// 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.Runtime.CompilerServices;
using CommunityToolkit.HighPerformance.Enumerables;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace CommunityToolkit.HighPerformance.UnitTests.Extensions;

public partial class Test_ArrayExtensions
{
    [TestMethod]
    public void Test_ArrayExtensions_2D_DangerousGetReference_Int()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        // See comments in Test_ArrayExtensions.1D for how these tests work
        ref int r0 = ref array.DangerousGetReference();
        ref int r1 = ref array[0, 0];

        Assert.IsTrue(Unsafe.AreSame(ref r0, ref r1));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_DangerousGetReference_String()
    {
        string[,] array =
        {
            { "a", "bb", "ccc" },
            { "dddd", "eeeee", "ffffff" }
        };

        ref string r0 = ref array.DangerousGetReference();
        ref string r1 = ref array[0, 0];

        Assert.IsTrue(Unsafe.AreSame(ref r0, ref r1));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_DangerousGetReferenceAt_Zero()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        ref int r0 = ref array.DangerousGetReferenceAt(0, 0);
        ref int r1 = ref array[0, 0];

        Assert.IsTrue(Unsafe.AreSame(ref r0, ref r1));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_DangerousGetReferenceAt_Index()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        ref int r0 = ref array.DangerousGetReferenceAt(1, 3);
        ref int r1 = ref array[1, 3];

        Assert.IsTrue(Unsafe.AreSame(ref r0, ref r1));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan2DAndFillArrayMid()
    {
        bool[,] test = new bool[4, 5];

        // To fill an array we now go through the Span2D<T> type, which includes all
        // the necessary logic to perform the operation. In these tests we just create
        // one through the extension, slice it and then fill it. For instance in this
        // one, we're creating a Span2D<bool> from coordinates (1, 1), with a height of
        // 2 and a width of 2, and then filling it. Then we just compare the results.
        test.AsSpan2D(1, 1, 2, 3).Fill(true);

        bool[,]? expected = new[,]
        {
            { false, false, false, false, false },
            { false,  true,  true,  true, false },
            { false,  true,  true,  true, false },
            { false, false, false, false, false },
        };

        CollectionAssert.AreEqual(expected, test);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan2DAndFillArrayTwice()
    {
        bool[,] test = new bool[4, 5];

        test.AsSpan2D(0, 0, 2, 1).Fill(true);
        test.AsSpan2D(1, 3, 2, 2).Fill(true);

        bool[,]? expected = new[,]
        {
            { true,  false, false, false, false },
            { true,  false, false,  true,  true },
            { false, false, false,  true,  true },
            { false, false, false, false, false },
        };

        CollectionAssert.AreEqual(expected, test);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan2DAndFillArrayBottomEdgeBoundary()
    {
        bool[,] test = new bool[4, 5];

        test.AsSpan2D(1, 2, 3, 2).Fill(true);

        bool[,]? expected = new[,]
        {
            { false, false, false, false, false },
            { false, false,  true,  true, false },
            { false, false,  true,  true, false },
            { false, false,  true,  true, false },
        };

        CollectionAssert.AreEqual(expected, test);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan2DAndFillArrayBottomRightCornerBoundary()
    {
        bool[,] test = new bool[5, 4];

        test.AsSpan2D(3, 2, 2, 2).Fill(true);

        bool[,]? expected = new[,]
        {
            { false, false, false, false },
            { false, false, false, false },
            { false, false, false, false },
            { false, false,  true,  true },
            { false, false,  true,  true },
        };

        CollectionAssert.AreEqual(expected, test);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_GetRow_Rectangle()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        // Here we use the enumerator on the RefEnumerator<T> type to traverse items in a row
        // by reference. For each one, we check that the reference does in fact point to the
        // item we expect in the underlying array (in this case, items on row 1).
        int j = 0;
        foreach (ref int value in array.GetRow(1))
        {
            Assert.IsTrue(Unsafe.AreSame(ref value, ref array[1, j++]));
        }

        // Check that RefEnumerable<T>.ToArray() works correctly
        CollectionAssert.AreEqual(array.GetRow(1).ToArray(), new[] { 5, 6, 7, 8 });

