using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;

namespace DTS.Common.Utilities
{
    /// <summary>
    /// this is a class for doing natural string compares like in explorer (using the explorer function)
    /// http://msdn.microsoft.com/en-us/library/bb759947%28VS.85%29.aspx
    /// </summary>
    /// <remarks>requires XP or greater</remarks>
    public class NaturalStringComparer : IComparer<string>
    {
        [DllImport("shlwapi.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
        static extern int StrCmpLogicalW(String x, String y);

        /// <summary>
        /// do a natural string compare between two strings
        /// </summary>
        /// <param name="x">left string to compare</param>
        /// <param name="y">right string to compare</param>
        /// <returns>-1 if natural order of x is less than y, +1 if x is after y, 0 if they are equal</returns>
        public int Compare(string x, string y)
        {
            if (null == x) { return -1; }
            if (null == y) { return 1; }
            return StrCmpLogicalW(x, y);
        }

        public static int StaticCompare(string x, string y)
        {
            if (null == x) { return -1; }
            if (null == y) { return 1; }
            return StrCmpLogicalW(x, y);
        }
    }
}