/mcs/tools/sqlmetal/src/DbLinq/Data/Linq/DataContext.cs

#region MIT license

// 

// MIT license

//

// Copyright (c) 2007-2008 Jiri Moudry, Pascal Craponne

// 

// Permission is hereby granted, free of charge, to any person obtaining a copy

// of this software and associated documentation files (the "Software"), to deal

// in the Software without restriction, including without limitation the rights

// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the Software is

// furnished to do so, subject to the following conditions:

// 

// The above copyright notice and this permission notice shall be included in

// all copies or substantial portions of the Software.

// 

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

// THE SOFTWARE.

// 

#endregion



using System;

using System.Collections;

using System.Data;

using System.Data.Common;

using System.Data.Linq;

using System.Data.Linq.Mapping;

using System.Linq.Expressions;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Reflection;

using System.Reflection.Emit;



#if MONO_STRICT

using AttributeMappingSource  = System.Data.Linq.Mapping.AttributeMappingSource;

#else

using AttributeMappingSource  = DbLinq.Data.Linq.Mapping.AttributeMappingSource;

#endif



using DbLinq;

using DbLinq.Data.Linq;

using DbLinq.Data.Linq.Database;

using DbLinq.Data.Linq.Database.Implementation;

using DbLinq.Data.Linq.Identity;

using DbLinq.Data.Linq.Implementation;

using DbLinq.Data.Linq.Mapping;

using DbLinq.Data.Linq.Sugar;

using DbLinq.Factory;

using DbLinq.Util;

using DbLinq.Vendor;



#if MONO_STRICT

namespace System.Data.Linq

#else

namespace DbLinq.Data.Linq

#endif

{

    public partial class DataContext : IDisposable

    {

        //private readonly Dictionary<string, ITable> _tableMap = new Dictionary<string, ITable>();

        private readonly Dictionary<Type, ITable> _tableMap = new Dictionary<Type, ITable>();



        public MetaModel Mapping { get; private set; }

        // PC question: at ctor, we get a IDbConnection and the Connection property exposes a DbConnection

        //              WTF?

        public DbConnection Connection { get { return DatabaseContext.Connection as DbConnection; } }



        // all properties below are set public to optionally be injected

        internal IVendor Vendor { get; set; }

        internal IQueryBuilder QueryBuilder { get; set; }

        internal IQueryRunner QueryRunner { get; set; }

        internal IMemberModificationHandler MemberModificationHandler { get; set; }

        internal IDatabaseContext DatabaseContext { get; private set; }

        // /all properties...



        private bool objectTrackingEnabled = true;

        private bool deferredLoadingEnabled = true;



        private bool queryCacheEnabled = false;



        /// <summary>

        /// Disable the QueryCache: this is surely good for rarely used Select, since preparing

        /// the SelectQuery to be cached could require more time than build the sql from scratch.

        /// </summary>

        [DBLinqExtended]

        public bool QueryCacheEnabled 

        {

            get { return queryCacheEnabled; }

            set { queryCacheEnabled = value; }

        }



        private IEntityTracker currentTransactionEntities;

        private IEntityTracker CurrentTransactionEntities

        {

            get

            {

                if (this.currentTransactionEntities == null)

                {

                    if (this.ObjectTrackingEnabled)

                        this.currentTransactionEntities = new EntityTracker();

                    else

                        this.currentTransactionEntities = new DisabledEntityTracker();

                }

                return this.currentTransactionEntities;

            }

        }



        private IEntityTracker allTrackedEntities;

        private IEntityTracker AllTrackedEntities

        {

            get

            {

                if (this.allTrackedEntities == null)

                {

                    allTrackedEntities = ObjectTrackingEnabled

                        ? (IEntityTracker) new EntityTracker()

                        : (IEntityTracker) new DisabledEntityTracker();

                }

                return this.allTrackedEntities;

            }

        }



        private IIdentityReaderFactory identityReaderFactory;

        private readonly IDictionary<Type, IIdentityReader> identityReaders = new Dictionary<Type, IIdentityReader>();



        /// <summary>

        /// The default behavior creates one MappingContext.

        /// </summary>

        [DBLinqExtended]

        internal virtual MappingContext _MappingContext { get; set; }



        [DBLinqExtended]

        internal IVendorProvider _VendorProvider { get; set; }



        public DataContext(IDbConnection connection, MappingSource mapping)

        {

            Profiler.At("START DataContext(IDbConnection, MappingSource)");

            Init(new DatabaseContext(connection), mapping, null);

            Profiler.At("END DataContext(IDbConnection, MappingSource)");

        }



        public DataContext(IDbConnection connection)

        {

            Profiler.At("START DataContext(IDbConnection)");

            if (connection == null)

                throw new ArgumentNullException("connection");



            Init(new DatabaseContext(connection), null, null);

            Profiler.At("END DataContext(IDbConnection)");

        }



        [DbLinqToDo]

        public DataContext(string fileOrServerOrConnection, MappingSource mapping)

        {

            Profiler.At("START DataContext(string, MappingSource)");

            if (fileOrServerOrConnection == null)

                throw new ArgumentNullException("fileOrServerOrConnection");

            if (mapping == null)

                throw new ArgumentNullException("mapping");



            if (File.Exists(fileOrServerOrConnection))

                throw new NotImplementedException("File names not supported.");



            // Is this a decent server name check?