        // Test an empty array
        Assert.AreSame(new int[1, 0].GetRow(0).ToArray(), Array.Empty<int>());

        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetRow(-1));
        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetRow(3));

        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetRow(20));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_GetColumn_Rectangle()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        // Same as above, but this time we iterate a column instead (so non contiguous items)
        int i = 0;
        foreach (ref int value in array.GetColumn(1))
        {
            Assert.IsTrue(Unsafe.AreSame(ref value, ref array[i++, 1]));
        }

        CollectionAssert.AreEqual(array.GetColumn(1).ToArray(), new[] { 2, 6, 10 });

        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetColumn(-1));
        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetColumn(4));

        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetColumn(20));
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_GetRow_Empty()
    {
        int[,] array = new int[0, 0];

        // Try to get a row from an empty array (the row index isn't in range)
        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetRow(0).ToArray());
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_GetRowOrColumn_Helpers()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 },
            { 13, 14, 15, 16 }
        };

        // Get a row and test the Clear method. Note that the Span2D<T> here is sliced
        // starting from the second column, so this method should clear the row from index 1.
        array.AsSpan2D(1, 1, 3, 3).GetRow(0).Clear();

        int[,] expected =
        {
            { 1, 2, 3, 4 },
            { 5, 0, 0, 0 },
            { 9, 10, 11, 12 },
            { 13, 14, 15, 16 }
        };

        CollectionAssert.AreEqual(array, expected);

        // Same as before, but this time we fill a column with a value
        array.GetColumn(2).Fill(42);

        expected = new[,]
        {
            { 1, 2, 42, 4 },
            { 5, 0, 42, 0 },
            { 9, 10, 42, 12 },
            { 13, 14, 42, 16 }
        };

        CollectionAssert.AreEqual(array, expected);

        int[] copy = new int[4];

        // Get a row and copy items to a target span (in this case, wrapping an array)
        array.GetRow(2).CopyTo(copy);

        int[] result = { 9, 10, 42, 12 };

        CollectionAssert.AreEqual(copy, result);

        // Same as above, but copying from a column (so we test non contiguous sequences too)
        array.GetColumn(1).CopyTo(copy);

        result = new[] { 2, 0, 10, 14 };

        CollectionAssert.AreEqual(copy, result);

        // Some invalid attempts to copy to an empty span or sequence
        _ = Assert.ThrowsException<ArgumentException>(() => array.GetRow(0).CopyTo(default(RefEnumerable<int>)));
        _ = Assert.ThrowsException<ArgumentException>(() => array.GetRow(0).CopyTo(default(Span<int>)));

        _ = Assert.ThrowsException<ArgumentException>(() => array.GetColumn(0).CopyTo(default(RefEnumerable<int>)));
        _ = Assert.ThrowsException<ArgumentException>(() => array.GetColumn(0).CopyTo(default(Span<int>)));

        // Same as CopyTo, but this will fail gracefully with an invalid target
        Assert.IsTrue(array.GetRow(2).TryCopyTo(copy));
        Assert.IsFalse(array.GetRow(0).TryCopyTo(default(Span<int>)));

        result = new[] { 9, 10, 42, 12 };

        CollectionAssert.AreEqual(copy, result);

        // Also fill a row and then further down clear a column (trying out all possible combinations)
        array.GetRow(2).Fill(99);

        expected = new[,]
        {
            { 1, 2, 42, 4 },
            { 5, 0, 42, 0 },
            { 99, 99, 99, 99 },
            { 13, 14, 42, 16 }
        };

        CollectionAssert.AreEqual(array, expected);

        array.GetColumn(2).Clear();

        expected = new[,]
        {
            { 1, 2, 0, 4 },
            { 5, 0, 0, 0 },
            { 99, 99, 0, 99 },
            { 13, 14, 0, 16 }
        };

        CollectionAssert.AreEqual(array, expected);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_ReadOnlyGetRowOrColumn_Helpers()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 },
            { 13, 14, 15, 16 }
        };

        // This test pretty much does the same things as the method above, but this time
        // using a source ReadOnlySpan2D<T>, so that the sequence type being tested is
        // ReadOnlyRefEnumerable<T> instead (which shares most features but is separate).
        ReadOnlySpan2D<int> span2D = array;

        int[] copy = new int[4];

        span2D.GetRow(2).CopyTo(copy);

        int[] result = { 9, 10, 11, 12 };

