import SwiftUI
import LChatCore

// 🤖 iOS host for Eleven's native onboarding conversation (setup / welcome):
// owns the model's lifecycle and wires the finish chips' thread hop into the
// navigation path. Models are cached per thread so leaving and returning
// resumes the same run (the flow itself also resumes from recorded state).
struct ElevenChatScreen: View {
    let instance: SavedInstance
    let thread: ChatThread
    @ObservedObject var store: ThreadStore
    @Binding var path: [Route]
    @State private var model: ElevenConversationModel?
    @State private var showDiscover = false
    @State private var showQuickForm = false
    @State private var showSignIn = false
    /// The key/access step's "Sign in" chip presents the ordinary doors —
    /// its own model, so a sign-in taken here behaves exactly like one taken
    /// on the first-run screen (same adopt seam, same last-used marker).
    @StateObject private var signIn = HomeSignInModel()
    @ScaledMetric(relativeTo: .body) private var chatFontSize: CGFloat = 17
    @AppStorage("nativeTheme") private var themeName = "classic"

    var body: some View {
        Group {
            if let model {
                ElevenChatView(model: model, theme: .named(themeName))
                    .environment(\.chatFontSize, chatFontSize)
            } else {
                ProgressView()
            }
        }
        .navigationTitle(thread.title)
        .navigationBarTitleDisplayMode(.inline)
        .sheet(isPresented: $showDiscover) {
            // The community directory (shared view; web: showDiscover) — the
            // welcome finish's "Browse open groups" chip lands here.
            NavigationStack {
                DiscoverGroupsView(store: store) { id in
                    showDiscover = false
                    path.append(.thread(id))
                }
            }
        }
        .sheet(isPresented: $showQuickForm) {
            // "Fill in a form instead" — the whole conversation's questions at
            // once; submitting fast-fills the flow's records and it resumes.
            if let model {
                ElevenQuickFormView(model: model)
            }
        }
        .sheet(isPresented: $showSignIn) {
            // iOS 18 gates the ceremony (PRF); below it the chip is never
            // offered at all — signInToEleven stays nil, so the flow records
            // where the key actually lives instead of pitching.
            if #available(iOS 18.0, *) {
                NavigationStack { SignInFirstRun(model: signIn) }
            }
        }
        // The doors don't dismiss themselves (first-run swaps the whole
        // screen instead); close on a landed sign-in, and the conversation's
        // settle picks the session up from there.
        .onChange(of: signIn.phase) { _, phase in
            if phase.signedIn { showSignIn = false }
        }
        .onAppear {
            guard model == nil else { return }
            let m = ElevenConversationCache.shared.model(for: instance, thread: thread,
                                                         myUserId: store.myUserId)
            m?.openQuickForm = { showQuickForm = true }
            m?.openThread = { id in path.append(.thread(id)) }
            m?.openAdmin = {
                Task { @MainActor in
                    if let id = await store.openOrCreateAppThread(app: "admin", title: "Admin") {
                        path.append(.thread(id))
                    }
                }
            }
            m?.openDiscover = { showDiscover = true }
            if #available(iOS 18.0, *) {
                m?.signInToEleven = { showSignIn = true }
            }
            // Outgoing payloads stamp the SavedInstance's name — persist a
            // flow rename, the way ServerSettingsSheet persists a manual one.
            m?.onNameSet = { name in
                var instances = InstancesStore.load()
                if let i = instances.firstIndex(where: { $0.id == instance.id }) {
                    instances[i].screenName = name
                    InstancesStore.save(instances)
                }
            }
            m?.start(roster: store.roster, threads: store.threads)
            model = m
        }
    }
}