using Microsoft.EntityFrameworkCore;

using SharpRepository.Repository;

using SharpRepository.Repository.Caching;

using SharpRepository.Repository.FetchStrategies;

using System;

using System.ComponentModel.DataAnnotations;

using System.Linq;

using System.Reflection;

namespace SharpRepository.EfCoreRepository

{

public class EfCoreRepositoryBase<T, TKey> : LinqRepositoryBase<T, TKey> where T : class

{

protected DbSet<T> DbSet { get; private set; }

protected DbContext Context { get; private set; }

internal EfCoreRepositoryBase(DbContext dbContext, ICachingStrategy<T, TKey> cachingStrategy = null) : base(cachingStrategy)

{

if (dbContext == null) throw new ArgumentNullException("dbContext");

Initialize(dbContext);

}

private void Initialize(DbContext dbContext)

{

Context = dbContext;

DbSet = Context.Set<T>();

}

protected override void AddItem(T entity)

{

if (typeof(TKey) == typeof(Guid) || typeof(TKey) == typeof(string))

{

TKey id;

if (GetPrimaryKey(entity, out id) && Equals(id, default(TKey)))

{

id = GeneratePrimaryKey();

SetPrimaryKey(entity, id);

}

}

DbSet.Add(entity);

}

protected override void DeleteItem(T entity)

{

DbSet.Attach(entity);

DbSet.Remove(entity);

}

protected override void UpdateItem(T entity)

{

var entry = Context.Entry<T>(entity);

try

{

if (entry.State == EntityState.Detached)

{

TKey key;

if (GetPrimaryKey(entity, out key))

{

// check to see if this item is already attached

// if it is then we need to copy the values to the attached value instead of changing the State to modified since it will throw a duplicate key exception

// specifically: "An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key."

var attachedEntity = Context.Set<T>().Find(key);

if (attachedEntity != null)

{

Context.Entry(attachedEntity).CurrentValues.SetValues(entity);

return;

}

}

}

}

catch (Exception)

{

// ignore and try the default behavior

}

// default

entry.State = EntityState.Modified;

}

protected override void SaveChanges()

{

Context.SaveChanges();

}

protected override IQueryable<T> BaseQuery(IFetchStrategy<T> fetchStrategy = null)

{

var query = DbSet.AsQueryable();

return fetchStrategy == null ? query : fetchStrategy.IncludePaths.Aggregate(query, (current, path) => current.Include(path));

}

// we override the implementation fro LinqBaseRepository becausee this is built in and doesn't need to find the key column and do dynamic expressions, etc.

// this also provides the EF5 first level caching out of the box

protected override T GetQuery(TKey key, IFetchStrategy<T> fetchStrategy)

{

return fetchStrategy == null ? DbSet.Find(key) : base.GetQuery(key, fetchStrategy);

}

protected override PropertyInfo GetPrimaryKeyPropertyInfo()

{

// checks for the Code First KeyAttribute and if not there do the normal checks

var type = typeof(T);

var keyType = typeof(TKey);

return type.GetProperties().FirstOrDefault(x => x.GetCustomAttributes(typeof(KeyAttribute)).Any() && x.PropertyType == keyType)

?? base.GetPrimaryKeyPropertyInfo();

}

public override void Dispose()

{

Dispose(true);

GC.SuppressFinalize(this);

}

protected virtual void Dispose(bool disposing)

{

if (!disposing) return;

if (Context == null) return;

Context.Dispose();

Context = null;

}

protected virtual TKey GeneratePrimaryKey()

{

if (typeof(TKey) == typeof(Guid))

{

return (TKey)Convert.ChangeType(Guid.NewGuid(), typeof(TKey));

}

if (typeof(TKey) == typeof(string))

{

return (TKey)Convert.ChangeType(Guid.NewGuid().ToString(), typeof(TKey));

}

throw new InvalidOperationException("Primary key could not be generated. This only works for GUID, Int32 and String.");

}

}

}