Templates, Inversion of Control, Factories, and so on

using System;

namespace Pfz.Databasing.Managers
{
	/// <summary>
	/// Structure used to set the OrderBy of advanced parameters.
	/// </summary>
	public struct OrderByIndex:
		IEquatable<OrderByIndex>
	{
		/// <summary>
		/// Creates a new OrderByIndex, with the given index (1 based), and telling if it
		/// is descending or not.
		/// </summary>
		public OrderByIndex(int index, bool isDescending=false)
		{
			_index = index;
			_isDescending = isDescending;
		}

		private int _index;
		/// <summary>
		/// Gets the index of the column. It is 1-based.
		/// </summary>
		public int Index
		{
			get
			{
				return _index;
			}
		}

		private bool _isDescending;
		/// <summary>
		/// Gets a value indicading if this order by item is descending.
		/// </summary>
		public bool IsDescending
		{
			get
			{
				return _isDescending;
			}
		}

		/// <summary>
		/// Gets the number of the index and an DESC if it is descending.
		/// </summary>
		public override string ToString()
		{
			if (_isDescending)
				return _index + " DESC";

			return _index.ToString();
		}

		/// <summary>
		/// Compares this OrderByIndex with another object.
		/// </summary>
		public override bool Equals(object obj)
		{
			if (obj is OrderByIndex)
			{
				OrderByIndex other = (OrderByIndex)obj;
				return Equals(other);
			}

			return false;
		}

		/// <summary>
		/// Gets the HashCode of this index.
		/// </summary>
		public override int GetHashCode()
		{
			if (_isDescending)
				return -_index;

			return _index;
		}

		/// <summary>
		/// Compares this OrderByIndex with another one.
		/// </summary>
		public bool Equals(OrderByIndex other)
		{
			return _index == other._index && _isDescending == other._isDescending;
		}

		/// <summary>
		/// Compares two OrderByIndexes for equality.
		/// </summary>
		public static bool operator == (OrderByIndex a, OrderByIndex b)
		{
			return a.Equals(b);
		}

		/// <summary>
		/// Compares two OrderByIndexes for equality.
		/// </summary>
		public static bool operator != (OrderByIndex a, OrderByIndex b)
		{
			return !a.Equals(b);
		}
	}
}