Flaro/Flixy/Views/LiveTV/LiveTVView.swift

import SwiftUI
import FlixyDesign
import FlixyPlayback
import PlexKit

/// Live-TV mit Programmführer.
struct LiveTVView: View {
    @Environment(FlixySession.self) private var session
    @Environment(PlaybackCoordinator.self) private var playback
    @Environment(PlaybackSettings.self) private var settings
    @Environment(NetworkConditions.self) private var network

    @State private var availability: LiveTVAvailability?
    @State private var channels: [PlexChannel] = []
    @State private var programs: [String: [PlexProgram]] = [:]
    @State private var isTuning: String?

    var body: some View {
        Group {
            switch availability {
            case nil:
                ProgressView().frame(maxWidth: .infinity, maxHeight: .infinity)

            case .notConfigured:
                // Der häufigste Fall — Live-TV verlangt eine Fernsehkarte oder
                // einen Netzwerk-Tuner am Server. Ein Fehlerdialog wäre hier
                // irreführend: es ist nichts kaputt, es ist nur nichts da.
                ContentUnavailableView {
                    Label("liveTV.notConfigured.title", systemImage: "antenna.radiowaves.left.and.right.slash")
                } description: {
                    Text("liveTV.notConfigured.description")
                }

            case .failed(let message):
                ContentUnavailableView {
                    Label("error.title", systemImage: "exclamationmark.triangle")
                } description: {
                    Text(message)
                } actions: {
                    Button("action.retry") { Task { await load() } }
                }

            case .available where channels.isEmpty:
                ContentUnavailableView {
                    Label("liveTV.noChannels.title", systemImage: "tv")
                } description: {
                    Text("liveTV.noChannels.description")
                }

            case .available:
                guide
            }
        }
        .background(Color.flixyCanvas)
        .navigationTitle(Text("sidebar.liveTV"))
        .navigationBarTitleDisplayMode(.inline)
        .task { await load() }
        .refreshable { await load() }
    }

    private var guide: some View {
        ScrollView {
            LazyVStack(spacing: 0) {
                ForEach(channels) { channel in
                    ChannelRow(
                        channel: channel,
                        programs: programs[channel.id] ?? [],
                        isTuning: isTuning == channel.id,
                        onTune: { Task { await tune(channel) } }
                    )
                    Divider().overlay(Color.flixySeparator)
                }
            }
        }
    }

    private func load() async {
        guard let server = session.server else { return }

        let availability = await server.liveTVAvailability()
        self.availability = availability

        guard case .available(let dvrs) = availability, let dvr = dvrs.first else { return }
        channels = (try? await server.channels(inDVR: dvr)) ?? []

        // Der Programmführer kommt getrennt: er kann ausfallen, ohne dass
        // deshalb das Umschalten unmöglich wäre. Eine Senderliste ohne
        // Programm ist immer noch nützlich.
        guard let provider = await server.electronicProgramGuideIdentifier() else { return }
        let now = Date()
        let entries = (try? await server.guide(
            providerIdentifier: provider,
            from: now.addingTimeInterval(-3_600),
            to: now.addingTimeInterval(6 * 3_600)
        )) ?? []

        programs = Dictionary(grouping: entries.compactMap { program in
            program.channelID.map { (key: $0, program: program) }
        }, by: \.key).mapValues { pairs in
            pairs.map(\.program).sorted { $0.startsAt < $1.startsAt }
        }
    }

    private func tune(_ channel: PlexChannel) async {
        guard let server = session.server, isTuning == nil else { return }
        isTuning = channel.id
        defer { isTuning = nil }

        let policy = settings.policy(for: network)
        guard (try? await server.tune(channel: channel, maximumBitrate: policy.maximumBitrate)) != nil
        else { return }

        // Live-TV läuft über denselben Player wie alles andere. Der Schlüssel
        // ist der Sender, nicht ein Titel — der Player holt sich den Strom
        // über die Einschalt-Adresse.
        playback.request = PlaybackRequest(
            ratingKey: channel.id,
            title: channel.title,
            mediaIndex: 0,
            startTime: .zero
        )
    }
}

/// Eine Senderzeile mit dem, was gerade und als Nächstes läuft.
private struct ChannelRow: View {
    let channel: PlexChannel
    let programs: [PlexProgram]
    let isTuning: Bool
    let onTune: () -> Void

    @Environment(FlixySession.self) private var session
    @Environment(\.flixyAccent) private var accent

    private var current: PlexProgram? { programs.first { $0.isRunning() } }
    private var next: PlexProgram? { programs.first { $0.startsAt > Date() } }

    var body: some View {
        Button(action: onTune) {
            HStack(spacing: FlixySpacing.regular) {
                FlixyArtwork(
                    url: session.server?.artworkURL(path: channel.thumb, width: 120, height: 120),
                    aspectRatio: 1,
                    fallbackSymbol: "tv"
                )
                .frame(width: 44, height: 44)
                .clipShape(.rect(cornerRadius: 4))

                VStack(alignment: .leading, spacing: 2) {
                    HStack(spacing: FlixySpacing.snug) {
                        if let number = channel.channelIdentifier {
                            Text(number)
                                .font(.system(.caption, design: .monospaced))
                                .foregroundStyle(Color.flixyTextMuted)
                        }
                        Text(channel.title)
                            .font(.flixyCardTitle)
                            .foregroundStyle(Color.flixyTextPrimary)
                            .lineLimit(1)
                    }

                    if let current {
                        Text(current.title)
                            .font(.flixyCaption)
                            .foregroundStyle(Color.flixyTextSecondary)
                            .lineLimit(1)
                        // Der Balken zeigt, wie weit die Sendung ist — beim
                        // Umschalten die nützlichste Angabe überhaupt.
                        WatchProgressBar(fraction: current.progress())
                            .padding(.top, 2)
                    } else {
                        Text("liveTV.noProgram")
                            .font(.flixyCaption)
                            .foregroundStyle(Color.flixyTextMuted)
                    }

                    if let next {
                        Text("liveTV.next \(next.startsAt.formatted(date: .omitted, time: .shortened)) \(next.title)")
                            .font(.flixyCaption)
                            .foregroundStyle(Color.flixyTextMuted)
                            .lineLimit(1)
                    }
                }

                Spacer()

                if isTuning {
                    ProgressView().controlSize(.small)
                } else {
                    Image(systemName: "play.circle")
                        .font(.title3)
                        .foregroundStyle(accent)
                }
            }
            .padding(.horizontal, FlixySpacing.screenMargin)
            .padding(.vertical, FlixySpacing.regular)
            .contentShape(.rect)
        }
        .buttonStyle(.plain)
        .accessibilityElement(children: .combine)
    }
}