Support multiple instances to allow multiple screens

DeskPad.xcodeproj/project.pbxproj

@@ -22,6 +22,7 @@
 		6DC044522801877F00281728 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6DC044512801877F00281728 /* AppDelegate.swift */; };
 		6DC044562801878100281728 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 6DC044552801878100281728 /* Assets.xcassets */; };
 		6DC04461280191EB00281728 /* main.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6DC04460280191EB00281728 /* main.swift */; };
+    70EA23072E38CF4A00B8ED62 /* SerialNumberManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 70EA23062E38CF4A00B8ED62 /* SerialNumberManager.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -42,6 +43,7 @@
 		6DC044512801877F00281728 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		6DC044552801878100281728 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		6DC0445A2801878100281728 /* DeskPad.entitlements */ = {isa = PBXFileReference; lastKnownFileType = text.plist.entitlements; path = DeskPad.entitlements; sourceTree = "<group>"; };
+    70EA23062E38CF4A00B8ED62 /* SerialNumberManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SerialNumberManager.swift; sourceTree = "<group>"; };
 		6DC04460280191EB00281728 /* main.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = main.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -133,6 +135,7 @@
 			children = (
 				6DC04460280191EB00281728 /* main.swift */,
 				6D2F1485280C20C800A3A2E5 /* SubscriberViewController.swift */,
+        70EA23062E38CF4A00B8ED62 /* SerialNumberManager.swift */,
 				6DC044512801877F00281728 /* AppDelegate.swift */,
 				6D2F1483280C201B00A3A2E5 /* Backend */,
 				6D2F1484280C202700A3A2E5 /* Frontend */,
@@ -247,6 +250,7 @@
 				6D2F148C280C20D000A3A2E5 /* Store.swift in Sources */,
 				6D2F1486280C20C800A3A2E5 /* SubscriberViewController.swift in Sources */,
 				6D68E1AF287ABB9900CD574A /* ScreenConfigurationSideEffect.swift in Sources */,
+        70EA23072E38CF4A00B8ED62 /* SerialNumberManager.swift in Sources */,
 				6D41B0A12879FABE007CEB2F /* MouseLocationState.swift in Sources */,
 				6D2F148A280C20D000A3A2E5 /* AppState.swift in Sources */,
 				6D2F148B280C20D000A3A2E5 /* SideEffectsMiddleware.swift in Sources */,

DeskPad/AppDelegate.swift

@@ -11,12 +11,13 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     func applicationDidFinishLaunching(_: Notification) {
         let viewController = ScreenViewController()
         window = NSWindow(contentViewController: viewController)
+        window.bind(NSBindingName.title, to: viewController, withKeyPath: "title")
         window.delegate = viewController
-        window.title = "DeskPad"
+        // window.title = "DeskPad"
         window.makeKeyAndOrderFront(nil)
         window.titlebarAppearsTransparent = true
         window.isMovableByWindowBackground = true
-        window.titleVisibility = .hidden
+        // window.titleVisibility = .hidden
         window.backgroundColor = .white
         window.contentMinSize = CGSize(width: 400, height: 300)
         window.contentMaxSize = CGSize(width: 3840, height: 2160)
@@ -26,6 +27,12 @@ class AppDelegate: NSObject, NSApplicationDelegate {
         let mainMenu = NSMenu()
         let mainMenuItem = NSMenuItem()
         let subMenu = NSMenu(title: "MainMenu")
+        let newMenuItem = NSMenuItem(
+            title: "Create New Screen",
+            action: #selector(spawnNewInstance),
+            keyEquivalent: "n"
+        )
+        subMenu.addItem(newMenuItem)
         let quitMenuItem = NSMenuItem(
             title: "Quit",
             action: #selector(NSApp.terminate),
@@ -42,4 +49,11 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     func applicationShouldTerminateAfterLastWindowClosed(_: NSApplication) -> Bool {
         return true
     }
+
+    @objc func spawnNewInstance() {
+        let task = Process()
+        task.launchPath = "/usr/bin/open"
+        task.arguments = ["-n", Bundle.main.bundlePath]
+        try? task.run()
+    }
 }

