// 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.Helpers;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace CommunityToolkit.HighPerformance.UnitTests.Extensions;

[TestClass]
public class Test_ObjectMarshal
{
    [TestMethod]
    public void Test_DangerousGetObjectDataByteOffset()
    {
        TestClass? a = new() { Number = 42, Character = 'a', Text = "Hello" };

        IntPtr ptr = ObjectMarshal.DangerousGetObjectDataByteOffset(a, ref a.Number);

        ref int number = ref ObjectMarshal.DangerousGetObjectDataReferenceAt<int>(a, ptr);

        Assert.IsTrue(Unsafe.AreSame(ref a.Number, ref number));

        ptr = ObjectMarshal.DangerousGetObjectDataByteOffset(a, ref a.Character);

        ref char character = ref ObjectMarshal.DangerousGetObjectDataReferenceAt<char>(a, ptr);

        Assert.IsTrue(Unsafe.AreSame(ref a.Character, ref character));

        ptr = ObjectMarshal.DangerousGetObjectDataByteOffset(a, ref a.Text);

        ref string text = ref ObjectMarshal.DangerousGetObjectDataReferenceAt<string>(a, ptr);

        Assert.IsTrue(Unsafe.AreSame(ref a.Text, ref text));
    }

    internal class TestClass
    {
        public int Number;
        public char Character;
        public string? Text;
    }

    [TestMethod]
    public void Test_BoxOfT_PrimitiveTypes()
    {
        Test(true);
        Test(false);
        Test<byte>(27);
        Test('a');
        Test(4221124);
        Test(3.14f);
        Test(8394324ul);
        Test(184013.234324);
    }

    [TestMethod]
    public void Test_BoxOfT_OtherTypes()
    {
        Test(DateTime.Now);
        Test(Guid.NewGuid());
    }

    internal struct TestStruct : IEquatable<TestStruct>
    {
        public int Number;
        public char Character;
        public string Text;

        /// <inheritdoc/>
        public bool Equals(TestStruct other)
        {
            return
                this.Number == other.Number &&
                this.Character == other.Character &&
                this.Text == other.Text;
        }
    }

    [TestMethod]
    public void TestBoxOfT_CustomStruct()
    {
        TestStruct a = new() { Number = 42, Character = 'a', Text = "Hello" };
        TestStruct b = new() { Number = 38293, Character = 'z', Text = "World" };

        Test(a);
        Test(b);
    }

    /// <summary>
    /// Tests the extensions type for a given value.
    /// </summary>
    /// <typeparam name="T">The type to test.</typeparam>
    /// <param name="value">The initial <typeparamref name="T"/> value.</param>
    private static void Test<T>(T value)
        where T : struct, IEquatable<T>
    {
        object obj = value;

        bool success = obj.TryUnbox(out T result);

        Assert.IsTrue(success);
        Assert.AreEqual(value, result);

        success = obj.TryUnbox(out decimal test);

        Assert.IsFalse(success);
        Assert.AreEqual(test, default);

        result = ObjectMarshal.DangerousUnbox<T>(obj);

        Assert.AreEqual(value, result);
    }
}