import AVFoundation
import AVKit
import OSLog
import SwiftUI

private struct StreamSelection: Identifiable {
    let id: String
}

private let multiViewLogger = Logger(subsystem: "com.treyt.mlbTVOS", category: "MultiView")

private func logMultiView(_ message: String) {
    multiViewLogger.debug("\(message, privacy: .public)")
    print("[MultiView] \(message)")
}

private func multiViewStatusDescription(_ status: AVPlayer.Status) -> String {
    switch status {
    case .unknown: "unknown"
    case .readyToPlay: "readyToPlay"
    case .failed: "failed"
    @unknown default: "unknown-future"
    }
}

private func multiViewItemStatusDescription(_ status: AVPlayerItem.Status) -> String {
    switch status {
    case .unknown: "unknown"
    case .readyToPlay: "readyToPlay"
    case .failed: "failed"
    @unknown default: "unknown-future"
    }
}

private func multiViewTimeControlDescription(_ status: AVPlayer.TimeControlStatus) -> String {
    switch status {
    case .paused: "paused"
    case .waitingToPlayAtSpecifiedRate: "waitingToPlayAtSpecifiedRate"
    case .playing: "playing"
    @unknown default: "unknown-future"
    }
}

private func multiViewHeaderKeysDescription(_ headers: [String: String]) -> String {
    guard !headers.isEmpty else { return "none" }
    return headers.keys.sorted().joined(separator: ",")
}

struct MultiStreamView: View {
    @Environment(GamesViewModel.self) private var viewModel
    @State private var selectedStream: StreamSelection?
    @State private var showFullScreen = false

    var body: some View {
        ZStack(alignment: .bottom) {
            LinearGradient(
                colors: [
                    Color(red: 0.03, green: 0.04, blue: 0.08),
                    Color(red: 0.02, green: 0.05, blue: 0.1),
                    Color(red: 0.01, green: 0.02, blue: 0.05),
                ],
                startPoint: .topLeading,
                endPoint: .bottomTrailing
            )
            .ignoresSafeArea()

            if viewModel.activeStreams.isEmpty {
                emptyState
            } else {
                VStack(spacing: 0) {
                    toolbar
                        .padding(.horizontal, 40)
                        .padding(.top, 26)
                        .padding(.bottom, 18)

                    MultiViewCanvas(
                        contentInsets: 18,
                        gap: 14,
                        videoGravity: .resizeAspectFill,
                        cornerRadius: 22,
                        onSelect: { stream in
                            selectedStream = StreamSelection(id: stream.id)
                        }
                    )
                    .padding(.horizontal, 18)
                    .padding(.bottom, 82)
                }

                ScoresTickerView()
                    .allowsHitTesting(false)
                    .padding(.horizontal, 18)
                    .padding(.bottom, 14)
            }
        }
        .fullScreenCover(isPresented: $showFullScreen) {
            MultiStreamFullScreenView()
        }
        .sheet(item: $selectedStream) { selection in
            StreamControlSheet(
                streamID: selection.id,
                onRemove: {
                    viewModel.removeStream(id: selection.id)
                    selectedStream = nil
                }
            )
        }
        .onAppear {
            viewModel.startAutoRefresh()
        }
        .onDisappear {
            viewModel.stopAutoRefresh()
        }
    }

    private var emptyState: some View {
        VStack(spacing: 24) {
            Image(systemName: "rectangle.split.2x2")
                .font(.system(size: 82, weight: .light))
                .foregroundStyle(.white.opacity(0.14))

            Text("No Active Streams")
                .font(.system(size: 30, weight: .bold, design: .rounded))
                .foregroundStyle(.white.opacity(0.9))

            Text("Add broadcasts from Games to build a quadbox, then pick the main tile and live audio here.")
                .font(.system(size: 18, weight: .medium))
                .foregroundStyle(.white.opacity(0.38))
                .multilineTextAlignment(.center)
                .frame(maxWidth: 560)
        }
        .padding(40)
    }

    private var toolbar: some View {
        VStack(alignment: .leading, spacing: 18) {
            HStack(alignment: .top, spacing: 24) {
                VStack(alignment: .leading, spacing: 10) {
                    Text("Multi-View 2.0")
                        .font(.system(size: 32, weight: .bold, design: .rounded))
                        .foregroundStyle(.white)

                    Text("Choose the main tile, route audio to the game you want, and reorder feeds without leaving the grid.")
                        .font(.system(size: 15, weight: .medium))
                        .foregroundStyle(.white.opacity(0.58))
                }

                Spacer()

                HStack(spacing: 10) {
                    infoChip(
                        title: "\(viewModel.activeStreams.count)/4",
                        icon: "rectangle.split.2x2",
                        tint: .white
                    )
                    infoChip(
                        title: viewModel.multiViewLayoutMode.title,
                        icon: viewModel.multiViewLayoutMode.systemImage,
                        tint: .blue
                    )
                    infoChip(
                        title: viewModel.activeAudioStream?.label ?? "All Muted",
                        icon: viewModel.activeAudioStream == nil ? "speaker.slash.fill" : "speaker.wave.2.fill",
                        tint: viewModel.activeAudioStream == nil ? .white : .green
                    )
                }
            }

            HStack(spacing: 14) {
                MultiViewLayoutPicker(compact: false)

                Spacer()

                Button {
                    showFullScreen = true
                } label: {
                    toolbarButtonLabel(
                        title: "Full Screen",
                        icon: "arrow.up.left.and.arrow.down.right",
                        tint: .white,
                        destructive: false
                    )
                }
                .platformCardStyle()

                Button {
                    viewModel.clearAllStreams()
                } label: {
                    toolbarButtonLabel(
                        title: "Clear All",
                        icon: "xmark",
                        tint: .red,
                        destructive: true
                    )
                }
                .platformCardStyle()
            }
        }
    }

    private func infoChip(title: String, icon: String, tint: Color) -> some View {
        HStack(spacing: 8) {
            Image(systemName: icon)
                .font(.system(size: 12, weight: .bold))
            Text(title)
                .font(.system(size: 14, weight: .semibold))
                .lineLimit(1)
        }
        .foregroundStyle(tint.opacity(0.95))
        .padding(.horizontal, 12)
        .padding(.vertical, 9)
        .background(
            RoundedRectangle(cornerRadius: 999)
                .fill(.white.opacity(0.08))
        )
    }

    private func toolbarButtonLabel(title: String, icon: String, tint: Color, destructive: Bool) -> some View {
        HStack(spacing: 8) {
            Image(systemName: icon)
                .font(.system(size: 13, weight: .bold))
            Text(title)
                .font(.system(size: 15, weight: .semibold))
        }
        .foregroundStyle(tint.opacity(0.9))
        .padding(.horizontal, 18)
        .padding(.vertical, 12)
        .background(
            RoundedRectangle(cornerRadius: 999)
                .fill(destructive ? .red.opacity(0.12) : .white.opacity(0.08))
        )
    }
}

private struct MultiViewCanvas: View {
    @Environment(GamesViewModel.self) private var viewModel
    #if os(tvOS)
    @FocusState private var focusedStreamID: String?
    #endif

    let contentInsets: CGFloat
    let gap: CGFloat
    let videoGravity: AVLayerVideoGravity
    let cornerRadius: CGFloat
    let onSelect: (ActiveStream) -> Void

    var body: some View {
        GeometryReader { geo in
            let frames = multiViewFrames(
                count: viewModel.activeStreams.count,
                mode: viewModel.multiViewLayoutMode,
                size: geo.size,
                inset: contentInsets,
                gap: gap
            )
            #if os(tvOS)
            let focusEntries = Array(viewModel.activeStreams.enumerated()).compactMap { index, stream -> MultiViewFocusEntry? in
                guard index < frames.count else { return nil }
                return MultiViewFocusEntry(streamID: stream.id, frame: frames[index])
            }
            #endif

