using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;
using NAudio.CoreAudioApi;
using ytLive;
using ytLive.Helpers;
using ytLive.Models;
using ytLive.Services;
using ytLive.Services.Audio;

namespace ytLive.ViewModels;

public partial class MainViewModel
{
    private readonly DispatcherTimer _volumeFlashTimer;
    private readonly DispatcherTimer _gameVolumeFlashTimer;
    private double _audioLevel;
    private bool _volumeAdjusting;
    private bool _volumeFlash;
    private double _micVolume = 0.8;
    private bool _micMuted;
    private double? _volumeBeforeMute;
    private string? _micSourceName;
    private MicStatus _micStatus = MicStatus.NotConnected;
    private double _gameAudioLevel;
    private bool _gameVolumeAdjusting;
    private bool _gameVolumeFlash;
    private double _gameVolume = 1.0;
    private bool _gameMuted;
    private double? _gameVolumeBeforeMute;
    private int _audioSyncOffsetMs;
    private AudioGainProvider? _gainProvider;
    private readonly IMicrophoneEnumerator _microphoneEnumerator;
    private readonly AudioMixer _audioMixer;

    public ICommand ToggleMicMuteCommand { get; }
    public ICommand ToggleGameMuteCommand { get; }
    public ICommand OpenMicPickerCommand { get; }

    // ─── Audio: the mic bar (meter + volume + mute + status dot) is always
    // ─── visible; the game bar (meter + volume + mute) appears only while a
    // ─── full-screen game is producing sound. Both meters preview live. ───

    /// <summary>Live mic input level (0..1) — fed by the audio mixer once capture
    /// lands; 0 with no input. Read by the meter, scaled by MicVolume.</summary>
    public double AudioLevel
    {
        get => _audioLevel;
        set
        {
            if (SetProperty(ref _audioLevel, Math.Clamp(value, 0, 1)))
            {
                OnPropertyChanged(nameof(MeterFillWidth));
                OnPropertyChanged(nameof(MeterBrush));
                OnPropertyChanged(nameof(MicMeterFraction));
                UpdateDuckState();
                RaiseMasterReadouts();
                OnPropertyChanged(nameof(TraxMeterFraction));
                OnPropertyChanged(nameof(MicMeterFraction));
                OnPropertyChanged(nameof(MicVolumeDb));
                OnPropertyChanged(nameof(MicVolumeDbLabel));
            }
        }
    }

    /// <summary>Displayed meter level: 0 while muted; the volume position while
    /// the slider is being dragged (or briefly after an unmute, so the restored
    /// level flashes on the bar) so the creator sees where they're setting it;
    /// otherwise the realtime live level scaled by volume (raising the volume
    /// moves ambient noise up the bar). Read-only meter.</summary>
    private double MeterLevel => MicMuted ? 0 : _volumeAdjusting || _volumeFlash ? MicVolume : AudioLevelMeter.ToDisplay((float)(AudioLevel * MicVolume));

    public double MeterFillWidth => MeterLevel * 288;

    public string MeterBrush => MeterLevel switch
    {
        < 0.6 => ThemeBrush.Hex("Brush.Meter.Nominal"),
        < 0.8 => ThemeBrush.Hex("Brush.Meter.Caution"),
        _ => ThemeBrush.Hex("Brush.Meter.Peak"),
    };

    /// <summary>Previewes the volume position while the slider is dragged; the
    /// bar returns to the live level on release (empty when there is no input).
    /// Starting a drag cancels any pending unmute flash.</summary>
    public void SetVolumeAdjusting(bool adjusting)
    {
        if (adjusting)
            CancelVolumeFlash();
        if (SetProperty(ref _volumeAdjusting, adjusting))
        {
            OnPropertyChanged(nameof(MeterFillWidth));
            OnPropertyChanged(nameof(MeterBrush));
        }
    }

    private void BeginVolumeFlash()
    {
        _volumeFlash = true;
        OnPropertyChanged(nameof(MeterFillWidth));
        OnPropertyChanged(nameof(MeterBrush));
        _volumeFlashTimer.Stop();
        _volumeFlashTimer.Start();
    }

    private void EndVolumeFlash()
    {
        _volumeFlashTimer.Stop();
        if (_volumeFlash)
        {
            _volumeFlash = false;
            OnPropertyChanged(nameof(MeterFillWidth));
            OnPropertyChanged(nameof(MeterBrush));
        }
    }

    private void CancelVolumeFlash()
    {
        _volumeFlashTimer.Stop();
        _volumeFlash = false;
    }

