// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.Reflection;

namespace Microsoft.AspNetCore.Components.Routing
{
#if NET6_0_OR_GREATER
    internal readonly struct RouteKey : IEquatable<RouteKey>
    {
        public readonly Assembly? AppAssembly;
        public readonly HashSet<Assembly>? AdditionalAssemblies;

        public RouteKey(Assembly? appAssembly, IEnumerable<Assembly>? additionalAssemblies)
        {
            AppAssembly = appAssembly;
            AdditionalAssemblies = additionalAssemblies is null ? null : new HashSet<Assembly>(additionalAssemblies);
        }

        public override bool Equals(object? obj)
        {
            return obj is RouteKey other && Equals(other);
        }

        public bool Equals(RouteKey other)
        {
            if (!Equals(AppAssembly, other.AppAssembly))
            {
                return false;
            }

            if (AdditionalAssemblies is null && other.AdditionalAssemblies is null)
            {
                return true;
            }

            if (AdditionalAssemblies is null || other.AdditionalAssemblies is null)
            {
                return false;
            }

            return AdditionalAssemblies.Count == other.AdditionalAssemblies.Count &&
                AdditionalAssemblies.SetEquals(other.AdditionalAssemblies);
        }

        public override int GetHashCode()
        {
            if (AppAssembly is null)
            {
                return 0;
            }

            if (AdditionalAssemblies is null)
            {
                return AppAssembly.GetHashCode();
            }

            // Producing a hash code that includes individual assemblies requires it to have a stable order.
            // We'll avoid the cost of sorting and simply include the number of assemblies instead.
            return HashCode.Combine(AppAssembly, AdditionalAssemblies.Count);
        }
    }
#endif
}
