/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 * 
 *  http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

using System;
using System.Collections.Generic;
using System.Linq;

using Amazon.DynamoDBv2.DocumentModel;
using Amazon.DynamoDBv2.Model;

namespace Amazon.DynamoDBv2.DataModel
{
    /// <summary>
    /// Context object for using the DataModel mode of DynamoDB.
    /// Used to interact with the service, save/load objects, etc.
    /// </summary>
    public partial class DynamoDBContext : IDynamoDBContext
    {
        #region Save async

        /// <summary>
        /// Initiates the asynchronous execution of the Save operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Save"/>
        /// </summary>
        /// <typeparam name="T">Type to save as.</typeparam>
        /// <param name="value">Object to save.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndSave
        ///         operation.</returns>
        public IAsyncResult BeginSave<T>(T value, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { SaveHelper<T>(value, null); return null; }, callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Save operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Save"/>
        /// </summary>
        /// <typeparam name="T">Type to save as.</typeparam>
        /// <param name="value">Object to save.</param>
        /// <param name="operationConfig">Overriding configuration.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndSave
        ///         operation.</returns>
        public IAsyncResult BeginSave<T>(T value, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { SaveHelper<T>(value, operationConfig); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the Save operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Save"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginSave.</param>
        public void EndSave(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region Load async

        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="hashKey">Hash key element of the target item.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(object hashKey, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(hashKey, null, null), callback, state);
        }
        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="hashKey">Hash key element of the target item.</param>
        /// <param name="rangeKey">Range key element of the target item.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(object hashKey, object rangeKey, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(hashKey, rangeKey, null), callback, state);
        }
        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="hashKey">Hash key element of the target item.</param>
        /// <param name="operationConfig">Overriding configuration.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(object hashKey, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(hashKey, null, operationConfig), callback, state);
        }
        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="hashKey">Hash key element of the target item.</param>
        /// <param name="rangeKey">Range key element of the target item.</param>
        /// <param name="operationConfig">Overriding configuration.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(object hashKey, object rangeKey, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(hashKey, rangeKey, operationConfig), callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="keyObject">Key of the target item.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(T keyObject, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(keyObject, null), callback, state);
        }
        /// <summary>
        /// Initiates the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <typeparam name="T">Type to populate.</typeparam>
        /// <param name="keyObject">Key of the target item.</param>
        /// <param name="operationConfig">Overriding configuration.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndLoad
        ///         operation.</returns>
        public IAsyncResult BeginLoad<T>(T keyObject, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => LoadHelper<T>(keyObject, operationConfig), callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the Load operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Load"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginLoad.</param>
        /// <returns>
        /// Object of type T, populated with properties of item loaded from DynamoDB.
        /// </returns>
        public T EndLoad<T>(IAsyncResult asyncResult)
        {
            return DynamoDBAsyncExecutor.EndOperation<T>(asyncResult);
        }

        #endregion

        #region Delete async

        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="value">Object to delete.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(T value, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(value, null); return null; }, callback, state);
        }
        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="value">Object to delete.</param>
        /// <param name="operationConfig">Overriding configuration.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(T value, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(value, operationConfig); return null; }, callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKey">Hash key element of the object to delete.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(object hashKey, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(hashKey, null, null); return null; }, callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKey">Hash key element of the object to delete.</param>
        /// <param name="operationConfig">Config object which can be used to override that table used.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(object hashKey, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(hashKey, null, operationConfig); return null; }, callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKey">Hash key element of the object to delete.</param>
        /// <param name="rangeKey">Range key element of the object to delete.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(object hashKey, object rangeKey, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(hashKey, rangeKey, null); return null; }, callback, state);
        }

        /// <summary>
        /// Initiates the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKey">Hash key element of the object to delete.</param>
        /// <param name="rangeKey">Range key element of the object to delete.</param>
        /// <param name="operationConfig">Config object which can be used to override that table used.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginDelete<T>(object hashKey, object rangeKey, DynamoDBOperationConfig operationConfig, AsyncCallback callback, object state)
        {
            return DynamoDBAsyncExecutor.BeginOperation(() => { DeleteHelper<T>(hashKey, rangeKey, operationConfig); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the Delete operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.Delete"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginDelete.</param>
        public void EndDelete(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region BatchGet async