DeskPad/Frontend/Screen/ScreenViewController.swift

@@ -20,16 +20,19 @@ class ScreenViewController: SubscriberViewController<ScreenViewData>, NSWindowDe
 
     override func viewDidLoad() {
         super.viewDidLoad()
+        SerialNumberManager.shared.claimSerial()
+        let serial = SerialNumberManager.shared.claimedSerial ?? 0x0001
+        title = "Screen \(serial)"
 
         let descriptor = CGVirtualDisplayDescriptor()
         descriptor.setDispatchQueue(DispatchQueue.main)
-        descriptor.name = "DeskPad Display"
+        descriptor.name = "DeskPad Display \(serial)"
         descriptor.maxPixelsWide = 3840
         descriptor.maxPixelsHigh = 2160
         descriptor.sizeInMillimeters = CGSize(width: 1600, height: 1000)
         descriptor.productID = 0x1234
         descriptor.vendorID = 0x3456
-        descriptor.serialNum = 0x0001
+        descriptor.serialNum = serial
 
         let display = CGVirtualDisplay(descriptor: descriptor)
         store.dispatch(ScreenViewAction.setDisplayID(display.displayID))
@@ -120,4 +123,8 @@ class ScreenViewController: SubscriberViewController<ScreenViewData>, NSWindowDe
         )
         store.dispatch(MouseLocationAction.requestMove(toPoint: onScreenPoint))
     }
+
+    func applicationWillTerminate(_: Notification) {
+        SerialNumberManager.shared.releaseSerial()
+    }
 }

DeskPad/SerialNumberManager.swift

@@ -0,0 +1,84 @@
+import Cocoa
+
+class SerialNumberManager {
+    static let shared = SerialNumberManager()
+
+    private(set) var claimedSerial: UInt32?
+
+    private let fileCoordinator = NSFileCoordinator()
+    private let registryURL: URL
+
+    private init() {
+        let fileManager = FileManager.default
+        guard let appSupportURL = fileManager.urls(for: .applicationSupportDirectory, in: .userDomainMask).first else {
+            fatalError("Could not find Application Support directory.")
+        }
+
+        let bundleID = Bundle.main.bundleIdentifier ?? "com.example.YourAppBundleID"
+        let appDirectoryURL = appSupportURL.appendingPathComponent(bundleID, isDirectory: true)
+
+        try? fileManager.createDirectory(at: appDirectoryURL, withIntermediateDirectories: true, attributes: nil)
+
+        registryURL = appDirectoryURL.appendingPathComponent("serials.json", isDirectory: false)
+    }
+
+    func claimSerial() {
+        var coordinationError: NSError?
+
+        fileCoordinator.coordinate(writingItemAt: registryURL, options: .forMerging, error: &coordinationError) { url in
+            var activeSerials = [pid_t: UInt32]()
+            if let data = try? Data(contentsOf: url),
+               let decoded = try? JSONDecoder().decode([pid_t: UInt32].self, from: data)
+            {
+                activeSerials = decoded
+            }
+
+            for (pid, _) in activeSerials {
+                if NSRunningApplication(processIdentifier: pid) == nil {
+                    activeSerials.removeValue(forKey: pid)
+                }
+            }
+
+            let usedSerials = Set<UInt32>(activeSerials.values)
+            var newSerial: UInt32 = 1
+            while usedSerials.contains(newSerial) {
+                newSerial += 1
+            }
+
+            let myPID = ProcessInfo.processInfo.processIdentifier
+            activeSerials[myPID] = newSerial
+            self.claimedSerial = newSerial
+
+            if let data = try? JSONEncoder().encode(activeSerials) {
+                try? data.write(to: url, options: .atomic)
+            }
+        }
+
+        if let error = coordinationError {
+            print("🚨 Coordination Error during claim: \(error)")
+        }
+    }
+
+    func releaseSerial() {
+        var coordinationError: NSError?
+
+        fileCoordinator.coordinate(writingItemAt: registryURL, options: .forMerging, error: &coordinationError) { url in
+            guard let data = try? Data(contentsOf: url),
+                  var activeSerials = try? JSONDecoder().decode([pid_t: Int].self, from: data)
+            else {
+                return
+            }
+
+            let myPID = ProcessInfo.processInfo.processIdentifier
+            if activeSerials.removeValue(forKey: myPID) != nil {
+                if let data = try? JSONEncoder().encode(activeSerials) {
+                    try? data.write(to: url, options: .atomic)
+                }
+            }
+        }
+
+        if let error = coordinationError {
+            print("🚨 Coordination Error during release: \(error)")
+        }
+    }
+}