using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using Microsoft.Win32;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services;
using ytLive.Services.Encoder;

namespace ytLive.ViewModels;

public partial class MainViewModel : ViewModelBase
{

    /// <summary>Entry point for the primary Start button (and the start/stop hotkey):
    /// routes to a record session or the YouTube go-live dialog by the pill state.</summary>
    private void StartSession()
    {
        if (IsLive || IsRecording) return;
        var streaming = OnAirPillOn;
        var recording = RecordPillOn;
        // The scoreboard's scope is the session: every start clears it (creator ruling 2026-10-30).
        StartScoreboardSession();

        if (!streaming && !recording)
        {
            // Nothing armed = "record something" (local recording needs no account,
            // 2026-09-01): a Start that silently no-ops is the dead end the design
            // principle forbids. The pill lights so reality and intent agree.
            RecordPillOn = true;
            BeginRecordOnly();
            return;
        }

        if (!streaming)
        {
            BeginRecordOnly();
            return;
        }
        if (!IsConnected)
        {
            // ON-AIR armed signed-out: intent (the pill stayed lit) is reality-aware.
            // A signed-out go-live would dead-end in the account dialog {DASH} so Start
            // turns the intent into the sign-in face instead. Reality and intent meet
            // at the account connection; the pill keeps its light either way.
            _ = SignInAsync();
            return;
        }
        BeginGoLive(recording);
    }

    /// <summary>Record-only (REC pill on, ON-AIR off): no YouTube dialog — recording
    /// is local and works signed-out. Generates the auto-named file and starts the
    /// pipeline immediately.</summary>
    private async void BeginRecordOnly()
    {
        var path = StartRecordFile();
        if (path == null)
        {
            _notifications.Error("Couldn't record", "No record output path could be created.");
            return;
        }
        _recordStartTime = DateTime.Now;
        _liveElapsed = TimeSpan.Zero;
        _recordLength = TimeSpan.Zero;
        ResetHealth(StreamStatus.Offline);
        if (!TryStartAudioPipe()) return;
        IsRecording = true;
        LiveScene = StagedScene;
        await _framePump.StartAsync();
    }

    /// <summary>Starts the live audio pipe, or explains why it cannot and rolls the session back.
    /// <para>This used to throw straight out of the Go Live button: the pipe server allows one instance,
    /// so with a second LlamaCasty running on the same machine the click killed the app
    /// ("All pipe instances are busy", 2026-11-06). A click must never be able to end the process.</para>
    /// </summary>
    private bool TryStartAudioPipe()
    {
        var pipeName = InstanceProfile.AudioPipeName(EncoderOptions.DefaultAudioPipeName);
        try
        {
            _audioMixer.StartLive(pipeName);
            AppLog.Write($"Audio pipe: {pipeName}");
            return true;
        }
        catch (Exception ex)
        {
            AppLog.Write(ex, "Audio pipe could not be started — session aborted");
            _notifications.Error("Couldn't start the audio",
                "Another copy of LlamaCasty is already using the audio pipe. Close it, then try again.");
            StopStream();
            return false;
        }
    }

    /// <summary>Builds the Start Stream dialog's model from the Stream Info tab. Re-reads the store
    /// first: the form is loaded once at startup, and a second LlamaCasty on the same profile (the dev
    /// instance, or Release recording while Debug goes live) writes its edits straight to the store, so
    /// this process's copy can be empty while the tab the creator filled in is not (2026-11-06).</summary>
    internal GoLiveViewModel CreateGoLiveDialog()
    {
        BroadcastForm.Load();
        var dialog = new GoLiveViewModel(() => SignInAsync(), _youtubeAuth.CurrentChannel)
        {
            StreamTitle = BroadcastForm.Title,
            StreamDescription = BroadcastForm.Description,
        };
        AppLog.Write($"Go Live dialog: title='{dialog.StreamTitle}' description={dialog.StreamDescription.Length} chars");
        return dialog;
    }

    private void BeginGoLive(bool alsoRecord)
    {
        var dialog = CreateGoLiveDialog();
        var window = new ytLive.GoLiveWindow(dialog) { Owner = System.Windows.Application.Current.MainWindow };
        if (window.ShowDialog() != true) return;