        /// <summary>
        /// Issues a batch-get request with multiple batches.
        ///
        /// Results are stored in the individual batches.
        /// </summary>
        /// <param name="batches">Configured BatchGet objects</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndExecuteBatchGet
        ///         operation.</returns>
        public IAsyncResult BeginExecuteBatchGet(BatchGet[] batches, AsyncCallback callback, object state)
        {
            MultiTableBatchGet superBatch = new MultiTableBatchGet(batches);
            return DynamoDBAsyncExecutor.BeginOperation(() => { superBatch.ExecuteHelper(); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the ExecuteBatchGet operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.ExecuteBatchGet"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginExecuteBatchGet.</param>
        public void EndExecuteBatchGet(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region BatchWrite async

        /// <summary>
        /// Issues a batch-write request with multiple batches.
        /// </summary>
        /// <param name="batches">Configured BatchWrite objects</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        ///          procedure using the AsyncState property.</param>
        /// <returns>An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        ///         operation.</returns>
        public IAsyncResult BeginExecuteBatchWrite(BatchWrite[] batches, AsyncCallback callback, object state)
        {
            MultiTableBatchWrite superBatch = new MultiTableBatchWrite(batches);
            return DynamoDBAsyncExecutor.BeginOperation(() => { superBatch.ExecuteHelper(); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the ExecuteBatchWrite operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.ExecuteBatchWrite"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginExecuteBatchWrite.</param>
        public void EndExecuteBatchWrite(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region TransactGet async

        /// <summary>
        /// Issues a transactional get request with multiple TransactGet objects.
        /// Results are stored in the individual TransactGet objects.
        /// </summary>
        /// <param name="transactionParts">Configured TransactGet objects.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">
        /// A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        /// procedure using the AsyncState property.
        /// </param>
        /// <returns>
        /// An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndExecuteBatchGet
        /// operation.
        /// </returns>
        public IAsyncResult BeginExecuteTransactGet(TransactGet[] transactionParts, AsyncCallback callback, object state)
        {
            MultiTableTransactGet transaction = new MultiTableTransactGet(transactionParts);
            return DynamoDBAsyncExecutor.BeginOperation(() => { transaction.ExecuteHelper(); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the ExecuteTransactGet operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.ExecuteTransactGet"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginExecuteTransactGet.</param>
        public void EndExecuteTransactGet(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region TransactWrite async

        /// <summary>
        /// Issues a transactional write request with multiple TransactWrite objects.
        /// </summary>
        /// <param name="transactionParts">Configured TransactWrite objects.</param>
        /// <param name="callback">An AsyncCallback delegate that is invoked when the operation completes.</param>
        /// <param name="state">
        /// A user-defined state object that is passed to the callback procedure. Retrieve this object from within the callback
        /// procedure using the AsyncState property.
        /// </param>
        /// <returns>
        /// An IAsyncResult that can be used to poll or wait for results, or both; this value is also needed when invoking EndDelete
        /// operation.
        /// </returns>
        public IAsyncResult BeginExecuteTransactWrite(TransactWrite[] transactionParts, AsyncCallback callback, object state)
        {
            MultiTableTransactWrite transaction = new MultiTableTransactWrite(transactionParts);
            return DynamoDBAsyncExecutor.BeginOperation(() => { transaction.ExecuteHelper(); return null; }, callback, state);
        }

        /// <summary>
        /// Finishes the asynchronous execution of the ExecuteTransactWrite operation.
        /// <seealso cref="Amazon.DynamoDBv2.DataModel.DynamoDBContext.ExecuteTransactWrite"/>
        /// </summary>
        /// <param name="asyncResult">The IAsyncResult returned by the call to BeginExecuteTransactWrite.</param>
        public void EndExecuteTransactWrite(IAsyncResult asyncResult)
        {
            DynamoDBAsyncExecutor.EndOperation(asyncResult);
        }

