import Cocoa

class TerminalViewController: NSViewController, NSTextViewDelegate {
    var textView: NSTextView!
    var shellTask: Process?
    var inputPipe: Pipe?
    var outputPipe: Pipe?
    var promptPosition = 0
    
    override func loadView() {
        let scrollView = NSScrollView(frame: NSRect(x: 0, y: 0, width: 800, height: 600))
        scrollView.autoresizingMask = [.width, .height]
        scrollView.hasVerticalScroller = true
        
        textView = NSTextView(frame: scrollView.bounds)
        textView.autoresizingMask = [.width, .height]
        textView.backgroundColor = .black
        textView.textColor = .green
        textView.font = NSFont.monospacedSystemFont(ofSize: 14, weight: .regular)
        textView.isEditable = true
        textView.delegate = self
        
        scrollView.documentView = textView
        self.view = scrollView
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        appendText("Simple Terminal v1.0\n")
        appendText("Type commands and press Enter\n")
        appendText("Type 'exit' to quit\n\n")
        startShell()
    }
    
    func startShell() {
        shellTask = Process()
        inputPipe = Pipe()
        outputPipe = Pipe()
        
        shellTask?.executableURL = URL(fileURLWithPath: "/bin/zsh")
        shellTask?.arguments = ["-i"]
        shellTask?.environment = [
            "TERM": "dumb",
            "PS1": "$ ",
            "PATH": ProcessInfo.processInfo.environment["PATH"] ?? "/usr/bin:/bin:/usr/sbin:/sbin",
            "HOME": ProcessInfo.processInfo.environment["HOME"] ?? ""
        ]
        shellTask?.standardInput = inputPipe
        shellTask?.standardOutput = outputPipe
        shellTask?.standardError = outputPipe
        
        outputPipe?.fileHandleForReading.readabilityHandler = { [weak self] handle in
            let data = handle.availableData
            if data.count > 0, let output = String(data: data, encoding: .utf8) {
                DispatchQueue.main.async {
                    self?.appendText(output)
                }
            }
        }
        
        do {
            try shellTask?.run()
        } catch {
            appendText("Error starting shell: \(error)\n")
        }
        
        showPrompt()
    }
    
    func showPrompt() {
        appendText("$ ")
        promptPosition = textView.string.count
    }
    
    func appendText(_ text: String) {
        // Strip ANSI escape codes for simpler display
        let cleaned = text.replacingOccurrences(of: "\u{1B}\\[[0-9;]*[a-zA-Z]", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\u{1B}\\][0-9];[^\u{07}]*\u{07}", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\\]633;[^\u{07}]*\u{07}", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\\]697;[^\u{07}]*\u{07}", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\\]1;[^\u{07}]*\u{07}", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\\]2;[^\u{07}]*\u{07}", with: "", options: .regularExpression)
            .replacingOccurrences(of: "\\]7;[^\u{07}]*\\\\", with: "", options: .regularExpression)
        
        let attr = NSAttributedString(string: cleaned, attributes: [
            .foregroundColor: NSColor.green,
            .font: NSFont.monospacedSystemFont(ofSize: 14, weight: .regular)
        ])
        textView.textStorage?.append(attr)
        textView.scrollToEndOfDocument(nil)
    }
    
    func textView(_ textView: NSTextView, shouldChangeTextIn range: NSRange, replacementString: String?) -> Bool {
        // Don't allow editing before prompt
        if range.location < promptPosition {
            return false
        }
        
        // Handle Enter key
        if replacementString == "\n" {
            let command = String(textView.string.suffix(from: textView.string.index(textView.string.startIndex, offsetBy: promptPosition)))
            executeCommand(command)
            return false
        }
        
        return true
    }
    
    func executeCommand(_ command: String) {
        appendText("\n")
        
        let trimmed = command.trimmingCharacters(in: .whitespacesAndNewlines)
        
        if trimmed == "exit" {
            NSApp.terminate(nil)
            return
        }
        
        if trimmed == "clear" {
            textView.string = ""
            showPrompt()
            return
        }
        
        if !trimmed.isEmpty {
            if let data = (trimmed + "\n").data(using: .utf8) {
                inputPipe?.fileHandleForWriting.write(data)
            }
        }
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            self?.showPrompt()
        }
    }
    
    deinit {
        shellTask?.terminate()
    }
}

class AppDelegate: NSObject, NSApplicationDelegate {
    var window: NSWindow!
    
    func applicationDidFinishLaunching(_ notification: Notification) {
        window = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 800, height: 600),
            styleMask: [.titled, .closable, .miniaturizable, .resizable],
            backing: .buffered,
            defer: false
        )
        window.center()
        window.title = "Simple Terminal"
        
        let viewController = TerminalViewController()
        window.contentViewController = viewController
        
        window.makeKeyAndOrderFront(nil)
        NSApp.activate(ignoringOtherApps: true)
    }
    
    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
        return true
    }
}

let app = NSApplication.shared
let delegate = AppDelegate()
app.delegate = delegate
app.run()