Light ORM Library for .NET

using System;
using System.Data;
using System.Collections.Generic;

namespace Light
{
	/// <summary>
	/// Represents a query that can limit the records
	/// affected by a delete or select statements.
	/// </summary>
	public class Query : Light.Model.ParamContainer, IEquatable<Query>
	{
		private string whereClause;
		private string orderClause;
		
		/// <summary>
		/// Creates a new query.
		/// </summary>
		public Query() : this(null)
		{}
		
		/// <summary>
		/// Creates a new query with given WHERE clause.
		/// </summary>
		/// <param name="whereClause">WHERE clause</param>
		public Query(string whereClause) : this(whereClause, null, null)
		{}
		
		/// <summary>
		/// Creates a new query with given WHERE and ORDER BY clauses.
		/// </summary>
		/// <param name="whereClause">WHERE clause</param>
		/// <param name="orderClause">ORDER BY clause</param>
		public Query(string whereClause, string orderClause)
			: this(whereClause, orderClause, null)
		{}
		
		/// <summary>
		/// Creates a new query with given WHERE clause
		/// and a list of parameters used in the WHERE clause.
		/// </summary>
		/// <param name="whereClause">WHERE clause</param>
		/// <param name="parameters">list of parameters</param>
		public Query(string whereClause, IEnumerable<Parameter> parameters)
			: this(whereClause, null, parameters)
		{}
		
		/// <summary>
		/// Creates a new query with given WHERE and ORDER BY clauses
		/// and a list of parameters used in the WHERE clause.
		/// </summary>
		/// <param name="whereClause">WHERE clause</param>
		/// <param name="orderClause">ORDER BY clause</param>
		/// <param name="parameters">list of parameters</param>
		public Query(string whereClause, string orderClause, IEnumerable<Parameter> parameters)
		{
			this.whereClause = whereClause;
			this.orderClause = orderClause;
			if(parameters != null)
				this.parameters.AddRange(parameters);
		}
		
		/// <summary>
		/// Gets or sets the WHERE clause.
		/// Do NOT use the "WHERE" keyword in this clause.
		/// </summary>
		public string Where
		{
			get { return whereClause; }
			set { whereClause = value; }
		}
		
		/// <summary>
		/// Gets or sets the ORDER BY clause.
		/// Do NOT use the "ORDER BY" keyword in this clause.
		/// </summary>
		public string Order
		{
			get { return orderClause; }
			set { orderClause = value; }
		}
		
		/// <summary>
		/// Adds given parameter to this query.
		/// </summary>
		/// <param name="parameter">parameter to add</param>
		/// <returns>returns a reference to this query after adding given parameter</returns>
		public Query Add(Parameter parameter)
		{
			if(parameter != null)
				parameters.Add(parameter);
			return this;
		}
		
		/// <summary>
		/// Adds given parameters to this query.
		/// </summary>
		/// <param name="parameters">parameters to add</param>
		/// <returns>returns a reference to this query after adding given parameters</returns>
		public Query Add(params Parameter[] parameters)
		{
			this.parameters.AddRange(parameters);
			return this;
		}
		
		/// <summary>
		/// Sets the where clause of this query.
		/// </summary>
		/// <param name="whereClause">where clause</param>
		/// <returns>reference to this query</returns>
		public Query SetWhere(string whereClause)
		{
			this.whereClause = whereClause;
			return this;
		}
		
		/// <summary>
		/// Sets the order clause of this query.
		/// </summary>
		/// <param name="orderClause">order clause</param>
		/// <returns>reference to this query</returns>
		public Query SetOrder(string orderClause)
		{
			this.orderClause = orderClause;
			return this;
		}
		
		#region - IEquatable -
		/// <summary>
		/// Checks for equality with another object.
		/// </summary>
		/// <param name="obj">another object</param>
		/// <returns>true if equal, false otherwise</returns>
		public override bool Equals(object obj)
		{
			if(obj is Query)
				return Equals((Query)obj);
			else
				return false;
		}
		
		/// <summary>
		/// Checks for equality with another query object.
		/// </summary>
		/// <param name="other">another query</param>
		/// <returns>true if equal, false otherwise</returns>
		public bool Equals(Query other)
		{
			return whereClause == null ? other.whereClause == null : whereClause.Equals(other.whereClause) &&
				orderClause == null ? other.orderClause == null : orderClause.Equals(other.orderClause);
		}
		
		/// <summary>
		/// Gets the hash code for this instance.
		/// </summary>
		/// <returns>hash code</returns>
		public override int GetHashCode()
		{
			return base.GetHashCode();
		}
		#endregion
		
		/// <summary>
		/// Gets a null query.
		/// </summary>
		public static Query Null
		{
			get { return null; }
		}
	}
}