            // It assumes that the connection string will have at least 2

            // parameters (separated by ';')

            if (!fileOrServerOrConnection.Contains(";"))

                throw new NotImplementedException("Server name not supported.");



            // Assume it's a connection string...

            IVendor ivendor = GetVendor(ref fileOrServerOrConnection);



            IDbConnection dbConnection = ivendor.CreateDbConnection(fileOrServerOrConnection);

            Init(new DatabaseContext(dbConnection), mapping, ivendor);

            Profiler.At("END DataContext(string, MappingSource)");

        }



        /// <summary>

        /// Construct DataContext, given a connectionString.

        /// To determine which DB type to go against, we look for 'DbLinqProvider=xxx' substring.

        /// If not found, we assume that we are dealing with MS Sql Server.

        /// 

        /// Valid values are names of provider DLLs (or any other DLL containing an IVendor implementation)

        /// DbLinqProvider=Mysql

        /// DbLinqProvider=Oracle etc.

        /// </summary>

        /// <param name="connectionString">specifies file or server connection</param>

        [DbLinqToDo]

        public DataContext(string fileOrServerOrConnection)

        {

            Profiler.At("START DataContext(string)");

            IVendor ivendor = GetVendor(ref fileOrServerOrConnection);



            IDbConnection dbConnection = ivendor.CreateDbConnection(fileOrServerOrConnection);

            Init(new DatabaseContext(dbConnection), null, ivendor);



            Profiler.At("END DataContext(string)");

        }



        private IVendor GetVendor(ref string connectionString)

        {

            if (connectionString == null)

                throw new ArgumentNullException("connectionString");



            Assembly assy;

            string vendorClassToLoad;

            GetVendorInfo(ref connectionString, out assy, out vendorClassToLoad);



            var types =

                from type in assy.GetTypes()

                where type.Name.ToLowerInvariant() == vendorClassToLoad.ToLowerInvariant() &&

                    type.GetInterfaces().Contains(typeof(IVendor)) &&

                    type.GetConstructor(Type.EmptyTypes) != null

                select type;

            if (!types.Any())

            {

                throw new ArgumentException(string.Format("Found no IVendor class in assembly `{0}' named `{1}' having a default constructor.",

                    assy.GetName().Name, vendorClassToLoad));

            }

            else if (types.Count() > 1)

            {

                throw new ArgumentException(string.Format("Found too many IVendor classes in assembly `{0}' named `{1}' having a default constructor.",

                    assy.GetName().Name, vendorClassToLoad));

            }

            return (IVendor) Activator.CreateInstance(types.First());

        }



        private void GetVendorInfo(ref string connectionString, out Assembly assembly, out string typeName)

        {

            System.Text.RegularExpressions.Regex reProvider

                = new System.Text.RegularExpressions.Regex(@"DbLinqProvider=([\w\.]+);?");



            string assemblyName = null;

            string vendor;

            if (!reProvider.IsMatch(connectionString))

            {

                vendor       = "SqlServer";

                assemblyName = "DbLinq.SqlServer";

            }

            else

            {

                var match    = reProvider.Match(connectionString);

                vendor       = match.Groups[1].Value;

                assemblyName = "DbLinq." + vendor;



                //plain DbLinq - non MONO: 

                //IVendor classes are in DLLs such as "DbLinq.MySql.dll"

                if (vendor.Contains("."))

                {

                    //already fully qualified DLL name?

                    throw new ArgumentException("Please provide a short name, such as 'MySql', not '" + vendor + "'");

                }



                //shorten: "DbLinqProvider=X;Server=Y" -> ";Server=Y"

                connectionString = reProvider.Replace(connectionString, "");

            }



            typeName = vendor + "Vendor";



            try

            {

#if MONO_STRICT

                assembly = typeof (DataContext).Assembly; // System.Data.Linq.dll

#else

                assembly = Assembly.Load(assemblyName);

#endif

            }

            catch (Exception e)

            {

                throw new ArgumentException(

                        string.Format(

                            "Unable to load the `{0}' DbLinq vendor within assembly '{1}.dll'.",

                            assemblyName, vendor),

                        "connectionString", e);

            }

        }



        private void Init(IDatabaseContext databaseContext, MappingSource mappingSource, IVendor vendor)

        {

            if (databaseContext == null)

                throw new ArgumentNullException("databaseContext");



            // Yes, .NET throws an NRE for this.  Why it's not ArgumentNullException, I couldn't tell you.

            if (databaseContext.Connection.ConnectionString == null)

                throw new NullReferenceException();



            string connectionString = databaseContext.Connection.ConnectionString;

            _VendorProvider = ObjectFactory.Get<IVendorProvider>();

            Vendor = vendor ?? 

                (connectionString != null ? GetVendor(ref connectionString) : null) ??

#if MOBILE

                _VendorProvider.FindVendorByProviderType(typeof(DbLinq.Sqlite.SqliteSqlProvider));

#else

                _VendorProvider.FindVendorByProviderType(typeof(SqlClient.Sql2005Provider));

#endif

            

            DatabaseContext = databaseContext;



            MemberModificationHandler = ObjectFactory.Create<IMemberModificationHandler>(); // not a singleton: object is stateful

            QueryBuilder = ObjectFactory.Get<IQueryBuilder>();

            QueryRunner = ObjectFactory.Get<IQueryRunner>();



            //EntityMap = ObjectFactory.Create<IEntityMap>();

            identityReaderFactory = ObjectFactory.Get<IIdentityReaderFactory>();



            _MappingContext = new MappingContext();



            // initialize the mapping information

            if (mappingSource == null)

                mappingSource = new AttributeMappingSource();

            Mapping = mappingSource.GetModel(GetType());

        }



        /// <summary>

        /// Checks if the table is allready mapped or maps it if not.

