// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace Microsoft.AspNetCore.Mvc.Infrastructure;
 
internal sealed class StringArrayComparer : IEqualityComparer<string[]>
{
    public static readonly StringArrayComparer Ordinal = new StringArrayComparer(StringComparer.Ordinal);
 
    public static readonly StringArrayComparer OrdinalIgnoreCase = new StringArrayComparer(StringComparer.OrdinalIgnoreCase);
 
    private readonly StringComparer _valueComparer;
 
    private StringArrayComparer(StringComparer valueComparer)
    {
        _valueComparer = valueComparer;
    }
 
    public bool Equals(string[]? x, string[]? y)
    {
        if (object.ReferenceEquals(x, y))
        {
            return true;
        }
 
        if (x == null && y == null)
        {
            return true;
        }
 
        if (x == null || y == null)
        {
            return false;
        }
 
        if (x.Length != y.Length)
        {
            return false;
        }
 
        for (var i = 0; i < x.Length; i++)
        {
            if (string.IsNullOrEmpty(x[i]) && string.IsNullOrEmpty(y[i]))
            {
                continue;
            }
 
            if (!_valueComparer.Equals(x[i], y[i]))
            {
                return false;
            }
        }
 
        return true;
    }
 
    public int GetHashCode(string[] obj)
    {
        if (obj == null)
        {
            return 0;
        }
 
        var hash = new HashCode();
        for (var i = 0; i < obj.Length; i++)
        {
            // Route values define null and "" to be equivalent.
            hash.Add(obj[i] ?? string.Empty, _valueComparer);
        }
 
        return hash.ToHashCode();
    }
}