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;

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

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

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