// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using BenchmarkDotNet.Attributes;
using Microsoft.AspNetCore.Http;

namespace Microsoft.AspNetCore.Routing
{
    public class EndpointMetadataCollectionBenchmark
    {
        private object[] _items;
        private EndpointMetadataCollection _collection;

        [Params(3, 10, 25)]
        public int Count { get; set; }

        [GlobalSetup]
        public void Setup()
        {
            var seeds = new Type[]
            {
                typeof(Metadata1),
                typeof(Metadata2),
                typeof(Metadata3),
                typeof(Metadata4),
                typeof(Metadata5),
                typeof(Metadata6),
                typeof(Metadata7),
                typeof(Metadata8),
                typeof(Metadata9),
            };

            _items = new object[Count];
            for (var i = 0; i < _items.Length; i++)
            {
                _items[i] = seeds[i % seeds.Length];
            }

            _collection = new EndpointMetadataCollection(_items);
        }

        // This is a synthetic baseline that visits each item and does an as-cast.
        [Benchmark(Baseline = true, OperationsPerInvoke = 5)]
        public void Baseline()
        {
            var items = _items;
            for (var i = items.Length - 1; i >= 0; i--)
            {
                GC.KeepAlive(_items[i] as IMetadata1);
            }

            for (var i = items.Length - 1; i >= 0; i--)
            {
                GC.KeepAlive(_items[i] as IMetadata2);
            }

            for (var i = items.Length - 1; i >= 0; i--)
            {
                GC.KeepAlive(_items[i] as IMetadata3);
            }

            for (var i = items.Length - 1; i >= 0; i--)
            {
                GC.KeepAlive(_items[i] as IMetadata4);
            }

            for (var i = items.Length - 1; i >= 0; i--)
            {
                GC.KeepAlive(_items[i] as IMetadata5);
            }
        }

        [Benchmark(OperationsPerInvoke = 5)]
        public void GetMetadata()
        {
            GC.KeepAlive(_collection.GetMetadata<IMetadata1>());
            GC.KeepAlive(_collection.GetMetadata<IMetadata2>());
            GC.KeepAlive(_collection.GetMetadata<IMetadata3>());
            GC.KeepAlive(_collection.GetMetadata<IMetadata4>());
            GC.KeepAlive(_collection.GetMetadata<IMetadata5>());
        }

        [Benchmark(OperationsPerInvoke = 5)]
        public void GetOrderedMetadata()
        {
            foreach (var item in _collection.GetOrderedMetadata<IMetadata1>())
            {
                GC.KeepAlive(item);
            }

            foreach (var item in _collection.GetOrderedMetadata<IMetadata2>())
            {
                GC.KeepAlive(item);
            }

            foreach (var item in _collection.GetOrderedMetadata<IMetadata3>())
            {
                GC.KeepAlive(item);
            }

            foreach (var item in _collection.GetOrderedMetadata<IMetadata4>())
            {
                GC.KeepAlive(item);
            }

            foreach (var item in _collection.GetOrderedMetadata<IMetadata5>())
            {
                GC.KeepAlive(item);
            }
        }

        private interface IMetadata1 { }
        private interface IMetadata2 { }
        private interface IMetadata3 { }
        private interface IMetadata4 { }
        private interface IMetadata5 { }
        private class Metadata1 : IMetadata1 { }
        private class Metadata2 : IMetadata2 { }
        private class Metadata3 : IMetadata3 { }
        private class Metadata4 : IMetadata4 { }
        private class Metadata5 : IMetadata5 { }
        private class Metadata6 : IMetadata1, IMetadata2 { }
        private class Metadata7 : IMetadata2, IMetadata3 { }
        private class Metadata8 : IMetadata4, IMetadata5 { }
        private class Metadata9 : IMetadata1, IMetadata2 { }
    }
}