using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.Data.Common.CommandTrees;
using System.Data.Entity;
using System.Data.EntityClient;
using System.Data.Metadata.Edm;
using System.Data.Objects.DataClasses;
using System.Data.SqlClient;
using System.Linq;
using System.Linq.Dynamic;
using System.Linq.Expressions;
using System.Reflection;
using System.Text;
using System.Data.Objects;
using EntityFramework.Mapping;
using EntityFramework.Reflection;
 
namespace EntityFramework.Extensions
{
    /// <summary>
    /// An extensions class for batch queries.
    /// </summary>
    public static class BatchExtensions
    {
        /// <summary>
        /// Executes a delete statement using the query to filter the rows to be deleted.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to delete from.</param>
        /// <param name="query">The IQueryable used to generate the where clause for the delete statement.</param>
        /// <returns>The number of row deleted.</returns>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Delete<TEntity>(
            this ObjectSet<TEntity> source,
            IQueryable<TEntity> query)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
 
            if (query == null)
                throw new ArgumentNullException("query");
 
            ObjectContext objectContext = source.Context;
            if (objectContext == null)
                throw new ArgumentException("The ObjectContext for the source query can not be null.", "source");
 
            EntityMap entityMap = source.GetEntityMap<TEntity>();
            if (entityMap == null)
                throw new ArgumentException("Could not load the entity mapping information for the source ObjectSet.", "source");
 
            ObjectQuery<TEntity> objectQuery = query.ToObjectQuery();
            if (objectQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "query");
 
            return Delete(objectContext, entityMap, objectQuery);
        }
 
        /// <summary>
        /// Executes a delete statement using an expression to filter the rows to be deleted.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to delete from.</param>
        /// <param name="filterExpression">The filter expression used to generate the where clause for the delete statement.</param>
        /// <returns>The number of row deleted.</returns>
        /// <example>Delete all users with email domain @test.com.
        /// <code><![CDATA[
        /// var db = new TrackerEntities();
        /// string emailDomain = "@test.com";
        /// int count = db.Users.Delete(u => u.Email.EndsWith(emailDomain));
        /// ]]></code>
        /// </example>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Delete<TEntity>(
            this ObjectSet<TEntity> source,
            Expression<Func<TEntity, bool>> filterExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (filterExpression == null)
                throw new ArgumentNullException("filterExpression");
 
            return source.Delete(source.Where(filterExpression));
        }
 
        /// <summary>
        /// Executes a delete statement using the query to filter the rows to be deleted.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to delete from.</param>
        /// <param name="query">The IQueryable used to generate the where clause for the delete statement.</param>
        /// <returns>The number of row deleted.</returns>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Delete<TEntity>(
           this DbSet<TEntity> source,
           IQueryable<TEntity> query)
           where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (query == null)
                throw new ArgumentNullException("query");
 
            ObjectQuery<TEntity> sourceQuery = source.ToObjectQuery();
            if (sourceQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "source");
 
            ObjectContext objectContext = sourceQuery.Context;
            if (objectContext == null)
                throw new ArgumentException("The ObjectContext for the source query can not be null.", "source");
 
            EntityMap entityMap = sourceQuery.GetEntityMap<TEntity>();
            if (entityMap == null)
                throw new ArgumentException("Could not load the entity mapping information for the source ObjectSet.", "source");
 
            ObjectQuery<TEntity> objectQuery = query.ToObjectQuery();
            if (objectQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "query");
 
            return Delete(objectContext, entityMap, objectQuery);
        }
 
        /// <summary>
        /// Executes a delete statement using an expression to filter the rows to be deleted.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to delete from.</param>
        /// <param name="filterExpression">The filter expression used to generate the where clause for the delete statement.</param>
        /// <returns>The number of row deleted.</returns>
        /// <example>Delete all users with email domain @test.com.
        /// <code><![CDATA[
        /// var db = new TrackerContext();
        /// string emailDomain = "@test.com";
        /// int count = db.Users.Delete(u => u.Email.EndsWith(emailDomain));
        /// ]]></code>
        /// </example>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Delete<TEntity>(
            this DbSet<TEntity> source,
            Expression<Func<TEntity, bool>> filterExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (filterExpression == null)
                throw new ArgumentNullException("filterExpression");
 
            return source.Delete(source.Where(filterExpression));
        }
 
 
        /// <summary>
        /// Executes an update statement using the query to filter the rows to be updated.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to update.</param>
        /// <param name="query">The query used to generate the where clause.</param>
        /// <param name="updateExpression">The MemberInitExpression used to indicate what is updated.</param>
        /// <returns>The number of row updated.</returns>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Update<TEntity>(
            this ObjectSet<TEntity> source,
            IQueryable<TEntity> query,
            Expression<Func<TEntity, TEntity>> updateExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (query == null)
                throw new ArgumentNullException("query");
            if (updateExpression == null)
                throw new ArgumentNullException("updateExpression");
 
