import AppKit
import Foundation

struct CompanionBootstrap: Codable {
  struct Gateway: Codable {
    let url: String
    let token: String?
  }
  struct Node: Codable {
    let nodeId: String
    let role: String
    let platform: String
    let capabilities: [String]
  }
  struct Runtime: Codable {
    let heartbeatSeconds: Int
    let handoffTimeoutMs: Int
    let autoReconnect: Bool
  }
  let schemaVersion: Int
  let generatedAt: String
  let gateway: Gateway
  let node: Node
  let runtime: Runtime
}

final class CompanionProcessController {
  private var process: Process?
  private var isRunning = false
  private(set) var lastError: String?
  private let bootstrap: CompanionBootstrap

  init(bootstrap: CompanionBootstrap) {
    self.bootstrap = bootstrap
  }

  func start() {
    guard process == nil else { return }
    let proc = Process()
    proc.executableURL = URL(fileURLWithPath: "/usr/bin/env")
    var args: [String] = [
      "flynn",
      "companion",
      "--url", bootstrap.gateway.url,
      "--node-id", bootstrap.node.nodeId,
      "--role", bootstrap.node.role,
      "--platform", bootstrap.node.platform,
      "--heartbeat", String(bootstrap.runtime.heartbeatSeconds),
      "--handoff-timeout", String(bootstrap.runtime.handoffTimeoutMs),
    ]
    if let token = bootstrap.gateway.token, !token.isEmpty {
      args += ["--token", token]
    }
    for capability in bootstrap.node.capabilities {
      args += ["--capability", capability]
    }
    if !bootstrap.runtime.autoReconnect {
      args.append("--once")
    }
    proc.arguments = args
    proc.terminationHandler = { [weak self] p in
      DispatchQueue.main.async {
        self?.process = nil
        self?.isRunning = false
        if p.terminationStatus != 0 {
          self?.lastError = "companion exited with status \(p.terminationStatus)"
        }
      }
    }

    do {
      try proc.run()
      process = proc
      isRunning = true
      lastError = nil
    } catch {
      lastError = error.localizedDescription
      process = nil
      isRunning = false
    }
  }

  func stop() {
    process?.terminate()
    process = nil
    isRunning = false
  }

  func runHandoff(message: String) {
    guard !message.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else { return }
    let proc = Process()
    proc.executableURL = URL(fileURLWithPath: "/usr/bin/env")
    var args: [String] = [
      "flynn",
      "companion",
      "--once",
      "--url", bootstrap.gateway.url,
      "--node-id", bootstrap.node.nodeId,
      "--role", bootstrap.node.role,
      "--platform", bootstrap.node.platform,
      "--handoff-timeout", String(bootstrap.runtime.handoffTimeoutMs),
      "--handoff", message,
    ]
    if let token = bootstrap.gateway.token, !token.isEmpty {
      args += ["--token", token]
    }
    proc.arguments = args
    do {
      try proc.run()
    } catch {
      lastError = "handoff failed: \(error.localizedDescription)"
    }
  }

  var running: Bool { isRunning }
}

final class AppDelegate: NSObject, NSApplicationDelegate {
  private var statusItem: NSStatusItem!
  private var startItem: NSMenuItem!
  private var stopItem: NSMenuItem!
  private var handoffItem: NSMenuItem!
  private var errorItem: NSMenuItem!
  private var controller: CompanionProcessController!
  private var refreshTimer: Timer?

  func applicationDidFinishLaunching(_ notification: Notification) {
    let bootstrap = Self.loadBootstrap()
    controller = CompanionProcessController(bootstrap: bootstrap)
    statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
    let menu = NSMenu()
    startItem = NSMenuItem(title: "Start Companion", action: #selector(startCompanion), keyEquivalent: "s")
    stopItem = NSMenuItem(title: "Stop Companion", action: #selector(stopCompanion), keyEquivalent: "x")
    handoffItem = NSMenuItem(title: "Send Handoff...", action: #selector(sendHandoff), keyEquivalent: "h")
    errorItem = NSMenuItem(title: "Last error: (none)", action: nil, keyEquivalent: "")
    errorItem.isEnabled = false
    menu.addItem(startItem)
    menu.addItem(stopItem)
    menu.addItem(handoffItem)
    menu.addItem(NSMenuItem.separator())
    menu.addItem(errorItem)
    menu.addItem(NSMenuItem.separator())
    menu.addItem(NSMenuItem(title: "Quit", action: #selector(quitApp), keyEquivalent: "q"))
    startItem.target = self
    stopItem.target = self
    handoffItem.target = self
    statusItem.menu = menu
    refreshUI()
    refreshTimer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { [weak self] _ in
      self?.refreshUI()
    }
  }

  func applicationWillTerminate(_ notification: Notification) {
    refreshTimer?.invalidate()
    controller.stop()
  }

  @objc private func startCompanion() {
    controller.start()
    refreshUI()
  }

  @objc private func stopCompanion() {
    controller.stop()
    refreshUI()
  }

  @objc private func sendHandoff() {
    let alert = NSAlert()
    alert.messageText = "Companion Handoff"
    alert.informativeText = "Send a one-shot handoff message through Flynn companion."
    let input = NSTextField(frame: NSRect(x: 0, y: 0, width: 280, height: 24))
    input.placeholderString = "message"
    alert.accessoryView = input
    alert.addButton(withTitle: "Send")
    alert.addButton(withTitle: "Cancel")
    let response = alert.runModal()
    if response == .alertFirstButtonReturn {
      controller.runHandoff(message: input.stringValue)
      refreshUI()
    }
  }

  @objc private func quitApp() {
    NSApplication.shared.terminate(nil)
  }

  private func refreshUI() {
    if controller.running {
      statusItem.button?.title = "F*"
      startItem.isEnabled = false
      stopItem.isEnabled = true
    } else {
      statusItem.button?.title = controller.lastError == nil ? "F" : "F!"
      startItem.isEnabled = true
      stopItem.isEnabled = false
    }
    let errorText = controller.lastError ?? "(none)"
    errorItem.title = "Last error: \(errorText)"
  }

  static func loadBootstrap() -> CompanionBootstrap {
    guard let url = Bundle.module.url(forResource: "companion.bootstrap", withExtension: "json"),
          let data = try? Data(contentsOf: url),
          let decoded = try? JSONDecoder().decode(CompanionBootstrap.self, from: data)
    else {
      fatalError("Failed to load companion.bootstrap.json resource")
    }
    return decoded
  }
}

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