import SwiftUI

#if os(iOS)
  import UIKit
#else
  import AppKit
#endif

/// Call → Copy Invite Link (⌘⇧I): the meeting's invitation on the
/// clipboard without opening the share sheet.
///
/// It asks the server the way the Share button does — `POST
/// /m/{sqid}/share`, which hands a member the meeting's current sealed
/// invitation, and mints one only if there is none. It never replaces or
/// revokes a link (see store.shareLink and
/// TestShareReusesSealedInvitationAndPreservesLegacyLinks).
public enum InviteLinkCopy {
  public enum Rule: Equatable, Sendable {
    /// The menu item is off: there is no call to invite anyone to.
    case unavailable
    /// On, and a press copies the link.
    case copy
    /// On, and a press says why there is nothing to copy, rather than a
    /// beep: a guest cannot share a meeting, and before the meeting has
    /// said who you are, nobody knows yet.
    case explain(String)
  }

  public static let shortcut = KeyboardShortcut("i", modifiers: [.command, .shift])
  public static let title = "Copy Invite Link"

  /// Whether ⌘⇧I does anything, and what.
  public static func rule(inCall: Bool, phase: String?, standing: String) -> Rule {
    guard inCall, phase != "ended" else { return .unavailable }
    switch standing {
    case "member": return .copy
    case "": return .explain("The invite link isn’t ready yet. Try again in a moment.")
    default: return .explain("Only members of this meeting can share its invite link.")
    }
  }
}

extension Call {
  /// Copies the meeting's invite link, or says why not, in `notice` (the
  /// brief message over the stage) and to VoiceOver.
  public func copyInviteLink(inCall: Bool = true) async {
    switch InviteLinkCopy.rule(inCall: inCall, phase: state?.phase, standing: standing) {
    case .unavailable: return
    case .explain(let why): say(why)
    case .copy:
      if invitationURL == nil { await loadInvitation() }
      guard let url = invitationURL else {
        say("Could not get the invite link. Try again.")
        return
      }
      #if os(iOS)
        UIPasteboard.general.url = url
      #else
        NSPasteboard.general.clearContents()
        NSPasteboard.general.setString(url.absoluteString, forType: .string)
      #endif
      say("Invite link copied")
    }
  }

  /// A short message over the call that goes by itself: never a dialog.
  func say(_ text: String) {
    toastSerial += 1
    let serial = toastSerial
    toast = text
    AccessibilityNotification.Announcement(text).post()
    Task { @MainActor [weak self] in
      try? await Task.sleep(for: .seconds(2.5))
      guard let self, self.toastSerial == serial else { return }
      self.toast = nil
    }
  }
}

/// The call's brief message ("Invite link copied"), over the stage.
/// Announced when it is set, so this is hidden from VoiceOver.
public struct CallToast: View {
  @ObservedObject private var call: Call
  public init(call: Call) { self.call = call }
  public var body: some View {
    VStack {
      if let text = call.toast {
        Label(text, systemImage: text == "Invite link copied" ? "link" : "info.circle")
          .font(.callout.weight(.medium))
          .padding(.horizontal, 14).padding(.vertical, 8)
          .background(.regularMaterial, in: Capsule())
          .shadow(color: .black.opacity(0.2), radius: 8, y: 2)
          .transition(.opacity)
          .accessibilityHidden(true)
      }
    }
    .animation(.easeInOut(duration: 0.15), value: call.toast)
    .allowsHitTesting(false)
  }
}

/// The Call menu's items, in order, as data the app builds its menu from
/// and the tests can read: title and shortcut.
public enum CallMenuItem: CaseIterable, Sendable {
  case mute
  case copyInviteLink

  public func title(muted: Bool) -> String {
    switch self {
    case .mute: muted ? "Unmute Microphone" : "Mute Microphone"
    case .copyInviteLink: InviteLinkCopy.title
    }
  }

  public var shortcut: KeyboardShortcut {
    switch self {
    case .mute: KeyboardShortcut("m", modifiers: [.command, .shift])
    case .copyInviteLink: InviteLinkCopy.shortcut
    }
  }
}