/*
   Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
   SPDX-License-Identifier: Apache-2.0
*/
/**
 * Before running this C++ code example, set up your development environment, including your credentials.
 *
 * For more information, see the following documentation topic:
 *
 * https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/getting-started.html
 *
 * For information on the structure of the code examples and how to build and run the examples, see
 * https://docs.aws.amazon.com/sdk-for-cpp/v1/developer-guide/getting-started-code-examples.html.
 *
 **/

#include <aws/core/Aws.h>
#include <aws/dynamodb/DynamoDBClient.h>
#include <aws/dynamodb/model/AttributeDefinition.h>
#include <aws/dynamodb/model/BatchGetItemRequest.h>
#include <aws/dynamodb/model/KeysAndAttributes.h>
#include <iostream>
#include "dynamodb_samples.h"

/*
 *  For instructions on populating a table with sample data, see
 *  https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SampleData.html.
 *
 *  This example uses the "Forum.json" and "ProductCatalog.json" sample data.
 */

//snippet-start:[cpp.example_code.dynamodb.batch_get_item]
//! Batch get items from different Amazon DynamoDB tables.
/*!
  \sa batchGetItem()
  \param clientConfiguration: AWS client configuration.
  \return bool: Function succeeded.
 */
bool AwsDoc::DynamoDB::batchGetItem(
        const Aws::Client::ClientConfiguration &clientConfiguration) {
    Aws::DynamoDB::DynamoDBClient dynamoClient(clientConfiguration);

    Aws::DynamoDB::Model::BatchGetItemRequest request;

    // Table1: Forum.
    Aws::String table1Name = "Forum";
    Aws::DynamoDB::Model::KeysAndAttributes table1KeysAndAttributes;

    // Table1: Projection expression.
    table1KeysAndAttributes.SetProjectionExpression("#n, Category, Messages, #v");

    // Table1: Expression attribute names.
    Aws::Http::HeaderValueCollection headerValueCollection;
    headerValueCollection.emplace("#n", "Name");
    headerValueCollection.emplace("#v", "Views");
    table1KeysAndAttributes.SetExpressionAttributeNames(headerValueCollection);

    // Table1: Set key name, type, and value to search.
    std::vector<Aws::String> nameValues = {"Amazon DynamoDB", "Amazon S3"};
    for (const Aws::String &name: nameValues) {
        Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> keys;
        Aws::DynamoDB::Model::AttributeValue key;
        key.SetS(name);
        keys.emplace("Name", key);
        table1KeysAndAttributes.AddKeys(keys);
    }

    Aws::Map<Aws::String, Aws::DynamoDB::Model::KeysAndAttributes> requestItems;
    requestItems.emplace(table1Name, table1KeysAndAttributes);

    // Table2: ProductCatalog.
    Aws::String table2Name = "ProductCatalog";
    Aws::DynamoDB::Model::KeysAndAttributes table2KeysAndAttributes;
    table2KeysAndAttributes.SetProjectionExpression("Title, Price, Color");

    // Table2: Set key name, type, and value to search.
    std::vector<Aws::String> idValues = {"102", "103", "201"};
    for (const Aws::String &id: idValues) {
        Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> keys;
        Aws::DynamoDB::Model::AttributeValue key;
        key.SetN(id);
        keys.emplace("Id", key);
        table2KeysAndAttributes.AddKeys(keys);
    }

    requestItems.emplace(table2Name, table2KeysAndAttributes);

    bool result = true;
    do {  // Use a do loop to handle pagination.
        request.SetRequestItems(requestItems);
        const Aws::DynamoDB::Model::BatchGetItemOutcome &outcome = dynamoClient.BatchGetItem(
                request);

        if (outcome.IsSuccess()) {
            for (const auto &responsesMapEntry: outcome.GetResult().GetResponses()) {
                Aws::String tableName = responsesMapEntry.first;
                const Aws::Vector<Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue>> &tableResults = responsesMapEntry.second;
                std::cout << "Retrieved " << tableResults.size()
                          << " responses for table '" << tableName << "'.\n"
                          << std::endl;
                if (tableName == "Forum") {

                    std::cout << "Name | Category | Message | Views" << std::endl;
                    for (const Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> &item: tableResults) {
                        std::cout << item.at("Name").GetS() << " | ";
                        std::cout << item.at("Category").GetS() << " | ";
                        std::cout << (item.count("Message") == 0 ? "" : item.at(
                                "Messages").GetN()) << " | ";
                        std::cout << (item.count("Views") == 0 ? "" : item.at(
                                "Views").GetN()) << std::endl;
                    }
                }
                else {
                    std::cout << "Title | Price | Color" << std::endl;
                    for (const Aws::Map<Aws::String, Aws::DynamoDB::Model::AttributeValue> &item: tableResults) {
                        std::cout << item.at("Title").GetS() << " | ";
                        std::cout << (item.count("Price") == 0 ? "" : item.at(
                                "Price").GetN());
                        if (item.count("Color")) {
                            std::cout << " | ";
                            for (const std::shared_ptr<Aws::DynamoDB::Model::AttributeValue> &listItem: item.at(
                                    "Color").GetL())
                                std::cout << listItem->GetS() << " ";
                        }
                        std::cout << std::endl;
                    }
                }
                std::cout << std::endl;
            }

            // If necessary, repeat request for remaining items.
            requestItems = outcome.GetResult().GetUnprocessedKeys();
        }
        else {
            std::cerr << "Batch get item failed: " << outcome.GetError().GetMessage()
                      << std::endl;
            result = false;
            break;
        }
    } while (!requestItems.empty());

    return result;
}
//snippet-end:[cpp.example_code.dynamodb.batch_get_item]

/*
 *
 *  main function
 *
 *  Usage: 'run_batch_get_item'
 *
 *  Prerequisites: Pre-populated DynamoDB tables.
 *
 *  For instructions on populating a table with sample data, see
 *  https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SampleData.html.
 *
 *  This example uses the "Forum.json" and "ProductCatalog.json" sample data.
 *  This example requires pre-populated "Forum" and "ProductCatalog" tables.
 *
 */

#ifndef TESTING_BUILD

int main(int argc, char **argv) {
    (void) argc; // Suppress unused warning.
    (void) argv; // Suppress unused warning.
    Aws::SDKOptions options;
    Aws::InitAPI(options);
    {
        Aws::Client::ClientConfiguration clientConfig;
        // Optional: Set to the AWS Region (overrides config file).
        // clientConfig.region = "us-east-1";

        AwsDoc::DynamoDB::batchGetItem(clientConfig);
    }
    Aws::ShutdownAPI(options);
    return 0;
}

#endif // TESTING_BUILD