using System;

using System.CodeDom;

using System.Collections.Generic;

using System.Text;

using Otis.CodeGen;



namespace Otis.Functions

{

	public class AvgFunction : SimpleFunctionBase

	{

		public override IEnumerable<CodeStatement> GetInitializationStatements(AggregateFunctionContext context)

		{

			List<CodeStatement> statements = new List<CodeStatement>(base.GetInitializationStatements(context));



			CodeStatement st = new CodeVariableDeclarationStatement(typeof(int),

				GetCounterObjectName(context),

				new CodeSnippetExpression("0"));



			statements.Add(st);



			return statements;

		}



		protected override string GetResultExpression()

		{

			return string.Format("{0}/{1}", Context.FunctionObjectName, GetCounterObjectName(Context));

		}



		private static string GetCounterObjectName(AggregateFunctionContext context)

		{

			return context.FunctionObjectName + "_Cnt";

		}



		protected override string GetFormatForExecutedExpression(AggregateFunctionContext context)

		{

			// todo: test

			return string.Format("FN_OBJ = FN_OBJ + CURR_ITEM; {0}++;", GetCounterObjectName(context));

		}



		protected override Type GetDefaultTargetType()

		{

			return typeof(double);

		}

	}

}