using System;
using System.IO;
using System.Linq;
using Db4objects.Db4o;
using Db4objects.Db4o.Linq;

namespace Db4OSeries
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            File.Delete("database.db4o");
            using (var db = StartDataBase())
            {
                StoreMates(db);
            }
            using (var db = StartDataBase())
            {
                var person = LoadMius(db);
                try
                {
                    WithoutActivation(person);
                }
                catch (NullReferenceException e)
                {
                    Console.Out.WriteLine("Exception thrown because we accessed a unactivated object");
                }
                WithoutActivation(person, db);
                Console.Out.WriteLine("Press any key to end");

                LostUpdate(person, db);
            }
            using (var db = StartDataBase())
            {
                var person = LoadMius(db);
                LostUpdate(person, db);
            }
            using (var db = StartDataBase())
            {
                var person = LoadMius(db);
                Console.Out.WriteLine(person.SirName);
                Console.Out.WriteLine(person.Boss.SirName);
            }
            Console.ReadKey();
        }

        private static Person LoadMius(IEmbeddedObjectContainer db)
        {
            return (from Person p in db
                    where p.FirstName.Equals("Mius")
                    select p).Single();
        }

        private static void LostUpdate(Person person, IObjectContainer db)
        {
            person.SirName = "Cool-NewName";
            person.Boss.SirName = "Cool-NewBoss";

            // doesn't work, because in doesn't traverse over the boss-reference
            db.Store(person);

            // instead use
            // db.Ext().Store(person, 2);
            // or store explicit the boss aswell 
            // db.Store(person.Boss);
        }

        private static void WithoutActivation(Person person)
        {
            while (null != person)
            {
                // on the last person 'Julius Caesar' properties are null, hence this will fail 
                Console.Out.WriteLine(
                    string.Format("Persons initials {0}.{1}.", person.FirstName[0], person.SirName[0]));
                person = person.Boss;
            }
        }

        private static void WithoutActivation(Person person, IObjectContainer db)
        {
            while (null != person)
            {
                db.Activate(person, 1);
                Console.Out.WriteLine(
                    string.Format("Persons initials {0}.{1}.", person.FirstName[0], person.SirName[0]));
                person = person.Boss;
            }
        }

        private static IEmbeddedObjectContainer StartDataBase()
        {
            return Db4oEmbedded.OpenFile(Db4oEmbedded.NewConfiguration(), "database.db4o");
        }

        private static void StoreMates(IObjectContainer container)
        {
            var ceo = new Person("Julius", "Caesar");
            var firstGeneral = new Person("NoIdea", "WhoCareus", ceo);
            var secondGeneral = new Person("Master", "Chiefius", firstGeneral);
            var captain = new Person("Biggest", "Halo-Geekius", secondGeneral);
            var officer = new Person("Plus", "Nixus", captain);
            var normalPerson = new Person("Mius", "Dius", officer);
            container.Store(normalPerson);
        }
    }
}