import SwiftUI

struct iPhoneLibraryView: View {
    @State private var viewModel = iPhoneLibraryViewModel()

    var body: some View {
        NavigationStack {
            List {
                if let currentTitle = viewModel.nowPlaying.title {
                    Section("Now Playing") {
                        HStack(alignment: .center) {
                            VStack(alignment: .leading, spacing: 4) {
                                Text(currentTitle)
                                    .font(.headline)
                                if let artist = viewModel.nowPlaying.artist {
                                    Text(artist)
                                        .foregroundStyle(.secondary)
                                }
                                Text(viewModel.nowPlaying.isPlaying ? "Playing offline" : "Paused")
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }

                            Spacer()

                            if let trackID = viewModel.nowPlaying.trackID {
                                Button(viewModel.nowPlaying.isPlaying ? "Pause" : "Play") {
                                    viewModel.togglePlayback(trackID: trackID)
                                }
                                .buttonStyle(.borderedProminent)
                            }
                        }
                    }
                }

                Section("Remote tracks: \(viewModel.remoteTracks.count)") {
                    ForEach(viewModel.remoteTracks) { track in
                        VStack(alignment: .leading, spacing: 6) {
                            HStack(alignment: .top) {
                                VStack(alignment: .leading, spacing: 4) {
                                    Text(track.title)
                                        .font(.headline)
                                    Text(track.artist)
                                        .foregroundStyle(.secondary)
                                }

                                Spacer()

                                Text(track.statusText)
                                    .font(.caption.weight(.semibold))
                                    .padding(.horizontal, 10)
                                    .padding(.vertical, 4)
                                    .background(statusColor(for: track.statusText), in: Capsule())
                                    .foregroundStyle(.white)
                            }
                            Text("Duration: \(track.durationText)")
                                .font(.subheadline)
                                .foregroundStyle(.secondary)
                            Text("Remote track ID: \(track.remoteTrackID)")
                                .font(.caption)
                                .foregroundStyle(.tertiary)
                                .textSelection(.enabled)

                            HStack {
                                Button("Download") {
                                    Task {
                                        await viewModel.downloadTrack(trackID: track.id)
                                    }
                                }
                                .buttonStyle(.bordered)
                                .disabled(!track.canDownload)

                                if track.canPlay {
                                    Button(track.playButtonTitle) {
                                        viewModel.togglePlayback(trackID: track.id)
                                    }
                                    .buttonStyle(.borderedProminent)
                                }
                            }

                            if let error = track.lastDownloadError,
                               track.statusText == "Failed"
                            {
                                Text(error)
                                    .font(.caption)
                                    .foregroundStyle(.red)
                            }
                        }
                        .padding(.vertical, 4)
                    }
                }
            }
            .overlay {
                overlayView
            }
            .navigationTitle("Velody")
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button("Sync Remote Library") {
                        Task {
                            await viewModel.refreshSync()
                        }
                    }
                    .disabled(viewModel.state == .loading)
                }
            }
            .safeAreaInset(edge: .bottom) {
                VStack(alignment: .leading, spacing: 4) {
                    if let playbackError = viewModel.nowPlaying.errorMessage {
                        Text(playbackError)
                            .font(.footnote)
                            .foregroundStyle(.red)
                    }

                    Text(viewModel.syncStatus)
                        .font(.footnote)
                        .foregroundStyle(.secondary)
                }
                .padding()
                .frame(maxWidth: .infinity, alignment: .leading)
                .background(.ultraThinMaterial)
            }
        }
        .task {
            await viewModel.loadIfNeeded()
        }
    }

    @ViewBuilder
    private var overlayView: some View {
        switch viewModel.state {
        case .idle:
            if viewModel.remoteTracks.isEmpty {
                ContentUnavailableView(
                    "No Remote Library Yet",
                    systemImage: "music.note.list",
                    description: Text("Tap Sync Remote Library to fetch metadata from the backend.")
                )
            }
        case .loading:
            ProgressView("Syncing remote library...")
        case .success:
            EmptyView()
        case .empty:
            ContentUnavailableView(
                "Empty Remote Library",
                systemImage: "music.note.list",
                description: Text("The backend returned no remote tracks for this iPhone.")
            )
        case .networkError(let message):
            if viewModel.remoteTracks.isEmpty {
                ContentUnavailableView(
                    "Network Error",
                    systemImage: "wifi.exclamationmark",
                    description: Text(message)
                )
            }
        }
    }

    private func statusColor(for status: String) -> Color {
        switch status {
        case "Downloading":
            return .orange
        case "Downloaded":
            return .green
        case "Failed":
            return .red
        default:
            return .gray
        }
    }
}