    /// <summary>Mic gain (0..1). Running to 0 mutes (the speaker flips to muted);
    /// moving up from 0 unmutes (the mute indicator clears). The level being left
    /// is remembered so the speaker button can restore it.</summary>
    public double MicVolume
    {
        get => _micVolume;
        set
        {
            var clamped = Math.Clamp(value, 0, 1);
            if (clamped == 0 && !_micMuted)
                _volumeBeforeMute ??= _micVolume;
            if (SetProperty(ref _micVolume, clamped))
            {
                var muted = clamped == 0;
                if (_micMuted != muted)
                {
                    _micMuted = muted;
                    OnPropertyChanged(nameof(MicMuted));
                    OnPropertyChanged(nameof(MicMuteText));
                }
                if (!muted)
                    _volumeBeforeMute = null;
                OnPropertyChanged(nameof(MeterFillWidth));
                OnPropertyChanged(nameof(MeterBrush));
            }
        }
    }

    /// <summary>The fader's face, in dB (−60 … +6, 0 = unity). The model keeps linear gain; this is
    /// the same value expressed the way a person reads a mixer — and the only thing the dock binds.
    /// </summary>
    public double MicVolumeDb
    {
        get => Helpers.GainDb.ToDb(MicVolume);
        set
        {
            var gain = Helpers.GainDb.FromDb(value);
            if (Math.Abs(gain - MicVolume) < 1e-6) return;
            MicVolume = gain;
            OnPropertyChanged(nameof(MicVolumeDb));
            OnPropertyChanged(nameof(MicVolumeDbLabel));
        }
    }

    /// <summary>"-6.0 dB" beside the fader; "−∞ dB" at the floor.</summary>
    public string MicVolumeDbLabel => Helpers.GainDb.Label(MicVolumeDb) + " dB";

    /// <summary>The ladder's input: a 0…1 display fraction of what was MEASURED (already scaled by
    /// the volume and muted state), never the gain setting.</summary>
    public double MicMeterFraction => MeterLevel;

    /// <summary>Read-only: true whenever the volume is 0. Only MicVolume may
    /// change it, so the slider and the speaker can never disagree.</summary>
    public bool MicMuted => _micMuted;

    public string MicMuteText => MicMuted ? "Unmute" : "Mute";

    /// <summary>Name of the picked voice source, shown left-justified INSIDE the meter
    /// bar (FontSize 10, ellipsized to the bar) — ai.md is the authority here.</summary>
    public string? MicSourceName
    {
        get => _micSourceName;
        private set => SetProperty(ref _micSourceName, value);
    }

    /// <summary>Global audio-sync offset in milliseconds (−500..500, default 0):
    /// POSITIVE delays the whole mix so audio lands on the video when it runs
    /// AHEAD (OBS's lip-sync fix); NEGATIVE advances it by dropping the first
    /// |N| ms of the live stream head when audio runs BEHIND the video.
    /// Consumed live by the mixer via a Func seam; persisted with the layout.</summary>
    public int AudioSyncOffsetMs
    {
        get => _audioSyncOffsetMs;
        set
        {
            var clamped = Math.Clamp(value, -500, 500);
            if (!SetProperty(ref _audioSyncOffsetMs, clamped)) return;
            OnPropertyChanged(nameof(SyncOffsetLabel));
            ScheduleSave();
        }
    }

    // ─── Master strip ────────────────────────────────────────────────────────

    private bool _monoOutput;

    /// <summary>Collapse the output to mono. Persisted, because a creator who needs it needs it on
    /// every session — an accessibility switch that resets is an accessibility failure.</summary>
    public bool MonoOutput
    {
        get => _monoOutput;
        set
        {
            if (!SetProperty(ref _monoOutput, value)) return;
            _audioMixer.MonoOutput = value;
            _layoutStore.SaveMonoOutput(value);
        }
    }

