// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Concurrent;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Components.HotReload;
 
namespace Microsoft.AspNetCore.Components.Authorization;
 
internal static class AttributeAuthorizeDataCache
{
    static AttributeAuthorizeDataCache()
    {
        if (HotReloadManager.IsSupported)
        {
            HotReloadManager.Default.OnDeltaApplied += ClearCache;
        }
    }
 
    private static readonly ConcurrentDictionary<Type, (IAuthorizeData[]? AuthorizeData, object[]? Metadata)> _cache = new();
 
    private static void ClearCache() => _cache.Clear();
 
    public static IAuthorizeData[]? GetAuthorizeDataForType(Type type)
        => GetAuthorizationDataForType(type).AuthorizeData;
 
    public static object[]? GetAuthorizationMetadataForType(Type type)
        => GetAuthorizationDataForType(type).Metadata;
 
    private static (IAuthorizeData[]? AuthorizeData, object[]? Metadata) GetAuthorizationDataForType(Type type)
    {
        if (!_cache.TryGetValue(type, out var result))
        {
            result = ComputeAuthorizationDataForType(type);
            _cache[type] = result; // Safe race - doesn't matter if it overwrites
        }
 
        return result;
    }
 
    private static (IAuthorizeData[]? AuthorizeData, object[]? Metadata) ComputeAuthorizationDataForType(Type type)
    {
        var allAttributes = type.GetCustomAttributes(inherit: true);
        List<IAuthorizeData>? authorizeDatas = null;
        for (var i = 0; i < allAttributes.Length; i++)
        {
            if (allAttributes[i] is IAllowAnonymous)
            {
                return (null, null);
            }
 
            if (allAttributes[i] is IAuthorizeData authorizeData)
            {
                authorizeDatas ??= new();
                authorizeDatas.Add(authorizeData);
            }
        }
 
        return (authorizeDatas?.ToArray(), allAttributes);
    }
}