvent.ModifierFlags
-
-            var description: String {
-                var key = self.key
-
-                // Note: the order below matters; it matches the ordering modifiers
-                // shown for macOS menu shortcut labels.
-                if modifiers.contains(.command) { key = "⌘\(key)" }
-                if modifiers.contains(.shift) { key = "⇧\(key)" }
-                if modifiers.contains(.option) { key = "⌥\(key)" }
-                if modifiers.contains(.control) { key = "⌃\(key)" }
-
-                return key
-            }
-        }
-
         /// Return the key equivalent for the given action. The action is the name of the action
         /// in the Ghostty configuration. For example `keybind = cmd+q=quit` in Ghostty
         /// configuration would be "quit" action.
@@ -115,33 +96,7 @@ extension Ghostty {
             guard let cfg = self.config else { return nil }
 
             let trigger = ghostty_config_trigger(cfg, action, UInt(action.count))
-            let equiv: String
-            switch (trigger.tag) {
-            case GHOSTTY_TRIGGER_TRANSLATED:
-                if let v = Ghostty.keyEquivalent(key: trigger.key.translated) {
-                    equiv = v
-                } else {
-                    return nil
-                }
-
-            case GHOSTTY_TRIGGER_PHYSICAL:
-                if let v = Ghostty.keyEquivalent(key: trigger.key.physical) {
-                    equiv = v
-                } else {
-                    return nil
-                }
-
-            case GHOSTTY_TRIGGER_UNICODE:
-                equiv = String(trigger.key.unicode)
-
-            default:
-                return nil
-            }
-
-            return KeyEquivalent(
-                key: equiv,
-                modifiers: Ghostty.eventModifierFlags(mods: trigger.mods)
-            )
+            return Ghostty.keyEquivalent(for: trigger)
         }
 #endif
 
diff --git a/macos/Sources/Ghostty/Ghostty.Input.swift b/macos/Sources/Ghostty/Ghostty.Input.swift
index d7fd96f12..43bf8d096 100644
--- a/macos/Sources/Ghostty/Ghostty.Input.swift
+++ b/macos/Sources/Ghostty/Ghostty.Input.swift
@@ -2,11 +2,68 @@ import Cocoa
 import GhosttyKit
 
 extension Ghostty {
+    // MARK: Key Equivalents
+
     /// Returns the "keyEquivalent" string for a given input key. This doesn't always have a corresponding key.
     static func keyEquivalent(key: ghostty_input_key_e) -> String? {
         return Self.keyToEquivalent[key]
     }
 
+    /// A convenience struct that has the key + modifiers for some keybinding.
+    struct KeyEquivalent: CustomStringConvertible {
+        let key: String
+        let modifiers: NSEvent.ModifierFlags
+
+        var description: String {
+            var key = self.key
+
+            // Note: the order below matters; it matches the ordering modifiers
+            // shown for macOS menu shortcut labels.
+            if modifiers.contains(.command) { key = "⌘\(key)" }
+            if modifiers.contains(.shift) { key = "⇧\(key)" }
+            if modifiers.contains(.option) { key = "⌥\(key)" }
+            if modifiers.contains(.control) { key = "⌃\(key)" }
+
+            return key
+        }
+    }
+
+    /// Return the key equivalent for the given trigger.
+    ///
+    /// Returns nil if the trigger can't be processed. This should only happen for unknown trigger types
+    /// or keys.
+    static func keyEquivalent(for trigger: ghostty_input_trigger_s) -> KeyEquivalent? {
+        let equiv: String
+        switch (trigger.tag) {
+        case GHOSTTY_TRIGGER_TRANSLATED:
+            if let v = Ghostty.keyEquivalent(key: trigger.key.translated) {
+                equiv = v
+            } else {
+                return nil
+            }
+
+        case GHOSTTY_TRIGGER_PHYSICAL:
+            if let v = Ghostty.keyEquivalent(key: trigger.key.physical) {
+                equiv = v
+            } else {
+                return nil
+            }
+
+        case GHOSTTY_TRIGGER_UNICODE:
+            equiv = String(trigger.key.unicode)
+
+        default:
+            return nil
+        }
+
+        return KeyEquivalent(
+            key: equiv,
+            modifiers: Ghostty.eventModifierFlags(mods: trigger.mods)
+        )
+    }
+
+    // MARK: Mods
+
     /// Returns the event modifier flags set for the Ghostty mods enum.
     static func eventModifierFlags(mods: ghostty_input_mods_e) -> NSEvent.ModifierFlags {
         var flags = NSEvent.ModifierFlags(rawValue: 0);
diff --git a/macos/Sources/Ghostty/Package.swift b/macos/Sources/Ghostty/Package.swift
index 1c5695319..63a41596a 100644
--- a/macos/Sources/Ghostty/Package.swift
+++ b/macos/Sources/Ghostty/Package.swift
@@ -262,7 +262,12 @@ extension Ghostty.Notification {
 