    /// <summary>Master ladder input: the measured mix, 0…1 on the same display scale.</summary>
    public double MasterMeterFraction => AudioLevelMeter.ToDisplay(_audioMixer.MasterLevel);

    public string MasterLevelLabel => Helpers.GainDb.Label(Helpers.GainDb.ToDb(_audioMixer.MasterLevel)) + " dB";

    /// <summary>True when the mix's channels differ by more than 6 dB — the one thing L/R is
    /// genuinely good for, shown as one flag instead of two ladders.</summary>
    public bool MasterImbalance => _audioMixer.MasterImbalanceDb > 6f;

    private void RaiseMasterReadouts()
    {
        OnPropertyChanged(nameof(MasterMeterFraction));
        OnPropertyChanged(nameof(MasterLevelLabel));
        OnPropertyChanged(nameof(MasterImbalance));
    }

    /// <summary>"0 ms (aligned)", "+50 ms", "−120 ms" — what the dock shows beside the slider.</summary>
    public string SyncOffsetLabel => AudioSyncOffsetMs == 0
        ? "0 ms (aligned)"
        : (AudioSyncOffsetMs > 0 ? "+" : "−") + Math.Abs(AudioSyncOffsetMs) + " ms";

    /// <summary>Preset buttons in the LIP-SYNC bay. 0 is the detent: the offset that means "the
    /// lip-sync is right", so it deserves one click, not a drag.</summary>
    internal void SetSyncOffset(int milliseconds) => AudioSyncOffsetMs = milliseconds;

    private void ToggleMicMute()
    {
        if (MicMuted)
        {
            MicVolume = _volumeBeforeMute ?? 0.8;
            BeginVolumeFlash();
        }
        else
        {
            _volumeBeforeMute = MicVolume;
            MicVolume = 0;
        }
    }

    private void PickMicrophone()
    {
        var dialog = new MicPickerDialog(new MicPickerViewModel(_microphoneEnumerator))
        {
            Owner = System.Windows.Application.Current?.MainWindow
        };
        if (dialog.ShowDialog() == true && dialog.PickedDevice != null)
        {
            MicSourceName = dialog.PickedDevice.DisplayName;
            _layoutStore.SaveMicSourceName(MicSourceName); // persist across restarts
            _audioMixer.RestartMic(); // swap the live device immediately
        }
    }

    // ─── Mic status dot (the MIC button) ───

    private static SolidColorBrush MicProblemBrush => ThemeBrush.Get("Brush.Secondary");

    /// <summary>Mic connection state, driven by the mixer's MicConnected/MicFailed
    /// events and the startup device check (see StartMicCaptureAsync).</summary>
    public MicStatus MicStatus
    {
        get => _micStatus;
        private set
        {
            if (SetProperty(ref _micStatus, value))
            {
                OnPropertyChanged(nameof(MicStatusBrush));
                OnPropertyChanged(nameof(MicStatusToolTip));
            }
        }
    }

    /// <summary>Status dot: green = connected, yellow = problem with the requested
    /// connection, red = not connected (no device / not started).</summary>
    public SolidColorBrush MicStatusBrush => MicStatus switch
    {
        MicStatus.Connected => BarOnBrush,
        MicStatus.Problem => MicProblemBrush,
        _ => BarOffBrush,
    };

    public string MicStatusToolTip => MicStatus switch
    {
        MicStatus.Connected => "Mic connected — click to change",
        MicStatus.Problem => "Mic problem — the requested microphone is unavailable (in use or unplugged). Click to change",
        _ => "No mic connected — click to choose a microphone",
    };
    // ─── Game audio bar (desktop/game): always visible — a mirror of the mic bar
    // ─── (meter + mute + volume). Desktop/game audio is automatic (WASAPI loopback). ───
    // Test seam (mirrors LayoutPathOverride/RegistrarOverride): the volume slider is
    // stream-honest AND speaker-honest — the real path writes the Windows endpoint.
    // Tests must never hijack the machine's actual volume, so they swap the push out.
    internal static Action<double>? VolumePushOverride;

    private static void PushSystemVolume(double volume)
    {
        if (VolumePushOverride is { } push)
        {
            push(volume);
            return;
        }
        try
        {
            using var enumerator = new MMDeviceEnumerator();
            using var device = enumerator.GetDefaultAudioEndpoint(DataFlow.Render, Role.Multimedia);
            device.AudioEndpointVolume.MasterVolumeLevelScalar = (float)volume;
        }
        catch { }
    }