            ObjectContext objectContext = source.Context;
            if (objectContext == null)
                throw new ArgumentException("The ObjectContext for the source query can not be null.", "source");
 
            EntityMap entityMap = source.GetEntityMap<TEntity>();
            if (entityMap == null)
                throw new ArgumentException("Could not load the entity mapping information for the source ObjectSet.", "source");
 
            ObjectQuery<TEntity> objectQuery = query.ToObjectQuery();
            if (objectQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "query");
 
            return Update(objectContext, entityMap, objectQuery, updateExpression);
        }
 
        /// <summary>
        /// Executes an update statement using an expression to filter the rows that are updated.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to update.</param>
        /// <param name="filterExpression">The filter expression used to generate the where clause.</param>
        /// <param name="updateExpression">The MemberInitExpression used to indicate what is updated.</param>
        /// <returns>The number of row updated.</returns>
        /// <example>Update all users in the test.com domain to be inactive.
        /// <code><![CDATA[
        /// var db = new TrackerEntities();
        /// string emailDomain = "@test.com";
        /// int count = db.Users.Update(
        ///   u => u.Email.EndsWith(emailDomain),
        ///   u => new User { IsApproved = false, LastActivityDate = DateTime.Now });
        /// ]]></code>
        /// </example>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Update<TEntity>(
            this ObjectSet<TEntity> source,
            Expression<Func<TEntity, bool>> filterExpression,
            Expression<Func<TEntity, TEntity>> updateExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (filterExpression == null)
                throw new ArgumentNullException("filterExpression");
 
            return source.Update(source.Where(filterExpression), updateExpression);
        }
 
        /// <summary>
        /// Executes an update statement using the query to filter the rows to be updated.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to update.</param>
        /// <param name="query">The query used to generate the where clause.</param>
        /// <param name="updateExpression">The MemberInitExpression used to indicate what is updated.</param>
        /// <returns>The number of row updated.</returns>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Update<TEntity>(
            this DbSet<TEntity> source,
            IQueryable<TEntity> query,
            Expression<Func<TEntity, TEntity>> updateExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (query == null)
                throw new ArgumentNullException("query");
            if (updateExpression == null)
                throw new ArgumentNullException("updateExpression");
 
            ObjectQuery<TEntity> sourceQuery = source.ToObjectQuery();
            if (sourceQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "source");
 
            ObjectContext objectContext = sourceQuery.Context;
            if (objectContext == null)
                throw new ArgumentException("The ObjectContext for the source query can not be null.", "source");
 
            EntityMap entityMap = sourceQuery.GetEntityMap<TEntity>();
            if (entityMap == null)
                throw new ArgumentException("Could not load the entity mapping information for the source.", "source");
 
            ObjectQuery<TEntity> objectQuery = query.ToObjectQuery();
            if (objectQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery or DbQuery.", "query");
 
            return Update(objectContext, entityMap, objectQuery, updateExpression);
        }
 
        /// <summary>
        /// Executes an update statement using an expression to filter the rows that are updated.
        /// </summary>
        /// <typeparam name="TEntity">The type of the entity.</typeparam>
        /// <param name="source">The source used to determine the table to update.</param>
        /// <param name="filterExpression">The filter expression used to generate the where clause.</param>
        /// <param name="updateExpression">The MemberInitExpression used to indicate what is updated.</param>
        /// <returns>The number of row updated.</returns>
        /// <example>Update all users in the test.com domain to be inactive.
        /// <code><![CDATA[
        /// var db = new TrackerContext();
        /// string emailDomain = "@test.com";
        /// int count = db.Users.Update(
        ///   u => u.Email.EndsWith(emailDomain),
        ///   u => new User { IsApproved = false, LastActivityDate = DateTime.Now });
        /// ]]></code>
        /// </example>
        /// <remarks>
        /// When executing this method, the statement is immediately executed on the database provider
        /// and is not part of the change tracking system.  Also, changes will not be reflected on
        /// any entities that have already been materialized in the current context.       
        /// </remarks>
        public static int Update<TEntity>(
            this DbSet<TEntity> source,
            Expression<Func<TEntity, bool>> filterExpression,
            Expression<Func<TEntity, TEntity>> updateExpression)
            where TEntity : class
        {
            if (source == null)
                throw new ArgumentNullException("source");
            if (filterExpression == null)
                throw new ArgumentNullException("filterExpression");
 
