import Cocoa

// MARK: - Terminal Session
class TerminalSession: NSObject, NSTextViewDelegate {
    var textView: NSTextView!
    var shellTask: Process?
    var inputPipe: Pipe?
    var outputPipe: Pipe?
    var promptPosition = 0
    var sessionID: UUID
    var title: String
    private var outputBuffer: String = ""
    
    init(title: String = "Terminal") {
        self.sessionID = UUID()
        self.title = title
        super.init()
    }
    
    func setupTextView(frame: NSRect) {
        let scrollView = NSScrollView(frame: frame)
        scrollView.autoresizingMask = [.width, .height]
        scrollView.hasVerticalScroller = true
        
        textView = NSTextView(frame: scrollView.bounds)
        textView.autoresizingMask = [.width, .height]
        applyTheme()
        textView.isEditable = true
        textView.delegate = self
        textView.font = NSFont(name: TerminalSettings.shared.fontName, size: TerminalSettings.shared.fontSize)
        
        scrollView.documentView = textView
    }
    
    func applyTheme() {
        let theme = TerminalSettings.shared.theme
        textView?.backgroundColor = theme.background
        textView?.textColor = theme.foreground
        textView?.insertionPointColor = theme.cursor
        textView?.selectedTextAttributes = [
            .backgroundColor: theme.selection
        ]
    }
    
    func startShell() {
        shellTask = Process()
        inputPipe = Pipe()
        outputPipe = Pipe()
        
        shellTask?.executableURL = URL(fileURLWithPath: "/bin/zsh")
        shellTask?.arguments = ["-i"]
        shellTask?.environment = [
            "TERM": "xterm-256color",
            "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()
            appendText("Enhanced Terminal v2.0\n")
            appendText("Type 'help' for commands, Cmd+K for AI, Cmd+P for snippets\n\n")
            showPrompt()
        } catch {
            appendText("Error starting shell: \(error)\n")
        }
    }
    
    func showPrompt() {
        appendText("$ ")
        promptPosition = textView.string.count
    }
    
    func appendText(_ text: String) {
        let cleaned = cleanANSI(text)
        let theme = TerminalSettings.shared.theme
        let attr = NSAttributedString(string: cleaned, attributes: [
            .foregroundColor: theme.foreground,
            .font: NSFont(name: TerminalSettings.shared.fontName, size: TerminalSettings.shared.fontSize) ?? NSFont.monospacedSystemFont(ofSize: TerminalSettings.shared.fontSize, weight: .regular)
        ])
        textView.textStorage?.append(attr)
        textView.scrollToEndOfDocument(nil)
    }
    
    private func cleanANSI(_ text: String) -> String {
        return 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)
    }
    
    func textView(_ textView: NSTextView, shouldChangeTextIn range: NSRange, replacementString: String?) -> Bool {
        if range.location < promptPosition {
            return false
        }
        
        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 == "help" {
            showHelp()
            showPrompt()
            return
        }
        
        if !trimmed.isEmpty {
            HistoryManager.shared.addCommand(trimmed)
            if let data = (trimmed + "\n").data(using: .utf8) {
                inputPipe?.fileHandleForWriting.write(data)
            }
        }
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) { [weak self] in
            self?.showPrompt()
        }
    }
    
    private func showHelp() {
        appendText("""
        Enhanced Terminal Commands:
        - Cmd+T: New tab
        - Cmd+W: Close tab
        - Cmd+D: Split pane vertically
        - Cmd+Shift+D: Split pane horizontally
        - Cmd+K: AI command generation
        - Cmd+P: Open snippets
        - Cmd+R: Search history
        - Cmd+,: Settings
        - clear: Clear screen
        - exit: Quit application
        
        """)
    }
    
    func cleanup() {
        shellTask?.terminate()
        outputPipe?.fileHandleForReading.readabilityHandler = nil
    }
    
    deinit {
        cleanup()
    }
}

// MARK: - Tab Manager
class TabManager {
    var tabs: [TerminalSession] = []
    var currentIndex: Int = 0
    
    func addTab(title: String = "Terminal") -> TerminalSession {
        let session = TerminalSession(title: title)
        tabs.append(session)
        currentIndex = tabs.count - 1
        return session
    }
    
    func removeTab(at index: Int) {
        guard index < tabs.count else { return }
        tabs[index].cleanup()
        tabs.remove(at: index)
        if currentIndex >= tabs.count {
            currentIndex = max(0, tabs.count - 1)
        }
    }
    
    func selectTab(at index: Int) {
        guard index < tabs.count else { return }
        currentIndex = index
    }
    
    func getCurrentSession() -> TerminalSession? {
        guard currentIndex < tabs.count else { return nil }
        return tabs[currentIndex]
    }
}