            ZStack(alignment: .topLeading) {
                ForEach(Array(viewModel.activeStreams.enumerated()), id: \.element.id) { index, stream in
                    if index < frames.count {
                        let frame = frames[index]
                        tileView(for: stream, frame: frame, position: index + 1)
                    }
                }
            }
            .platformFocusSection()
            #if os(tvOS)
            .onMoveCommand { direction in
                let currentID = focusedStreamID ?? viewModel.audioFocusStreamID ?? viewModel.activeStreams.first?.id
                if let nextID = nextMultiViewFocusID(
                    from: currentID,
                    direction: direction,
                    entries: focusEntries
                ) {
                    focusedStreamID = nextID
                }
            }
            #endif
        }
        #if os(tvOS)
        .onAppear {
            if focusedStreamID == nil {
                focusedStreamID = viewModel.audioFocusStreamID ?? viewModel.activeStreams.first?.id
            }
        }
        .onChange(of: viewModel.activeStreams.map(\.id)) { _, streamIDs in
            if let focusedStreamID, streamIDs.contains(focusedStreamID) {
                return
            }
            self.focusedStreamID = viewModel.audioFocusStreamID ?? streamIDs.first
        }
        .onChange(of: focusedStreamID) { _, streamID in
            guard let streamID else { return }
            if viewModel.audioFocusStreamID != streamID {
                viewModel.setAudioFocus(streamID: streamID)
            }
        }
        #endif
    }

    @ViewBuilder
    private func tileView(for stream: ActiveStream, frame: CGRect, position: Int) -> some View {
        let tile = MultiStreamTile(
            stream: stream,
            position: position,
            isPrimary: viewModel.isPrimaryStream(stream.id),
            isAudioFocused: viewModel.audioFocusStreamID == stream.id,
            isFocused: {
                #if os(tvOS)
                focusedStreamID == stream.id
                #else
                false
                #endif
            }(),
            showsPrimaryBadge: viewModel.multiViewLayoutMode == .spotlight
                && viewModel.isPrimaryStream(stream.id)
                && viewModel.activeStreams.count > 1,
            videoGravity: videoGravity,
            cornerRadius: cornerRadius,
            onSelect: { onSelect(stream) }
        )

        #if os(tvOS)
        tile
            .frame(width: frame.width, height: frame.height)
            .position(x: frame.midX, y: frame.midY)
            .focused($focusedStreamID, equals: stream.id)
        #else
        tile
            .frame(width: frame.width, height: frame.height)
            .position(x: frame.midX, y: frame.midY)
        #endif
    }
}

private struct MultiStreamTile: View {
    let stream: ActiveStream
    let position: Int
    let isPrimary: Bool
    let isAudioFocused: Bool
    let isFocused: Bool
    let showsPrimaryBadge: Bool
    let videoGravity: AVLayerVideoGravity
    let cornerRadius: CGFloat
    let onSelect: () -> Void

    @Environment(GamesViewModel.self) private var viewModel
    @State private var player: AVPlayer?
    @State private var hasError = false
    @State private var startupPlaybackTask: Task<Void, Never>?
    @State private var werkoutMonitorTask: Task<Void, Never>?
    @State private var clipTimeLimitObserver: Any?
    @State private var isAdvancingClip = false
    @StateObject private var playbackDiagnostics = MultiStreamPlaybackDiagnostics()
    @State private var audioDiagnostics: AudioDiagnostics?

    private static let maxClipDuration: Double = 15.0
    private static var audioSessionConfigured = false

    var body: some View {
        ZStack {
            videoLayer

            LinearGradient(
                colors: [
                    .black.opacity(0.68),
                    .black.opacity(0.08),
                    .black.opacity(0.52),
                ],
                startPoint: .top,
                endPoint: .bottom
            )

            VStack(spacing: 0) {
                HStack(alignment: .top, spacing: 10) {
                    HStack(spacing: 10) {
                        Text("\(position)")
                            .font(.system(size: 12, weight: .bold, design: .rounded))
                            .foregroundStyle(.white.opacity(0.95))
                            .frame(width: 24, height: 24)
                            .background(.black.opacity(0.58))
                            .clipShape(Circle())

                        Text(stream.label)
                            .font(.system(size: 16, weight: .bold, design: .rounded))
                            .foregroundStyle(.white)
                            .lineLimit(1)
                    }
                    .padding(.horizontal, 12)
                    .padding(.vertical, 9)
                    .background(.black.opacity(0.52))
                    .clipShape(RoundedRectangle(cornerRadius: 12))

                    Spacer()

                    HStack(spacing: 8) {
                        if showsPrimaryBadge {
                            tileBadge(title: "MAIN", color: .blue)
                        }
                        if isAudioFocused {
                            tileBadge(title: "AUDIO", color: .green)
                        } else {
                            tileBadge(title: "MUTED", color: .white.opacity(0.7))
                        }
                    }
                }

                Spacer()

                HStack {
                    Spacer()

                    if let statusText = tileStatusText, !statusText.isEmpty {
                        Text(statusText)
                            .font(.system(size: 13, weight: .semibold, design: .rounded))
                            .foregroundStyle(.white.opacity(0.82))
                            .padding(.horizontal, 10)
                            .padding(.vertical, 6)
                            .background(.black.opacity(0.48))
                            .clipShape(Capsule())
                    }
                }
            }
            .padding(14)
        }
        .background(.black)
        .overlay(tileBorder)
        .clipShape(RoundedRectangle(cornerRadius: cornerRadius))
        .contentShape(RoundedRectangle(cornerRadius: cornerRadius))
        .scaleEffect(isFocused ? 1.025 : 1.0)
        .shadow(
            color: isFocused ? .blue.opacity(0.22) : isAudioFocused ? .green.opacity(0.22) : .black.opacity(0.28),
            radius: isFocused ? 26 : 20,
            y: 10
        )
        .animation(.easeOut(duration: 0.18), value: isFocused)
        .platformFocusable()
        .onAppear {
            logMultiView("tile appeared id=\(stream.id) label=\(stream.label)")
        }
        .onDisappear {
            logMultiView("tile disappeared id=\(stream.id) label=\(stream.label)")
            startupPlaybackTask?.cancel()
            startupPlaybackTask = nil
            werkoutMonitorTask?.cancel()
            werkoutMonitorTask = nil
            if let player {
                removeClipTimeLimit(from: player)
                player.pause()
            }
            player = nil
            playbackDiagnostics.clear(streamID: stream.id, reason: "tile disappeared")
            audioDiagnostics?.detach()
            audioDiagnostics = nil
        }
        #if os(tvOS)
        .focusEffectDisabled()
        .onPlayPauseCommand {
            if player?.rate == 0 {
                player?.play()
            } else {
                player?.pause()
            }
        }
        #endif
        .onTapGesture {
            onSelect()
        }
        .task(id: stream.id) {
            await startStream()
        }
    }