        /// </summary>

        /// <param name="tableType">Type of the table.</param>

        /// <exception cref="InvalidOperationException">Thrown if the table is not mappable.</exception>

        private void CheckTableMapping(Type tableType)

        {

            //This will throw an exception if the table is not found

            if(Mapping.GetTable(tableType) == null)

            {

                throw new InvalidOperationException("The type '" + tableType.Name + "' is not mapped as a Table.");

            }

        }



        /// <summary>

        /// Returns a Table for the type TEntity.

        /// </summary>

        /// <exception cref="InvalidOperationException">If the type TEntity is not mappable as a Table.</exception>

        /// <typeparam name="TEntity">The table type.</typeparam>

        public Table<TEntity> GetTable<TEntity>() where TEntity : class

        {

            return (Table<TEntity>)GetTable(typeof(TEntity));

        }



        /// <summary>

        /// Returns a Table for the given type.

        /// </summary>

        /// <param name="type">The table type.</param>

        /// <exception cref="InvalidOperationException">If the type is not mappable as a Table.</exception>

        public ITable GetTable(Type type)

        {

            Profiler.At("DataContext.GetTable(typeof({0}))", type != null ? type.Name : null);

            ITable tableExisting;

            if (_tableMap.TryGetValue(type, out tableExisting))

                return tableExisting;



            //Check for table mapping

            CheckTableMapping(type);



            var tableNew = Activator.CreateInstance(

                              typeof(Table<>).MakeGenericType(type)

                              , BindingFlags.NonPublic | BindingFlags.Instance

                              , null

                              , new object[] { this }

                              , System.Globalization.CultureInfo.CurrentCulture) as ITable;



            _tableMap[type] = tableNew;

            return tableNew;

        }



        public void SubmitChanges()

        {

            SubmitChanges(ConflictMode.FailOnFirstConflict);

        }



        /// <summary>

        /// Pings database

        /// </summary>

        /// <returns></returns>

        public bool DatabaseExists()

        {

            try

            {

                return Vendor.Ping(this);

            }

            catch (Exception)

            {

                return false;

            }

        }



        /// <summary>

        /// Commits all pending changes to database 

        /// </summary>

        /// <param name="failureMode"></param>

        public virtual void SubmitChanges(ConflictMode failureMode)

        {

            if (this.objectTrackingEnabled == false)

                throw new InvalidOperationException("Object tracking is not enabled for the current data context instance.");

            using (DatabaseContext.OpenConnection()) //ConnMgr will close connection for us

            {

                if (Transaction != null)

                    SubmitChangesImpl(failureMode);

                else

                {

                    using (IDbTransaction transaction = DatabaseContext.CreateTransaction())

                    {

                        try

                        {

                            Transaction = (DbTransaction) transaction;

                            SubmitChangesImpl(failureMode);

                            // TODO: handle conflicts (which can only occur when concurrency mode is implemented)

                            transaction.Commit();

                        }

                        finally

                        {

                            Transaction = null;

                        }

                    }

                }

            }

        }



        void SubmitChangesImpl(ConflictMode failureMode)

        {

            var queryContext = new QueryContext(this);



            // There's no sense in updating an entity when it's going to 

            // be deleted in the current transaction, so do deletes first.

            foreach (var entityTrack in CurrentTransactionEntities.EnumerateAll().ToList())

            {

                switch (entityTrack.EntityState)

                {

                    case EntityState.ToDelete:

                        var deleteQuery = QueryBuilder.GetDeleteQuery(entityTrack.Entity, queryContext);

                        QueryRunner.Delete(entityTrack.Entity, deleteQuery);



                        UnregisterDelete(entityTrack.Entity);

                        AllTrackedEntities.RegisterToDelete(entityTrack.Entity);

                        AllTrackedEntities.RegisterDeleted(entityTrack.Entity);

                        break;

                    default:

                        // ignore.

                        break;

                }

            }

            foreach (var entityTrack in CurrentTransactionEntities.EnumerateAll()

                    .Concat(AllTrackedEntities.EnumerateAll())

                    .ToList())

            {

                switch (entityTrack.EntityState)

                {

                    case EntityState.ToInsert:

                        foreach (var toInsert in GetReferencedObjects(entityTrack.Entity))

                        {

                            InsertEntity(toInsert, queryContext);

                        }

                        break;

                    case EntityState.ToWatch:

                        foreach (var toUpdate in GetReferencedObjects(entityTrack.Entity))

                        {

                            UpdateEntity(toUpdate, queryContext);

                        }

                        break;

                    default:

                        throw new ArgumentOutOfRangeException();

                }

            }

        }



        private IEnumerable<object> GetReferencedObjects(object value)

        {

            var values = new EntitySet<object>();

            FillReferencedObjects(value, values);

            return values;

        }



        // Breadth-first traversal of an object graph

        private void FillReferencedObjects(object parent, EntitySet<object> values)