    /// <summary>Live desktop/game input level (0..1), fed by the mixer's loopback
    /// capture. Read by the game meter, scaled by GameAudioVolume.</summary>
    public double GameAudioLevel
    {
        get => _gameAudioLevel;
        set
        {
            if (SetProperty(ref _gameAudioLevel, Math.Clamp(value, 0, 1)))
            {
                OnPropertyChanged(nameof(GameMeterFillWidth));
                OnPropertyChanged(nameof(GameMeterBrush));
            }
        }
    }

    /// <summary>Displayed game meter level: 0 while muted; the volume position
    /// while the slider is dragged (or briefly after an unmute flash); otherwise
    /// the realtime live level scaled by volume — the WASAPI loopback tap is
    /// PRE-endpoint-volume (creator's 20%-volume/pegged-meter observation,
    /// 2026-09-01), so the meter must multiply by GameAudioVolume itself, exactly
    /// like the stream gain does (the mic formula always did; the clone dropped it).</summary>
    private double GameMeterLevel => GameMuted ? 0 : _gameVolumeAdjusting || _gameVolumeFlash ? GameAudioVolume : Math.Min(1, AudioLevelMeter.ToDisplay((float)GameAudioLevel) * GameAudioVolume);

    public double GameMeterFillWidth => GameMeterLevel * 288;

    /// <summary>Ladder input: a 0…1 display fraction of what was measured.</summary>
    public double GameMeterFraction => GameMeterLevel;

    /// <summary>The game fader's dB face (−60 … +6). Same rule as the mic: the model keeps linear
    /// gain; the dock shows decibels.</summary>
    public double GameVolumeDb
    {
        get => Helpers.GainDb.ToDb(GameAudioVolume);
        set
        {
            var gain = Helpers.GainDb.FromDb(value);
            if (Math.Abs(gain - GameAudioVolume) < 1e-6) return;
            GameAudioVolume = gain;
            OnPropertyChanged(nameof(GameVolumeDb));
            OnPropertyChanged(nameof(GameVolumeDbLabel));
        }
    }

    public string GameVolumeDbLabel => Helpers.GainDb.Label(GameVolumeDb) + " dB";

    /// <summary>True while the mic is ducking the game/desktop bed (the mixer's own value).</summary>
    public bool IsGameDucking { get; private set; }

    /// <summary>"−12.0 dB" — the badge text, computed from the same gain the mixer applied.</summary>
    public string GameDuckLabel => Helpers.GainDb.Label(Helpers.GainDb.ToDb(_audioMixer.DuckGain)) + " DUCK";

    public string GameMeterBrush => GameMeterLevel switch
    {
        < 0.6 => ThemeBrush.Hex("Brush.Meter.Nominal"),
        < 0.8 => ThemeBrush.Hex("Brush.Meter.Caution"),
        _ => ThemeBrush.Hex("Brush.Meter.Peak"),
    };

    public void SetGameVolumeAdjusting(bool adjusting)
    {
        if (adjusting)
            CancelGameVolumeFlash();
        if (SetProperty(ref _gameVolumeAdjusting, adjusting))
        {
            OnPropertyChanged(nameof(GameMeterFillWidth));
            OnPropertyChanged(nameof(GameMeterBrush));
        }
    }

    private void BeginGameVolumeFlash()
    {
        _gameVolumeFlash = true;
        OnPropertyChanged(nameof(GameMeterFillWidth));
        OnPropertyChanged(nameof(GameMeterBrush));
        _gameVolumeFlashTimer.Stop();
        _gameVolumeFlashTimer.Start();
    }

    private void EndGameVolumeFlash()
    {
        _gameVolumeFlashTimer.Stop();
        if (_gameVolumeFlash)
        {
            _gameVolumeFlash = false;
            OnPropertyChanged(nameof(GameMeterFillWidth));
            OnPropertyChanged(nameof(GameMeterBrush));
        }
    }

    private void CancelGameVolumeFlash()
    {
        _gameVolumeFlashTimer.Stop();
        _gameVolumeFlash = false;
    }

