using BusinessLogic.Authentication.Identity;
using DataAccess.Persistence;
using Microsoft.AspNet.Identity.EntityFramework;
using System;
using System.Data.Entity.Core.Mapping;
using System.Data.Entity.Core.Metadata.Edm;
using System.Data.Entity.Infrastructure;
using System.Linq;

namespace DataAccess.Extensions
{
    public static class IncomeDbContextExtensions
    {
        public static TableMetadata TableMetadataForEntityType(this IdentityDbContext<PaymentsUser> context, Type type)
        {
            var metadata = ((IObjectContextAdapter)context).ObjectContext.MetadataWorkspace;

            // Get the part of the model that contains info about the actual CLR types
            var items = (ObjectItemCollection)metadata.GetItemCollection(DataSpace.OSpace);

            // Get the entity type from the model that maps to the CLR type
            var entityType = metadata
                .GetItems<EntityType>(DataSpace.OSpace)
                .Single(p => items.GetClrType(p) == type);

            // Get the entity set that uses this entity type
            var entitySet = metadata
                .GetItems<EntityContainer>(DataSpace.CSpace)
                .Single()
                .EntitySets
                .Single(p => p.ElementType.Name == entityType.Name);

            // Find the mapping between conceptual and storage model for this entity set
            var mapping = metadata.GetItems<EntityContainerMapping>(DataSpace.CSSpace)
                .Single()
                .EntitySetMappings
                .Single(p => p.EntitySet == entitySet);

            // Find the storage entity set (table) that the entity is mapped
            var table = mapping
                .EntityTypeMappings.Single()
                .Fragments.Single()
                .StoreEntitySet;

            return new TableMetadata
            {
                Schema = (string)table.MetadataProperties["Schema"].Value ?? table.Schema,
                Name = (string)table.MetadataProperties["Table"].Value ?? table.Name,
                Keys = entityType.KeyProperties.Select(p => p.Name),
                NonKeyFields = entityType.DeclaredProperties.Select(p => p.Name).Except(entityType.KeyProperties.Select(p => p.Name))
            };
        }
    }
}