        CollectionAssert.AreEqual(copy, result);

        span2D.GetColumn(1).CopyTo(copy);

        result = new[] { 2, 6, 10, 14 };

        CollectionAssert.AreEqual(copy, result);

        _ = Assert.ThrowsException<ArgumentException>(() => ((ReadOnlySpan2D<int>)array).GetRow(0).CopyTo(default(RefEnumerable<int>)));
        _ = Assert.ThrowsException<ArgumentException>(() => ((ReadOnlySpan2D<int>)array).GetRow(0).CopyTo(default(Span<int>)));

        _ = Assert.ThrowsException<ArgumentException>(() => ((ReadOnlySpan2D<int>)array).GetColumn(0).CopyTo(default(RefEnumerable<int>)));
        _ = Assert.ThrowsException<ArgumentException>(() => ((ReadOnlySpan2D<int>)array).GetColumn(0).CopyTo(default(Span<int>)));

        Assert.IsTrue(span2D.GetRow(2).TryCopyTo(copy));
        Assert.IsFalse(span2D.GetRow(2).TryCopyTo(default(Span<int>)));

        result = new[] { 9, 10, 11, 12 };

        CollectionAssert.AreEqual(copy, result);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_RefEnumerable_Misc()
    {
        int[,] array1 =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 },
            { 13, 14, 15, 16 }
        };

        int[,] array2 = new int[4, 4];

        // Copy to enumerable with source step == 1, destination step == 1
        array1.GetRow(0).CopyTo(array2.GetRow(0));

        // Copy enumerable with source step == 1, destination step != 1
        array1.GetRow(1).CopyTo(array2.GetColumn(1));

        // Copy enumerable with source step != 1, destination step == 1
        array1.GetColumn(2).CopyTo(array2.GetRow(2));

        // Copy enumerable with source step != 1, destination step != 1
        array1.GetColumn(3).CopyTo(array2.GetColumn(3));

        int[,] result =
        {
            { 1, 5, 3, 4 },
            { 0, 6, 0, 8 },
            { 3, 7, 11, 12 },
            { 0, 8, 0, 16 }
        };

        CollectionAssert.AreEqual(array2, result);

        // Test a valid and an invalid TryCopyTo call with the RefEnumerable<T> overload
        bool shouldBeTrue = array1.GetRow(0).TryCopyTo(array2.GetColumn(0));
        bool shouldBeFalse = array1.GetRow(0).TryCopyTo(default(RefEnumerable<int>));

        result = new[,]
        {
            { 1, 5, 3, 4 },
            { 2, 6, 0, 8 },
            { 3, 7, 11, 12 },
            { 4, 8, 0, 16 }
        };

        CollectionAssert.AreEqual(array2, result);

        Assert.IsTrue(shouldBeTrue);
        Assert.IsFalse(shouldBeFalse);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_GetColumn_Empty()
    {
        int[,] array = new int[0, 0];

        _ = Assert.ThrowsException<ArgumentOutOfRangeException>(() => array.GetColumn(0).ToArray());
    }

#if NET6_0_OR_GREATER
    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan_Empty()
    {
        int[,] array = new int[0, 0];

        Span<int> span = array.AsSpan();

        // Check that the empty array was loaded properly
        Assert.AreEqual(span.Length, array.Length);
        Assert.IsTrue(span.IsEmpty);
    }

    [TestMethod]
    public void Test_ArrayExtensions_2D_AsSpan_Populated()
    {
        int[,] array =
        {
            { 1, 2, 3, 4 },
            { 5, 6, 7, 8 },
            { 9, 10, 11, 12 }
        };

        Span<int> span = array.AsSpan();

        // Test the total length of the span
        Assert.AreEqual(span.Length, array.Length);

        ref int r0 = ref array[0, 0];
        ref int r1 = ref span[0];

        // Similarly to the top methods, here we compare a given reference to
        // ensure they point to the right element back in the original array.
        Assert.IsTrue(Unsafe.AreSame(ref r0, ref r1));
    }
#endif
}