        StreamTitle = dialog.StreamTitle;
        StreamDescription = dialog.StreamDescription;
        StreamVisibility = dialog.Visibility; // always "Private" (ship step 7)
        BroadcastForm.CaptureGoLive(dialog.StreamTitle, dialog.StreamDescription, DateTime.UtcNow);
        StartStreamingSession(alsoRecord);
    }

    /// <summary>TASK 41 — Test stream: one click, no dialog. Every broadcast is
    /// already private-only (ship step 7), so there is nothing to confirm; the test
    /// session reuses the ENTIRE real go-live pipeline (reusable stream, broadcast
    /// create, RTMP push, chat poll) with IsTestStream flipped so the face says TEST
    /// and the Test drawer opens once the liveChatId resolves. No "last live" stamp:
    /// a rehearsal isn't a broadcast the creator took on the record.</summary>
    private void BeginTestStream()
    {
        if (!CanStartTest) return;
        // Test is stream-world-only, so the ON-AIR intent is armed by the time we
        // get here — but arm it explicitly anyway: the encoder output gate reads the
        // pill (StreamEnabled = OnAirPillOn), and a test that never armed the pill
        // boots a pump with zero outputs and dies on "At least one output required".
        OnAirPillOn = true;
        IsTestStream = true; // before StreamStatus so the visuals initialize gold
        StreamTitle = BroadcastForm.Title;
        StreamDescription = BroadcastForm.Description;
        StreamVisibility = "Private";
        StartStreamingSession(alsoRecord: false);
    }

    /// <summary>Boots the streaming face of ANY session (dialog go-live or test):
    /// status streaming, audio live, timer reset, optional recording, then the async
    /// broadcast preparation. The test path skips BroadcastForm.CaptureGoLive by
    /// design and never records.</summary>
    private void StartStreamingSession(bool alsoRecord)
    {
        WindowTitle = string.IsNullOrWhiteSpace(StreamTitle)
            ? "LlamaCasty"
            : $"{StreamTitle} — LlamaCasty";
        StreamStatus = StreamStatus.Streaming;
        // TASK 3·20: the session report window starts here. Derived on demand from YouTube, never
        // persisted, and reset when the session ends.
        _sessionStartedAtUtc = DateTime.UtcNow;
        ResetHealth(StreamStatus.Streaming);
        if (!TryStartAudioPipe()) return;
        _liveElapsed = TimeSpan.Zero;
        _recordLength = TimeSpan.Zero;
        StartStepDownWatch();
        StartClipRing();

        var recordStarted = false;
        if (alsoRecord)
        {
            if (StartRecordFile() == null)
            {
                _notifications.Error("Couldn't record",
                    "No record output path could be created — streaming continues without recording.");
            }
            else
            {
                _recordStartTime = DateTime.Now;
                recordStarted = true;
            }
        }
        IsRecording = recordStarted;

        _ = PrepareAndStartLiveAsync();
    }

    /// <summary>Creates the record file (auto-named <c>ty-…-0000.mp4</c> in the record
    /// folder) and returns its path, or null when the folder can't be prepared.</summary>

    /// <summary>TASK 32·5 — is YouTube's ingest reachable right now? A false answer aborts go-live
    /// before anything is created on YouTube: "I forgot the VPN" used to produce a broadcast that
    /// nobody ever saw, and the app looked live while the push had nowhere to go.</summary>
    internal async Task<bool> IngestPreflightAsync(string rtmpUrl)
    {
        var probe = IngestProbeOverride ?? new TcpIngestProbe();
        if (await probe.CanReachAsync(rtmpUrl)) return true;