    @ViewBuilder
    private var videoLayer: some View {
        if let player {
            MultiStreamPlayerLayerView(player: player, streamID: stream.id, videoGravity: videoGravity)
                .onAppear {
                    logMultiView("videoLayer showing player id=\(stream.id) rate=\(player.rate) muted=\(player.isMuted) gravity=\(videoGravity.rawValue)")
                }
        } else if hasError {
            Color.black.overlay {
                VStack(spacing: 10) {
                    Image(systemName: "exclamationmark.triangle.fill")
                        .font(.system(size: 28))
                        .foregroundStyle(.red.opacity(0.9))
                    Text("Stream unavailable")
                        .font(.system(size: 15, weight: .semibold))
                        .foregroundStyle(.white.opacity(0.82))
                }
            }
        } else {
            Color.black.overlay {
                VStack(spacing: 10) {
                    ProgressView()
                    Text("Loading feed")
                        .font(.system(size: 15, weight: .semibold))
                        .foregroundStyle(.white.opacity(0.72))
                }
            }
        }
    }

    private var tileBorder: some View {
        RoundedRectangle(cornerRadius: cornerRadius)
            .stroke(
                isAudioFocused ? .green.opacity(0.95) : isFocused ? .blue.opacity(0.9) : isPrimary ? .white.opacity(0.28) : .white.opacity(0.12),
                lineWidth: isAudioFocused || isFocused ? 3 : isPrimary ? 2 : 1
            )
    }

    private var tileStatusText: String? {
        if stream.game.isLive {
            return stream.game.currentInningDisplay ?? stream.game.status.label
        }
        if stream.game.isFinal {
            return "Final"
        }
        if stream.game.status.isScheduled {
            return stream.game.startTime ?? stream.game.status.label
        }
        return stream.game.status.label
    }

    private func tileBadge(title: String, color: Color) -> some View {
        Text(title)
            .font(.system(size: 11, weight: .bold, design: .rounded))
            .foregroundStyle(color.opacity(0.98))
            .padding(.horizontal, 10)
            .padding(.vertical, 6)
            .background(.black.opacity(0.5))
            .clipShape(Capsule())
    }

    private var multiViewStartupResolution: String {
        viewModel.defaultResolution
    }

    private func startStream() async {
        logMultiView(
            "startStream begin id=\(stream.id) label=\(stream.label) hasInlinePlayer=\(player != nil) hasSharedPlayer=\(stream.player != nil) hasOverrideURL=\(stream.overrideURL != nil) hasOverrideHeaders=\(stream.overrideHeaders != nil)"
        )

        if let player {
            playbackDiagnostics.attach(
                to: player,
                streamID: stream.id,
                label: stream.label,
                onPlaybackEnded: playbackEndedHandler(for: player)
            )
            scheduleStartupPlaybackRecovery(for: player)
            installClipTimeLimit(on: player)
            attachAudioDiagnostics(to: player)
            logMultiView("startStream reused inline player id=\(stream.id) muted=\(player.isMuted)")
            return
        }

        if !Self.audioSessionConfigured {
            do {
                try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
                try AVAudioSession.sharedInstance().setActive(true)
                Self.audioSessionConfigured = true
                logMultiView("startStream audio session configured id=\(stream.id) mode=default")
            } catch {
                logMultiView("startStream audio session failed id=\(stream.id) error=\(error.localizedDescription)")
            }
        }

        if let existingPlayer = stream.player {
            self.player = existingPlayer
            hasError = false
            playbackDiagnostics.attach(
                to: existingPlayer,
                streamID: stream.id,
                label: stream.label,
                onPlaybackEnded: playbackEndedHandler(for: existingPlayer)
            )
            scheduleStartupPlaybackRecovery(for: existingPlayer)
            installClipTimeLimit(on: existingPlayer)
            attachAudioDiagnostics(to: existingPlayer)
            logMultiView("startStream reused shared player id=\(stream.id) muted=\(existingPlayer.isMuted)")
            return
        }

        let url: URL?
        if let overrideURL = stream.overrideURL {
            url = overrideURL
            logMultiView("startStream using override URL id=\(stream.id) url=\(overrideURL.absoluteString)")
        } else {
            url = await viewModel.resolveStreamURL(
                for: stream,
                resolutionOverride: multiViewStartupResolution,
                preserveServerResolutionWhenBest: false
            )
        }
        guard let url else {
            hasError = true
            logMultiView("startStream failed id=\(stream.id) resolveStreamURL returned nil")
            return
        }

        let avPlayer = makePlayer(url: url, headers: stream.overrideHeaders)
        avPlayer.automaticallyWaitsToMinimizeStalling = false
        avPlayer.currentItem?.preferredForwardBufferDuration = 2

        self.player = avPlayer
        // Set mute state BEFORE playback to prevent audio spikes
        viewModel.attachPlayer(avPlayer, to: stream.id)
        playbackDiagnostics.attach(
            to: avPlayer,
            streamID: stream.id,
            label: stream.label,
            onPlaybackEnded: playbackEndedHandler(for: avPlayer)
        )
        scheduleStartupPlaybackRecovery(for: avPlayer)
        attachAudioDiagnostics(to: avPlayer)
        logMultiView("startStream attached player id=\(stream.id) muted=\(avPlayer.isMuted) startupResolution=\(multiViewStartupResolution) fastStart=true calling playImmediately(atRate: 1.0)")
        avPlayer.playImmediately(atRate: 1.0)
        installClipTimeLimit(on: avPlayer)
    }

    private func makePlayer(url: URL, headers: [String: String]?) -> AVPlayer {
        let headers = headers ?? [:]
        logMultiView(
            "startStream creating AVPlayer id=\(stream.id) url=\(url.absoluteString) headerKeys=\(multiViewHeaderKeysDescription(headers))"
        )

        let item = makePlayerItem(url: url, headers: headers)
        let player = AVPlayer(playerItem: item)
        player.appliesMediaSelectionCriteriaAutomatically = false
        logMultiView("startStream configured AVPlayer id=\(stream.id) appliesMediaSelectionCriteriaAutomatically=false")
        return player
    }

    private func makePlayerItem(url: URL, headers: [String: String]) -> AVPlayerItem {
        let item: AVPlayerItem
        if headers.isEmpty {
            item = AVPlayerItem(url: url)
        } else {
            let assetOptions: [String: Any] = [
                "AVURLAssetHTTPHeaderFieldsKey": headers,
            ]
            let asset = AVURLAsset(url: url, options: assetOptions)
            item = AVPlayerItem(asset: asset)
        }
        item.allowedAudioSpatializationFormats = []
        logMultiView("startStream configured player item id=\(stream.id) allowedAudioSpatializationFormats=[]")
        pinAudioSelection(on: item)
        return item
    }

    /// Pin the HLS audio rendition so ABR can't swap channel layouts mid-stream.
    private func pinAudioSelection(on item: AVPlayerItem) {
        let streamID = stream.id
        Task { @MainActor in
            await enforcePinnedMultiStreamAudioSelection(on: item, streamID: streamID)
        }
    }

    private func scheduleStartupPlaybackRecovery(for player: AVPlayer) {
        startupPlaybackTask?.cancel()

        let streamID = stream.id
        let label = stream.label
        startupPlaybackTask = Task { @MainActor in
            let retryDelays: [Double] = [0.35, 1.0, 2.0, 4.0]

            for delay in retryDelays {
                try? await Task.sleep(for: .seconds(delay))
                guard !Task.isCancelled else { return }
                guard let currentPlayer = self.player, currentPlayer === player else {
                    logMultiView("startupRecovery abort id=\(streamID) label=\(label) reason=player-changed")
                    return
                }

                let itemStatus = multiViewItemStatusDescription(player.currentItem?.status ?? .unknown)
                let likelyToKeepUp = player.currentItem?.isPlaybackLikelyToKeepUp ?? false
                let bufferEmpty = player.currentItem?.isPlaybackBufferEmpty ?? false
                let timeControl = multiViewTimeControlDescription(player.timeControlStatus)
                let startupSatisfied = player.rate > 0 && (itemStatus == "readyToPlay" || likelyToKeepUp)
                logMultiView(
                    "startupRecovery check id=\(streamID) delay=\(delay)s rate=\(player.rate) timeControl=\(timeControl) itemStatus=\(itemStatus) likelyToKeepUp=\(likelyToKeepUp) bufferEmpty=\(bufferEmpty)"
                )

