using System.Windows.Input;
using ytLive.Helpers;

namespace ytLive.ViewModels;

/// <summary>Which half of the top bar's dual segment is in force.</summary>
public enum BarWorld
{
    /// <summary>Build Scenes — the edit surface. The default at launch (creator ruling 2026-11-12).</summary>
    Build,

    /// <summary>Record / Go Live — the output surface: which output, and the one action that starts it.</summary>
    Output,
}

/// <summary>
/// The top bar's one decision (creator ruling 2026-11-12): <c>[ Build Scenes ][ Record / Go Live ]</c>.
/// Build Scenes <b>is</b> edit mode — there is no separate EDIT toggle any more, so "may I edit?" and
/// "which world am I in?" cannot disagree.
///
/// <para>Clicking the highlighted segment is not a no-op: it re-enters that world, which matters while a
/// session runs because Build Scenes is the only way back to the layers (see
/// <see cref="LockEditWhileLive"/>).</para>
/// </summary>
public partial class MainViewModel
{
    private BarWorld _barWorld = BarWorld.Build;

    public BarWorld BarWorld => _barWorld;

    public bool IsBuildWorld => _barWorld == BarWorld.Build;
    public bool IsOutputWorld => _barWorld == BarWorld.Output;

    /// <summary>The output stage belongs to the Record / Go Live world, and only while nothing is
    /// running — a live session cannot change its output, so its switch is not offered.</summary>
    public bool ShowOutputStage => IsOutputWorld && IsOffline && !IsRecording;

    // ─── The output stage's three states (creator, builds 728/729) ───
    // 1. nothing chosen:      [YouTube] [Local MP4]
    // 2. YouTube chosen:      [YouTube(red)] [Live Stream] [Private Stream]   (Private = the test run)
    // 3. Local MP4 chosen:    [Local MP4(red)] [Start Recording] -> [End Recording] while recording
    public bool ShowOutputChoice => ShowOutputStage && !RecordPillOn && !OnAirPillOn;
    public bool ShowYouTubeSelected => ShowOutputStage && OnAirPillOn;
    public bool ShowLocalMp4Selected => ShowOutputStage && RecordPillOn;
    /// <summary>The YouTube chip shows while nothing is chosen and while YouTube IS the choice; once
    /// Local MP4 is chosen the MP4 chip replaces it in the left slot (creator, build 729).</summary>
    public bool YouTubeChipVisible => ShowOutputChoice || ShowYouTubeSelected;
    public bool LocalMp4ChipVisible => ShowOutputChoice || ShowLocalMp4Selected;

    public bool ShowStartRecordingAction => ShowLocalMp4Selected && !IsRecording;
    public bool ShowEndRecordingAction => ShowLocalMp4Selected && IsRecording;

    public ICommand SelectYouTubeCommand { get; private set; } = null!;
    public ICommand SelectLocalMp4Command { get; private set; } = null!;
    public ICommand StartRecordingCommand { get; private set; } = null!;
    public ICommand TestStreamCommand { get; private set; } = null!;
    public ICommand GoLiveCommand { get; private set; } = null!;

    public ICommand EnterBuildWorldCommand { get; private set; } = null!;
    public ICommand EnterOutputWorldCommand { get; private set; } = null!;

    private void InitializeWorldCommands()
    {
        SelectYouTubeCommand = new RelayCommand(_ => OnAirPillOn = true, _ => ShowOutputChoice);
        SelectLocalMp4Command = new RelayCommand(_ => RecordPillOn = true, _ => ShowOutputChoice);
        StartRecordingCommand = new RelayCommand(_ => BeginRecordOnly(), _ => ShowStartRecordingAction);
        // A signed-out press starts the sign-in flow instead of sitting dead (no-dead-ends rule).
        TestStreamCommand = new RelayCommand(_ =>
        {
            if (!IsConnected) { _ = SignInAsync(); return; }
            BeginTestStream();
        }, _ => ShowYouTubeSelected);
        GoLiveCommand = new RelayCommand(_ =>
        {
            if (!IsConnected) { _ = SignInAsync(); return; }
            StartSession();
        }, _ => ShowYouTubeSelected);

        EnterBuildWorldCommand = new RelayCommand(_ => EnterWorld(BarWorld.Build));
        EnterOutputWorldCommand = new RelayCommand(_ => EnterWorld(BarWorld.Output));
    }

    /// <summary>Everything the output stage shows or hides, in one place so no caller can forget
    /// one of them.</summary>
    internal void RaiseOutputStage()
    {
        OnPropertyChanged(nameof(ShowOutputStage));
        OnPropertyChanged(nameof(ShowOutputChoice));
        OnPropertyChanged(nameof(ShowYouTubeSelected));
        OnPropertyChanged(nameof(YouTubeChipVisible));
        OnPropertyChanged(nameof(LocalMp4ChipVisible));
        OnPropertyChanged(nameof(ShowLocalMp4Selected));
        OnPropertyChanged(nameof(ShowStartRecordingAction));
        OnPropertyChanged(nameof(ShowEndRecordingAction));
    }

    /// <summary>Switches worlds. Re-entering the current one still re-asserts its edit state, which is
    /// what lets a creator take EDIT back mid-show by clicking Build Scenes.</summary>
    internal void EnterWorld(BarWorld world)
    {
        _barWorld = world;

        // Entering a world starts with NOTHING chosen inside it (creator, build 729): the output
        // switches are a fresh decision each time, not a remembered one.
        if (world == BarWorld.Output)
        {
            RecordPillOn = false;
            OnAirPillOn = false;
        }

        OnPropertyChanged(nameof(BarWorld));
        OnPropertyChanged(nameof(IsBuildWorld));
        OnPropertyChanged(nameof(IsOutputWorld));
        EditingActive = world == BarWorld.Build;
        OnPropertyChanged(nameof(ShowOutputStage));
        RaiseOutputStage();
    }
}