// Copyright (c) Six Labors.
// Licensed under the Apache License, Version 2.0.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using Microsoft.DotNet.RemoteExecutor;
using Xunit.Abstractions;

namespace SixLabors.ImageSharp.Tests.TestUtilities
{
    /// <summary>
    /// Allows the testing against specific feature sets.
    /// </summary>
    public static class FeatureTestRunner
    {
        private static readonly char[] SplitChars = new[] { ',', ' ' };

        /// <summary>
        /// Allows the deserialization of parameters passed to the feature test.
        /// <remark>
        /// <para>
        /// This is required because <see cref="RemoteExecutor"/> does not allow
        /// marshalling of fields so we cannot pass a wrapped <see cref="Action{T}"/>
        /// allowing automatic deserialization.
        /// </para>
        /// </remark>
        /// </summary>
        /// <typeparam name="T">The type to deserialize to.</typeparam>
        /// <param name="value">The string value to deserialize.</param>
        /// <returns>The <see cref="T"/> value.</returns>
        public static T Deserialize<T>(string value)
            where T : IXunitSerializable
            => BasicSerializer.Deserialize<T>(value);

        /// <summary>
        /// Runs the given test <paramref name="action"/> within an environment
        /// where the given <paramref name="intrinsics"/> features.
        /// </summary>
        /// <param name="action">The test action to run.</param>
        /// <param name="intrinsics">The intrinsics features.</param>
        public static void RunWithHwIntrinsicsFeature(
            Action action,
            HwIntrinsics intrinsics)
        {
            if (!RemoteExecutor.IsSupported)
            {
                return;
            }

            foreach (KeyValuePair<HwIntrinsics, string> intrinsic in intrinsics.ToFeatureKeyValueCollection())
            {
                var processStartInfo = new ProcessStartInfo();
                if (intrinsic.Key != HwIntrinsics.AllowAll)
                {
                    processStartInfo.Environment[$"COMPlus_{intrinsic.Value}"] = "0";

                    RemoteExecutor.Invoke(
                        action,
                        new RemoteInvokeOptions
                        {
                            StartInfo = processStartInfo
                        })
                        .Dispose();
                }
                else
                {
                    // Since we are running using the default architecture there is no
                    // point creating the overhead of running the action in a separate process.
                    action();
                }
            }
        }

        /// <summary>
        /// Runs the given test <paramref name="action"/> within an environment
        /// where the given <paramref name="intrinsics"/> features.
        /// </summary>
        /// <param name="action">
        /// The test action to run.
        /// The parameter passed will be a string representing the currently testing <see cref="HwIntrinsics"/>.</param>
        /// <param name="intrinsics">The intrinsics features.</param>
        public static void RunWithHwIntrinsicsFeature(
            Action<string> action,
            HwIntrinsics intrinsics)
        {
            if (!RemoteExecutor.IsSupported)
            {
                return;
            }

            foreach (KeyValuePair<HwIntrinsics, string> intrinsic in intrinsics.ToFeatureKeyValueCollection())
            {
                var processStartInfo = new ProcessStartInfo();
                if (intrinsic.Key != HwIntrinsics.AllowAll)
                {
                    processStartInfo.Environment[$"COMPlus_{intrinsic.Value}"] = "0";

                    RemoteExecutor.Invoke(
                        action,
                        intrinsic.Key.ToString(),
                        new RemoteInvokeOptions
                        {
                            StartInfo = processStartInfo
                        })
                        .Dispose();
                }
                else
                {
                    // Since we are running using the default architecture there is no
                    // point creating the overhead of running the action in a separate process.
                    action(intrinsic.Key.ToString());
                }
            }
        }

        /// <summary>
        /// Runs the given test <paramref name="action"/> within an environment
        /// where the given <paramref name="intrinsics"/> features.
        /// </summary>
        /// <param name="action">The test action to run.</param>
        /// <param name="intrinsics">The intrinsics features.</param>
        /// <param name="serializable">The value to pass as a parameter to the test action.</param>
        public static void RunWithHwIntrinsicsFeature<T>(
            Action<string> action,
            HwIntrinsics intrinsics,
            T serializable)
            where T : IXunitSerializable
        {
            if (!RemoteExecutor.IsSupported)
            {
                return;
            }

            foreach (KeyValuePair<HwIntrinsics, string> intrinsic in intrinsics.ToFeatureKeyValueCollection())
            {
                var processStartInfo = new ProcessStartInfo();
                if (intrinsic.Key != HwIntrinsics.AllowAll)
                {
                    processStartInfo.Environment[$"COMPlus_{intrinsic.Value}"] = "0";

