//*********************************************************************
// 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.Data.SqlClient;
using System.Collections;

namespace ASPNET.StarterKit.TimeTracker.DataAccessLayer
{
	//*********************************************************************
	//
	// The SqlHelper class is intended to encapsulate high performance, scalable best practices for 
	// common uses of SqlClient.
	//
	//*********************************************************************

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

		private SqlHelper() {}

		//*********************************************************************
		//
		// 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.
		// 
		// param name="command" The command to which the parameters will be added
		// param name="commandParameters" an array of SqlParameters tho be added to command
		//
		//*********************************************************************

		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);
			}
		}

		//*********************************************************************
		//
		// This method assigns an array of values to an array of SqlParameters.
		// 
		// param name="commandParameters" array of SqlParameters to be assigned values
		// param name="parameterValues" array of objects holding the values to be assigned
		//
		//*********************************************************************

		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];
			}
		}

		//*********************************************************************
		//
		// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
		// to the provided command.
		// 
		// param name="command" the SqlCommand to be prepared
		// param name="connection" a valid SqlConnection, on which to execute this command
		// param name="transaction" a valid SqlTransaction, or 'null'
		// param name="commandType" the CommandType (stored procedure, text, etc.)
		// param name="commandText" the stored procedure name or T-SQL command
		// param name="commandParameters" an array of SqlParameters to be associated with the command or 'null' if no parameters are required
		//
		//*********************************************************************

		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;
		}

		//*********************************************************************
		//
		// Execute a SqlCommand (that returns no resultset) against the database specified in the connection string 
		// using the provided parameters.
		//
		// e.g.:  
		//  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		//
		// param name="connectionString" a valid connection string for a SqlConnection
		// param name="commandType" the CommandType (stored procedure, text, etc.)
		// param name="commandText" the stored procedure name or T-SQL command
		// param name="commandParameters" an array of SqlParamters used to execute the command
		// returns an int representing the number of rows affected by the command
		//
		//*********************************************************************

		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);
			}
		}

		//*********************************************************************
		//
		// 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.
		// 
		// 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);
		//
		// param name="connectionString" a valid connection string for a SqlConnection
		// param name="spName" the name of the stored prcedure
		// param name="parameterValues" an array of objects to be assigned as the input values of the stored procedure
		// returns an int representing the number of rows affected by the command
		//
		//*********************************************************************

		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);
			}
		}

		//*********************************************************************
		//
		// Execute a SqlCommand (that returns no resultset) against the specified SqlConnection 
		// using the provided parameters.
		// 
		// e.g.:  
		//  int result = ExecuteNonQuery(conn, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
		// 
		// param name="connection" a valid SqlConnection 
		// param name="commandType" the CommandType (stored procedure, text, etc.) 
		// param name="commandText" the stored procedure name or T-SQL command 
		// param name="commandParameters" an array of SqlParamters used to execute the command 
		// returns an int representing the number of rows affected by the command
		//
		//*********************************************************************

		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();
			
			// detach the SqlParameters from the command object, so they can be used again.
			cmd.Parameters.Clear();
			return retval;
		}

		//*********************************************************************
		//
		// Execute a SqlCommand (that returns a resultset) against the database specified in the connection string 
		// using the provided parameters.
		// 
		// e.g.:  
		//  DataSet ds = ExecuteDataset(connString, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="commandType" the CommandType (stored procedure, text, etc.) 
		// param name="commandText" the stored procedure name or T-SQL command 
		// param name="commandParameters" an array of SqlParamters used to execute the command 
		// returns a dataset containing the resultset generated by the command
		//
		//*********************************************************************

		public static DataSet ExecuteDataset(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 ExecuteDataset(cn, commandType, commandText, commandParameters);
			}
		}

		//*********************************************************************
		//
		// Execute a stored procedure via a SqlCommand (that returns a 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.
		// 
		// This method provides no access to output parameters or the stored procedure's return value parameter.
		// 
		// e.g.:  
		//  DataSet ds = ExecuteDataset(connString, "GetOrders", 24, 36);
		// 
		// param name="connectionString" a valid connection string for a SqlConnection
		// param name="spName" the name of the stored procedure
		// param name="parameterValues" an array of objects to be assigned as the input values of the stored procedure
		// returns a dataset containing the resultset generated by the command
		//
		//*********************************************************************

		public static DataSet ExecuteDataset(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 ExecuteDataset(connectionString, CommandType.StoredProcedure, spName, commandParameters);
			}
				//otherwise we can just call the SP without params
			else 
			{
				return ExecuteDataset(connectionString, CommandType.StoredProcedure, spName);
			}
		}
		
