using System;
using System.Collections.Generic;
using System.Reflection;

namespace JBLib.Collections
{
    [Serializable]
    public class ObjectComparer<T> : IComparer<T>
    {
        public ObjectComparer( params string[] fields )
            : this( fields, new bool[fields.Length] ) { }

        public ObjectComparer( string[] fields, bool[] descending )
        {
            Fields = fields;
            Descending = descending;
        }

        protected string[] Fields;

        protected bool[] Descending;

        #region IComparer<T> Members

        public int Compare( T x, T y )
        {
            Type typex = x.GetType();
            Type typey = y.GetType();

            for( int i = 0; i < Fields.Length; i++ )
            {
                PropertyInfo pix = typex.GetProperty( Fields[i] );
                PropertyInfo piy = typey.GetProperty( Fields[i] );

                IComparable pvalx = ( IComparable )pix.GetValue( x, null );
                object pvaly = piy.GetValue( y, null );

                int iResult = pvalx.CompareTo( pvaly );
                if( iResult != 0 )
                {
                    if( Descending[i] )
                    {
                        return -iResult;
                    }
                    else
                    {
                        return iResult;
                    }
                }
            }

            return 0;
        }

        #endregion
    }
}