using DynamicExpression = System.Linq.Dynamic.DynamicExpression;

namespace DynamicExpr
{
    public class Test
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public decimal Price { get; set; }
       
    }
    class Program
    {
        static readonly List<Test> List = new List<Test> { new Test { Id = 1, Name = "aa", Price = 23 },
            new Test { Id = 2, Name = "bb", Price = 200 }, new Test { Id = 3, Name = "cc", Price = 200 } }; 
        static readonly Dictionary<string,object> WhereDictionary=new Dictionary<string, object>(); 
        private static object Func;

        static void Main(string[] args)
        {
           // WhereDictionary.Add("Id", 2);
           // WhereDictionary.Add("Name", "bb");
            WhereDictionary.Add("Price", 200);
            
            var acc = WhereDictionary.Aggregate<KeyValuePair<string, object>, Expression<Func<Test, bool>>>(null, 
                (current, o) => current.And(ExpressionCore<Test>(o.Key, o.Value)));
            Console.Write(List.Where(acc.Compile()).Count());
            Console.Read();

        }

        public static Expression<Func<T, bool>> ExpressionCore<T>(string namePropery, params object[] valuObjects)
        {
            return DynamicExpression.ParseLambda<T,bool>(namePropery+"= @0", valuObjects);
        }

       
    }

    public static class Helper
    {
         public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> a, Expression<Func<T, bool>> b)
        {
            if (b != null && a == null)
                return b;
            if (b == null&&a!=null)
               throw new Exception("asshole");
            var p = a.Parameters[0];
            var visitor = new SubstExpressionVisitor();
            visitor.Subst[b.Parameters[0]] = p;
            Expression body = Expression.AndAlso(a.Body, visitor.Visit(b.Body));
            return Expression.Lambda<Func<T, bool>>(body, p);
        }
    }

    internal class SubstExpressionVisitor : ExpressionVisitor
    {
        public Dictionary<Expression, Expression> Subst = new Dictionary<Expression, Expression>();
        protected override Expression VisitParameter(ParameterExpression node)
        {
            Expression newValue;
            return Subst.TryGetValue(node, out newValue) ? newValue : node;
        }
    }

       public static Expression<Func<T, bool>> ExpressionCoreOrderBy<T>(params object[] propertyName)
        {
            return DynamicExpression.ParseLambda<T, bool>("@0", propertyName);
        }

//сумматор

       public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> a, Expression<Func<T, bool>> b)
        {
            if (b != null && a == null)
                return b;

            var p = a.Parameters[0];
            var visitor = new SubstExpressionVisitor();
            visitor.Subst[b.Parameters[0]] = p;
            Expression body = Expression.OrElse(a.Body, visitor.Visit(b.Body));
            return Expression.Lambda<Func<T, bool>>(body, p);
        }