        {

            if (parent == null)

                return;

            var children = new Queue<object>();

			children.Enqueue(parent);

			while (children.Count > 0)

			{

                object value = children.Dequeue();

                values.Add(value);

                IEnumerable<MetaAssociation> associationList = Mapping.GetMetaType(value.GetType()).Associations.Where(a => !a.IsForeignKey);

                if (associationList.Any())

			    {

				    foreach (MetaAssociation association in associationList)

                    {

                        var memberData = association.ThisMember;

                        var entitySetValue = memberData.Member.GetMemberValue(value);



                        if (entitySetValue != null)

                        {

						    var hasLoadedOrAssignedValues = entitySetValue.GetType().GetProperty("HasLoadedOrAssignedValues");

						    if (!((bool)hasLoadedOrAssignedValues.GetValue(entitySetValue, null)))

							    continue;   // execution deferred; ignore.

						    foreach (var o in ((IEnumerable)entitySetValue))

							    children.Enqueue(o);

					    }

                    }

                }

			}

        }



        private void InsertEntity(object entity, QueryContext queryContext)

        {

            var insertQuery = QueryBuilder.GetInsertQuery(entity, queryContext);

            QueryRunner.Insert(entity, insertQuery);

            Register(entity);

            UpdateReferencedObjects(entity);

            MoveToAllTrackedEntities(entity, true);

        }



        private void UpdateEntity(object entity, QueryContext queryContext)

        {

            if (!AllTrackedEntities.ContainsReference(entity))

                InsertEntity(entity, queryContext);

            else if (MemberModificationHandler.IsModified(entity, Mapping))

            {

                var modifiedMembers = MemberModificationHandler.GetModifiedProperties(entity, Mapping);

                var updateQuery = QueryBuilder.GetUpdateQuery(entity, modifiedMembers, queryContext);

                QueryRunner.Update(entity, updateQuery, modifiedMembers);



                RegisterUpdateAgain(entity);

                UpdateReferencedObjects(entity);

                MoveToAllTrackedEntities(entity, false);

            }

        }



        private void UpdateReferencedObjects(object root)

        {

            var metaType = Mapping.GetMetaType(root.GetType());

            foreach (var assoc in metaType.Associations)

            {

                var memberData = assoc.ThisMember;

				//This is not correct - AutoSyncing applies to auto-updating columns, such as a TimeStamp, not to foreign key associations, which is always automatically synched

				//Confirmed against default .NET l2sql - association columns are always set, even if AutoSync==AutoSync.Never

				//if (memberData.Association.ThisKey.Any(m => (m.AutoSync != AutoSync.Always) && (m.AutoSync != sync)))

                //    continue;

                var oks = memberData.Association.OtherKey.Select(m => m.StorageMember).ToList();

                if (oks.Count == 0)

                    continue;

                var pks = memberData.Association.ThisKey

                    .Select(m => m.StorageMember.GetMemberValue(root))

                    .ToList();

                if (pks.Count != oks.Count)

                    throw new InvalidOperationException(

                        string.Format("Count of primary keys ({0}) doesn't match count of other keys ({1}).",

                            pks.Count, oks.Count));

                var members = memberData.Member.GetMemberValue(root) as IEnumerable;

                if (members == null)

                    continue;

                foreach (var member in members)

                {

                    for (int i = 0; i < pks.Count; ++i)

                    {

                        oks[i].SetMemberValue(member, pks[i]);

                    }

                }

            }

        }



        private void MoveToAllTrackedEntities(object entity, bool insert)

        {

            if (!ObjectTrackingEnabled)

                return;

            if (CurrentTransactionEntities.ContainsReference(entity))

            {

                CurrentTransactionEntities.RegisterToDelete(entity);

                if (!insert)

                    CurrentTransactionEntities.RegisterDeleted(entity);

            }

            if (!AllTrackedEntities.ContainsReference(entity))

            {

                var identityReader = _GetIdentityReader(entity.GetType());

                AllTrackedEntities.RegisterToWatch(entity, identityReader.GetIdentityKey(entity));

            }

        }



        /// <summary>

        /// TODO - allow generated methods to call into stored procedures

        /// </summary>

        [DBLinqExtended]

        internal IExecuteResult _ExecuteMethodCall(DataContext context, System.Reflection.MethodInfo method, params object[] sqlParams)

        {

            using (DatabaseContext.OpenConnection())

            {

                System.Data.Linq.IExecuteResult result = Vendor.ExecuteMethodCall(context, method, sqlParams);

                return result;

            }

        }



        [DbLinqToDo]

        protected IExecuteResult ExecuteMethodCall(object instance, System.Reflection.MethodInfo methodInfo, params object[] parameters)

        {

            throw new NotImplementedException();

        }



        #region Identity management



        [DBLinqExtended]

        internal IIdentityReader _GetIdentityReader(Type t)

        {

            IIdentityReader identityReader;

            if (!identityReaders.TryGetValue(t, out identityReader))

            {

                identityReader = identityReaderFactory.GetReader(t, this);

                identityReaders[t] = identityReader;

            }

            return identityReader;

        }



        [DBLinqExtended]

        internal object _GetRegisteredEntity(object entity)

        {

            // TODO: check what is faster: by identity or by ref

            var identityReader = _GetIdentityReader(entity.GetType());

            var identityKey = identityReader.GetIdentityKey(entity);

            if (identityKey == null) // if we don't have an entitykey here, it means that the entity has no PK

                return entity;

            // even 

            var registeredEntityTrack = 

                CurrentTransactionEntities.FindByIdentity(identityKey) ??