                if startupSatisfied {
                    logMultiView("startupRecovery satisfied id=\(streamID) delay=\(delay)s")
                    return
                }

                if player.rate == 0 {
                    logMultiView("startupRecovery replay id=\(streamID) delay=\(delay)s")
                    player.playImmediately(atRate: 1.0)
                }
            }
        }
    }

    private func currentStreamURL(for player: AVPlayer) -> URL? {
        (player.currentItem?.asset as? AVURLAsset)?.url
    }

    private func attachAudioDiagnostics(to player: AVPlayer) {
        if audioDiagnostics == nil {
            audioDiagnostics = AudioDiagnostics(tag: "multi:\(stream.label)")
        }
        audioDiagnostics?.attach(to: player)
    }


    private func installClipTimeLimit(on player: AVPlayer) {
        removeClipTimeLimit(from: player)
        guard stream.id == SpecialPlaybackChannelConfig.werkoutNSFWStreamID else { return }
        let limit = CMTime(seconds: Self.maxClipDuration, preferredTimescale: 600)
        logMultiView("installClipTimeLimit id=\(stream.id) limit=\(Self.maxClipDuration)s")
        clipTimeLimitObserver = player.addBoundaryTimeObserver(
            forTimes: [NSValue(time: limit)],
            queue: .main
        ) { [weak player] in
            guard let player else {
                logMultiView("clipTimeLimit STOPPED id=\(stream.id) reason=player-deallocated")
                return
            }
            let currentTime = CMTimeGetSeconds(player.currentTime())
            logMultiView("clipTimeLimit fired id=\(stream.id) currentTime=\(String(format: "%.1f", currentTime))s rate=\(player.rate) — advancing")
            Task { @MainActor in
                await playNextWerkoutClip(on: player)
            }
        }
    }

    private func removeClipTimeLimit(from player: AVPlayer) {
        if let observer = clipTimeLimitObserver {
            player.removeTimeObserver(observer)
            clipTimeLimitObserver = nil
        }
    }

    private func playbackEndedHandler(for player: AVPlayer) -> (@MainActor @Sendable () async -> Void)? {
        guard stream.id == SpecialPlaybackChannelConfig.werkoutNSFWStreamID else { return nil }
        return {
            let currentTime = CMTimeGetSeconds(player.currentTime())
            logMultiView("playbackEnded (didPlayToEnd) id=\(stream.id) currentTime=\(String(format: "%.1f", currentTime))s rate=\(player.rate)")
            await playNextWerkoutClip(on: player)
        }
    }

    private func playNextWerkoutClip(on player: AVPlayer) async {
        guard !isAdvancingClip else {
            logMultiView("playNextWerkoutClip SKIPPED id=\(stream.id) reason=already-advancing")
            return
        }
        isAdvancingClip = true
        defer { isAdvancingClip = false }

        let currentURL = currentStreamURL(for: player)
        let playerRate = player.rate
        let playerStatus = player.status.rawValue
        let itemStatus = player.currentItem?.status.rawValue ?? -1
        let timeControl = player.timeControlStatus.rawValue
        logMultiView(
            "playNextWerkoutClip begin id=\(stream.id) currentURL=\(currentURL?.absoluteString ?? "nil") playerRate=\(playerRate) playerStatus=\(playerStatus) itemStatus=\(itemStatus) timeControl=\(timeControl)"
        )

        let resolveStart = Date()
        guard let nextURL = await viewModel.resolveNextAuthenticatedFeedURLForActiveStream(
            id: stream.id,
            feedURL: SpecialPlaybackChannelConfig.werkoutNSFWFeedURL,
            headers: SpecialPlaybackChannelConfig.werkoutNSFWHeaders,
            maxRetries: 3
        ) else {
            let elapsedMs = Int(Date().timeIntervalSince(resolveStart) * 1000)
            logMultiView("playNextWerkoutClip STOPPED id=\(stream.id) reason=resolve-nil-after-retries elapsedMs=\(elapsedMs)")
            return
        }
        let resolveMs = Int(Date().timeIntervalSince(resolveStart) * 1000)
        logMultiView("playNextWerkoutClip resolved id=\(stream.id) resolveMs=\(resolveMs) nextURL=\(nextURL.lastPathComponent)")

        let nextItem = makePlayerItem(
            url: nextURL,
            headers: stream.overrideHeaders ?? SpecialPlaybackChannelConfig.werkoutNSFWHeaders
        )
        nextItem.preferredForwardBufferDuration = 2
        player.replaceCurrentItem(with: nextItem)
        player.automaticallyWaitsToMinimizeStalling = false
        playbackDiagnostics.attach(
            to: player,
            streamID: stream.id,
            label: stream.label,
            onPlaybackEnded: playbackEndedHandler(for: player)
        )
        scheduleStartupPlaybackRecovery(for: player)
        logMultiView("playNextWerkoutClip replay id=\(stream.id) url=\(nextURL.lastPathComponent)")
        player.playImmediately(atRate: 1.0)
        installClipTimeLimit(on: player)

        // Monitor for failure and auto-skip to next clip
        werkoutMonitorTask?.cancel()
        werkoutMonitorTask = Task { @MainActor in
            for checkDelay in [1.0, 3.0] {
                try? await Task.sleep(for: .seconds(checkDelay))
                guard !Task.isCancelled else { return }
                let postItemStatus = player.currentItem?.status
                let error = player.currentItem?.error?.localizedDescription ?? "nil"
                logMultiView(
                    "playNextWerkoutClip postCheck id=\(stream.id) delay=\(checkDelay)s rate=\(player.rate) itemStatus=\(postItemStatus?.rawValue ?? -1) error=\(error)"
                )
                if postItemStatus == .failed {
                    logMultiView("playNextWerkoutClip AUTO-SKIP id=\(stream.id) reason=item-failed error=\(error)")
                    await playNextWerkoutClip(on: player)
                    return
                }
            }
        }
    }
}

@MainActor
private func enforcePinnedMultiStreamAudioSelection(on item: AVPlayerItem, streamID: String) async {
    let asset = item.asset
    guard let group = try? await asset.loadMediaSelectionGroup(for: .audible),
          let option = preferredMultiStreamAudioOption(in: group) else { return }
    let current = item.currentMediaSelection.selectedMediaOption(in: group)
    if current != option {
        item.select(option, in: group)
    }
    logMultiView(
        "pinAudioSelection id=\(streamID) selected=\(option.displayName) current=\(current?.displayName ?? "nil") options=\(group.options.count)"
    )
}

private func preferredMultiStreamAudioOption(in group: AVMediaSelectionGroup) -> AVMediaSelectionOption? {
    let defaultOption = group.defaultOption
    return group.options.max { lhs, rhs in
        multiStreamAudioPreferenceScore(for: lhs, defaultOption: defaultOption) < multiStreamAudioPreferenceScore(for: rhs, defaultOption: defaultOption)
    } ?? defaultOption ?? group.options.first
}

private func multiStreamAudioPreferenceScore(for option: AVMediaSelectionOption, defaultOption: AVMediaSelectionOption?) -> Int {
    let name = option.displayName.lowercased()
    var score = 0