        AppLog.Write("Ingest unreachable — go-live aborted before creating a broadcast",
            AppLogMessageType.Error, AppLogErrorClass.Class1);
        _notifications.Error("Can't reach YouTube's ingest",
            "Nothing was created on YouTube. Check your network or VPN, then try again.");
        StopStream(); // rollback: no ghost broadcast, no half-lit session
        return false;
    }

    /// <summary>One-click go-live (TASK 5): ensure the reusable stream, create a
    /// broadcast bound to it, then start the frame pump. The pump reads the RTMP
    /// URL once at startup (FramePump.StartAsync), so the stream URL must be set
    /// before the pump starts — hence the ordering here. Failures surface as an
    /// error health state, never a crash.</summary>
    private async Task PrepareAndStartLiveAsync()
    {
        try
        {
            // TASK 32·5 — prevention. With a cached ingest URL we probe BEFORE the first API call, so
            // a dead network costs nothing and leaves nothing behind on YouTube. First run (no cached
            // URL yet) probes once the stream is resolved, still before any broadcast is created.
            var cachedIngest = _reusableStreamUrl;
            if (!string.IsNullOrWhiteSpace(cachedIngest) && !await IngestPreflightAsync(cachedIngest))
                return;

            var stream = await _youtubeStream.GetOrCreateReusableStreamAsync();
            if (stream == null)
            {
                AppLog.Write("Reusable stream unavailable; check the OAuth session",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
                _notifications.Error("Couldn't go live",
                    "The reusable stream is unavailable — check the YouTube sign-in and try again.");
                StopStream(); // full rollback — audio loop + recording + pills, no Error-status zombie
                return;
            }
            _reusableStream = stream;
            _reusableStreamUrl = stream.RtmpUrl;
            _layoutStore.SaveReusableStream(stream);

            if (string.IsNullOrWhiteSpace(cachedIngest) && !await IngestPreflightAsync(stream.RtmpUrl))
                return;

            _currentBroadcastId = await _youtubeStream.CreateBroadcast(
                StreamTitle, StreamDescription, DateTime.UtcNow);
            _broadcastSeenLive = false;
            if (_currentBroadcastId == null)
            {
                AppLog.Write("Broadcast creation failed; check the OAuth session",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
                _notifications.Error("Couldn't go live", "YouTube rejected the broadcast — check the sign-in and try again.");
                StopStream(); // full rollback
                return;
            }
            AppLog.WriteSuccess($"Broadcast created: {_currentBroadcastId}");
            OnPropertyChanged(nameof(CurrentBroadcastId));

            // ⛔ THE BINDING — the call whose absence is why nothing ever went live
            // (2026-10-04). Sending `contentDetails.boundStreamId` on the insert does NOT
            // bind: the insert is accepted, its sibling fields take effect, and the
            // broadcast still comes back `bound=NONE`, sits in lifeCycleStatus `created`
            // forever ("incomplete settings"), so `enableAutoStart` has no bound stream to
            // fire from and close-out 403s `invalidTransition`. Meanwhile ffmpeg happily
            // pushes ~99MB into the reusable stream, because a reusable stream accepts
            // bytes for a broadcast that is not watching — which is why every symptom
            // pointed away from the binding.
            //
            // Failure here is fatal to the session, not cosmetic: an unbound broadcast can
            // never go live, so continuing would present a live-looking UI over a broadcast
            // that is quietly never going to be seen.
            var bindError = await _youtubeStream.BindBroadcastAsync(_currentBroadcastId, stream.Id);
            if (bindError != null)
            {
                AppLog.Write($"Stream binding failed: {bindError}",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
                // Show the real reason. "Check the sign-in" would be wrong for five of the
                // six documented bind failures, and would hide our own ordering bug behind
                // a plausible excuse — see BindFailureMessage.
                _notifications.Error("Couldn't go live", bindError);
                StopStream(); // full rollback
                return;
            }

            if (string.IsNullOrWhiteSpace(StreamTitle) && string.IsNullOrWhiteSpace(StreamDescription))
            {
                BroadcastForm.IsDrawerOpen = true;
                _notifications.Warning("Complete your broadcast details",
                    "Your title and description are empty — fill them in from the Text panel on the right.");
            }
        }
        catch (Exception ex)
        {
            AppLog.Write($"Go-live preparation failed: {ex.Message}",
                AppLogMessageType.Error, AppLogErrorClass.Class2);
            _notifications.Error("Couldn't go live", ex.Message);
            StopStream(); // full rollback — a created broadcast (if any) gets the close-out
            return;
        }

