// 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.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;

namespace CommunityToolkit.Mvvm;

/// <summary>
/// Internal polyfill for <see cref="System.ArgumentNullException"/>.
/// </summary>
internal sealed class ArgumentNullException
{
    /// <summary>
    /// Throws an <see cref="System.ArgumentNullException"/> if <paramref name="argument"/> is <see langword="null"/>.
    /// </summary>
    /// <param name="argument">The reference type argument to validate as non-<see langword="null"/>.</param>
    /// <param name="paramName">The name of the parameter with which <paramref name="argument"/> corresponds.</param>
    [MethodImpl(MethodImplOptions.AggressiveInlining)]
    public static void ThrowIfNull([NotNull] object? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
    {
        if (argument is null)
        {
            Throw(paramName);
        }
    }

    /// <summary>
    /// A specialized version for generic values.
    /// </summary>
    /// <typeparam name="T">The type of values to check.</typeparam>
    /// <remarks>
    /// This type is needed because if there had been a generic overload with a generic parameter, all calls
    /// would have just been bound by that by the compiler instead of the <see cref="object"/> overload.
    /// </remarks>
    public static class For<T>
    {
        /// <summary>
        /// Throws an <see cref="System.ArgumentNullException"/> if <paramref name="argument"/> is <see langword="null"/>.
        /// </summary>
        /// <param name="argument">The reference type argument to validate as non-<see langword="null"/>.</param>
        /// <param name="paramName">The name of the parameter with which <paramref name="argument"/> corresponds.</param>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void ThrowIfNull([NotNull] T? argument, [CallerArgumentExpression(nameof(argument))] string? paramName = null)
        {
            if (argument is null)
            {
                Throw(paramName);
            }
        }
    }

    /// <summary>
    /// Throws an <see cref="System.ArgumentNullException"/>.
    /// </summary>
    /// <param name="paramName">The name of the parameter that failed validation.</param>
    [DoesNotReturn]
    private static void Throw(string? paramName)
    {
        throw new System.ArgumentNullException(paramName);
    }
}