//===============================================================================
// Microsoft Data Access Application Block for .NET
// http://msdn.microsoft.com/library/en-us/dnbda/html/daab-rm.asp
//
// SQLHelper.cs
//
// This file contains the implementations of the SqlHelper and SqlHelperParameterCache
// classes.
//
// For more information see the Data Access Application Block Implementation Overview. 
// 
//===============================================================================
// Copyright (C) 2000-2001 Microsoft Corporation
// All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR
// FITNESS FOR A PARTICULAR PURPOSE.
//==============================================================================

using System;
using System.Data;
using System.Xml;
using System.Data.SqlClient;
using System.Collections;


namespace Microsoft.ApplicationBlocks.Data
{
	/// <summary>
	/// The SqlHelper class is intended to encapsulate high performance, scalable best practices for 
	/// common uses of SqlClient.
	/// </summary>
	public sealed class SqlHelper
	{
		#region private utility methods & constructors

		//Since this class provides only static methods, make the default constructor private to prevent 
		//instances from being created with "new SqlHelper()".
		private SqlHelper() {}



		/// <summary>
		/// This method is used to attach array of SqlParameters to a SqlCommand.
		/// 
		/// This method will assign a value of DbNull to any parameter with a direction of
		/// InputOutput and a value of null.  
		/// 
		/// This behavior will prevent default values from being used, but
		/// this will be the less common case than an intended pure output parameter (derived as InputOutput)
		/// where the user provided no input value.
		/// </summary>
		/// <param name="command">The command to which the parameters will be added</param>
		/// <param name="commandParameters">an array of SqlParameters tho be added to command</param>
		private static void AttachParameters(SqlCommand command, SqlParameter[] commandParameters)
		{
			foreach (SqlParameter p in commandParameters)
			{
				//check for derived output value with no value assigned
				if ((p.Direction == ParameterDirection.InputOutput) && (p.Value == null))
				{
					p.Value = DBNull.Value;
				}
				
				command.Parameters.Add(p);
			}
		}

		/// <summary>
		/// This method assigns an array of values to an array of SqlParameters.
		/// </summary>
		/// <param name="commandParameters">array of SqlParameters to be assigned values</param>
		/// <param name="parameterValues">array of objects holding the values to be assigned</param>
		private static void AssignParameterValues(SqlParameter[] commandParameters, object[] parameterValues)
		{
			if ((commandParameters == null) || (parameterValues == null)) 
			{
				//do nothing if we get no data
				return;
			}

			// we must have the same number of values as we pave parameters to put them in
			if (commandParameters.Length != parameterValues.Length)
			{
				throw new ArgumentException("Parameter count does not match Parameter Value count.");
			}

			//iterate through the SqlParameters, assigning the values from the corresponding position in the 
			//value array
			for (int i = 0, j = commandParameters.Length; i < j; i++)
			{
				commandParameters[i].Value = parameterValues[i];
			}
		}

		/// <summary>
		/// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
		/// to the provided command.
		/// </summary>
		/// <param name="command">the SqlCommand to be prepared</param>
		/// <param name="connection">a valid SqlConnection, on which to execute this command</param>
		/// <param name="transaction">a valid SqlTransaction, or 'null'</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParameters to be associated with the command or 'null' if no parameters are required</param>
		private static void PrepareCommand(SqlCommand command, SqlConnection connection, SqlTransaction transaction, CommandType commandType, string commandText, SqlParameter[] commandParameters)
		{
			//if the provided connection is not open, we will open it
			if (connection.State != ConnectionState.Open)
			{
				connection.Open();
			}

			//associate the connection with the command
			command.Connection = connection;

			//set the command text (stored procedure name or SQL statement)
			command.CommandText = commandText;

			//if we were provided a transaction, assign it.
			if (transaction != null)
			{
				command.Transaction = transaction;
			}

			//set the command type
			command.CommandType = commandType;

			//attach the command parameters if they are provided
			if (commandParameters != null)
			{
				AttachParameters(command, commandParameters);
			}

			return;
		}


		#endregion private utility methods & constructors

		#region ExecuteNonQuery

		/// <summary>
		/// Execute a SqlCommand (that returns no resultset and takes no parameters) against the database specified in 
		/// the connection string. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders");
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText)
		{
			//pass through the call providing null for the set of SqlParameters
			return ExecuteNonQuery(connectionString, commandType, commandText, (SqlParameter[])null);
		}

		/// <summary>
		/// Execute a SqlCommand (that returns no resultset) against the database specified in the connection string 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery(string connectionString, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{
			//create & open a SqlConnection, and dispose of it after we are done.
			using (SqlConnection cn = new SqlConnection(connectionString))
			{
				cn.Open();

				//call the overload that takes a connection in place of the connection string
				return ExecuteNonQuery(cn, commandType, commandText, commandParameters);
			}
		}

		/// <summary>
		/// Execute a stored procedure via a SqlCommand (that returns no resultset) against the database specified in 
		/// the connection string using the provided parameter values.  This method will query the database to discover the parameters for the 
		/// stored procedure (the first time each stored procedure is called), and assign the values based on parameter order.
		/// </summary>
		/// <remarks>
		/// This method provides no access to output parameters or the stored procedure's return value parameter.
		/// 
		/// e.g.:  
		///  int result = ExecuteNonQuery(connString, "PublishOrders", 24, 36);
		/// </remarks>
		/// <param name="connectionString">a valid connection string for a SqlConnection</param>
		/// <param name="spName">the name of the stored prcedure</param>
		/// <param name="parameterValues">an array of objects to be assigned as the input values of the stored procedure</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery(string connectionString, string spName, params object[] parameterValues)
		{
			//if we receive parameter values, we need to figure out where they go
			if ((parameterValues != null) && (parameterValues.Length > 0)) 
			{
				//pull the parameters for this stored procedure from the parameter cache (or discover them & populate the cache)
				SqlParameter[] commandParameters = SqlHelperParameterCache.GetSpParameterSet(connectionString, spName);

				//assign the provided values to these parameters based on parameter order
				AssignParameterValues(commandParameters, parameterValues);

				//call the overload that takes an array of SqlParameters
				return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName, commandParameters);
			}
				//otherwise we can just call the SP without params
			else 
			{
				return ExecuteNonQuery(connectionString, CommandType.StoredProcedure, spName);
			}
		}

		/// <summary>
		/// Execute a SqlCommand (that returns no resultset and takes no parameters) against the provided SqlConnection. 
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders");
		/// </remarks>
		/// <param name="connection">a valid SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText)
		{
			//pass through the call providing null for the set of SqlParameters
			return ExecuteNonQuery(connection, commandType, commandText, (SqlParameter[])null);
		}

		/// <summary>
		/// Execute a SqlCommand (that returns no resultset) against the specified SqlConnection 
		/// using the provided parameters.
		/// </summary>
		/// <remarks>
		/// e.g.:  
		///  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		/// </remarks>
		/// <param name="connection">a valid SqlConnection</param>
		/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
		/// <param name="commandText">the stored procedure name or T-SQL command</param>
		/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
		/// <returns>an int representing the number of rows affected by the command</returns>
		public static int ExecuteNonQuery(SqlConnection connection, CommandType commandType, string commandText, params SqlParameter[] commandParameters)
		{	
			//create a command and prepare it for execution
			SqlCommand cmd = new SqlCommand();
			PrepareCommand(cmd, connection, (SqlTransaction)null, commandType, commandText, commandParameters);
			
			//finally, execute the command.
			int retval = cmd.ExecuteNonQuery();