using System;
using System.Linq;
using NRules;
using NRules.Diagnostics;
using NRules.Fluent;
using NRules.Fluent.Dsl;

namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            var ruleRepository = new RuleRepository();
            ruleRepository.Load(spec => spec.From(
                typeof(TestRule),
                typeof(TestRule2),
                typeof(TestRule3)));

            var sessionFactory = ruleRepository.Compile();

            var session = sessionFactory.CreateSession();
            session.AttachLogs();

            session.Insert(new SalesOrder
            {
                TotalPrice = 100,
                ChargeShipping = true
            });

            session.Fire();

            var salesOrder = session.Query<SalesOrder>().First();
            Console.WriteLine("Shipping={0}", salesOrder.ChargeShipping);
            Console.WriteLine("TotalPrice={0}", salesOrder.TotalPrice);
        }
    }

    public class SalesOrder
    {
        public decimal TotalPrice { get; set; }
        public bool ChargeShipping { get; set; }

        public SalesOrder()
        {
            ChargeShipping = true;
        }

        public void FreeShipping()
        {
            ChargeShipping = false;
        }

        public void ApplyDiscount()
        {
            TotalPrice = TotalPrice * 0.9m;
        }

        public void ApplyShipping()
        {
            ChargeShipping = true;
        }

        public override string ToString()
        {
            return string.Format("SalesOrder[P={0},S={1}]", TotalPrice, ChargeShipping);
        }
    }

    [Name("FreeShipping")]
    public class TestRule : Rule
    {
        public override void Define()
        {
            SalesOrder salesOrder = null;

            When()
                .Match(() => salesOrder, so => so.TotalPrice >= 100, so => so.ChargeShipping);

            Then()
                .Do(cxt => salesOrder.FreeShipping())
                .Do(cxt => cxt.Update(salesOrder));
        }
    }

    [Name("ApplyShipping")]
    public class TestRule3 : Rule
    {
        public override void Define()
        {
            SalesOrder salesOrder = null;

            When()
                .Match(() => salesOrder, so => so.TotalPrice < 100, so => !so.ChargeShipping);

            Then()
                .Do(cxt => salesOrder.ApplyShipping())
                .Do(cxt => cxt.Update(salesOrder));
        }
    }

    [Name("ApplyDiscount")]
    public class TestRule2 : Rule
    {
        public override void Define()
        {
            SalesOrder salesOrder = null;

            When()
                .Match(() => salesOrder, so => so.TotalPrice >= 50);

            Then()
                .Do(cxt => salesOrder.ApplyDiscount())
                .Do(cxt => cxt.Update(salesOrder));
        }
    }

    public static class RuleLog
    {
        public static void AttachLogs(this ISession session)
        {
            session.Events.FactInsertingEvent += FactInserting;
            session.Events.FactUpdatingEvent += FactUpdating;
            session.Events.ActivationCreatedEvent += ActivationCreated;
            session.Events.ActivationDeletedEvent += ActivationDeleted;
            session.Events.RuleFiringEvent += RuleFiring;
            session.Events.RuleFiredEvent += RuleFired;
        }

        private static void FactInserting(object sender, WorkingMemoryEventArgs e)
        {
            Console.WriteLine("Inserting {0}", e.Fact.Value);
        }

        private static void FactUpdating(object sender, WorkingMemoryEventArgs e)
        {
            Console.WriteLine("Updating {0}", e.Fact.Value);
        }

        static void ActivationCreated(object sender, AgendaEventArgs e)
        {
            Console.WriteLine("Activated {0} {1}", e.Rule.Name, string.Join(",", e.Facts.Select(f => f.Value)));
        }

        static void ActivationDeleted(object sender, AgendaEventArgs e)
        {
            Console.WriteLine("Deactivated {0} {1}", e.Rule.Name, string.Join(",", e.Facts.Select(f => f.Value)));
        }

        private static void RuleFiring(object sender, AgendaEventArgs e)
        {
            Console.WriteLine("Firing {0} {1}", e.Rule.Name, string.Join(",", e.Facts.Select(f => f.Value)));
        }

        private static void RuleFired(object sender, AgendaEventArgs e)
        {
            Console.WriteLine("Fired {0} {1}", e.Rule.Name, string.Join(",", e.Facts.Select(f => f.Value)));
        }
    }
}

//Output:
/*
Inserting SalesOrder[P=100,S=True]
Activated FreeShipping SalesOrder[P=100,S=True]
Activated ApplyDiscount SalesOrder[P=100,S=True]
Firing FreeShipping SalesOrder[P=100,S=True]
Updating SalesOrder[P=100,S=False]
Deactivated FreeShipping SalesOrder[P=100,S=False]
Activated ApplyDiscount SalesOrder[P=100,S=False]
Fired FreeShipping SalesOrder[P=100,S=False]
Firing ApplyDiscount SalesOrder[P=100,S=False]
Updating SalesOrder[P=90.0,S=False]
Activated ApplyDiscount SalesOrder[P=90.0,S=False]
Activated ApplyShipping SalesOrder[P=90.0,S=False]
Fired ApplyDiscount SalesOrder[P=90.0,S=False]
Firing ApplyDiscount SalesOrder[P=90.0,S=False]
Updating SalesOrder[P=81.00,S=False]
Activated ApplyDiscount SalesOrder[P=81.00,S=False]
Activated ApplyShipping SalesOrder[P=81.00,S=False]
Fired ApplyDiscount SalesOrder[P=81.00,S=False]
Firing ApplyShipping SalesOrder[P=81.00,S=False]
Updating SalesOrder[P=81.00,S=True]
Activated ApplyDiscount SalesOrder[P=81.00,S=True]
Deactivated ApplyShipping SalesOrder[P=81.00,S=True]
Fired ApplyShipping SalesOrder[P=81.00,S=True]
Firing ApplyDiscount SalesOrder[P=81.00,S=True]
Updating SalesOrder[P=72.900,S=True]
Activated ApplyDiscount SalesOrder[P=72.900,S=True]
Fired ApplyDiscount SalesOrder[P=72.900,S=True]
Firing ApplyDiscount SalesOrder[P=72.900,S=True]
Updating SalesOrder[P=65.6100,S=True]
Activated ApplyDiscount SalesOrder[P=65.6100,S=True]
Fired ApplyDiscount SalesOrder[P=65.6100,S=True]
Firing ApplyDiscount SalesOrder[P=65.6100,S=True]
Updating SalesOrder[P=59.04900,S=True]
Activated ApplyDiscount SalesOrder[P=59.04900,S=True]
Fired ApplyDiscount SalesOrder[P=59.04900,S=True]
Firing ApplyDiscount SalesOrder[P=59.04900,S=True]
Updating SalesOrder[P=53.144100,S=True]
Activated ApplyDiscount SalesOrder[P=53.144100,S=True]
Fired ApplyDiscount SalesOrder[P=53.144100,S=True]
Firing ApplyDiscount SalesOrder[P=53.144100,S=True]
Updating SalesOrder[P=47.8296900,S=True]
Deactivated ApplyDiscount SalesOrder[P=47.8296900,S=True]
Fired ApplyDiscount SalesOrder[P=47.8296900,S=True]
Shipping=True
TotalPrice=47.8296900
*/