        // The pump is what pushes RTMP; enableAutoStart flips the broadcast ready→live
        // only once frames flow. The liveChatId (snippet.liveChatId) does not exist
        // before that (2026-09-25 diagnosis), so chat resolution runs AFTER the pump
        // starts. Chat is non-fatal — if it fails, the stream continues without chat.
        LiveScene = StagedScene;
        ApplyEditLockForSession(starting: true);
        await _framePump.StartAsync(); // never throws; failures log + surface via Failed

        // Check promptly until YouTube confirms the broadcast is live. Health
        // polling returns to its normal interval after that confirmation.
        _healthPollTimer.Interval = TimeSpan.FromSeconds(2);
        _healthPollTimer.Start();
        _ = PollHealthAsync();

        string? liveChatId = null;
        try
        {
            if (_currentBroadcastId != null)
                liveChatId = await _youtubeStream.GetBroadcastLiveChatIdAsync(_currentBroadcastId);
            if (liveChatId != null)
            {
                _youtubeChat.Start(liveChatId);
                AppLog.Write($"Chat polling started: {liveChatId}");
            }
            else
            {
                AppLog.Write("Could not retrieve liveChatId; chat polling disabled",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
            }
        }
        catch (Exception chatEx)
        {
            AppLog.Write($"Chat start failed (non-fatal): {chatEx.Message}",
                AppLogMessageType.Error, AppLogErrorClass.Class2);
        }

        // TASK 41: a test broadcast hands its session to the Test drawer once
        // the liveChatId resolves — Mock Chat Input + simulated events need it.
        if (IsTestStream && _currentBroadcastId != null)
        {
            TestSession.BeginTest(_currentBroadcastId, liveChatId);
            AppLog.Write($"Test session dock open for {_currentBroadcastId}");
        }

    }

    private void OnHealthPollTick(object? sender, EventArgs e) => _ = PollHealthAsync();

    /// <summary>One liveStreams.list poll (TASK 5 item 3): updates the YouTube
    /// health state + the report-by-exception banner. Never throws — a poll
    /// failure logs and leaves the last state untouched.
    ///
    /// Also piggybacks the broadcast diagnostic (2026-10-04) — the health poll was
    /// already running during a stream but only ever read the STREAM's health, which
    /// is why two test runs could push 100MB to YouTube and still leave the app
    /// unable to say whether the broadcast had ever left `ready`. Deliberately
    /// self-limiting: it only logs while the broadcast has NOT reached `live`, so it
    /// shouts exactly when something is wrong and goes quiet once healthy, rather than
    /// adding a permanent per-tick line to the log.</summary>
    private async Task PollHealthAsync()
    {
        if (_reusableStream == null || !IsLive) return;
        try
        {
            var health = await _youtubeStream.GetStreamHealthAsync(_reusableStream.Id);
            if (health == null)
            {
                AppLog.Write("Stream health poll failed; check the OAuth session",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
            }
            else
            {
                CurrentHealth.HealthStatus = health.HealthStatus;
                CurrentHealth.HealthMessage = health.HealthStatus;
                CurrentHealth.ConfigurationIssues.Clear();
                CurrentHealth.ConfigurationIssues.AddRange(health.ConfigurationIssues);
                OnPropertyChanged(nameof(CurrentHealth));
                ApplyHealthIssue(health.ConfigurationIssues);
            }

            if (!string.IsNullOrWhiteSpace(_currentBroadcastId) && !_broadcastSeenLive)
            {
                var lifeCycle = await _youtubeStream.LogBroadcastDiagnosticsAsync(_currentBroadcastId, _reusableStream.Id);
                ApplyBroadcastLifecycleStatus(lifeCycle);
            }
        }
        catch (Exception ex)
        {
            AppLog.Write($"Stream health poll failed: {ex.Message}",
                AppLogMessageType.Error, AppLogErrorClass.Class2);
        }
    }