                    RemoteExecutor.Invoke(
                        action,
                        BasicSerializer.Serialize(serializable),
                        new RemoteInvokeOptions
                        {
                            StartInfo = processStartInfo
                        })
                        .Dispose();
                }
                else
                {
                    // Since we are running using the default architecture there is no
                    // point creating the overhead of running the action in a separate process.
                    action(BasicSerializer.Serialize(serializable));
                }
            }
        }

        /// <summary>
        /// Runs the given test <paramref name="action"/> within an environment
        /// where the given <paramref name="intrinsics"/> features.
        /// </summary>
        /// <param name="action">The test action to run.</param>
        /// <param name="intrinsics">The intrinsics features.</param>
        /// <param name="serializable">The value to pass as a parameter to the test action.</param>
        public static void RunWithHwIntrinsicsFeature<T>(
            Action<string, string> action,
            HwIntrinsics intrinsics,
            T serializable)
            where T : IXunitSerializable
        {
            if (!RemoteExecutor.IsSupported)
            {
                return;
            }

            foreach (KeyValuePair<HwIntrinsics, string> intrinsic in intrinsics.ToFeatureKeyValueCollection())
            {
                var processStartInfo = new ProcessStartInfo();
                if (intrinsic.Key != HwIntrinsics.AllowAll)
                {
                    processStartInfo.Environment[$"COMPlus_{intrinsic.Value}"] = "0";

                    RemoteExecutor.Invoke(
                        action,
                        BasicSerializer.Serialize(serializable),
                        intrinsic.Key.ToString(),
                        new RemoteInvokeOptions
                        {
                            StartInfo = processStartInfo
                        })
                        .Dispose();
                }
                else
                {
                    // Since we are running using the default architecture there is no
                    // point creating the overhead of running the action in a separate process.
                    action(BasicSerializer.Serialize(serializable), intrinsic.Key.ToString());
                }
            }
        }

        internal static Dictionary<HwIntrinsics, string> ToFeatureKeyValueCollection(this HwIntrinsics intrinsics)
        {
            // Loop through and translate the given values into COMPlus equivaluents
            var features = new Dictionary<HwIntrinsics, string>();
            foreach (string intrinsic in intrinsics.ToString("G").Split(SplitChars, StringSplitOptions.RemoveEmptyEntries))
            {
                var key = (HwIntrinsics)Enum.Parse(typeof(HwIntrinsics), intrinsic);
                switch (intrinsic)
                {
                    case nameof(HwIntrinsics.DisableSIMD):
                        features.Add(key, "FeatureSIMD");
                        break;

                    case nameof(HwIntrinsics.AllowAll):

                        // Not a COMPlus value. We filter in calling method.
                        features.Add(key, nameof(HwIntrinsics.AllowAll));
                        break;

                    default:
                        features.Add(key, intrinsic.Replace("Disable", "Enable"));
                        break;
                }
            }

            return features;
        }
    }

    /// <summary>
    /// See <see href="https://github.com/dotnet/runtime/blob/50ac454d8d8a1915188b2a4bb3fff3b81bf6c0cf/src/coreclr/src/jit/jitconfigvalues.h#L224"/>
    /// <remarks>
    /// <see cref="DisableSIMD"/> ends up impacting all SIMD support(including System.Numerics)
    /// but not things like <see cref="DisableBMI1"/>, <see cref="DisableBMI2"/>, and <see cref="DisableLZCNT"/>.
    /// </remarks>
    /// </summary>
    [Flags]
#pragma warning disable RCS1135 // Declare enum member with zero value (when enum has FlagsAttribute).
    public enum HwIntrinsics
#pragma warning restore RCS1135 // Declare enum member with zero value (when enum has FlagsAttribute).
    {
        // Use flags so we can pass multiple values without using params.
        // Don't base on 0 or use inverse for All as that doesn't translate to string values.
        DisableSIMD = 1 << 0,
        DisableHWIntrinsic = 1 << 1,
        DisableSSE = 1 << 2,
        DisableSSE2 = 1 << 3,
        DisableAES = 1 << 4,
        DisablePCLMULQDQ = 1 << 5,
        DisableSSE3 = 1 << 6,
        DisableSSSE3 = 1 << 7,
        DisableSSE41 = 1 << 8,
        DisableSSE42 = 1 << 9,
        DisablePOPCNT = 1 << 10,
        DisableAVX = 1 << 11,
        DisableFMA = 1 << 12,
        DisableAVX2 = 1 << 13,
        DisableBMI1 = 1 << 14,
        DisableBMI2 = 1 << 15,
        DisableLZCNT = 1 << 16,
        AllowAll = 1 << 17
    }
}