    if option == defaultOption { score += 40 }
    if name.contains("stereo") || name.contains("2.0") || name.contains("main") { score += 30 }
    if name.contains("english") || name.contains("eng") { score += 20 }
    if name.contains("surround") || name.contains("5.1") || name.contains("atmos") { score -= 30 }
    if name.contains("spanish") || name.contains("sap") || name.contains("descriptive") || name.contains("alternate") {
        score -= 25
    }
    if option.hasMediaCharacteristic(.describesVideoForAccessibility) {
        score -= 40
    }

    return score
}

private struct MultiStreamPlayerLayerView: UIViewRepresentable {
    let player: AVPlayer
    let streamID: String
    let videoGravity: AVLayerVideoGravity

    func makeUIView(context: Context) -> MultiStreamPlayerLayerContainerView {
        let view = MultiStreamPlayerLayerContainerView(videoGravity: videoGravity)
        view.playerLayer.player = player
        logMultiView("playerLayer makeUIView id=\(streamID) rate=\(player.rate) gravity=\(videoGravity.rawValue)")
        return view
    }

    func updateUIView(_ uiView: MultiStreamPlayerLayerContainerView, context: Context) {
        if uiView.playerLayer.player !== player {
            uiView.playerLayer.player = player
            logMultiView("playerLayer updateUIView reassigned player id=\(streamID) rate=\(player.rate)")
        }
        if uiView.playerLayer.videoGravity != videoGravity {
            uiView.playerLayer.videoGravity = videoGravity
            logMultiView("playerLayer updateUIView changed gravity id=\(streamID) gravity=\(videoGravity.rawValue)")
        }
    }

    static func dismantleUIView(_ uiView: MultiStreamPlayerLayerContainerView, coordinator: ()) {
        uiView.playerLayer.player = nil
    }
}

private final class MultiStreamPlayerLayerContainerView: UIView {
    override class var layerClass: AnyClass { AVPlayerLayer.self }

    var playerLayer: AVPlayerLayer {
        layer as! AVPlayerLayer
    }

    init(videoGravity: AVLayerVideoGravity) {
        super.init(frame: .zero)
        backgroundColor = .black
        playerLayer.videoGravity = videoGravity
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = .black
        playerLayer.videoGravity = .resizeAspectFill
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

private final class MultiStreamPlaybackDiagnostics: ObservableObject {
    private var playerObservations: [NSKeyValueObservation] = []
    private var notificationTokens: [NSObjectProtocol] = []
    private var attachedPlayerIdentifier: ObjectIdentifier?
    private var attachedItemIdentifier: ObjectIdentifier?

    func attach(
        to player: AVPlayer,
        streamID: String,
        label: String,
        onPlaybackEnded: (@MainActor @Sendable () async -> Void)? = nil
    ) {
        let playerIdentifier = ObjectIdentifier(player)
        let itemIdentifier = player.currentItem.map { ObjectIdentifier($0) }
        if attachedPlayerIdentifier == playerIdentifier, attachedItemIdentifier == itemIdentifier {
            return
        }

        clear(streamID: streamID, reason: "reattach")
        attachedPlayerIdentifier = playerIdentifier
        attachedItemIdentifier = itemIdentifier

        logMultiView("diagnostics attach id=\(streamID) label=\(label) playerRate=\(player.rate)")

        playerObservations.append(
            player.observe(\.status, options: [.initial, .new]) { player, _ in
                logMultiView("player status id=\(streamID) status=\(multiViewStatusDescription(player.status)) error=\(player.error?.localizedDescription ?? "nil")")
            }
        )

        playerObservations.append(
            player.observe(\.timeControlStatus, options: [.initial, .new]) { player, _ in
                let reason = player.reasonForWaitingToPlay?.rawValue ?? "nil"
                logMultiView("player timeControl id=\(streamID) status=\(multiViewTimeControlDescription(player.timeControlStatus)) reason=\(reason) rate=\(player.rate)")
            }
        )

        playerObservations.append(
            player.observe(\.reasonForWaitingToPlay, options: [.initial, .new]) { player, _ in
                logMultiView("player waitingReason id=\(streamID) value=\(player.reasonForWaitingToPlay?.rawValue ?? "nil")")
            }
        )

        guard let item = player.currentItem else {
            logMultiView("diagnostics attach id=\(streamID) missing currentItem")
            return
        }

        playerObservations.append(
            item.observe(\.status, options: [.initial, .new]) { item, _ in
                logMultiView("playerItem status id=\(streamID) status=\(multiViewItemStatusDescription(item.status)) error=\(item.error?.localizedDescription ?? "nil")")
            }
        )

        playerObservations.append(
            item.observe(\.isPlaybackBufferEmpty, options: [.initial, .new]) { item, _ in
                logMultiView("playerItem bufferEmpty id=\(streamID) value=\(item.isPlaybackBufferEmpty)")
            }
        )

        playerObservations.append(
            item.observe(\.isPlaybackLikelyToKeepUp, options: [.initial, .new]) { item, _ in
                logMultiView("playerItem likelyToKeepUp id=\(streamID) value=\(item.isPlaybackLikelyToKeepUp)")
            }
        )

        playerObservations.append(
            item.observe(\.isPlaybackBufferFull, options: [.initial, .new]) { item, _ in
                logMultiView("playerItem bufferFull id=\(streamID) value=\(item.isPlaybackBufferFull)")
            }
        )

        notificationTokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemPlaybackStalled,
                object: item,
                queue: .main
            ) { _ in
                logMultiView("playerItem stalled id=\(streamID)")
            }
        )

        notificationTokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemFailedToPlayToEndTime,
                object: item,
                queue: .main
            ) { notification in
                let error = notification.userInfo?[AVPlayerItemFailedToPlayToEndTimeErrorKey] as? NSError
                logMultiView("playerItem failedToEnd id=\(streamID) error=\(error?.localizedDescription ?? "nil")")
            }
        )

        notificationTokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemDidPlayToEndTime,
                object: item,
                queue: .main
            ) { _ in
                logMultiView("playerItem didPlayToEnd id=\(streamID)")
                guard let onPlaybackEnded else { return }
                Task { @MainActor in
                    await onPlaybackEnded()
                }
            }
        )

        notificationTokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemNewErrorLogEntry,
                object: item,
                queue: .main
            ) { _ in
                let event = item.errorLog()?.events.last
                logMultiView("playerItem errorLog id=\(streamID) domain=\(event?.errorDomain ?? "nil") statusCode=\(event?.errorStatusCode ?? 0) comment=\(event?.errorComment ?? "nil")")
            }
        )

        notificationTokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemNewAccessLogEntry,
                object: item,
                queue: .main
            ) { _ in
                if let event = item.accessLog()?.events.last {
                    logMultiView("playerItem accessLog id=\(streamID) indicatedBitrate=\(Int(event.indicatedBitrate)) observedBitrate=\(Int(event.observedBitrate)) transferDuration=\(event.transferDuration)")
                } else {
                    logMultiView("playerItem accessLog id=\(streamID) missing event")
                }
            }
        )
    }

    func clear(streamID: String, reason: String) {
        if !playerObservations.isEmpty || !notificationTokens.isEmpty {
            logMultiView("diagnostics clear id=\(streamID) reason=\(reason)")
        }
        playerObservations.removeAll()
        for token in notificationTokens {
            NotificationCenter.default.removeObserver(token)
        }
        notificationTokens.removeAll()
        attachedPlayerIdentifier = nil
        attachedItemIdentifier = nil
    }

    deinit {
        playerObservations.removeAll()
        for token in notificationTokens {
            NotificationCenter.default.removeObserver(token)
        }
        notificationTokens.removeAll()
    }
}

private struct MultiViewLayoutPicker: View {
    @Environment(GamesViewModel.self) private var viewModel
    let compact: Bool