		//*********************************************************************
		//
		// Execute a SqlCommand (that returns a resultset) against the specified SqlConnection 
		// using the provided parameters.
		// 
		// e.g.:  
		//  DataSet ds = ExecuteDataset(conn, CommandType.StoredProcedure, "GetOrders", new SqlParameter("@prodid", 24));
		//
		// param name="connection" a valid SqlConnection
		// param name="commandType" the CommandType (stored procedure, text, etc.)
		// param name="commandText" the stored procedure name or T-SQL command
		// param name="commandParameters" an array of SqlParamters used to execute the command
		// returns a dataset containing the resultset generated by the command
		//
		//*********************************************************************

		public static DataSet ExecuteDataset(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);
			
			//create the DataAdapter & DataSet
			SqlDataAdapter da = new SqlDataAdapter(cmd);
			DataSet ds = new DataSet();

			//fill the DataSet using default values for DataTable names, etc.
			da.Fill(ds);
			
			// detach the SqlParameters from the command object, so they can be used again.			
			cmd.Parameters.Clear();
			
			//return the dataset
			return ds;						
		}

		//*********************************************************************
		//
		// Execute a SqlCommand (that returns a 1x1 resultset) against the database specified in the connection string 
		// using the provided parameters.
		// 
		// e.g.:  
		//  int orderCount = (int)ExecuteScalar(connString, CommandType.StoredProcedure, "GetOrderCount", new SqlParameter("@prodid", 24));
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="commandType" the CommandType (stored procedure, text, etc.) 
		// param name="commandText" the stored procedure name or T-SQL command 
		// param name="commandParameters" an array of SqlParamters used to execute the command 
		// returns an object containing the value in the 1x1 resultset generated by the command
		//
		//*********************************************************************

		public static object ExecuteScalar(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 ExecuteScalar(cn, commandType, commandText, commandParameters);
			}
		}

		//*********************************************************************
		//
		// Execute a stored procedure via a SqlCommand (that returns a 1x1 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.
		// 
		// This method provides no access to output parameters or the stored procedure's return value parameter.
		// 
		// e.g.:  
		//  int orderCount = (int)ExecuteScalar(connString, "GetOrderCount", 24, 36);
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="spName" the name of the stored procedure 
		// param name="parameterValues" an array of objects to be assigned as the input values of the stored procedure 
		// returns an object containing the value in the 1x1 resultset generated by the command
		//
		//*********************************************************************

		public static object ExecuteScalar(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 ExecuteScalar(connectionString, CommandType.StoredProcedure, spName, commandParameters);
			}
				//otherwise we can just call the SP without params
			else 
			{
				return ExecuteScalar(connectionString, CommandType.StoredProcedure, spName);
			}
		}

		//*********************************************************************
		//
		// Execute a SqlCommand (that returns a 1x1 resultset) against the specified SqlConnection 
		// using the provided parameters.
		// 
		// e.g.:  
		//  int orderCount = (int)ExecuteScalar(conn, CommandType.StoredProcedure, "GetOrderCount", new SqlParameter("@prodid", 24));
		// 
		// param name="connection" a valid SqlConnection 
		// param name="commandType" the CommandType (stored procedure, text, etc.) 
		// param name="commandText" the stored procedure name or T-SQL command 
		// param name="commandParameters" an array of SqlParamters used to execute the command 
		// returns an object containing the value in the 1x1 resultset generated by the command
		//
		//*********************************************************************

		public static object ExecuteScalar(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);
			
			//execute the command & return the results
			object retval = cmd.ExecuteScalar();
			
			// detach the SqlParameters from the command object, so they can be used again.
			cmd.Parameters.Clear();
			return retval;
			
