using System.Linq;

using System;

using Raven.Client.Documents;

using Raven.Client.Documents.Operations;

using Raven.Client.Documents.Queries;

using System.Threading.Tasks;

using System.Collections.Generic;

​

namespace TestProgram

{   

    public class Program

    {

        private const string TestDBName = "Hogwarts";       

        private static DocumentStore Store  { get; set; }

​

        public static async Task Main()

        {

            Store = new DocumentStore {

                Database = TestDBName, 

                Urls = new[]{"http://live-test.ravendb.net"}

            };

            Store.Initialize();

            // Clean up previous test data.

            await Truncate("Contacts");

            // Create some mock data to play with.

            var contacts = await MockData();

            await ExampleThatWorks(contacts.Item1.Id);

            await ExampleThatDoesntWork(contacts.Item2.Id);

            // Cleanup

            Store.Dispose();

        }       

        private static async Task ExampleThatWorks(string contactId) 

        {           

            var attachments = new List<Attachment> 

            {

                new Attachment{ Id = Guid.NewGuid().ToString(), Name = "First.txt" },

                new Attachment{ Id = Guid.NewGuid().ToString(), Name = "Second.txt" }

            };

            foreach(var attachment in attachments)

            {

                await AddAttachment(contactId, attachment);

            }       

        }

        private static async Task ExampleThatDoesntWork(string contactId) 

        {           

            var attachments = new List<Attachment> 

            {

                new Attachment{ Id = Guid.NewGuid().ToString(), Name = "First.txt" },

                new Attachment{ Id = Guid.NewGuid().ToString(), Name = "Second.txt" }

            };

            var tasks = attachments.Select(x => AddAttachment(contactId, x)).ToList();  

            await Task.WhenAll(tasks);

        }

        private static async Task AddAttachment(string contactId, Attachment attachment) 

        {

            using (var session = Store.OpenAsyncSession())              

            {

                var contact = await session.LoadAsync<Contact>(contactId);              

                contact.Attachments.Add(attachment);

                await session.StoreAsync(contact);

                await session.SaveChangesAsync();

            }   

        }           

        private static async Task Truncate(string collectionName)

        {

            var queryToDelete = new IndexQuery {Query = $"FROM {collectionName}",};

            var operation = await Store.Operations.ForDatabase(TestDBName).SendAsync(

                new DeleteByQueryOperation(

                    queryToDelete, 

                    new QueryOperationOptions {

                        AllowStale = false

                    }

                )

            );

            await operation.WaitForCompletionAsync(TimeSpan.FromSeconds(60));

        }

        private static async Task<Tuple<Contact,Contact>> MockData()

        {

            using (var session = Store.OpenAsyncSession())

            {

                var harry = new Contact 

                {                   

                    Id = Guid.NewGuid().ToString(),

                    Workspace = "hogwarts",

                    DisplayName = "Harry Potter"

                };              

                var hermione = new Contact 

                {

                    Id = Guid.NewGuid().ToString(),

                    Workspace = "hogwarts",

                    DisplayName = "Hermione Granger"

                };

                await session.StoreAsync(harry);

                await session.StoreAsync(hermione);                 

                await session.SaveChangesAsync();

                return new Tuple<Contact, Contact>(harry, hermione);

            }   

        }

    }

    public class Contact

    {

        public string Id { get; set; }

        public string Workspace { get; set; }

        public string DisplayName { get; set; }

        public List<Attachment> Attachments { get; set; } = new List<Attachment>();

    }

    public class Attachment

    {

        public string Id { get; set; }

        public string Name { get; set; }        

    }

}