                AllTrackedEntities.FindByIdentity(identityKey);

            if (registeredEntityTrack != null)

                return registeredEntityTrack.Entity;

            return null;

        }



        //internal object GetRegisteredEntityByKey(IdentityKey identityKey)

        //{

        //    return EntityMap[identityKey];

        //}



        /// <summary>

        /// Registers an entity in a watch state

        /// </summary>

        /// <param name="entity"></param>

        /// <returns></returns>

        [DBLinqExtended]

        internal object _GetOrRegisterEntity(object entity)

        {

            var identityReader = _GetIdentityReader(entity.GetType());

            var identityKey = identityReader.GetIdentityKey(entity);

            SetEntitySetsQueries(entity);

            SetEntityRefQueries(entity);



            // if we have no identity, we can't track it

            if (identityKey == null)

                return entity;



            // try to find an already registered entity and return it

            var registeredEntityTrack = 

                CurrentTransactionEntities.FindByIdentity(identityKey) ??

                AllTrackedEntities.FindByIdentity(identityKey);

            if (registeredEntityTrack != null)

                return registeredEntityTrack.Entity;



            // otherwise, register and return

            AllTrackedEntities.RegisterToWatch(entity, identityKey);

            return entity;

        }



        readonly IDataMapper DataMapper = ObjectFactory.Get<IDataMapper>();

		private void SetEntityRefQueries(object entity)

		{

            if (!this.deferredLoadingEnabled)

                return;



            // BUG: This is ignoring External Mappings from XmlMappingSource.



			Type thisType = entity.GetType();

			IEnumerable<MetaAssociation> associationList = Mapping.GetMetaType(entity.GetType()).Associations.Where(a => a.IsForeignKey);

			foreach (MetaAssociation association in associationList)

			{

				//example of entityRef:Order.Employee

				var memberData = association.ThisMember;

				Type otherTableType = association.OtherType.Type;

				ParameterExpression p = Expression.Parameter(otherTableType, "other");



				var otherTable = GetTable(otherTableType);



				//ie:EmployeeTerritories.EmployeeID

				var foreignKeys = memberData.Association.ThisKey;

				BinaryExpression predicate = null;

				var otherPKs = memberData.Association.OtherKey;

				IEnumerator<MetaDataMember> otherPKEnumerator = otherPKs.GetEnumerator();



				if (otherPKs.Count != foreignKeys.Count)

					throw new InvalidOperationException("Foreign keys don't match ThisKey");

				foreach (MetaDataMember key in foreignKeys)

				{

					otherPKEnumerator.MoveNext();



					var thisForeignKeyProperty = (PropertyInfo)key.Member;

					object thisForeignKeyValue = thisForeignKeyProperty.GetValue(entity, null);



					if (thisForeignKeyValue != null)

					{

						BinaryExpression keyPredicate;

						if (!(thisForeignKeyProperty.PropertyType.IsNullable()))

						{

							keyPredicate = Expression.Equal(Expression.MakeMemberAccess(p, otherPKEnumerator.Current.Member),

																		Expression.Constant(thisForeignKeyValue));

						}

						else

						{

							var ValueProperty = thisForeignKeyProperty.PropertyType.GetProperty("Value");

							keyPredicate = Expression.Equal(Expression.MakeMemberAccess(p, otherPKEnumerator.Current.Member),

																	 Expression.Constant(ValueProperty.GetValue(thisForeignKeyValue, null)));

						}



						if (predicate == null)

							predicate = keyPredicate;

						else

							predicate = Expression.And(predicate, keyPredicate);

					}

				}

				IEnumerable query = null;

				if (predicate != null)

				{

					query = GetOtherTableQuery(predicate, p, otherTableType, otherTable) as IEnumerable;

					//it would be interesting surround the above query with a .Take(1) expression for performance.

				}



				// If no separate Storage is specified, use the member directly

				MemberInfo storage = memberData.StorageMember;

				if (storage == null)

					storage = memberData.Member;



				 // Check that the storage is a field or a writable property

				if (!(storage is FieldInfo) && !(storage is PropertyInfo && ((PropertyInfo)storage).CanWrite)) {

					throw new InvalidOperationException(String.Format(

						"Member {0}.{1} is not a field nor a writable property",

						storage.DeclaringType, storage.Name));

				}



				Type storageType = storage.GetMemberType();



				object entityRefValue = null;

				if (query != null)

					entityRefValue = Activator.CreateInstance(storageType, query);

				else

					entityRefValue = Activator.CreateInstance(storageType);



				storage.SetMemberValue(entity, entityRefValue);

			}

		}



        /// <summary>

        /// This method is executed when the entity is being registered. Each EntitySet property has a internal query that can be set using the EntitySet.SetSource method.

        /// Here we set the query source of each EntitySetProperty

        /// </summary>

        /// <param name="entity"></param>

        private void SetEntitySetsQueries(object entity)

        {

            if (!this.deferredLoadingEnabled)

                return;



            // BUG: This is ignoring External Mappings from XmlMappingSource.