    // Report-by-exception: good/ok/noData (or info-only issues) clear the banner;
    // the first warning/error issue raises it, colored by the worst severity.
    private void ApplyHealthIssue(List<StreamConfigurationIssue> issues)
    {
        var report = StreamHealthReporter.BannerFor(issues);
        if (report.Text == null)
        {
            HealthIssueBanner = null;
            HealthIssueBackground = "Transparent";
            return;
        }

        HealthIssueBackground = report.IsError
            ? ThemeBrush.Hex("Brush.ErrorContainer")
            : ThemeBrush.Hex("Brush.WarningContainer");
        HealthIssueBanner = report.Text;
    }

    /// <param name="afterFailure">True when the session is being torn down because something broke,
    /// not because the creator pressed Stop. A failure clears both outputs (there is no session and no
    /// choice worth keeping); a creator's Stop of a recording restores the Local MP4 pair.</param>
    private async void StopStream(bool afterFailure = false)
    {
        var dispatcher = Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
        {
            _ = dispatcher.BeginInvoke(new Action(() => StopStream()));
            return;
        }

        CancelStreamRecovery();   // a stop wins over a relaunch in flight
        StopStepDownWatch();
        StopClipRing();
        RemoveAttentionAlert("stream-recovery");
        var wasLive = IsLive;
        var wasRecording = IsRecording;
        var wasRecordingOnly = IsRecording && !IsLive && !afterFailure;

        StreamStatus = StreamStatus.Offline;
        _sessionStartedAtUtc = null;
        IsRecording = false;
        LiveScene = null;
        ApplyEditLockForSession(starting: false);
        // TASK 41: a stopped test broadcast forgets its drawer session (idempotent)
        // and drops the TEST face — a test never outlives its run.
        TestSession.EndTestSilently();
        IsTestStream = false;
        // Stop ends the session (creator ruling 2026-09-01): a lit pill with no session behind it is a
        // lie. Since build 730 the pills are the chosen OUTPUT, not an armed intent, so a finished
        // local recording returns to its idle pair — Local MP4 chosen, Start Recording beside it
        // (creator's words) — while a finished stream clears both and asks again.
        if (wasRecordingOnly)
        {
            RecordPillOn = true;
            OnAirPillOn = false;
        }
        else
        {
            RecordPillOn = false;
            OnAirPillOn = false;
        }
        WindowTitle = "LlamaCasty";
        // Deactivate zoom when stopping
        if (_zoomState.IsActive || _zoomState.IsMoving)
        {
            _zoomState.IsActive = false;
            _zoomState.IsMoving = false;
            OnPropertyChanged(nameof(IsZoomActive));
            OnPropertyChanged(nameof(ShowZoomOverlay));
            OnPropertyChanged(nameof(ZoomState));
            RebuildQualityDimRects();
        }
        ResetHealth(StreamStatus.Offline);
        // Stop chat polling first (TASK 9.4) — no more messages arriving while
        // we're tearing down the stream.
        _youtubeChat.Stop();
        // Close the audio pipe FIRST so ffmpeg sees EOF on the audio input,
        // then stop the pump (stdin EOF) — both inputs end and the encoder
        // finalizes the output. Audio capture itself is always-on (preview
        // monitoring); only the live/report pipe, the pump, and the session stop here.
        _audioMixer.StopLive();
        await _framePump.StopAsync();

        // Proper close-out (TASK 9 decision 6, built 2026-09-01): transition(complete)
        // AFTER the RTMP push is closed so no frames post-date the end — YouTube then
        // finalizes the VOD immediately instead of leaving viewers on a frozen
        // "stream offline" until enableAutoStop fires (~1 min). Log-only failure:
        // the backstop still ends the broadcast; a stop never fails over cosmetics.
        var endedBroadcastId = wasLive ? _currentBroadcastId : null;
        if (endedBroadcastId != null)
        {
            var closeOutError = await _youtubeStream.EndBroadcastAsync(endedBroadcastId);
            if (closeOutError != null)
                AppLog.Write($"End close-out: {closeOutError} — enableAutoStop will finish the broadcast",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
        }

