// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Drawing;
using CommunityToolkit.HighPerformance.Helpers;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using CommunityToolkit.HighPerformance.UnitTests.Buffers.Internals;

namespace CommunityToolkit.HighPerformance.UnitTests.Helpers;

public partial class Test_ParallelHelper
{
    /// <summary>
    /// Gets the list of counts to test the For2D extensions for
    /// </summary>
    private static ReadOnlySpan<Size> TestFor2DSizes => new[]
    {
        new Size(0, 0),
        new Size(0, 1),
        new Size(1, 1),
        new Size(3, 3),
        new Size(1024, 1024),
        new Size(512, 2175),
        new Size(4039, 11231)
    };

    [TestMethod]
    public unsafe void Test_ParallelHelper_For2DWithIndices()
    {
        foreach (Size size in TestFor2DSizes)
        {
            using UnmanagedSpanOwner<int> data = new(size.Height * size.Width);

            data.GetSpan().Clear();

            ParallelHelper.For2D(0, size.Height, 0, size.Width, new Assigner2D(size.Height, size.Width, data.Ptr));

            for (int i = 0; i < size.Height; i++)
            {
                for (int j = 0; j < size.Width; j++)
                {
                    if (data.Ptr[(i * size.Width) + j] != unchecked(i * 397 ^ j))
                    {
                        Assert.Fail($"Invalid item at position [{i},{j}], value was {data.Ptr[(i * size.Width) + j]} instead of {unchecked(i * 397 ^ j)}");
                    }
                }
            }
        }
    }

#if NET6_0_OR_GREATER
    [TestMethod]
    [ExpectedException(typeof(ArgumentException))]
    public void Test_ParallelHelper_For2DInvalidRange_FromEnd()
    {
        ParallelHelper.For2D<Assigner2D>(..^1, ..4);
    }

    [TestMethod]
    [ExpectedException(typeof(ArgumentException))]
    public void Test_ParallelHelper_For2DInvalidRange_RangeAll()
    {
        ParallelHelper.For2D<Assigner2D>(..5, ..);
    }

    [TestMethod]
    public unsafe void Test_ParallelHelper_For2DWithRanges()
    {
        foreach (Size size in TestFor2DSizes)
        {
            using UnmanagedSpanOwner<int> data = new(size.Height * size.Width);

            data.GetSpan().Clear();

            ParallelHelper.For2D(..size.Height, ..size.Width, new Assigner2D(size.Height, size.Width, data.Ptr));

            for (int i = 0; i < size.Height; i++)
            {
                for (int j = 0; j < size.Width; j++)
                {
                    if (data.Ptr[(i * size.Width) + j] != unchecked(i * 397 ^ j))
                    {
                        Assert.Fail($"Invalid item at position [{i},{j}], value was {data.Ptr[(i * size.Width) + j]} instead of {unchecked(i * 397 ^ j)}");
                    }
                }
            }
        }
    }
#endif

    /// <summary>
    /// A type implementing <see cref="IAction"/> to initialize a 2D array
    /// </summary>
    private readonly unsafe struct Assigner2D : IAction2D
    {
        private readonly int height;
        private readonly int width;
        private readonly int* ptr;

        public Assigner2D(int height, int width, int* ptr)
        {
            this.height = height;
            this.width = width;
            this.ptr = ptr;
        }

        /// <inheritdoc/>
        public void Invoke(int i, int j)
        {
            if ((uint)i >= (uint)this.height ||
                (uint)j >= (uint)this.width)
            {
                throw new IndexOutOfRangeException($"The target position was invalid, was [{i}, {j}], should've been in [0, {this.height}] and [0, {this.width}]");
            }

            if (this.ptr[(i * this.width) + j] != 0)
            {
                throw new InvalidOperationException($"Invalid target position [{i},{j}], was {this.ptr[(i * this.width) + j]} instead of 0");
            }

            this.ptr[(i * this.width) + j] = unchecked(i * 397 ^ j);
        }
    }
}