using System.IO;
using System.Windows.Media;
using Microsoft.Win32;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services.Audio;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    // TRAX (TASK 9): free background music at a fixed quiet volume, playing to
    // the default device so it rides the loopback into the stream. The button is a
    // toggle; its dot is green (playing) / red (error — a terse message scrolls in the
    // desktop-audio bar) / gray (idle or no track).
    private readonly ITraxPlayer _musicPlayer = TraxPlayerOverride?.Invoke() ?? new MusicPlayer();

    /// <summary>Test seam: a fake TRAX player (no audio device). Set before constructing.</summary>
    internal static Func<ITraxPlayer>? TraxPlayerOverride { get; set; }
    private Music? _music;
    private bool _musicPlaying;
    private bool _traxLoadInFlight;

    /// <summary>Hard ceiling on the TRAX reachability probe. A track on an offline
    /// network share blocks ~40s inside <c>MediaFoundationReader</c> before it throws
    /// 0x80070035, and that call sat on the startup path inside LoadLayout, so the
    /// window froze for the whole SMB timeout. The probe runs off the UI thread and is
    /// abandoned at this budget; the orphan thread stays parked until SMB gives up,
    /// which is the point — it is not the thread the creator is waiting on.</summary>
    internal static readonly TimeSpan TraxProbeBudget = TimeSpan.FromSeconds(2);

    private static readonly SolidColorBrush TraxIdleBrush = CreateBrush("#555");
    /// <summary>True while the TRAX background track is playing.</summary>
    public bool IsMusicPlaying
    {
        get => _musicPlaying;
        private set
        {
            if (SetProperty(ref _musicPlaying, value))
            {
                OnPropertyChanged(nameof(TraxDotBrush));
                OnPropertyChanged(nameof(TraxToolTip));
            }
        }
    }

    private string? _traxError;

    /// <summary>Error message from the last TRAX load/playback failure; null = no error.</summary>
    public string? TraxError
    {
        get => _traxError;
        private set
        {
            if (SetProperty(ref _traxError, value))
                OnPropertyChanged(nameof(TraxDotBrush));
        }
    }

    /// <summary>TRAX status dot: green = playing, red = the last load/play failed (the
    /// message scrolls in the desktop-audio bar), gray = idle or no track.</summary>
    public SolidColorBrush TraxDotBrush => _musicPlayer.IsPlaying
        ? BarOnBrush
        : TraxError != null ? BarOffBrush : TraxIdleBrush;

    /// <summary>Where TRAX starts: quiet background under the desktop bed. The ±5 dB buttons are the
    /// control surface — a creator who wants it louder clicks up three times rather than hunting a
    /// 6px thumb on a 148px dock. (Creator ruling 2026-10-30, from their own meter readings.)</summary>
    public const double TraxDefaultDb = -50;

    public const double TraxStepDb = 5;

    /// <summary>+6 dB is the ceiling; −60 dB is silence. The buttons disable at both ends.</summary>
    public bool CanRaiseTrax => TraxVolumeDb < Helpers.GainDb.MaxDb;

    public bool CanLowerTrax => TraxVolumeDb > Helpers.GainDb.FloorDb;

    public void StepTrax(int steps) => TraxVolumeDb += steps * TraxStepDb;

    /// <summary>The dock's TRAX level, in dB. Unity means the bed's design level, not the raw file.</summary>
    public double TraxVolumeDb
    {
        get => Helpers.GainDb.ToDb(_musicPlayer.UserGain);
        set
        {
            var gain = Helpers.GainDb.FromDb(value);
            if (Math.Abs(gain - _musicPlayer.UserGain) < 1e-6) return;
            _musicPlayer.UserGain = (float)gain;
            OnPropertyChanged(nameof(TraxVolumeDb));
            OnPropertyChanged(nameof(TraxVolumeDbLabel));
            OnPropertyChanged(nameof(CanRaiseTrax));
            OnPropertyChanged(nameof(CanLowerTrax));
        }
    }

    public string TraxVolumeDbLabel => Helpers.GainDb.Label(TraxVolumeDb) + " dB";

    /// <summary>The TRAX ladder: the player's own measured output, so "is music actually making
    /// sound" is answerable without hearing it.</summary>
    public double TraxMeterFraction =>
        IsMusicPlaying ? Services.Audio.AudioLevelMeter.ToDisplay(_musicPlayer.Level) : 0;

    /// <summary>Track name, or an honest "No track".</summary>
    public string TraxTrackLabel => _musicPlayer.TrackName ?? "No track";

    /// <summary>Same ducker signal as the game bay — the bed ducks with it.</summary>
    public bool IsTraxDucking => IsGameDucking;

    public string TraxToolTip => _musicPlayer.TrackName != null
        ? $"TRAX: {_musicPlayer.TrackName} — left-click {(IsMusicPlaying ? "pauses" : "plays")}, right-click chooses a track"
        : "No track — left-click or right-click to choose background music";

    /// <summary>Left-click on TRAX: no track → pick one; otherwise toggle play/pause.</summary>
    public void TraxLeftClick()
    {
        if (_music == null || string.IsNullOrWhiteSpace(_music.TrackPath))
            PickTraxTrack();
        else if (IsMusicPlaying)
            PauseTrax();
        else
            PlayTrax();
    }