        _currentBroadcastId = null;
        OnPropertyChanged(nameof(CurrentBroadcastId));

        // Creator ruling 2026-10-09: a PRIVATE broadcast ends like a recording — Enter keeps
        // it on YouTube, Escape deletes it.
        if (endedBroadcastId != null)
            await OfferToKeepPrivateBroadcastAsync(endedBroadcastId);

        if (wasRecording) await FinalizeRecordingAsync();

        // Explicit sign-out only (TASK 18): stopping the stream does NOT clear
        // the session/token — the creator signs out deliberately via the
        // Logout / Change Account commands.
        AppLog.Write(wasLive ? "Stream ended" : "Recording ended");
    }

    /// <summary>On stop the auto-named <c>ty-…-0000.mp4</c> file is renamed to carry
    /// the real recording length (<c>ty-…-hh2mm2.mp4</c>), with a numeric suffix on
    /// name collisions. Runs only after the pump has fully closed the file.</summary>



    /// <summary>Falls back to the user's Downloads folder when no preference is set;
    /// returns MyVideos if Downloads doesn't exist.</summary>

    // Full encoder options for the current tier, or null when no RTMP URL is
    // available — the pump then skips the encoder entirely (TASK 5 fills the seam).
    //
    // BOTH outputs (RTMP + local MP4) are encoded from this one option set, so the
    // output-profile rule is applied here, once: a capped build cannot stream 1080p and
    // record it too. See Models/OutputProfile.cs — pixels, not "720p".
    private EncoderOptions? BuildEncoderOptions()
    {
        var url = _rtmpUrlProvider();
        var quality = EffectiveQuality(OutputProfile.Resolve(SelectedQuality, QualityOptions, HasProOutput));
        // TASK 33: while a session is live, a step-down owns the emitted tier even though the dropdown
        // still shows what the creator picked. Their intent is not edited by the policy.
        if (_encoderTierOverride is { } landed)
            quality = new QualityOption($"{landed.Width}p{landed.Fps}", landed.Fps,
                landed.BitrateMbps, landed.Width, landed.Height);
        var compositor = BuildCompositorOptions();
        return new EncoderOptions
        {
            RtmpUrl = url ?? string.Empty,
            StreamEnabled = OnAirPillOn,
            RecordEnabled = RecordPillOn,
            RecordPath = _activeRecordPath,
            Width = quality.Width,
            Height = quality.Height,
            InputWidth = compositor.OutputWidth,
            InputHeight = compositor.OutputHeight,
            Fps = quality.Fps,
            BitrateKbps = (int)Math.Round(quality.Bitrate * 1000),
            // Same derivation as the mixer's StartLive call: a dev instance serves its own pipe.
            AudioPipeName = InstanceProfile.AudioPipeName(EncoderOptions.DefaultAudioPipeName),
            // TASK 65: null when clips are off, which leaves ffmpeg's command line untouched.
            ClipBuffer = _clipRing,
        };
    }

    // internal: test seam (mirrors LayoutPathOverride) — the rollback path is
    // unobservable without simulating a pump death; ytLive.Tests has InternalsVisibleTo.
    internal void OnFramePumpFailed(object? sender, string message)
    {
        // No zombies (2026-09-01): a dead pump means NO session — the old handler
        // toasted and (live-only) flipped StreamStatus, leaving a record-only session
        // with IsRecording=true and no encoder (first real launch proved it). The
        // failure now runs the NORMAL stop path on the UI thread (pills off, audio
        // loop closed, recording finalized, close-out if live), then explains itself.
        AppLog.Write($"Frame pump failed: {message}", AppLogMessageType.Error, AppLogErrorClass.Class2);
        void Handle()
        {
            var live = IsLive;
            _notifications.Error(live ? "The stream pipeline stopped" : "Recording stopped", message);
            StopStream(afterFailure: true);
        }
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(Handle);
        else
            Handle();
    }