			IEnumerable<MetaAssociation> associationList = Mapping.GetMetaType(entity.GetType()).Associations.Where(a => !a.IsForeignKey);



			if (associationList.Any())

			{

				foreach (MetaAssociation association in associationList)

                {

					//example of entitySet: Employee.EmployeeTerritories

					var memberData = association.ThisMember;

					Type otherTableType = association.OtherType.Type;

                    ParameterExpression p = Expression.Parameter(otherTableType, "other");



                    //other table:EmployeeTerritories

                    var otherTable = GetTable(otherTableType);



					var otherKeys = memberData.Association.OtherKey;

					var thisKeys = memberData.Association.ThisKey;

                    if (otherKeys.Count != thisKeys.Count)

                        throw new InvalidOperationException("This keys don't match OtherKey");

                    BinaryExpression predicate = null;

                    IEnumerator<MetaDataMember> thisKeyEnumerator = thisKeys.GetEnumerator();

					foreach (MetaDataMember otherKey in otherKeys)

                    {

                        thisKeyEnumerator.MoveNext();

                        //other table member:EmployeeTerritories.EmployeeID

						var otherTableMember = (PropertyInfo)otherKey.Member;



                        BinaryExpression keyPredicate;

                        if (!(otherTableMember.PropertyType.IsNullable()))

                        {

                            keyPredicate = Expression.Equal(Expression.MakeMemberAccess(p, otherTableMember),

                                                                        Expression.Constant(thisKeyEnumerator.Current.Member.GetMemberValue(entity)));

                        }

                        else

                        {

                            var ValueProperty = otherTableMember.PropertyType.GetProperty("Value");

                            keyPredicate = Expression.Equal(Expression.MakeMemberAccess(

                                                                        Expression.MakeMemberAccess(p, otherTableMember),

                                                                        ValueProperty),

                                                                     Expression.Constant(thisKeyEnumerator.Current.Member.GetMemberValue(entity)));

                        }

                        if (predicate == null)

                            predicate = keyPredicate;

                        else

                            predicate = Expression.And(predicate, keyPredicate);

                    }



                    var query = GetOtherTableQuery(predicate, p, otherTableType, otherTable);



					var entitySetValue = memberData.Member.GetMemberValue(entity);



                    if (entitySetValue == null)

                    {

						entitySetValue = Activator.CreateInstance(memberData.Member.GetMemberType());

						memberData.Member.SetMemberValue(entity, entitySetValue);

                    }



                    var hasLoadedOrAssignedValues = entitySetValue.GetType().GetProperty("HasLoadedOrAssignedValues");

                    if ((bool)hasLoadedOrAssignedValues.GetValue(entitySetValue, null))

                        continue;



                    var setSourceMethod = entitySetValue.GetType().GetMethod("SetSource");

                    setSourceMethod.Invoke(entitySetValue, new[] { query });

                    //employee.EmployeeTerritories.SetSource(Table[EmployeesTerritories].Where(other=>other.employeeID="WARTH"))

                }

            }

        }



		private static MethodInfo _WhereMethod;

        internal object GetOtherTableQuery(Expression predicate, ParameterExpression parameter, Type otherTableType, IQueryable otherTable)

        {

            if (_WhereMethod == null)

                System.Threading.Interlocked.CompareExchange (ref _WhereMethod, typeof(Queryable).GetMethods().First(m => m.Name == "Where"), null);



            //predicate: other.EmployeeID== "WARTH"

            Expression lambdaPredicate = Expression.Lambda(predicate, parameter);

            //lambdaPredicate: other=>other.EmployeeID== "WARTH"



			Expression call = Expression.Call(_WhereMethod.MakeGenericMethod(otherTableType), otherTable.Expression, lambdaPredicate);

            //Table[EmployeesTerritories].Where(other=>other.employeeID="WARTH")



            return otherTable.Provider.CreateQuery(call);

        }



        #endregion



        #region Insert/Update/Delete management



        /// <summary>

        /// Registers an entity for insert

        /// </summary>

        /// <param name="entity"></param>

        internal void RegisterInsert(object entity)

        {

            CurrentTransactionEntities.RegisterToInsert(entity);

        }



        private void DoRegisterUpdate(object entity)

        {

            if (entity == null)

                throw new ArgumentNullException("entity");



            if (!this.objectTrackingEnabled)

                return;



            var identityReader = _GetIdentityReader(entity.GetType());

            var identityKey = identityReader.GetIdentityKey(entity);

            // if we have no key, we can not watch

            if (identityKey == null || identityKey.Keys.Count == 0)

                return;

            // register entity

            AllTrackedEntities.RegisterToWatch(entity, identityKey);

        }



        /// <summary>

        /// Registers an entity for update

        /// The entity will be updated only if some of its members have changed after the registration

        /// </summary>

        /// <param name="entity"></param>

        internal void RegisterUpdate(object entity)

        {

            DoRegisterUpdate(entity);

			MemberModificationHandler.Register(entity, Mapping);

        }



        /// <summary>

        /// Registers or re-registers an entity and clears its state

        /// </summary>

        /// <param name="entity"></param>

        /// <returns></returns>

        internal object Register(object entity)

        {

            if (! this.objectTrackingEnabled)

                return entity;

            var registeredEntity = _GetOrRegisterEntity(entity);

            // the fact of registering again clears the modified state, so we're... clear with that