    /// <summary>Right-click on TRAX: always open the track picker (never the OS viewer).</summary>
    public void TraxRightClick() => PickTraxTrack();

    /// <summary>Open the track picker (the dock's right-click on the TRAX name).</summary>
    internal void ChooseTrack() => PickTraxTrack();

    private void PickTraxTrack()
    {
        var dialog = new OpenFileDialog
        {
            Title = "Choose background music",
            Filter = "Music (*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg)|*.mp3;*.wav;*.m4a;*.aac;*.flac;*.ogg|All files (*.*)|*.*",
        };
        if (dialog.ShowDialog() != true)
            return;

        _ = SetTraxTrackAsync(dialog.FileName, play: true);
    }

    /// <summary>Points TRAX at a track and loads it (optionally playing). The picker's path;
    /// internal so tests can load a track without the file dialog.</summary>
    internal Task SetTraxTrackAsync(string path, bool play)
    {
        _music = new Music { TrackPath = path, IsEnabled = true };
        return LoadTraxAsync(play);
    }

    /// <summary>Probes a path off the UI thread and gives up at <paramref name="budget"/>.
    /// A probe may time out — that is the whole point. False means offline, missing, or
    /// slower than the budget, and every one of those is a normal state, not an error.</summary>
    internal static async Task<bool> IsTrackReachableAsync(string path, TimeSpan budget, Func<string, bool> probe)
    {
        var probeTask = Task.Run(() =>
        {
            try
            {
                return probe(path);
            }
            catch
            {
                return false;
            }
        });

        var finished = await Task.WhenAny(probeTask, Task.Delay(budget)).ConfigureAwait(false);
        return finished == probeTask && await probeTask.ConfigureAwait(false);
    }

    private void LoadTrax(bool play) => _ = LoadTraxAsync(play);

    private async Task LoadTraxAsync(bool play)
    {
        var music = _music;
        if (music == null || string.IsNullOrWhiteSpace(music.TrackPath) || _traxLoadInFlight)
            return;

        _traxLoadInFlight = true;
        var loaded = false;
        try
        {
            var path = music.TrackPath;
            if (await IsTrackReachableAsync(path, TraxProbeBudget, File.Exists))
            {
                // Reached the share, so this bind is cheap and stays on the UI thread
                // with every other MusicPlayer mutation — no new race to reason about.
                _musicPlayer.Load(path);
                UpdateTraxLocalGain();
                music.IsEnabled = true;
                TraxError = null;
                loaded = true;
                if (play)
                    PlayTrax();
            }
            else
            {
                AppLog.Write($"TRAX: '{path}' unreachable within {TraxProbeBudget.TotalSeconds:0}s — not loading");
                TraxError = "TRAX: can't reach the track";
            }
        }
        catch (Exception ex)
        {
            AppLog.Write($"TRAX: failed to load '{music.TrackPath}': {ex.Message}");
            TraxError = "TRAX: can't load the track";
        }
        finally
        {
            _traxLoadInFlight = false;
            RefreshTraxUi();
            if (loaded)
                ScheduleSave();
        }
    }

    // Both toggle halves MUST refresh the UI: the dot and IsMusicPlaying used to update only
    // on load/playback-ended, so pressing TRAX started the music with the light still off —
    // and because IsMusicPlaying stayed false, the next press tried to play again instead of
    // pausing (2026-10-09 bug).
    private void PlayTrax()
    {
        try
        {
            _musicPlayer.Play();
            TraxError = _musicPlayer.IsPlaying ? null : "TRAX: no audio output";
            if (TraxError != null) AppLog.Write("TRAX: Play() returned but playback did not start (no output device?)");
        }
        catch (Exception ex)
        {
            AppLog.Write($"TRAX: play failed: {ex.Message}");
            TraxError = "TRAX: can't play the track";
        }
        RefreshTraxUi();
    }

    private void PauseTrax()
    {
        try
        {
            _musicPlayer.Pause();
        }
        catch (Exception ex)
        {
            AppLog.Write($"TRAX: pause failed: {ex.Message}");
        }
        RefreshTraxUi();
    }

    private void OnTraxPlaybackEnded(Exception? ex)
    {
        if (ex != null)
        {
            AppLog.Write($"TRAX: playback error: {ex.Message}");
            TraxError = "TRAX: playback stopped";
        }
        RefreshTraxUi();
    }

    private void RefreshTraxUi()
    {
        IsMusicPlaying = _musicPlayer.IsPlaying;
        OnPropertyChanged(nameof(TraxDotBrush));
        OnPropertyChanged(nameof(TraxToolTip));
    }

    /// <summary>Mirrors the desktop/game audio bar's volume and mute onto the
    /// music so the creator hears the controls work in the headphones (the
    /// track rides the loopback channel, so it must duck the same way locally).
    /// Called whenever the game volume/mute change and on TRAX load.</summary>
    private void UpdateTraxLocalGain()
    {
        _musicPlayer.LocalGain = GameMuted ? 0f : 1f;
    }
}