    // TASK 4 ship step 6: the encoder's parsed health (bitrate/FPS/dropped/
    // duration) lands in the bottom bar. The stderr loop raises on a background
    // thread — marshal to the UI thread like the audio level handlers.
    private void OnFramePumpHealthUpdated(object? sender, StreamHealth health)
    {
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(() => ApplyHealth(health));
        else
            ApplyHealth(health);
    }

    private void ApplyHealth(StreamHealth health)
    {
        CurrentHealth.Status = health.Status;
        CurrentHealth.CurrentBitrate = health.CurrentBitrate;
        CurrentHealth.FPS = health.FPS;
        CurrentHealth.DroppedFrames = health.DroppedFrames;
        CurrentHealth.StreamDuration = health.StreamDuration;
        CurrentHealth.LastError = health.LastError;
        CurrentHealth.HealthMessage = health.HealthMessage;
        OnPropertyChanged(nameof(CurrentHealth));
    }

    // Keeps the bottom-bar stats honest across sessions: dropped frames and the
    // elapsed duration must not linger from a previous go-live (bitrate/FPS stay
    // on the tier's targets — ApplyStreamQuality sets them on pick).
    private void ResetHealth(StreamStatus status)
    {
        CurrentHealth.Status = status;
        CurrentHealth.DroppedFrames = 0;
        CurrentHealth.StreamDuration = TimeSpan.Zero;
        CurrentHealth.LastError = null;
        CurrentHealth.HealthStatus = null;
        CurrentHealth.HealthMessage = null;
        CurrentHealth.ConfigurationIssues.Clear();
        HealthIssueBanner = null;
        HealthIssueBackground = "Transparent";
        OnPropertyChanged(nameof(CurrentHealth));
    }

    private void UpdateLiveVisuals()
    {
        var live = IsLive;
        // TEST keeps its gold identity. For a normal ON-AIR session, green means
        // YouTube has confirmed live; before then it keeps the existing red color.
        TopBarBackground = live
            ? IsTestStream
                ? ThemeBrush.Hex("Brush.TestContainer")
                : ThemeBrush.Hex(_youtubeBroadcastLive ? "Brush.Positive" : "Brush.Primary")
            : ThemeBrush.Hex("Brush.SurfaceContainer");
        PreviewGlowBrush = live
            ? ThemeBrush.Hex(IsTestStream ? "Brush.TestContainer" : "Brush.Primary")
            : "Transparent";
        PreviewGlowThickness = live ? new Thickness(3) : new Thickness(0);

        if (!live)
        {
            _healthPollTimer.Stop();
            _healthPollTimer.Interval = TimeSpan.FromSeconds(30);
        }

        // NOTE: the branding credit is deliberately NOT started/stopped here.
        // CREATOR RULING 2026-09-26 — it must appear in EVERY scene and in
        // recordings, not only while streaming. It used to be gated on IsLive, which
        // meant a recording made without ever going live carried no credit at all.
        // The presenter is started once for the life of the app (MainViewModel ctor);
        // the licence gate rides on BrandFlashPresenter.Enabled via IsPremium, so it
        // needs no live branch — IsPremium's setter pushes it from any thread.
        UpdateSessionTimer();
    }