    /// <summary>Game audio gain (0..1, unity default). Running to 0 mutes; the
    /// prior level is remembered so the speaker button can restore it.</summary>
    public double GameAudioVolume
    {
        get => _gameVolume;
        set
        {
            var clamped = Math.Clamp(value, 0, 1);
            if (clamped == 0 && !_gameMuted)
                _gameVolumeBeforeMute ??= _gameVolume;
            if (SetProperty(ref _gameVolume, clamped))
            {
                var muted = clamped == 0;
                if (_gameMuted != muted)
                {
                    _gameMuted = muted;
                    OnPropertyChanged(nameof(GameMuted));
                    OnPropertyChanged(nameof(GameMuteText));
                }
                if (!muted)
                    _gameVolumeBeforeMute = null;
                OnPropertyChanged(nameof(GameMeterFillWidth));
                OnPropertyChanged(nameof(GameMeterBrush));
                UpdateTraxLocalGain();
                PushSystemVolume(clamped);
            }
        }
    }

    /// <summary>Read-only: true whenever the volume is 0 (the slider and the
    /// speaker can never disagree).</summary>
    public bool GameMuted => _gameMuted;

    public string GameMuteText => GameMuted ? "Unmute" : "Mute";

    /// <summary>Badge state follows the mix, not a timer of its own: the level tick is already the
    /// moment the ducker has just run.</summary>
    private void UpdateDuckState()
    {
        var ducking = _audioMixer.DuckGain < 0.99f;
        if (ducking == IsGameDucking) return;
        IsGameDucking = ducking;
        OnPropertyChanged(nameof(IsGameDucking));
        OnPropertyChanged(nameof(GameDuckLabel));
    }

    private void ToggleGameMute()
    {
        if (GameMuted)
        {
            GameAudioVolume = _gameVolumeBeforeMute ?? 1.0;
            BeginGameVolumeFlash();
        }
        else
        {
            _gameVolumeBeforeMute = GameAudioVolume;
            GameAudioVolume = 0;
        }
    }
    private void OnMicLevelChanged(float level)
    {
        // NAudio raises on its capture thread; marshal to the UI thread so the
        // meter binding updates safely.
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(() => AudioLevel = level);
        else
            AudioLevel = level;
    }

    private void OnLoopbackLevelChanged(float level)
    {
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(() => GameAudioLevel = level);
        else
            GameAudioLevel = level;
    }

    private void OnMicConnected()
    {
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Connected);
        else
            MicStatus = MicStatus.Connected;
    }

    private void OnMicFailed(Exception ex)
    {
        // The mixer logs the failure detail; here we only flip the dot to yellow.
        var dispatcher = System.Windows.Application.Current?.Dispatcher;
        if (dispatcher != null && !dispatcher.CheckAccess())
            dispatcher.BeginInvoke(() => MicStatus = MicStatus.Problem);
        else
            MicStatus = MicStatus.Problem;
    }

    /// <summary>Starts capture once at startup: with no mic device present the
    /// dot stays red and capture never starts; otherwise the mixer starts and
    /// raises MicConnected (green) or MicFailed (yellow).</summary>
    private async Task StartMicCaptureAsync()
    {
        try
        {
            var mics = await _microphoneEnumerator.GetMicrophonesAsync();
            if (mics.Count == 0)
            {
                MicStatus = MicStatus.NotConnected;
                AppLog.Write("Mic: no capture devices found — mic capture not started");
                _notifications.Warning("No microphone found",
                    "Mic capture wasn't started — plug one in and pick it from the mixer.");
                return;
            }
            _audioMixer.Start();
            AppLog.Write("Audio: using system default mic + default output — assuming they are configured and available (device issues are out of scope).");
        }
        catch (Exception ex)
        {
            AppLog.Write($"Mic: device check failed: {ex.Message}");
        }
    }
}