// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.CodeAnalysis;
using System.Reflection.Metadata;
using Microsoft.AspNetCore.Components.HotReload;
 
[assembly: MetadataUpdateHandler(typeof(HotReloadManager))]
 
namespace Microsoft.AspNetCore.Components.HotReload;
 
internal sealed class HotReloadManager
{
    public static readonly HotReloadManager Default = new();
 
    private static readonly bool s_isSupported =
        AppContext.TryGetSwitch("System.Reflection.Metadata.MetadataUpdater.IsSupported", out bool isSupported) ? isSupported : true;
 
    [FeatureSwitchDefinition("System.Reflection.Metadata.MetadataUpdater.IsSupported")]
    internal static bool IsSupported => s_isSupported;
 
    /// <summary>
    /// Gets a value that determines if OnDeltaApplied is subscribed to.
    /// </summary>
    public bool IsSubscribedTo => OnDeltaApplied is not null;
 
    public event Action? OnDeltaApplied;
 
    /// <summary>
    /// MetadataUpdateHandler event. This is invoked by the hot reload host via reflection.
    /// </summary>
    public static void UpdateApplication(Type[]? _) => Default.OnDeltaApplied?.Invoke();
 
    // For testing purposes only
    internal void TriggerOnDeltaApplied() => OnDeltaApplied?.Invoke();
}