switchfocus.swift

#!/usr/bin/swift

import Cocoa

// Install with swiftc switchfocus.swift -o switchfocus

// Require command line arguments
guard CommandLine.arguments.count > 1 else {
    print("\(CommandLine.arguments[0]): Cycle focus between applications")
    print("Example Usage: \(CommandLine.arguments[0]) \"Code\" \"GoLand\" \"Xcode\"")
    exit(1)
}

// Get apps from command line arguments
let targetApps = Array(CommandLine.arguments.dropFirst())

func findNextActiveApp() {
    let workspace = NSWorkspace.shared
    let runningApps = workspace.runningApplications
    
    // Filter to only the specified apps that are running
    let activeApps = runningApps.filter { app in
        guard let name = app.localizedName else { return false }
        return targetApps.contains { name.contains($0) }
    }
    
    if activeApps.isEmpty {
        print("No matching applications from [\(targetApps.joined(separator: ", "))] are running")
        return
    }
    
    // Get current active app
    guard let currentApp = workspace.frontmostApplication else {
        print("Could not determine current active application")
        return
    }
    
    // Find current app's index
    let currentIndex = activeApps.firstIndex(where: { 
        $0.processIdentifier == currentApp.processIdentifier 
    }) ?? -1
    
    // Get next app to focus
    let nextIndex = (currentIndex + 1) % activeApps.count
    let nextApp = activeApps[nextIndex]
    
    // Activate next app
    let success = nextApp.activate()
    if success {
        print("Activated: \(nextApp.localizedName ?? "unknown")")
    }
}

findNextActiveApp()