namespace FilterDemo
{
        public enum CATAGORY { Food, Drink, Cloth, Office, Other };

        public class Goods
        {
                public int Price { private set; get; }
                public CATAGORY Category { private set; get; }
                public Goods(CATAGORY category, int price)
                {
                        Category = category;
                        Price = price;
                }
        }

        public interface Filter
        {
                bool Match(Goods goods);
        }

        public class PriceRangeFilter : Filter
        {
                int min;
                int max;
                public PriceRangeFilter(int min, int max)
                {
                        this.min = min;
                        this.max = max;
                }
                public bool Match(Goods goods)
                {
                        return (goods.Price >= min && goods.Price <= max);
                }
        }

        public class CategoryFilter : Filter
        {
                CATAGORY category;
                public CategoryFilter(CATAGORY category)
                {
                        this.category = category;
                }
                public bool Match(Goods goods)
                {
                        return (goods.Category == category);
                }
        }

        public class CompositeFilter : Filter
        {
                protected ArrayList filters = new ArrayList();
                public void AddFilters( params Filter[] filters)
                {
                        this.filters.AddRange(filters);
                }
                public void AddFilter(Filter filter)
                {
                        this.filters.Add(filter);
                }
                public bool Match(Goods goods)
                {
                        return false;
                }
        }

        public class AddFilter : CompositeFilter
        {
                public bool Match(Goods goods)
                {
                        foreach (Filter filter in filters)
                        {
                                if (!filter.Match(goods))
                                        return false;
                        }
                        return true;
                }
        }

        public class OrFilter : CompositeFilter
        {
                public bool Match(Goods goods)
                {
                        foreach(Filter filter in filters)
                        {
                                if(filter.Match(goods))
                                        return true;
                        }
                        return false;
                }
        }
}