import AppKit
import CallsKit
import SwiftUI

/// Offline visual fixtures of the shipping lobby. Only built into the test executable.
///
/// Every model reads its server from a throwaway defaults suite, so a
/// fixture neither sees nor changes the setting of whoever runs it.
@MainActor enum LobbySnapshots {
  static func save(to directory: String) async throws {
    NSApplication.shared.setActivationPolicy(.prohibited)
    let folder = URL(fileURLWithPath: directory)
    try FileManager.default.createDirectory(at: folder, withIntermediateDirectories: true)
    let suite = "CallsInterop.LobbySnapshots"
    guard let defaults = UserDefaults(suiteName: suite) else { return }
    defaults.removePersistentDomain(forName: suite)
    defer { defaults.removePersistentDomain(forName: suite) }
    for scheme in [ColorScheme.light, .dark] {
      for state in [
        "welcome", "signin", "home", "ready", "error", "expired", "link-other", "visiting",
      ] {
        let model = CallsModel(defaults: defaults)
        if state == "signin" {
          model.authenticating = true
          model.confirmationCode = "A1B2-C3D4"
          model.signin = URL(string: "https://example.invalid")
        }
        if state == "home" {
          model.signedIn = true
          model.canStart = true
          model.origin = "https://calls.oficina.works"
        }
        if state == "ready" {
          model.signedIn = true
          model.canStart = true
          model.origin = "https://calls.oficina.works"
          model.room = "team-catchup"
        }
        if state == "error" {
          model.error = "Could not reach calls.oficina.works. Choose Sign in to try again."
        }
        if state == "expired" {
          model.error = "Your sign-in to calls.oficina.works has ended. Choose Sign in to continue."
        }
        if state == "link-other" {
          model.pendingLink = "https://calls.example.org/j/invitation"
        }
        if state == "visiting" {
          model.signedIn = true
          model.visiting = true
          model.origin = "https://calls.example.org"
          model.room = "abc123"
        }
        try await render(
          CallsLobby(model: model), scheme: scheme, size: CGSize(width: 900, height: 720),
          to: folder.appendingPathComponent("\(state)-\(name(scheme)).png"))
      }
      // The same signed-out home at iPhone width, with the Change button
      // the phone's settings sheet is reached by.
      try await render(
        CallsLobby(model: CallsModel(defaults: defaults), openSettings: {}), scheme: scheme,
        size: CGSize(width: 390, height: 780),
        to: folder.appendingPathComponent("phone-welcome-\(name(scheme)).png"))
      try await render(
        GuestJoinView(model: CallsModel(defaults: defaults)) {}, scheme: scheme, size: nil,
        to: folder.appendingPathComponent("guest-\(name(scheme)).png"))
      try await render(
        GuestJoinView(
          model: CallsModel(defaults: defaults), link: "calls.example.org/settings", problem: true
        ) {}, scheme: scheme, size: nil,
        to: folder.appendingPathComponent("guest-invalid-\(name(scheme)).png"))
      try await render(
        ServerSettingsSheet(model: CallsModel(defaults: defaults)) {}, scheme: scheme,
        size: CGSize(width: 390, height: 520),
        to: folder.appendingPathComponent("phone-settings-\(name(scheme)).png"))
    }
    try await SettingsSnapshots.save(to: folder)
    try await MiniWindowSnapshots.save(to: folder)
    try await CallSnapshots.save(to: folder)
  }

  static func name(_ scheme: ColorScheme) -> String { scheme == .dark ? "dark" : "light" }

  /// Draws a view off screen into a PNG. A nil size takes the view's own.
  static func render(_ content: some View, scheme: ColorScheme, size: CGSize?, to file: URL)
    async throws
  {
    let view = NSHostingView(
      rootView: content.background(scheme == .dark ? Color(white: 0.12) : Color(white: 0.98))
        .environment(\.colorScheme, scheme))
    let frame = size ?? view.fittingSize
    view.frame.size = frame
    let window = NSWindow(
      contentRect: NSRect(origin: CGPoint(x: -2000, y: -2000), size: frame),
      styleMask: [.borderless], backing: .buffered, defer: false)
    window.isReleasedWhenClosed = false
    window.appearance = NSAppearance(named: scheme == .dark ? .darkAqua : .aqua)
    window.contentView = view
    window.orderFront(nil)
    try await Task.sleep(for: .milliseconds(300))
    view.layoutSubtreeIfNeeded()
    guard let bitmap = view.bitmapImageRepForCachingDisplay(in: view.bounds) else {
      throw CocoaError(.fileWriteUnknown)
    }
    view.cacheDisplay(in: view.bounds, to: bitmap)
    guard let data = bitmap.representation(using: .png, properties: [:]) else {
      throw CocoaError(.fileWriteUnknown)
    }
    try data.write(to: file)
    window.close()
  }
}