		}
	}

	//*********************************************************************
	//
	// SqlHelperParameterCache provides functions to leverage a static cache of procedure parameters, and the
	// ability to discover parameters for stored procedures at run-time.
	//
	//*********************************************************************

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

		private SqlHelperParameterCache() {}

		private static Hashtable paramCache = Hashtable.Synchronized(new Hashtable());

		//*********************************************************************
		//
		// resolve at run time the appropriate set of SqlParameters for a stored procedure
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="spName" the name of the stored procedure 
		// param name="includeReturnValueParameter" whether or not to include their return value parameter 
		//
		//*********************************************************************

		private static SqlParameter[] DiscoverSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)
		{
			using (SqlConnection cn = new SqlConnection(connectionString)) 
			using (SqlCommand cmd = new SqlCommand(spName,cn))
			{
				cn.Open();
				cmd.CommandType = CommandType.StoredProcedure;

				SqlCommandBuilder.DeriveParameters(cmd);

				if (!includeReturnValueParameter) 
				{
					cmd.Parameters.RemoveAt(0);
				}

				SqlParameter[] discoveredParameters = new SqlParameter[cmd.Parameters.Count];;

				cmd.Parameters.CopyTo(discoveredParameters, 0);

				return discoveredParameters;
			}
		}

		private static SqlParameter[] CloneParameters(SqlParameter[] originalParameters)
		{
			//deep copy of cached SqlParameter array
			SqlParameter[] clonedParameters = new SqlParameter[originalParameters.Length];

			for (int i = 0, j = originalParameters.Length; i < j; i++)
			{
				clonedParameters[i] = (SqlParameter)((ICloneable)originalParameters[i]).Clone();
			}

			return clonedParameters;
		}

		//*********************************************************************
		//
		// add parameter array to the cache
		//
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="commandText" the stored procedure name or T-SQL command 
		// param name="commandParameters" an array of SqlParamters to be cached 
		//
		//*********************************************************************

		public static void CacheParameterSet(string connectionString, string commandText, params SqlParameter[] commandParameters)
		{
			string hashKey = connectionString + ":" + commandText;

			paramCache[hashKey] = commandParameters;
		}

		//*********************************************************************
		//
		// Retrieve a parameter array from the cache
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="commandText" the stored procedure name or T-SQL command 
		// returns an array of SqlParamters
		//
		//*********************************************************************

		public static SqlParameter[] GetCachedParameterSet(string connectionString, string commandText)
		{
			string hashKey = connectionString + ":" + commandText;

			SqlParameter[] cachedParameters = (SqlParameter[])paramCache[hashKey];
			
			if (cachedParameters == null)
			{			
				return null;
			}
			else
			{
				return CloneParameters(cachedParameters);
			}
		}

		//*********************************************************************
		//
		// Retrieves the set of SqlParameters appropriate for the stored procedure
		// 
		// This method will query the database for this information, and then store it in a cache for future requests.
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="spName" the name of the stored procedure 
		// returns an array of SqlParameters
		//
		//*********************************************************************

		public static SqlParameter[] GetSpParameterSet(string connectionString, string spName)
		{
			return GetSpParameterSet(connectionString, spName, false);
		}

		//*********************************************************************
		//
		// Retrieves the set of SqlParameters appropriate for the stored procedure
		// 
		// This method will query the database for this information, and then store it in a cache for future requests.
		// 
		// param name="connectionString" a valid connection string for a SqlConnection 
		// param name="spName" the name of the stored procedure 
		// param name="includeReturnValueParameter" a bool value indicating whether the return value parameter should be included in the results 
		// returns an array of SqlParameters
		//
		//*********************************************************************

		public static SqlParameter[] GetSpParameterSet(string connectionString, string spName, bool includeReturnValueParameter)
		{
			string hashKey = connectionString + ":" + spName + (includeReturnValueParameter ? ":include ReturnValue Parameter":"");

			SqlParameter[] cachedParameters;
			
			cachedParameters = (SqlParameter[])paramCache[hashKey];

			if (cachedParameters == null)
			{			
				cachedParameters = (SqlParameter[])(paramCache[hashKey] = DiscoverSpParameterSet(connectionString, spName, includeReturnValueParameter));
			}
			
			return CloneParameters(cachedParameters);
		}
	}
}
