import SwiftUI

struct ContentView: View {
    @ObservedObject var store: PlayerStore
    @State private var showForget = false

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(spacing: 24) {
                    Label(store.status, systemImage: store.connected ? "wifi" : "wifi.slash")
                        .font(.subheadline).foregroundStyle(.secondary)
                    if store.connection == nil {
                        PairingView(store: store, discovery: store.discovery)
                    } else {
                        PlayerView(store: store)
                        Text(store.connection?.endpoint.host ?? "")
                            .font(.caption).foregroundStyle(.secondary)
                        if !store.connected {
                            Button("Подключиться снова") { store.resume() }
                        }
                        Button("Забыть компьютер", role: .destructive) { showForget = true }
                            .font(.footnote)
                    }
                    if let error = store.error {
                        Text(error).font(.callout).foregroundStyle(.red).textSelection(.enabled)
                    }
                }.padding(24)
            }
            .background(Color(.systemGroupedBackground))
            .navigationTitle("MusicBridge")
            .confirmationDialog("Забыть этот компьютер?", isPresented: $showForget, titleVisibility: .visible) {
                Button("Забыть", role: .destructive) { store.forget() }
            } message: {
                Text("Токен будет удалён с iPhone. Чтобы отозвать доступ на ПК, удалите устройство в окне MusicBridge.")
            }
        }.tint(.indigo)
    }
}

private struct PairingView: View {
    @ObservedObject var store: PlayerStore
    @ObservedObject var discovery: DiscoveryStore
    @State private var endpoint = "https://"
    @State private var fingerprint = ""
    @State private var code = ""
    @State private var invitation = ""
    @State private var showScanner = false

    var body: some View {
        VStack(alignment: .leading, spacing: 18) {
            Image(systemName: "desktopcomputer.and.arrow.down")
                .font(.system(size: 48)).foregroundStyle(.indigo)
                .frame(maxWidth: .infinity).accessibilityHidden(true)
            Text("Музыка на ПК. Управление здесь.").font(.title2.bold())
            Text("Откройте сопряжение в MusicBridge на Windows. Подключите iPhone к той же домашней сети.")
                .foregroundStyle(.secondary)
            Button { showScanner = true } label: {
                Label("Сканировать QR с ПК", systemImage: "qrcode.viewfinder")
                    .frame(maxWidth: .infinity)
            }.buttonStyle(.borderedProminent).controlSize(.large).disabled(store.pairing)
            Text("QR заполнит адрес, отпечаток и код. Затем нажмите «Подключить компьютер».")
                .font(.caption).foregroundStyle(.secondary)
            DisclosureGroup("Найти ПК в сети") {
                VStack(alignment: .leading, spacing: 12) {
                    Text(discovery.message).font(.footnote).foregroundStyle(.secondary)
                    ForEach(discovery.computers) { computer in
                        Button {
                            endpoint = computer.endpoint
                            fingerprint = computer.fingerprint
                            code = ""
                            store.error = nil
                        } label: {
                            VStack(alignment: .leading) {
                                Label(computer.name, systemImage: "desktopcomputer")
                                Text(computer.endpoint).font(.caption)
                            }
                        }
                    }
                    Text("Выберите ПК, сверьте весь отпечаток с его экраном и введите свежий код сопряжения.")
                        .font(.caption).foregroundStyle(.secondary)
                    Button("Повторить поиск") { discovery.restart() }
                    Button("Настройки доступа к сети") {
                        if let url = URL(string: UIApplication.openSettingsURLString) { UIApplication.shared.open(url) }
                    }
                }.padding(.top, 8)
            }.disabled(store.pairing)
            Group {
                TextField("Адрес ПК: https://192.168.1.10:8765", text: $endpoint).keyboardType(.URL)
                TextField("SHA-256 сертификата с экрана ПК", text: $fingerprint, axis: .vertical)
                    .lineLimit(2...4).font(.system(.footnote, design: .monospaced))
                TextField("Восьмизначный код", text: $code).keyboardType(.numberPad)
            }.textFieldStyle(.roundedBorder).textInputAutocapitalization(.never).autocorrectionDisabled()
            Text("Сверьте весь отпечаток с экраном ПК перед подключением.").font(.caption).foregroundStyle(.secondary)
            Button {
                Task { await store.pair(endpoint: endpoint.trimmingCharacters(in: .whitespacesAndNewlines),
                                        fingerprint: fingerprint.trimmingCharacters(in: .whitespacesAndNewlines),
                                        code: code.trimmingCharacters(in: .whitespacesAndNewlines)) }
            } label: {
                HStack {
                    if store.pairing { ProgressView().tint(.white) }
                    Text(store.pairing ? "Сопряжение…" : "Подключить компьютер")
                }.frame(maxWidth: .infinity)
            }.buttonStyle(.borderedProminent).controlSize(.large).disabled(store.pairing)
            DisclosureGroup("Импорт строки из QR") {
                VStack(spacing: 12) {
                    TextField("musicbridge://pair?data=…", text: $invitation, axis: .vertical)
                        .lineLimit(3...5).textInputAutocapitalization(.never).autocorrectionDisabled()
                    Button("Заполнить из приглашения") {
                        importText(invitation)
                    }
                }.padding(.top, 12)
            }.disabled(store.pairing)
        }
        .sheet(isPresented: $showScanner) { QRScannerSheet(receive: importText) }
        .onAppear { consumeIncoming() }
        .onChange(of: store.incomingInvitation) { _, _ in consumeIncoming() }
    }