     /// Notification that renderer health changed
     static let didUpdateRendererHealth = Notification.Name("com.mitchellh.ghostty.didUpdateRendererHealth")
+
+    /// Notifications related to key sequences
+    static let didContinueKeySequence = Notification.Name("com.mitchellh.ghostty.didContinueKeySequence")
+    static let didEndKeySequence = Notification.Name("com.mitchellh.ghostty.didEndKeySequence")
+    static let KeySequenceKey = didContinueKeySequence.rawValue + ".key"
 }
 
 // Make the input enum hashable.
-extension ghostty_input_key_e : Hashable {}
+extension ghostty_input_key_e : @retroactive Hashable {}
diff --git a/macos/Sources/Ghostty/SurfaceView.swift b/macos/Sources/Ghostty/SurfaceView.swift
index 5eb277ba1..b7643aada 100644
--- a/macos/Sources/Ghostty/SurfaceView.swift
+++ b/macos/Sources/Ghostty/SurfaceView.swift
@@ -184,6 +184,34 @@ extension Ghostty {
                 }
                 .ghosttySurfaceView(surfaceView)
 
+#if canImport(AppKit)
+                // If we are in the middle of a key sequence, then we show a visual element. We only
+                // support this on macOS currently although in theory we can support mobile with keyboards!
+                if !surfaceView.keySequence.isEmpty {
+                    let padding: CGFloat = 5
+                    VStack {
+                        Spacer()
+
+                        HStack {
+                            Text(verbatim: "Pending Key Sequence:")
+                            ForEach(0..<surfaceView.keySequence.count, id: \.description) { index in
+                                let key = surfaceView.keySequence[index]
+                                Text(verbatim: key.description)
+                                    .font(.system(.body, design: .monospaced))
+                                    .padding(3)
+                                    .background(
+                                        RoundedRectangle(cornerRadius: 5)
+                                            .fill(Color(NSColor.selectedTextBackgroundColor))
+                                    )
+                            }
+                        }
+                        .padding(.init(top: padding, leading: padding, bottom: padding, trailing: padding))
+                        .frame(maxWidth: .infinity)
+                        .background(.background)
+                    }
+                }
+#endif
+
                 // If we have a URL from hovering a link, we show that.
                 if let url = surfaceView.hoverUrl {
                     let padding: CGFloat = 3
diff --git a/macos/Sources/Ghostty/SurfaceView_AppKit.swift b/macos/Sources/Ghostty/SurfaceView_AppKit.swift
index d64c2fead..3b96ac012 100644
--- a/macos/Sources/Ghostty/SurfaceView_AppKit.swift
+++ b/macos/Sources/Ghostty/SurfaceView_AppKit.swift
@@ -30,6 +30,9 @@ extension Ghostty {
         // The hovered URL string
         @Published var hoverUrl: String? = nil
 
+        // The currently active key sequence. The sequence is not active if this is empty.
+        @Published var keySequence: [Ghostty.KeyEquivalent] = []
+
         // The time this surface last became focused. This is a ContinuousClock.Instant
         // on supported platforms.
         @Published var focusInstant: Any? = nil
@@ -132,6 +135,16 @@ extension Ghostty {
                 selector: #selector(onUpdateRendererHealth),
                 name: Ghostty.Notification.didUpdateRendererHealth,
                 object: self)
+            center.addObserver(
+                self,
+                selector: #selector(ghosttyDidContinueKeySequence),
+                name: Ghostty.Notification.didContinueKeySequence,
+                object: self)
+            center.addObserver(
+                self,
+                selector: #selector(ghosttyDidEndKeySequence),
+                name: Ghostty.Notification.didEndKeySequence,
+                object: self)
             center.addObserver(
                 self,
                 selector: #selector(windowDidChangeScreen),
@@ -316,6 +329,16 @@ extension Ghostty {
             healthy = health == GHOSTTY_RENDERER_HEALTH_OK
         }
 
+        @objc private func ghosttyDidContinueKeySequence(notification: SwiftUI.Notification) {
+            guard let keyAny = notification.userInfo?[Ghostty.Notification.KeySequenceKey] else { return }
+            guard let key = keyAny as? Ghostty.KeyEquivalent else { return }
+            keySequence.append(key)
+        }
+
+        @objc private func ghosttyDidEndKeySequence(notification: SwiftUI.Notification) {
+            keySequence = []
+        }
+
         @objc private func windowDidChangeScreen(notification: SwiftUI.Notification) {
             guard let window = self.window else { return }
             guard let object = notification.object as? NSWindow, window == object else { return }