        #endregion

        #region Scan async

        /// <summary>
        /// Configures an async Scan operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="conditions">
        /// Conditions that the results should meet.
        /// </param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> ScanAsync<T>(params ScanCondition[] conditions)
        {
            if (conditions == null)
                throw new ArgumentNullException("conditions");

            return ScanAsync<T>(conditions, null);
        }

        /// <summary>
        ///  Configures an async Scan operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="conditions">
        /// Conditions that the results should meet.
        /// </param>
        /// <param name="operationConfig">Config object which can be used to override that table used.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> ScanAsync<T>(IEnumerable<ScanCondition> conditions, DynamoDBOperationConfig operationConfig)
        {
            if (conditions == null)
                throw new ArgumentNullException("conditions");

            var scan = ConvertScan<T>(conditions, operationConfig);
            return FromSearchAsync<T>(scan);
        }

        /// <summary>
        ///  Configures an async Scan operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="scanConfig">Scan request object.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> FromScanAsync<T>(ScanOperationConfig scanConfig)
        {
            return FromScanAsync<T>(scanConfig, null);
        }

        /// <summary>
        ///  Configures an async Scan operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="scanConfig">Scan request object.</param>
        /// <param name="operationConfig">Config object which can be used to override the table used.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> FromScanAsync<T>(ScanOperationConfig scanConfig, DynamoDBOperationConfig operationConfig)
        {
            if (scanConfig == null) throw new ArgumentNullException("scanConfig");

            var scan = ConvertFromScan<T>(scanConfig, operationConfig);
            return FromSearchAsync<T>(scan);
        }

        #endregion

        #region Query async

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified hash primary key.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKeyValue">Hash key of the items to query.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> QueryAsync<T>(object hashKeyValue)
        {
            var query = ConvertQueryByValue<T>(hashKeyValue, null, null);
            return FromSearchAsync<T>(query);
        }

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified hash primary key.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKeyValue">Hash key of the items to query.</param>
        /// <param name="operationConfig">Config object which can be used to override the table used.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> QueryAsync<T>(object hashKeyValue, DynamoDBOperationConfig operationConfig)
        {
            ContextSearch query = ConvertQueryByValue<T>(hashKeyValue, null, operationConfig);
            return FromSearchAsync<T>(query);
        }

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified range element condition for a hash-and-range primary key.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKeyValue">Hash key of the items to query.</param>
        /// <param name="op">Operation of the condition.</param>
        /// <param name="values">
        /// Value(s) of the condition.
        /// For all operations except QueryOperator.Between, values should be one value.
        /// For QueryOperator.Between, values should be two values.
        /// </param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> QueryAsync<T>(object hashKeyValue, QueryOperator op, params object[] values)
        {
            if (values == null || values.Length == 0)
                throw new ArgumentOutOfRangeException("values");

            return QueryAsync<T>(hashKeyValue, op, values, null);
        }

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified range element condition for a hash-and-range primary key.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="hashKeyValue">Hash key of the items to query.</param>
        /// <param name="op">Operation of the condition.</param>
        /// <param name="values">
        /// Value(s) of the condition.
        /// For all operations except QueryOperator.Between, values should be one value.
        /// For QueryOperator.Between, values should be two values.
        /// </param>
        /// <param name="operationConfig">Config object which can be used to override the table used.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> QueryAsync<T>(object hashKeyValue, QueryOperator op, IEnumerable<object> values, DynamoDBOperationConfig operationConfig)
        {
            if (values == null)
                throw new ArgumentNullException("values");

            ContextSearch query = ConvertQueryByValue<T>(hashKeyValue, op, values, operationConfig);
            return FromSearchAsync<T>(query);
        }

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="queryConfig">Query request object.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> FromQueryAsync<T>(QueryOperationConfig queryConfig)
        {
            return FromQueryAsync<T>(queryConfig, null);
        }

        /// <summary>
        /// Configures an async Query operation against DynamoDB, finding items
        /// that match the specified conditions.
        /// </summary>
        /// <typeparam name="T">Type of object.</typeparam>
        /// <param name="queryConfig">Query request object.</param>
        /// <param name="operationConfig">Config object which can be used to override the table used.</param>
        /// <returns>AsyncSearch which can be used to retrieve DynamoDB data.</returns>
        public AsyncSearch<T> FromQueryAsync<T>(QueryOperationConfig queryConfig, DynamoDBOperationConfig operationConfig)
        {
            if (queryConfig == null) throw new ArgumentNullException("queryConfig");

            var query = ConvertFromQuery<T>(queryConfig, operationConfig);
            return FromSearchAsync<T>(query);
        }

        #endregion
    }
}