    private func consumeIncoming() {
        guard let text = store.incomingInvitation else { return }
        store.incomingInvitation = nil
        importText(text)
    }

    private func importText(_ text: String) {
        do {
            let parsed = try Invitation.parse(text.trimmingCharacters(in: .whitespacesAndNewlines))
            endpoint = parsed.endpoint
            fingerprint = parsed.certificateSha256
            code = parsed.code
            store.error = nil
        } catch { store.error = error.localizedDescription }
    }
}

private struct PlayerView: View {
    @ObservedObject var store: PlayerStore
    @State private var seekValue = 0.0
    @State private var seeking = false
    @State private var volumeValue = 0.0
    @State private var changingVolume = false

    var body: some View {
        VStack(spacing: 20) {
            Group {
                if let artwork = store.artwork {
                    Image(uiImage: artwork).resizable().scaledToFit()
                } else {
                    RoundedRectangle(cornerRadius: 24).fill(.indigo.opacity(0.12))
                        .overlay { Image(systemName: "music.note").font(.system(size: 72)).foregroundStyle(.indigo) }
                }
            }.frame(height: 270).clipShape(RoundedRectangle(cornerRadius: 24))
                .accessibilityLabel("Обложка трека")
            if let state = store.state {
                Text(state.hasSession ? (state.title.isEmpty ? "Без названия" : state.title) : "Откройте плеер на ПК")
                    .font(.title2.bold()).multilineTextAlignment(.center)
                Text(state.artist).foregroundStyle(.secondary)
                TimelineView(.periodic(from: .now, by: 0.25)) { timeline in
                    let position = state.position(elapsed: timeline.date.timeIntervalSince(store.receivedAt))
                    VStack {
                        Slider(value: Binding(get: { seeking ? seekValue : position }, set: { seekValue = $0 }),
                               in: state.minSeekSeconds...max(state.minSeekSeconds + 0.001, state.maxSeekSeconds)) { editing in
                            if editing { seekValue = position }
                            seeking = editing
                            if !editing { Task { await store.send("seek", value: seekValue) } }
                        }.disabled(!state.capabilities.seek || state.maxSeekSeconds <= state.minSeekSeconds || store.busy)
                            .accessibilityLabel("Позиция трека")
                        HStack {
                            Text(time((seeking ? seekValue : position) - state.startSeconds))
                            Spacer()
                            Text(time(state.endSeconds - state.startSeconds))
                        }.font(.caption.monospacedDigit()).foregroundStyle(.secondary)
                    }
                }
                HStack(spacing: 36) {
                    control("previous", icon: "backward.end.fill", label: "Предыдущий трек", enabled: state.capabilities.previous)
                    let playing = state.playbackStatus == "Playing"
                    let command = state.capabilities.toggle ? "toggle" : (playing ? "pause" : "play")
                    control(command, icon: playing ? "pause.circle.fill" : "play.circle.fill", label: playing ? "Пауза" : "Воспроизвести",
                            enabled: state.capabilities.toggle || (playing ? state.capabilities.pause : state.capabilities.play), size: 64)
                    control("next", icon: "forward.end.fill", label: "Следующий трек", enabled: state.capabilities.next)
                }
                HStack {
                    control("toggleMute", icon: state.muted == true ? "speaker.slash.fill" : "speaker.wave.2.fill",
                            label: state.muted == true ? "Включить звук ПК" : "Выключить звук ПК", enabled: state.muted != nil, size: 22)
                    Slider(value: Binding(get: { changingVolume ? volumeValue : (state.volume ?? 0) }, set: { volumeValue = $0 }), in: 0...1) { editing in
                        if editing { volumeValue = state.volume ?? 0 }
                        changingVolume = editing
                        if !editing { Task { await store.send("volume", value: volumeValue) } }
                    }.disabled(state.volume == nil || store.busy).accessibilityLabel("Системная громкость ПК")
                }
                ForEach([state.mediaError, state.volumeError, state.artworkError].compactMap { $0 }, id: \.self) {
                    Text($0).font(.caption).foregroundStyle(.secondary)
                }
            } else {
                Text("Ожидаем состояние компьютера").foregroundStyle(.secondary)
            }
        }.disabled(!store.connected)
    }

    private func control(_ type: String, icon: String, label: String, enabled: Bool, size: CGFloat = 28) -> some View {
        Button { Task { await store.send(type) } } label: {
            Image(systemName: icon).font(.system(size: size)).frame(minWidth: 44, minHeight: 44)
        }.disabled(!enabled || store.busy).accessibilityLabel(label)
    }

    private func time(_ seconds: Double) -> String {
        let value = Int(min(max(0, seconds), 359999))
        return String(format: "%d:%02d", value / 60, value % 60)
    }
}