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;
        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;
        }
        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);
        _audioMixer.StartLive(EncoderOptions.DefaultAudioPipeName);
        IsRecording = true;
        await _framePump.StartAsync();
    }

    private void BeginGoLive(bool alsoRecord)
    {
        var dialog = new GoLiveViewModel(() => SignInAsync(), _youtubeAuth.CurrentChannel)
        {
            StreamTitle = BroadcastForm.Title,
            StreamDescription = BroadcastForm.Description,
        };
        var window = new ytLive.GoLiveWindow(dialog) { Owner = System.Windows.Application.Current.MainWindow };
        if (window.ShowDialog() == true)
        {
            StreamTitle = dialog.StreamTitle;
            StreamDescription = dialog.StreamDescription;
            StreamVisibility = dialog.Visibility; // always "Private" (ship step 7)
            BroadcastForm.CaptureGoLive(dialog.StreamTitle, dialog.StreamDescription, DateTime.UtcNow);
            WindowTitle = string.IsNullOrWhiteSpace(dialog.StreamTitle)
                ? "LlamaCasty"
                : $"{dialog.StreamTitle} — LlamaCasty";
            StreamStatus = StreamStatus.Streaming;
            ResetHealth(StreamStatus.Streaming);
            _audioMixer.StartLive(EncoderOptions.DefaultAudioPipeName);
            _liveElapsed = TimeSpan.Zero;
            _recordLength = TimeSpan.Zero;

            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>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
        {
            var stream = await _youtubeStream.GetOrCreateReusableStreamAsync();
            if (stream == null)
            {
                AppLog.Write("Reusable stream unavailable; check the OAuth session");
                _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);

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

            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.");
            }

            // Start chat polling (TASK 9.4): fetch the liveChatId from the broadcast's
            // contentDetails, then start the poll loop. Chat is non-fatal — if it fails,
            // the stream continues without on-panel chat.
            try
            {
                var liveChatId = await _youtubeStream.GetBroadcastLiveChatIdAsync(_currentBroadcastId);
                if (liveChatId != null)
                {
                    _youtubeChat.Start(liveChatId);
                    AppLog.Write($"Chat polling started: {liveChatId}");
                }
                else
                {
                    AppLog.Write("Could not retrieve liveChatId; chat polling disabled");
                }
            }
            catch (Exception chatEx)
            {
                AppLog.Write($"Chat start failed (non-fatal): {chatEx.Message}");
            }
        }
        catch (Exception ex)
        {
            AppLog.Write($"Go-live preparation failed: {ex.Message}");
            _notifications.Error("Couldn't go live", ex.Message);
            StopStream(); // full rollback — a created broadcast (if any) gets the close-out
            return;
        }

        await _framePump.StartAsync(); // never throws; failures log + surface via Failed

        // Health polling (TASK 5 item 3): poll immediately, then every 30s while
        // live. Report-by-exception — a banner appears only on warning/error.
        _healthPollTimer.Start();
        _ = PollHealthAsync();
    }

    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.</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");
                return;
            }
            CurrentHealth.HealthStatus = health.HealthStatus;
            CurrentHealth.HealthMessage = health.HealthStatus;
            CurrentHealth.ConfigurationIssues.Clear();
            CurrentHealth.ConfigurationIssues.AddRange(health.ConfigurationIssues);
            OnPropertyChanged(nameof(CurrentHealth));
            ApplyHealthIssue(health.ConfigurationIssues);
        }
        catch (Exception ex)
        {
            AppLog.Write($"Stream health poll failed: {ex.Message}");
        }
    }

    // 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 ? "#8f1f1f" : "#b8860b";
        HealthIssueBanner = report.Text;
    }

    private async void StopStream()
    {
        var wasLive = IsLive;
        var wasRecording = IsRecording;

        StreamStatus = StreamStatus.Offline;
        IsRecording = false;
        // Stop ends EVERYTHING (creator ruling 2026-09-01): a lit pill with no session
        // behind it is a lie — the stuck REC pill after the failed 2026-09-01 recording
        // attempt was the report. Intent resets with reality; re-arming is one click.
        RecordPillOn = false;
        OnAirPillOn = false;
        WindowTitle = "LlamaCasty";
        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.
        if (wasLive && _currentBroadcastId != null)
        {
            var closeOutError = await _youtubeStream.EndBroadcastAsync(_currentBroadcastId);
            if (closeOutError != null)
                AppLog.Write($"End close-out: {closeOutError} — enableAutoStop will finish the broadcast");
        }

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

        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).
    private EncoderOptions? BuildEncoderOptions()
    {
        var url = _rtmpUrlProvider();
        var quality = SelectedQuality;
        return new EncoderOptions
        {
            RtmpUrl = url ?? string.Empty,
            StreamEnabled = OnAirPillOn,
            RecordEnabled = RecordPillOn,
            RecordPath = _activeRecordPath,
            Width = quality.Width,
            Height = quality.Height,
            Fps = quality.Fps,
            BitrateKbps = (int)Math.Round(quality.Bitrate * 1000),
        };
    }

    // 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}");
        void Handle()
        {
            var live = IsLive;
            _notifications.Error(live ? "The stream pipeline stopped" : "Recording stopped", message);
            StopStream();
        }
        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;
        TopBarBackground = live ? "#e94560" : "#16213e";
        PreviewGlowBrush = live ? "#e94560" : "Transparent";
        PreviewGlowThickness = live ? new Thickness(3) : new Thickness(0);

        if (live)
        {
            if (BrandFlashEnabled) StartBrandFlashTimer();
        }
        else
        {
            _healthPollTimer.Stop();
            _brandFlashTimer.Stop();
            _brandFlashOffTimer.Stop();
            BrandFlashActive = false;
        }
        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));
    }

    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 ? 0.35 : 1.0;
        OnPropertyChanged(nameof(RecDotOpacity));
    }
}