// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Collections.Generic;
using System.Linq;

namespace Microsoft.Build.Framework
{

#nullable enable

    /// <summary>
    /// The value of an item and any associated metadata to be added by an SDK resolver.  See <see cref="SdkResult.ItemsToAdd"/>
    /// </summary>
    public class SdkResultItem
    {
        public string ItemSpec { get; set; }
        public Dictionary<string, string>? Metadata { get; }

        public SdkResultItem()
        {
            ItemSpec = string.Empty;
            Metadata = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
        }

        /// <summary>
        /// Creates an <see cref="SdkResultItem"/>
        /// </summary>
        /// <param name="itemSpec">The value (itemspec) for the item</param>
        /// <param name="metadata">A dictionary of item metadata.  This should be created with <see cref="StringComparer.OrdinalIgnoreCase"/> for the comparer.</param>
        public SdkResultItem(string itemSpec, Dictionary<string, string>? metadata)
        {
            ItemSpec = itemSpec;
            Metadata = metadata;
        }

        public override bool Equals(object? obj)
        {
            if (obj is SdkResultItem item &&
                   ItemSpec == item.ItemSpec &&
                   item.Metadata is not null &&
                   Metadata?.Count == item.Metadata.Count)
            {
                return Metadata.All(m => item.Metadata.TryGetValue(m.Key, out var itemValue) && itemValue == m.Value);
            }
            return false;
        }

        public override int GetHashCode()
        {
            int hashCode = -849885975;
            hashCode = hashCode ^ ItemSpec.GetHashCode();

            if (Metadata != null)
            {
                foreach (var kvp in Metadata)
                {
                    hashCode ^= StringComparer.OrdinalIgnoreCase.GetHashCode(kvp.Key) * (StringComparer.OrdinalIgnoreCase.GetHashCode(kvp.Value ?? "V") + 1);
                }
            }

            return hashCode;
        }
    }
}