            return source.Update(source.Where(filterExpression), updateExpression);
        }
 
 
        private static int Delete<TEntity>(ObjectContext objectContext, EntityMap entityMap, ObjectQuery<TEntity> query)
            where TEntity : class
        {
            DbConnection deleteConnection = null;
            DbTransaction deleteTransaction = null;
            DbCommand deleteCommand = null;
            bool ownConnection = false;
            bool ownTransaction = false;
 
            try
            {
                // get store connection and transaction
                var store = GetStore(objectContext);
                deleteConnection = store.Item1;
                deleteTransaction = store.Item2;
 
                if (deleteConnection.State != ConnectionState.Open)
                {
                    deleteConnection.Open();
                    ownConnection = true;
                }
 
                if (deleteTransaction == null)
                {
                    deleteTransaction = deleteConnection.BeginTransaction();
                    ownTransaction = true;
                }
 
 
                deleteCommand = deleteConnection.CreateCommand();
                deleteCommand.Transaction = deleteTransaction;
                if (objectContext.CommandTimeout.HasValue)
                    deleteCommand.CommandTimeout = objectContext.CommandTimeout.Value;
 
                var innerSelect = GetSelectSql(query, entityMap, deleteCommand);
 
                var sqlBuilder = new StringBuilder(innerSelect.Length * 2);
 
                sqlBuilder.Append("DELETE ");
                sqlBuilder.Append(entityMap.TableName);
                sqlBuilder.AppendLine();
 
                sqlBuilder.AppendFormat("FROM {0} AS j0 INNER JOIN (", entityMap.TableName);
                sqlBuilder.AppendLine();
                sqlBuilder.AppendLine(innerSelect);
                sqlBuilder.Append(") AS j1 ON (");
 
                bool wroteKey = false;
                foreach (var keyMap in entityMap.KeyMaps)
                {
                    if (wroteKey)
                        sqlBuilder.Append(" AND ");
 
                    sqlBuilder.AppendFormat("j0.{0} = j1.{0}", keyMap.ColumnName);
                    wroteKey = true;
                }
                sqlBuilder.Append(")");
 
                deleteCommand.CommandText = sqlBuilder.ToString();
 
                int result = deleteCommand.ExecuteNonQuery();
 
                // only commit if created transaction
                if (ownTransaction)
                    deleteTransaction.Commit();
 
                return result;
            }
            finally
            {
                if (deleteCommand != null)
                    deleteCommand.Dispose();
                 
                if (deleteTransaction != null && ownTransaction)
                    deleteTransaction.Dispose();
 
                if (deleteConnection != null && ownConnection)
                    deleteConnection.Close();
            }
        }
 
        private static int Update<TEntity>(ObjectContext objectContext, EntityMap entityMap, ObjectQuery<TEntity> query, Expression<Func<TEntity, TEntity>> updateExpression)
            where TEntity : class
        {
            DbConnection updateConnection = null;
            DbTransaction updateTransaction = null;
            DbCommand updateCommand = null;
            bool ownConnection = false;
            bool ownTransaction = false;
 
            try
            {
                // get store connection and transaction
                var store = GetStore(objectContext);
                updateConnection = store.Item1;
                updateTransaction = store.Item2;
 
                if (updateConnection.State != ConnectionState.Open)
                {
                    updateConnection.Open();
                    ownConnection = true;
                }
 
                // use existing transaction or create new
                if (updateTransaction == null)
                {
                    updateTransaction = updateConnection.BeginTransaction();
                    ownTransaction = true;
                }
 
                updateCommand = updateConnection.CreateCommand();
                updateCommand.Transaction = updateTransaction;
                if (objectContext.CommandTimeout.HasValue)
                    updateCommand.CommandTimeout = objectContext.CommandTimeout.Value;
 
                var innerSelect = GetSelectSql(query, entityMap, updateCommand);
                var sqlBuilder = new StringBuilder(innerSelect.Length * 2);
 
                sqlBuilder.Append("UPDATE ");
                sqlBuilder.Append(entityMap.TableName);
                sqlBuilder.AppendLine(" SET ");
 
                var memberInitExpression = updateExpression.Body as MemberInitExpression;
                if (memberInitExpression == null)
                    throw new ArgumentException("The update expression must be of type MemberInitExpression.", "updateExpression");
 
                int nameCount = 0;
                bool wroteSet = false;
                foreach (MemberBinding binding in memberInitExpression.Bindings)
                {
                    if (wroteSet)
                        sqlBuilder.AppendLine(", ");
 