            MemberModificationHandler.Register(registeredEntity, Mapping);

            return registeredEntity;

        }



        /// <summary>

        /// Registers an entity for update

        /// The entity will be updated only if some of its members have changed after the registration

        /// </summary>

        /// <param name="entity"></param>

        /// <param name="entityOriginalState"></param>

        internal void RegisterUpdate(object entity, object entityOriginalState)

        {

            if (!this.objectTrackingEnabled)

                return;

            DoRegisterUpdate(entity);

            MemberModificationHandler.Register(entity, entityOriginalState, Mapping);

        }



        /// <summary>

        /// Clears the current state, and marks the object as clean

        /// </summary>

        /// <param name="entity"></param>

        internal void RegisterUpdateAgain(object entity)

        {

            if (!this.objectTrackingEnabled)

                return;

            MemberModificationHandler.ClearModified(entity, Mapping);

        }



        /// <summary>

        /// Registers an entity for delete

        /// </summary>

        /// <param name="entity"></param>

        internal void RegisterDelete(object entity)

        {

            if (!this.objectTrackingEnabled)

                return;

            CurrentTransactionEntities.RegisterToDelete(entity);

        }



        /// <summary>

        /// Unregisters entity after deletion

        /// </summary>

        /// <param name="entity"></param>

        internal void UnregisterDelete(object entity)

        {

            if (!this.objectTrackingEnabled)

                return;

            CurrentTransactionEntities.RegisterDeleted(entity);

        }



        #endregion



        /// <summary>

        /// Changed object determine 

        /// </summary>

        /// <returns>Lists of inserted, updated, deleted objects</returns>

        public ChangeSet GetChangeSet()

        {

            var inserts = new List<object>();

            var updates = new List<object>();

            var deletes = new List<object>();

            foreach (var entityTrack in CurrentTransactionEntities.EnumerateAll()

                    .Concat(AllTrackedEntities.EnumerateAll()))

            {

                switch (entityTrack.EntityState)

                {

                    case EntityState.ToInsert:

                        inserts.Add(entityTrack.Entity);

                        break;

                    case EntityState.ToWatch:

                        if (MemberModificationHandler.IsModified(entityTrack.Entity, Mapping))

                            updates.Add(entityTrack.Entity);

                        break;

                    case EntityState.ToDelete:

                        deletes.Add(entityTrack.Entity);

                        break;

                    default:

                        throw new ArgumentOutOfRangeException();

                }

            }

            return new ChangeSet(inserts, updates, deletes);

        }



        /// <summary>

        /// use ExecuteCommand to call raw SQL

        /// </summary>

        public int ExecuteCommand(string command, params object[] parameters)

        {

            var directQuery = QueryBuilder.GetDirectQuery(command, new QueryContext(this));

            return QueryRunner.Execute(directQuery, parameters);

        }



        /// <summary>

        /// Execute raw SQL query and return object

        /// </summary>

        public IEnumerable<TResult> ExecuteQuery<TResult>(string query, params object[] parameters) where TResult : new()

        {

            if (query == null)

                throw new ArgumentNullException("query");



            return CreateExecuteQueryEnumerable<TResult>(query, parameters);

        }



        private IEnumerable<TResult> CreateExecuteQueryEnumerable<TResult>(string query, object[] parameters)

            where TResult : new()

        {

            foreach (TResult result in ExecuteQuery(typeof(TResult), query, parameters))

                yield return result;

        }



        public IEnumerable ExecuteQuery(Type elementType, string query, params object[] parameters)

        {

            if (elementType == null)

                throw new ArgumentNullException("elementType");

            if (query == null)

                throw new ArgumentNullException("query");



            var queryContext = new QueryContext(this);

            var directQuery = QueryBuilder.GetDirectQuery(query, queryContext);

            return QueryRunner.ExecuteSelect(elementType, directQuery, parameters);

        }



        /// <summary>

        /// Gets or sets the load options

        /// </summary>

        [DbLinqToDo]

		public DataLoadOptions LoadOptions

		{

			get { throw new NotImplementedException(); }

			set { throw new NotImplementedException(); }

		}



        public DbTransaction Transaction {

            get { return (DbTransaction) DatabaseContext.CurrentTransaction; }

            set { DatabaseContext.CurrentTransaction = value; }

        }



        /// <summary>

        /// Runs the given reader and returns columns.

        /// </summary>

        /// <typeparam name="TResult">The type of the result.</typeparam>

        /// <param name="reader">The reader.</param>

        /// <returns></returns>

        public IEnumerable<TResult> Translate<TResult>(DbDataReader reader)

        {

            if (reader == null)

                throw new ArgumentNullException("reader");

            return CreateTranslateIterator<TResult>(reader);

        }



        IEnumerable<TResult> CreateTranslateIterator<TResult>(DbDataReader reader)

        {

            foreach (TResult result in Translate(typeof(TResult), reader))

                yield return result;

        }



        public IMultipleResults Translate(DbDataReader reader)

        {

            throw new NotImplementedException();

        }



        public IEnumerable Translate(Type elementType, DbDataReader reader)

        {

            if (elementType == null)

                throw new ArgumentNullException("elementType");

            if (reader == null)

                throw new ArgumentNullException("reader");



            return QueryRunner.EnumerateResult(elementType, reader, this);

        }



        public void Dispose()

        {

            //connection closing should not be done here.

