import SwiftUI

struct SettingsView: View {
    @ObservedObject var settings: SettingsStore
    /// The current voice session, directly observed so the Apply button's
    /// disabled state and help text update reactively when the session
    /// transitions (e.g. `.tearingDown` → `.failed`).
    @ObservedObject var session: VoiceSession
    /// Local draft of the server URL. Only written to `settings` when the user
    /// explicitly applies a value that passes validation — keystrokes never
    /// reach storage or the network layer.
    @State private var urlText: String = ""
    @State private var urlError: String?
    @State private var showVoicePicker = false
    @State private var savedURLConfirmation: String?
    @FocusState private var urlFocused: Bool
    init(settings: SettingsStore, session: VoiceSession) {
        self.settings = settings
        self.session = session
    }

    /// Whether the current session is safe to replace. Apply is permitted for
    /// `.idle` (no active call) and `.failed` (fully torn down after failure —
    /// the user needs to correct an unreachable server without relaunching).
    /// Disabled during `.tearingDown`, `.connecting`, `.waitingAgent`, and
    /// `.ready` to avoid disconnecting an active call or racing cleanup.
    private var canApplyServerURL: Bool {
        session.state == .idle || session.state.isFailed
    }

    var body: some View {
        Form {
            Section {
                Button {
                    showVoicePicker = true
                } label: {
                    LabeledContent("Speaking voice", value: Voices.display(for: settings.voiceID) ?? settings.voiceID)
                }
                Picker("Conversation mode", selection: $settings.textMode) {
                    Text("Voice").tag(false)
                    Text("Type · Microphone off").tag(true)
                }
            } header: {
                Text("Make it yours")
            } footer: {
                Text("Voice and typing preferences are saved on this iPhone. You can switch modes from the Talk tab.")
            }
            Section {
                Text("Server URL")
                    .font(.footnote.weight(.semibold))
                    .foregroundStyle(Nearlight.quiet)
                TextField(SettingsStore.defaultServerURL, text: $urlText)
                    .keyboardType(.URL)
                    .autocorrectionDisabled()
                    .textInputAutocapitalization(.never)
                    .accessibilityLabel("Server URL")
                    .focused($urlFocused)
                    .onAppear { urlText = settings.serverURL }
                    .onChange(of: urlText) { _, newValue in
                        // Keep confirmation across the asynchronous onChange
                        // caused by successful whitespace normalization.
                        guard newValue != savedURLConfirmation else { return }
                        savedURLConfirmation = nil
                        urlError = nil
                    }
                    .overlay(alignment: .trailing) {
                        if savedURLConfirmation != nil {
                            Image(systemName: "checkmark.circle")
                                .foregroundStyle(Nearlight.quiet)
                                .padding(.trailing, 8)
                                .accessibilityHidden(true)
                        }
                    }
                if let urlError {
                    Label(urlError, systemImage: "exclamationmark.circle")
                        .font(.footnote)
                        .foregroundStyle(Nearlight.alert)
                        .accessibilityIdentifier("settings.server.error")
                } else if savedURLConfirmation != nil {
                    Text("Server address saved.")
                        .font(.footnote)
                        .foregroundStyle(Nearlight.quiet)
                        .accessibilityIdentifier("settings.server.saved")
                }
                Button("Save server address") { applyServerURL() }
                    .disabled(!canApplyServerURL || urlText.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty || urlText == settings.serverURL)
                if !canApplyServerURL {
                    Text(session.state == .tearingDown
                         ? "Waiting for failure cleanup to finish…"
                         : "End the conversation before changing servers.")
                        .font(.footnote)
                        .foregroundStyle(Nearlight.quiet)
                }
                NavigationLink("Connection test") {
                    ConnectionTestView(settings: settings, bearerToken: session.bootstrapBearerToken)
                }
            } header: {
                Text("Connection")
            } footer: {
                Text("Hope runs on your own server. Your iPhone needs to be on the same network or a network that can reach it.")
            }
        }
        .navigationTitle("Settings")
        .navigationBarTitleDisplayMode(.inline)
        .scrollContentBackground(.hidden)
        .background(Nearlight.ground)
        .tint(Nearlight.rosewood)
        .sheet(isPresented: $showVoicePicker) {
            VoicePickerView(settings: settings, session: session)
        }

    }

    /// Validates the draft and persists it only on success. On failure the
    /// draft stays in the field with an inline error; `settings.serverURL` is
    /// left untouched so the active session keeps using its original URL.
    /// Guarded: only applies when the session is idle (no active call).
    private func applyServerURL() {
        savedURLConfirmation = nil
        guard canApplyServerURL else {
            urlError = "End the conversation before changing servers."
            return
        }
        let trimmed = urlText.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmed.isEmpty else {
            urlError = "Enter a server URL."
            return
        }
        switch ServerConfig.parse(trimmed) {
        case .success:
            settings.serverURL = trimmed
            urlText = trimmed
            urlError = nil
            savedURLConfirmation = trimmed
            urlFocused = false
        case .failure(let error):
            urlError = error.localizedDescription
            urlFocused = true
        }
    }
}

struct VoicePickerView: View {
    @ObservedObject var settings: SettingsStore
    @ObservedObject var session: VoiceSession
    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationStack {
            List {
                ForEach(Voices.all, id: \.id) { voice in
                    Button {
                        settings.voiceID = voice.id
                        Task { await session.selectVoice(voice.id) }
                        dismiss()
                    } label: {
                        HStack {
                            Text(voice.displayName)
                            if settings.voiceID == voice.id {
                                Spacer()
                                Image(systemName: "checkmark")
                                    .foregroundStyle(Nearlight.rosewood)
                            }
                        }
                    }
                    .accessibilityAddTraits(settings.voiceID == voice.id ? .isSelected : [])
                }
            }
            .navigationTitle("Voice")
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") { dismiss() }
                }
            }
        }
    }
}

#Preview {
    let previewSettings = SettingsStore()
    guard case .success(let previewConfig) = ServerConfig.parse(SettingsStore.defaultServerURL) else {
        return AnyView(Text("Invalid default server URL"))
    }
    let previewSession = VoiceSession(config: previewConfig, tokenClient: TokenClient(config: previewConfig), settings: previewSettings)
    return AnyView(NavigationStack {
        SettingsView(settings: previewSettings, session: previewSession)
    })
}