                    string propertyName = binding.Member.Name;
                    string columnName = entityMap.PropertyMaps
                        .Where(p => p.PropertyName == propertyName)
                        .Select(p => p.ColumnName)
                        .FirstOrDefault();
 
                    string parameterName = "p__update__" + nameCount++;
 
                    var memberAssignment = binding as MemberAssignment;
                    if (memberAssignment == null)
                        throw new ArgumentException("The update expression MemberBinding must only by type MemberAssignment.", "updateExpression");
 
                    object value;
                    if (memberAssignment.Expression.NodeType == ExpressionType.Constant)
                    {
                        var constantExpression = memberAssignment.Expression as ConstantExpression;
                        if (constantExpression == null)
                            throw new ArgumentException("The MemberAssignment expression is not a ConstantExpression.", "updateExpression");
 
                        value = constantExpression.Value;
                    }
                    else
                    {
                        LambdaExpression lambda = Expression.Lambda(memberAssignment.Expression, null);
                        value = lambda.Compile().DynamicInvoke();
                    }
 
                    var parameter = updateCommand.CreateParameter();
                    parameter.ParameterName = parameterName;
                    parameter.Value = value;
                    updateCommand.Parameters.Add(parameter);
 
                    sqlBuilder.AppendFormat("{0} = @{1}", columnName, parameterName);
                    wroteSet = true;
                }
 
                sqlBuilder.AppendLine(" ");
                sqlBuilder.AppendFormat("FROM {0} AS j0 INNER JOIN (", entityMap.TableName);
                sqlBuilder.AppendLine();
                sqlBuilder.AppendLine(innerSelect);
                sqlBuilder.Append(") AS j1 ON (");
 
                bool wroteKey = false;
                foreach (var keyMap in entityMap.KeyMaps)
                {
                    if (wroteKey)
                        sqlBuilder.Append(" AND ");
 
                    sqlBuilder.AppendFormat("j0.{0} = j1.{0}", keyMap.ColumnName);
                    wroteKey = true;
                }
                sqlBuilder.Append(")");
 
                updateCommand.CommandText = sqlBuilder.ToString();
 
                int result = updateCommand.ExecuteNonQuery();
 
                // only commit if created transaction
                if (ownTransaction)
                    updateTransaction.Commit();
 
                return result;
            }
            finally
            {
                if (updateCommand != null)
                    updateCommand.Dispose();
                if (updateTransaction != null && ownTransaction)
                    updateTransaction.Dispose();
                if (updateConnection != null && ownConnection)
                    updateConnection.Close();
            }
        }
 
        private static Tuple<DbConnection, DbTransaction> GetStore(ObjectContext objectContext)
        {
            DbConnection dbConnection = objectContext.Connection;
            var entityConnection = dbConnection as EntityConnection;
 
            // by-pass entity connection
            if (entityConnection == null)
                return new Tuple<DbConnection, DbTransaction>(dbConnection, null);
 
            DbConnection connection = entityConnection.StoreConnection;
 
            // get internal transaction
            dynamic connectionProxy = new DynamicProxy(entityConnection);
            dynamic entityTransaction = connectionProxy.CurrentTransaction;
            if (entityTransaction == null)
                return new Tuple<DbConnection, DbTransaction>(connection, null);
 
            DbTransaction transaction = entityTransaction.StoreTransaction;
            return new Tuple<DbConnection, DbTransaction>(connection, transaction);
        }
 
        private static string GetSelectSql<TEntity>(ObjectQuery<TEntity> query, EntityMap entityMap, DbCommand command)
            where TEntity : class
        {
            // changing query to only select keys
            var selector = new StringBuilder(50);
            selector.Append("new(");
            foreach (var propertyMap in entityMap.KeyMaps)
            {
                if (selector.Length > 4)
                    selector.Append((", "));
 
                selector.Append(propertyMap.PropertyName);
            }
            selector.Append(")");
 
            var selectQuery = DynamicQueryable.Select(query, selector.ToString());
            var objectQuery = selectQuery as ObjectQuery;
 
            if (objectQuery == null)
                throw new ArgumentException("The query must be of type ObjectQuery.", "query");
 
            string innerJoinSql = objectQuery.ToTraceString();
 
            // create parameters
            foreach (var objectParameter in objectQuery.Parameters)
            {
                var parameter = command.CreateParameter();
                parameter.ParameterName = objectParameter.Name;
                parameter.Value = objectParameter.Value;
 
                command.Parameters.Add(parameter);
            }
 
            return innerJoinSql;
        }
 
    }
}

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