            //read: http://msdn2.microsoft.com/en-us/library/bb292288.aspx



			//We own the instance of MemberModificationHandler - we must unregister listeners of entities we attached to

			MemberModificationHandler.UnregisterAll();

        }



        [DbLinqToDo]

        protected virtual void Dispose(bool disposing)

        {

            throw new NotImplementedException();

        }



        /// <summary>

        /// Creates a IDbDataAdapter. Used internally by Vendors

        /// </summary>

        /// <returns></returns>

        internal IDbDataAdapter CreateDataAdapter()

        {

            return DatabaseContext.CreateDataAdapter();

        }



        /// <summary>

        /// Sets a TextWriter where generated SQL commands are written

        /// </summary>

        public TextWriter Log { get; set; }



        /// <summary>

        /// Writes text on Log (if not null)

        /// Internal helper

        /// </summary>

        /// <param name="text"></param>

        internal void WriteLog(string text)

        {

            if (Log != null)

                Log.WriteLine(text);

        }



        /// <summary>

        /// Write an IDbCommand to Log (if non null)

        /// </summary>

        /// <param name="command"></param>

        internal void WriteLog(IDbCommand command)

        {

            if (Log != null)

            {

                Log.WriteLine(command.CommandText);

                foreach (IDbDataParameter parameter in command.Parameters)

                    WriteLog(parameter);

                Log.Write("--");

                Log.Write(" Context: {0}", Vendor.VendorName);

                Log.Write(" Model: {0}", Mapping.GetType().Name);

                Log.Write(" Build: {0}", Assembly.GetExecutingAssembly().GetName().Version);

                Log.WriteLine();

            }

        }



        /// <summary>

        /// Writes and IDbDataParameter to Log (if non null)

        /// </summary>

        /// <param name="parameter"></param>

        internal void WriteLog(IDbDataParameter parameter)

        {

            if (Log != null)

            {

                // -- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [2]

                // -- <name>: <direction> <type> (...) [<value>]

                Log.WriteLine("-- {0}: {1} {2} (Size = {3}; Prec = {4}; Scale = {5}) [{6}]",

                    parameter.ParameterName, parameter.Direction, parameter.DbType,

                    parameter.Size, parameter.Precision, parameter.Scale, parameter.Value);

            }

        }



        public bool ObjectTrackingEnabled

        {

            get { return this.objectTrackingEnabled; }

            set 

            {

                if (this.currentTransactionEntities != null && value != this.objectTrackingEnabled)

                    throw new InvalidOperationException("Data context options cannot be modified after results have been returned from a query.");

                this.objectTrackingEnabled = value;

            }

        }



        [DbLinqToDo]

        public int CommandTimeout

        {

            get { throw new NotImplementedException(); }

            set { throw new NotImplementedException(); }

        }



        public bool DeferredLoadingEnabled

        {

            get { return this.deferredLoadingEnabled; }

            set

            {

                if (this.currentTransactionEntities != null && value != this.deferredLoadingEnabled)

                    throw new InvalidOperationException("Data context options cannot be modified after results have been returned from a query.");

                this.deferredLoadingEnabled = value;

            }

        }



        [DbLinqToDo]

        public ChangeConflictCollection ChangeConflicts

        {

            get { throw new NotImplementedException(); }

        }



        [DbLinqToDo]

        public DbCommand GetCommand(IQueryable query)

        {

            DbCommand dbCommand = GetIDbCommand(query) as DbCommand;

            if (dbCommand == null)

                throw new InvalidOperationException();



            return dbCommand;

        }



        [DBLinqExtended]

        public IDbCommand GetIDbCommand(IQueryable query)

        {

            if (query == null)

                throw new ArgumentNullException("query");



            var qp = query.Provider as QueryProvider;

            if (qp == null)

                throw new InvalidOperationException();



            if (qp.ExpressionChain.Expressions.Count == 0)

                qp.ExpressionChain.Expressions.Add(CreateDefaultQuery(query));



            return qp.GetQuery(null).GetCommand().Command;

        }



        private Expression CreateDefaultQuery(IQueryable query)

        {

            // Manually create the expression tree for: IQueryable<TableType>.Select(e => e)

            var identityParameter = Expression.Parameter(query.ElementType, "e");

            var identityBody = Expression.Lambda(

                typeof(Func<,>).MakeGenericType(query.ElementType, query.ElementType),

                identityParameter,

                new[] { identityParameter }

            );



            return Expression.Call(

                typeof(Queryable),

                "Select",

                new[] { query.ElementType, query.ElementType },

                query.Expression,

                Expression.Quote(identityBody)

            );

        }



        [DbLinqToDo]

        public void Refresh(RefreshMode mode, IEnumerable entities)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        public void Refresh(RefreshMode mode, params object[] entities)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        public void Refresh(RefreshMode mode, object entity)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        public void DeleteDatabase()

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        public void CreateDatabase()

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        protected internal IQueryable<TResult> CreateMethodCallQuery<TResult>(object instance, MethodInfo methodInfo, params object[] parameters)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        protected internal void ExecuteDynamicDelete(object entity)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        protected internal void ExecuteDynamicInsert(object entity)

        {

            throw new NotImplementedException();

        }



        [DbLinqToDo]

        protected internal void ExecuteDynamicUpdate(object entity)

        {

            throw new NotImplementedException();

        }

    }

}