    var body: some View {
        HStack(spacing: compact ? 8 : 10) {
            ForEach(MultiViewLayoutMode.allCases) { mode in
                Button {
                    viewModel.multiViewLayoutMode = mode
                } label: {
                    HStack(spacing: 8) {
                        Image(systemName: mode.systemImage)
                            .font(.system(size: compact ? 11 : 12, weight: .bold))
                        Text(mode.title)
                            .font(.system(size: compact ? 13 : 14, weight: .semibold))
                    }
                    .foregroundStyle(viewModel.multiViewLayoutMode == mode ? .white : .white.opacity(0.62))
                    .padding(.horizontal, compact ? 12 : 14)
                    .padding(.vertical, compact ? 9 : 10)
                    .background(
                        RoundedRectangle(cornerRadius: 999)
                            .fill(viewModel.multiViewLayoutMode == mode ? .blue.opacity(0.28) : .white.opacity(0.06))
                    )
                    .overlay(
                        RoundedRectangle(cornerRadius: 999)
                            .stroke(viewModel.multiViewLayoutMode == mode ? .blue.opacity(0.9) : .white.opacity(0.12), lineWidth: 1)
                    )
                }
                .platformCardStyle()
            }
        }
    }
}

struct StreamControlSheet: View {
    let streamID: String
    let onRemove: () -> Void

    @Environment(GamesViewModel.self) private var viewModel
    @Environment(\.dismiss) private var dismiss

    private var stream: ActiveStream? {
        viewModel.activeStreams.first { $0.id == streamID }
    }

    private var isPrimary: Bool {
        viewModel.isPrimaryStream(streamID)
    }

    private var isAudioFocused: Bool {
        viewModel.audioFocusStreamID == streamID
    }

    private var forceMuteAudio: Bool {
        stream?.forceMuteAudio == true
    }

    var body: some View {
        ZStack {
            LinearGradient(
                colors: [
                    Color(red: 0.05, green: 0.06, blue: 0.1),
                    Color(red: 0.03, green: 0.04, blue: 0.08),
                ],
                startPoint: .topLeading,
                endPoint: .bottomTrailing
            )
            .ignoresSafeArea()

            if let stream {
                VStack(alignment: .leading, spacing: 26) {
                    VStack(alignment: .leading, spacing: 10) {
                        Text(stream.label)
                            .font(.system(size: 30, weight: .bold, design: .rounded))
                            .foregroundStyle(.white)

                        Text(stream.game.displayTitle)
                            .font(.system(size: 17, weight: .medium))
                            .foregroundStyle(.white.opacity(0.6))

                        HStack(spacing: 10) {
                            controlBadge(title: isPrimary ? "Primary Tile" : "Secondary Tile", tint: .blue)
                            controlBadge(
                                title: forceMuteAudio ? "Video Only" : (isAudioFocused ? "Live Audio" : "Muted"),
                                tint: forceMuteAudio ? .orange : (isAudioFocused ? .green : .white)
                            )
                        }
                    }

                    VStack(spacing: 14) {
                        HStack(spacing: 14) {
                            actionCard(
                                title: forceMuteAudio ? "Audio Disabled" : (isAudioFocused ? "Mute All" : "Listen Here"),
                                subtitle: forceMuteAudio ? "This channel is always muted." : (isAudioFocused ? "Silence the multiview mix." : "Route game audio to this tile."),
                                icon: forceMuteAudio ? "speaker.slash.circle.fill" : (isAudioFocused ? "speaker.slash.fill" : "speaker.wave.2.fill"),
                                tint: forceMuteAudio ? .orange : (isAudioFocused ? .white : .green),
                                disabled: forceMuteAudio
                            ) {
                                viewModel.toggleAudioFocus(streamID: streamID)
                            }

                            actionCard(
                                title: isPrimary ? "Already Main" : "Make Main Tile",
                                subtitle: "Spotlight layout always favors the first stream.",
                                icon: "arrow.up.left.and.arrow.down.right",
                                tint: .blue,
                                disabled: isPrimary
                            ) {
                                viewModel.promoteStream(id: streamID)
                            }
                        }

                        HStack(spacing: 14) {
                            actionCard(
                                title: "Move Earlier",
                                subtitle: "Shift this feed toward the front of the order.",
                                icon: "arrow.left",
                                tint: .white,
                                disabled: !viewModel.canMoveStream(id: streamID, direction: -1)
                            ) {
                                viewModel.moveStream(id: streamID, direction: -1)
                            }

                            actionCard(
                                title: "Move Later",
                                subtitle: "Shift this feed deeper into the stack.",
                                icon: "arrow.right",
                                tint: .white,
                                disabled: !viewModel.canMoveStream(id: streamID, direction: 1)
                            ) {
                                viewModel.moveStream(id: streamID, direction: 1)
                            }
                        }

                        actionCard(
                            title: "Remove from Multi-View",
                            subtitle: "Close this feed and free one slot immediately.",
                            icon: "trash.fill",
                            tint: .red,
                            disabled: false,
                            destructive: true,
                            wide: true
                        ) {
                            onRemove()
                        }
                    }

                    Spacer()
                }
                .padding(44)
            } else {
                VStack(spacing: 18) {
                    Text("Stream Removed")
                        .font(.system(size: 28, weight: .bold, design: .rounded))
                        .foregroundStyle(.white)
                    Text("This feed is no longer active.")
                        .font(.system(size: 17, weight: .medium))
                        .foregroundStyle(.white.opacity(0.6))
                }
                .padding(40)
            }
        }
    }

    private func controlBadge(title: String, tint: Color) -> some View {
        Text(title)
            .font(.system(size: 13, weight: .semibold))
            .foregroundStyle(tint.opacity(0.95))
            .padding(.horizontal, 12)
            .padding(.vertical, 8)
            .background(.white.opacity(0.08))
            .clipShape(Capsule())
    }

    private func actionCard(
        title: String,
        subtitle: String,
        icon: String,
        tint: Color,
        disabled: Bool,
        destructive: Bool = false,
        wide: Bool = false,
        action: @escaping () -> Void
    ) -> some View {
        Button {
            action()
            dismiss()
        } label: {
            VStack(alignment: .leading, spacing: 14) {
                Image(systemName: icon)
                    .font(.system(size: 22, weight: .bold))
                    .foregroundStyle(disabled ? .white.opacity(0.28) : tint.opacity(0.95))

                VStack(alignment: .leading, spacing: 6) {
                    Text(title)
                        .font(.system(size: 20, weight: .bold, design: .rounded))
                        .foregroundStyle(disabled ? .white.opacity(0.32) : .white)
                    Text(subtitle)
                        .font(.system(size: 14, weight: .medium))
                        .foregroundStyle(.white.opacity(disabled ? 0.2 : 0.5))
                }
            }
            .frame(maxWidth: .infinity, minHeight: wide ? 108 : 168, alignment: .leading)
            .padding(22)
            .background(
                RoundedRectangle(cornerRadius: 22)
                    .fill(destructive ? .red.opacity(0.12) : .white.opacity(0.06))
            )
            .overlay(
                RoundedRectangle(cornerRadius: 22)
                    .stroke(disabled ? .white.opacity(0.08) : tint.opacity(0.28), lineWidth: 1)
            )
        }
        .disabled(disabled)
        .platformCardStyle()
    }
}

struct MultiStreamFullScreenView: View {
    @Environment(GamesViewModel.self) private var viewModel
    @Environment(\.dismiss) private var dismiss
    @State private var selectedStream: StreamSelection?

    var body: some View {
        ZStack(alignment: .bottom) {
            Color.black.ignoresSafeArea()

