using System.Collections.Generic;

namespace StardewModdingAPI.Toolkit
{
    /// <summary>A comparer for semantic versions based on the <see cref="SemanticVersion.CompareTo(ISemanticVersion)"/> field.</summary>
    public class SemanticVersionComparer : IComparer<ISemanticVersion?>
    {
        /*********
        ** Accessors
        *********/
        /// <summary>A singleton instance of the comparer.</summary>
        public static SemanticVersionComparer Instance { get; } = new();


        /*********
        ** Public methods
        *********/
        /// <inheritdoc />
        public int Compare(ISemanticVersion? x, ISemanticVersion? y)
        {
            if (object.ReferenceEquals(x, y))
                return 0;

            if (x is null)
                return -1;
            if (y is null)
                return 1;

            return x.CompareTo(y);
        }
    }
}