#region Apache Notice
/*****************************************************************************
 * $Header: $
 * $Revision: 512878 $
 * $Date$
 * 
 * iBATIS.NET Data Mapper
 * Copyright (C) 2004 - Gilles Bayon
 *  
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 ********************************************************************************/
#endregion


using System;
using System.Text;

using Apache.Ibatis.DataMapper.Model.ParameterMapping;

namespace Apache.Ibatis.DataMapper.Configuration.Statements
{
	/// <summary>
	/// Summary description for SqlGenerator.
	/// </summary>
	public sealed class SqlGenerator
	{
		/// <summary>
		/// Creates SQL command text for a specified statement
		/// </summary>
		/// <param name="statement">The statement to build the SQL command text.</param>
		/// <returns>The SQL command text for the statement.</returns>
		public static string BuildQuery(IStatement statement)
		{
			string sqlText = string.Empty;

			if (statement is Select)
			{
				sqlText = BuildSelectQuery(statement);
			}
			else if (statement is Insert)
			{
				sqlText = BuildInsertQuery(statement);
			}
			else if (statement is Update)
			{
				sqlText = BuildUpdateQuery(statement);
			}
			else if (statement is Delete)
			{
				sqlText = BuildDeleteQuery(statement);
			}
			
			return sqlText;
		}


		/// <summary>
		/// Creates an select SQL command text for a specified statement
		/// </summary>
		/// <param name="statement">The statement to build the SQL command text.</param>
		/// <returns>The SQL command text for the statement.</returns>
		private static string BuildSelectQuery(IStatement statement)
		{
			StringBuilder output = new StringBuilder();
			Select select = (Select) statement;
			int columnCount = statement.ParameterMap.PropertiesList.Count;

			output.Append("SELECT ");

			// Create the list of columns
			for (int i = 0; i < columnCount; i++) 
			{
				ParameterProperty property = (ParameterProperty) statement.ParameterMap.PropertiesList[i];
						
				if (i < (columnCount - 1)) 
				{
					output.Append("\t" + property.ColumnName + " as "+property.PropertyName+",");
				} 
				else 
				{
					output.Append("\t" + property.ColumnName + " as "+property.PropertyName);
				}
			}

			output.Append(" FROM ");
			output.Append("\t" + select.Generate.Table + "");

			// Create the where clause

			string [] compositeKeyList = select.Generate.By.Split(new Char [] {','});
			if (compositeKeyList.Length > 0 && select.Generate.By.Length>0)
			{
				output.Append(" WHERE ");
				int length = compositeKeyList.Length;
				for (int i = 0; i < length; i++) 
				{
					string columnName = compositeKeyList[i];
						
					if (i > 0) 
					{
						output.Append("\tAND " + columnName + " = ?" );
					} 
					else 
					{
						output.Append("\t" + columnName + " = ?" );
					}
				}
			}

			// 'Select All' case
			if (statement.ParameterClass == null)
			{
				// The ParameterMap is just used to build the query
				// to avoid problems later, we set it to null
				statement.ParameterMap = null;
			}

			return output.ToString();
		}


		/// <summary>
		/// Creates an insert SQL command text for a specified statement
		/// </summary>
		/// <param name="statement">The statement to build the SQL command text.</param>
		/// <returns>The SQL command text for the statement.</returns>
		private static string BuildInsertQuery(IStatement statement)
		{
			StringBuilder output = new StringBuilder();
			Insert insert = (Insert) statement;
			int columnCount = statement.ParameterMap.PropertiesList.Count;

			output.Append("INSERT INTO " + insert.Generate.Table + " (");
				
			// Create the parameter list
			for (int i = 0; i < columnCount; i++) 
			{
				ParameterProperty property = (ParameterProperty) statement.ParameterMap.PropertiesList[i];
					
				// Append the column name as a parameter of the insert statement
				if (i < (columnCount - 1)) 
				{
					output.Append("\t" + property.ColumnName + ",");
				} 
				else 
				{
					output.Append("\t" + property.ColumnName + "");
				}
			}
				
			output.Append(") VALUES (");

			// Create the values list
			for (int i = 0; i < columnCount; i++) 
			{
				ParameterProperty property = (ParameterProperty) statement.ParameterMap.PropertiesList[i];
					
				// Append the necessary line breaks and commas
				if (i < (columnCount - 1)) 
				{
					output.Append("\t?,");
				} 
				else 
				{
					output.Append("\t?");
				}
			}

			output.Append(")");

			return output.ToString();
		}


		/// <summary>
		/// Creates an update SQL command text for a specified statement
		/// </summary>
		/// <param name="statement">The statement to build the SQL command text.</param>
		/// <returns>The SQL command text for the statement.</returns>
		private static string BuildUpdateQuery(IStatement statement)
		{
			StringBuilder output = new StringBuilder();
			Update update = (Update) statement;
			int columnCount = statement.ParameterMap.PropertiesList.Count;
			string[] keysList = update.Generate.By.Split(',');

			output.Append("UPDATE ");
			output.Append("\t" + update.Generate.Table + " ");
			output.Append("SET ");
					
			// Create the set statement
			for (int i = 0; i < columnCount; i++) 
			{
				ParameterProperty property = (ParameterProperty) statement.ParameterMap.PropertiesList[i];
						
				// Ignore key columns
				if (update.Generate.By.IndexOf(property.ColumnName) < 0) 
				{
					if (i < (columnCount-keysList.Length - 1)) 
					{
						output.Append("\t" + property.ColumnName + " = ?,");
					} 
					else 
					{
						output.Append("\t" + property.ColumnName + " = ? ");
					}
				}
			}

			output.Append(" WHERE ");
					
			// Create the where clause
			int length = keysList.Length;
			for (int i = 0; i < length; i++) 
			{
				string columnName = keysList[i];
						
				if (i > 0) 
				{
					output.Append("\tAND " + columnName + " = ?");
				} 
				else 
				{
					output.Append("\t " + columnName + " = ?");
				}
			}

			return output.ToString();
		}

		/// <summary>
		/// Creates an delete SQL command text for a specified statement
		/// </summary>
		/// <param name="statement">The statement to build the SQL command text.</param>
		/// <returns>The SQL command text for the statement.</returns>
		private static string BuildDeleteQuery(IStatement statement)
		{
			StringBuilder output = new StringBuilder();
			Delete delete = (Delete) statement;
			string[] keysList = delete.Generate.By.Split(',');

			output.Append("DELETE FROM");
			output.Append("\t" + delete.Generate.Table + "");
			output.Append(" WHERE ");

			// Create the where clause
			int length = keysList.Length;
			for (int i = 0; i < keysList.Length; i++) 
			{
				string columnName = keysList[i].Trim();
						
				if (i > 0) 
				{
					output.Append("\tAND " + columnName + " = ?");
				} 
				else 
				{
					output.Append("\t " + columnName + " = ?");
				}
			}

			return output.ToString();
		}
	}
}