            MultiViewCanvas(
                contentInsets: 10,
                gap: 10,
                videoGravity: .resizeAspect,
                cornerRadius: 12,
                onSelect: { stream in
                    selectedStream = StreamSelection(id: stream.id)
                }
            )
            .ignoresSafeArea()

            ScoresTickerView()
                .allowsHitTesting(false)
                .padding(.horizontal, 18)
                .padding(.bottom, 12)
        }
        .overlay(alignment: .topTrailing) {
            #if os(iOS)
            Button {
                dismiss()
            } label: {
                Image(systemName: "xmark.circle.fill")
                    .font(.system(size: 28, weight: .bold))
                    .foregroundStyle(.white.opacity(0.9))
                    .padding(20)
            }
            #endif
        }
        #if os(tvOS)
        .onExitCommand {
            dismiss()
        }
        #endif
        .onChange(of: viewModel.activeStreams.count) { _, count in
            if count == 0 {
                dismiss()
            }
        }
        .sheet(item: $selectedStream) { selection in
            StreamControlSheet(
                streamID: selection.id,
                onRemove: {
                    viewModel.removeStream(id: selection.id)
                    selectedStream = nil
                    if viewModel.activeStreams.isEmpty {
                        dismiss()
                    }
                }
            )
        }
        .onAppear {
            viewModel.startAutoRefresh()
        }
    }
}

private func multiViewFrames(
    count: Int,
    mode: MultiViewLayoutMode,
    size: CGSize,
    inset: CGFloat,
    gap: CGFloat
) -> [CGRect] {
    let width = max(size.width - (inset * 2), 0)
    let height = max(size.height - (inset * 2), 0)

    switch (mode, count) {
    case (_, 0):
        return []
    case (_, 1):
        return [CGRect(x: inset, y: inset, width: width, height: height)]
    case (.spotlight, 2):
        let primaryWidth = width * 0.66
        let secondaryWidth = width - primaryWidth - gap
        return [
            CGRect(x: inset, y: inset, width: primaryWidth, height: height),
            CGRect(x: inset + primaryWidth + gap, y: inset, width: secondaryWidth, height: height),
        ]
    case (.spotlight, 3):
        let primaryWidth = width * 0.66
        let railWidth = width - primaryWidth - gap
        let railHeight = (height - gap) / 2
        return [
            CGRect(x: inset, y: inset, width: primaryWidth, height: height),
            CGRect(x: inset + primaryWidth + gap, y: inset, width: railWidth, height: railHeight),
            CGRect(x: inset + primaryWidth + gap, y: inset + railHeight + gap, width: railWidth, height: railHeight),
        ]
    case (.spotlight, _):
        let primaryWidth = width * 0.68
        let railWidth = width - primaryWidth - gap
        let railHeight = (height - (gap * 2)) / 3
        return [
            CGRect(x: inset, y: inset, width: primaryWidth, height: height),
            CGRect(x: inset + primaryWidth + gap, y: inset, width: railWidth, height: railHeight),
            CGRect(x: inset + primaryWidth + gap, y: inset + railHeight + gap, width: railWidth, height: railHeight),
            CGRect(x: inset + primaryWidth + gap, y: inset + (railHeight * 2) + (gap * 2), width: railWidth, height: railHeight),
        ]
    case (.balanced, 2):
        let cellWidth = (width - gap) / 2
        return [
            CGRect(x: inset, y: inset, width: cellWidth, height: height),
            CGRect(x: inset + cellWidth + gap, y: inset, width: cellWidth, height: height),
        ]
    case (.balanced, 3):
        let cellWidth = (width - gap) / 2
        let cellHeight = (height - gap) / 2
        return [
            CGRect(x: inset, y: inset, width: cellWidth, height: cellHeight),
            CGRect(x: inset + cellWidth + gap, y: inset, width: cellWidth, height: cellHeight),
            CGRect(x: inset, y: inset + cellHeight + gap, width: width, height: cellHeight),
        ]
    default:
        let cellWidth = (width - gap) / 2
        let cellHeight = (height - gap) / 2
        return [
            CGRect(x: inset, y: inset, width: cellWidth, height: cellHeight),
            CGRect(x: inset + cellWidth + gap, y: inset, width: cellWidth, height: cellHeight),
            CGRect(x: inset, y: inset + cellHeight + gap, width: cellWidth, height: cellHeight),
            CGRect(x: inset + cellWidth + gap, y: inset + cellHeight + gap, width: cellWidth, height: cellHeight),
        ]
    }
}

private struct MultiViewFocusEntry {
    let streamID: String
    let frame: CGRect
}

#if os(tvOS)
private func nextMultiViewFocusID(
    from currentID: String?,
    direction: MoveCommandDirection,
    entries: [MultiViewFocusEntry]
) -> String? {
    guard !entries.isEmpty else { return nil }

    guard
        let currentID,
        let currentEntry = entries.first(where: { $0.streamID == currentID })
    else {
        return entries.first?.streamID
    }

    let candidates: [(entry: MultiViewFocusEntry, primaryDistance: CGFloat, secondaryDistance: CGFloat)] = entries.compactMap { candidate in
        guard candidate.streamID != currentEntry.streamID else { return nil }

        let xDelta = candidate.frame.midX - currentEntry.frame.midX
        let yDelta = candidate.frame.midY - currentEntry.frame.midY

        switch direction {
        case .left:
            guard xDelta < 0 else { return nil }
            return (candidate, abs(xDelta), abs(yDelta))
        case .right:
            guard xDelta > 0 else { return nil }
            return (candidate, abs(xDelta), abs(yDelta))
        case .up:
            guard yDelta < 0 else { return nil }
            return (candidate, abs(yDelta), abs(xDelta))
        case .down:
            guard yDelta > 0 else { return nil }
            return (candidate, abs(yDelta), abs(xDelta))
        default:
            return nil
        }
    }

    return candidates
        .sorted { lhs, rhs in
            if abs(lhs.primaryDistance - rhs.primaryDistance) > 1 {
                return lhs.primaryDistance < rhs.primaryDistance
            }
            return lhs.secondaryDistance < rhs.secondaryDistance
        }
        .first?
        .entry
        .streamID
}
#endif

// MARK: - AudioDiagnostics
//
// Audio-specific diagnostic logging. Attach one `AudioDiagnostics` per AVPlayer
// you want to track. Emits a `[AUDIO]`-prefixed 1 Hz heartbeat with rate,
// mute, time, bitrate, and route info — plus immediate logs on route changes,
// interruptions, access-log events, and media-selection changes.
//
// Grep Xcode console with `[AUDIO]` to isolate these lines.

