using System;
using System.IO;
using System.Collections;

namespace ln.templates.elements
{
    public class ConditionalElement : ContainerElement
    {
        private ContainerElement alternativeContainer;

        public Expression Expression { get; private set; }

        public ConditionalElement(ContainerElement container,Expression expression)
            :base(container)
        {
            Expression = expression;
            AlternativeContainer = new ContainerElement(null);
        }

        private bool IsTrue(object value)
        {
            return (
                (value != null) &&
                ((value is int) && ((int)value != 0)) ||
                ((value is double) && ((double)value != 0.0)) ||
                ((value is bool) && ((bool)value)) ||
                ((value is string) && (!String.Empty.Equals(value)))
                );
        }

        public override void Generate(TextWriter writer, Template.Context context)
        {
            if (Expression.IsTrue(context.ExpressionContext))
            {
                GenerateChildren(writer, context);
            }
            else if (AlternativeContainer != null)
            {
                AlternativeContainer.Generate(writer, context);
            }
        }

        public ContainerElement AlternativeContainer {
            get
            {
                return alternativeContainer;
            }
            set
            {
                if (alternativeContainer != null)
                {
                    alternativeContainer.Container = null;
                }
                if (value != null)
                {
                    value.Container = Container;
                }
                alternativeContainer = value;
            }
        }
    }

    public class IteratorElement : ConditionalElement
    {
        public String IterName { get; private set; }

        public IteratorElement(ContainerElement container,String iterName,Expression expression)
            :base(container, expression)
        {
            IterName = iterName;
        }

        public override void Generate(TextWriter writer, Template.Context context)
        {
            object v = Expression.Evaluate(context.ExpressionContext);

            if (v == null)
            {
                AlternativeContainer.Generate(writer, context);
            }
            else if (v is IEnumerable)
            {
                Template.Context icontext = new Template.Context(context,null);

                bool b = false;
                IEnumerable en = v as IEnumerable;
                foreach (object o in en)
                {
                    b = true;
                    icontext.ExpressionContext.SetMappedValue(IterName, o);
                    GenerateChildren(writer, icontext);
                }
            }

        }

    }

}