    /// <summary>Runs the elapsed/rec-dot-pulse timer while a session is active —
    /// live (Streaming) OR recording. Reset the elapsed when a new session starts.</summary>
    private void UpdateSessionTimer()
    {
        var active = IsLive || IsRecording;
        if (active)
        {
            _recDotPulse = 1.0;
            _liveTimer.Start();
        }
        else
        {
            _liveTimer.Stop();
            LiveElapsedText = "00:00:00";
            _recDotPulse = 1.0;
        }
        OnPropertyChanged(nameof(RecDotOpacity));
        OnPropertyChanged(nameof(LiveElapsedText));
        OnPropertyChanged(nameof(RecordChipText));
    }

    private void OnLiveTimerTick(object? sender, EventArgs e)
    {
        _liveElapsed = _liveElapsed.Add(TimeSpan.FromSeconds(1));
        LiveElapsedText = _liveElapsed.ToString(@"hh\:mm\:ss");
        _recordLength = _liveElapsed;
        _recDotPulse = _recDotPulse > 0.5 ? 0.2 : 1.0;
        OnPropertyChanged(nameof(RecDotOpacity));
        OnPropertyChanged(nameof(RecordChipText));

        // TASK 55·3: the last useful warning before the encoder fails for a reason it won't explain.
        if (IsRecording && !_lowDiskWarned && _recordFolder is { } folder
            && DiskSpaceGuard.FreeBytes(folder) is { } free
            && DiskSpaceGuard.ShouldWarnDuring(free))
        {
            _lowDiskWarned = true;
            _notifications.Warning("Disk space is nearly gone",
                "The recording may stop on its own. Free up space now, or stop and save what you have.");
        }
    }

    /// <summary>What happened to a finished broadcast at the keep-or-delete prompt.</summary>
    internal enum PrivateBroadcastOutcome { NotPrivate, Kept, Deleted, DeleteFailed }

    /// <summary>Test seam: answers the keep-or-delete prompt (title → keep?) instead of showing
    /// <see cref="KeepBroadcastDialog"/>. Mirrors the other static overrides.</summary>
    internal static Func<string, bool>? KeepBroadcastPromptOverride { get; set; }

    private async Task OfferToKeepPrivateBroadcastAsync(string broadcastId)
    {
        var title = BroadcastForm.Title;
        var (outcome, error) = await ClosePrivateBroadcastAsync(_youtubeStream, broadcastId,
            () => KeepBroadcastPromptOverride?.Invoke(title) ?? new KeepBroadcastDialog(title).ShowDialog() == true);
        switch (outcome)
        {
            case PrivateBroadcastOutcome.Kept:
                AppLog.Write($"Private broadcast kept: {broadcastId}");
                _notifications.Info("Broadcast kept", "It's on YouTube as a private video.");
                break;
            case PrivateBroadcastOutcome.Deleted:
                AppLog.Write($"Private broadcast deleted by creator: {broadcastId}");
                _notifications.Info("Broadcast deleted", "The broadcast was removed from YouTube.");
                break;
            case PrivateBroadcastOutcome.DeleteFailed:
                AppLog.Write($"Private broadcast delete failed: {broadcastId}: {error}",
                    AppLogMessageType.Error, AppLogErrorClass.Class2);
                _notifications.Error("Couldn't delete the broadcast",
                    $"{error}. It's still on YouTube as a private video — you can delete it in YouTube Studio.");
                break;
        }
    }

    /// <summary>The keep-or-delete decision for a finished broadcast. Asks ONLY when YouTube
    /// itself reports the broadcast as private (visibility can change mid-stream, so local state
    /// isn't trusted); an unreadable status asks nothing and deletes nothing. Keep = leave it;
    /// otherwise delete the video from YouTube.</summary>
    internal static async Task<(PrivateBroadcastOutcome Outcome, string? Error)> ClosePrivateBroadcastAsync(
        YouTubeStreamService youtube, string broadcastId, Func<bool> askKeep)
    {
        var privacy = await youtube.GetBroadcastPrivacyAsync(broadcastId);
        if (!string.Equals(privacy, "private", StringComparison.OrdinalIgnoreCase))
            return (PrivateBroadcastOutcome.NotPrivate, null);
        if (askKeep()) return (PrivateBroadcastOutcome.Kept, null);
        var error = await youtube.DeleteFinishedBroadcastAsync(broadcastId);
        return error == null ? (PrivateBroadcastOutcome.Deleted, null) : (PrivateBroadcastOutcome.DeleteFailed, error);
    }
}