@MainActor
final class AudioDiagnostics {
    private let tag: String
    private weak var player: AVPlayer?
    private var heartbeatTask: Task<Void, Never>?
    private var observations: [NSKeyValueObservation] = []
    private var tokens: [NSObjectProtocol] = []

    private static var processWideInstalled = false

    init(tag: String) {
        self.tag = tag
        AudioDiagnostics.installProcessWideObservers()
    }

    deinit {
        heartbeatTask?.cancel()
    }

    func attach(to player: AVPlayer) {
        detach()
        self.player = player
        log("attach rate=\(player.rate) isMuted=\(player.isMuted) volume=\(player.volume)")

        observations.append(
            player.observe(\.rate, options: [.new]) { [weak self] p, _ in
                Task { @MainActor in self?.log("rate-change rate=\(p.rate) tc=\(p.timeControlStatus.rawValue)") }
            }
        )
        observations.append(
            player.observe(\.isMuted, options: [.new]) { [weak self] p, _ in
                Task { @MainActor in self?.log("isMuted-change value=\(p.isMuted)") }
            }
        )
        observations.append(
            player.observe(\.volume, options: [.new]) { [weak self] p, _ in
                Task { @MainActor in self?.log("volume-change value=\(p.volume)") }
            }
        )

        if let item = player.currentItem {
            attachItemObservers(item)
        }
        observations.append(
            player.observe(\.currentItem, options: [.new]) { [weak self] p, _ in
                Task { @MainActor in
                    guard let self else { return }
                    self.log("currentItem-change newItem=\(p.currentItem != nil)")
                    if let item = p.currentItem {
                        self.attachItemObservers(item)
                    }
                }
            }
        )

        startHeartbeat()
    }

    func detach() {
        heartbeatTask?.cancel()
        heartbeatTask = nil
        observations.removeAll()
        for t in tokens {
            NotificationCenter.default.removeObserver(t)
        }
        tokens.removeAll()
        player = nil
    }

    private func attachItemObservers(_ item: AVPlayerItem) {
        tokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemNewAccessLogEntry,
                object: item,
                queue: .main
            ) { [weak self, weak item] _ in
                guard let self, let event = item?.accessLog()?.events.last else { return }
                Task { @MainActor in
                    self.log(
                        "accessLog indicated=\(Int(event.indicatedBitrate)) observed=\(Int(event.observedBitrate)) switches=\(event.numberOfMediaRequests) stalls=\(event.numberOfStalls) avgVideo=\(Int(event.averageVideoBitrate)) avgAudio=\(Int(event.averageAudioBitrate))"
                    )
                }
            }
        )

        tokens.append(
            NotificationCenter.default.addObserver(
                forName: .AVPlayerItemNewErrorLogEntry,
                object: item,
                queue: .main
            ) { [weak self, weak item] _ in
                guard let self, let event = item?.errorLog()?.events.last else { return }
                Task { @MainActor in
                    self.log("errorLog domain=\(event.errorDomain) statusCode=\(event.errorStatusCode) comment=\(event.errorComment ?? "nil")")
                }
            }
        )

        tokens.append(
            NotificationCenter.default.addObserver(
                forName: AVPlayerItem.mediaSelectionDidChangeNotification,
                object: item,
                queue: .main
            ) { [weak self, weak item] _ in
                guard let self, let item else { return }
                Task { @MainActor in
                    await enforcePinnedMultiStreamAudioSelection(on: item, streamID: self.tag)
                    let asset = item.asset
                    guard let group = try? await asset.loadMediaSelectionGroup(for: .audible),
                          let selected = item.currentMediaSelection.selectedMediaOption(in: group) else {
                        self.log("mediaSelection-change selected=nil")
                        return
                    }
                    let codec = (selected.mediaSubTypes as [NSNumber]).map { audioDiagFourCC($0.uint32Value) }.joined(separator: ",")
                    self.log("mediaSelection-change audio=\"\(selected.displayName)\" codec=\(codec)")
                }
            }
        )
    }

    private func startHeartbeat() {
        heartbeatTask?.cancel()
        heartbeatTask = Task { @MainActor [weak self] in
            while !Task.isCancelled {
                self?.emitHeartbeat()
                try? await Task.sleep(for: .seconds(1))
            }
        }
    }

    private func emitHeartbeat() {
        guard let player, let item = player.currentItem else { return }
        let currentTime = CMTimeGetSeconds(player.currentTime())
        let event = item.accessLog()?.events.last
        let indicated = event.map { Int($0.indicatedBitrate) } ?? 0
        let observed = event.map { Int($0.observedBitrate) } ?? 0
        log(
            "hb t=\(String(format: "%.1f", currentTime))s rate=\(player.rate) tc=\(player.timeControlStatus.rawValue) muted=\(player.isMuted) vol=\(String(format: "%.2f", player.volume)) indicated=\(indicated) observed=\(observed) ltku=\(item.isPlaybackLikelyToKeepUp) route=\(AudioDiagnostics.currentRouteDescription())"
        )
    }

    private func log(_ message: String) {
        let ts = AudioDiagnostics.timestamp()
        print("[AUDIO \(tag) \(ts)] \(message)")
    }

    // MARK: Process-wide

    private static func installProcessWideObservers() {
        guard !processWideInstalled else { return }
        processWideInstalled = true

        let session = AVAudioSession.sharedInstance()
        print("[AUDIO SYSTEM \(timestamp())] initial category=\(session.category.rawValue) mode=\(session.mode.rawValue) sampleRate=\(session.sampleRate) route=\(currentRouteDescription())")

        NotificationCenter.default.addObserver(
            forName: AVAudioSession.routeChangeNotification,
            object: nil,
            queue: .main
        ) { notification in
            let reasonValue = notification.userInfo?[AVAudioSessionRouteChangeReasonKey] as? UInt ?? 0
            let reason = AVAudioSession.RouteChangeReason(rawValue: reasonValue).map(audioDiagReasonDescription) ?? "unknown(\(reasonValue))"
            let prev = (notification.userInfo?[AVAudioSessionRouteChangePreviousRouteKey] as? AVAudioSessionRouteDescription).map(routeDescription) ?? "nil"
            print("[AUDIO SYSTEM \(timestamp())] routeChange reason=\(reason) previous=\(prev) current=\(currentRouteDescription())")
        }

        NotificationCenter.default.addObserver(
            forName: AVAudioSession.interruptionNotification,
            object: nil,
            queue: .main
        ) { notification in
            let typeValue = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? UInt ?? 0
            let type = AVAudioSession.InterruptionType(rawValue: typeValue).map(audioDiagInterruptionDescription) ?? "unknown(\(typeValue))"
            print("[AUDIO SYSTEM \(timestamp())] interruption type=\(type)")
        }
    }

    nonisolated static func currentRouteDescription() -> String {
        routeDescription(AVAudioSession.sharedInstance().currentRoute)
    }

    nonisolated static func routeDescription(_ route: AVAudioSessionRouteDescription) -> String {
        let outs = route.outputs.map { "\($0.portType.rawValue):\($0.portName)" }.joined(separator: ",")
        return outs.isEmpty ? "none" : outs
    }

    nonisolated static func timestamp() -> String {
        audioDiagTSFormatter.string(from: Date())
    }
}

private let audioDiagTSFormatter: DateFormatter = {
    let f = DateFormatter()
    f.dateFormat = "HH:mm:ss.SSS"
    return f
}()

private func audioDiagFourCC(_ raw: UInt32) -> String {
    let bytes: [UInt8] = [
        UInt8((raw >> 24) & 0xFF),
        UInt8((raw >> 16) & 0xFF),
        UInt8((raw >> 8) & 0xFF),
        UInt8(raw & 0xFF),
    ]
    let chars = bytes.map { b -> Character in
        let scalar = UnicodeScalar(b)
        return (0x20...0x7E).contains(b) ? Character(scalar) : "?"
    }
    return String(chars)
}

private func audioDiagReasonDescription(_ reason: AVAudioSession.RouteChangeReason) -> String {
    switch reason {
    case .unknown: "unknown"
    case .newDeviceAvailable: "newDeviceAvailable"
    case .oldDeviceUnavailable: "oldDeviceUnavailable"
    case .categoryChange: "categoryChange"
    case .override: "override"
    case .wakeFromSleep: "wakeFromSleep"
    case .noSuitableRouteForCategory: "noSuitableRouteForCategory"
    case .routeConfigurationChange: "routeConfigurationChange"
    @unknown default: "unknown-future"
    }
}

private func audioDiagInterruptionDescription(_ type: AVAudioSession.InterruptionType) -> String {
    switch type {
    case .began: "began"
    case .ended: "ended"
    @unknown default: "unknown-future"
    }
}