/*
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.
You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License 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.
*/

package com.ilmlf.delivery.api.handlers;

import static software.amazon.lambda.powertools.logging.CorrelationIdPathConstants.API_GATEWAY_REST;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
import com.ilmlf.delivery.api.handlers.service.SlotService;
import com.ilmlf.delivery.api.handlers.util.ApiUtil;
import com.ilmlf.delivery.api.handlers.util.SlotParser;
import java.util.ArrayList;
import java.util.List;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import software.amazon.cloudwatchlogs.emf.logger.MetricsLogger;
import software.amazon.cloudwatchlogs.emf.model.DimensionSet;
import software.amazon.cloudwatchlogs.emf.model.Unit;
import software.amazon.lambda.powertools.logging.Logging;
import software.amazon.lambda.powertools.logging.LoggingUtils;
import software.amazon.lambda.powertools.metrics.Metrics;
import software.amazon.lambda.powertools.metrics.MetricsUtils;
import software.amazon.lambda.powertools.tracing.Tracing;

/**
 * A Lambda handler for CreateSlot API Call.
 */
public class CreateSlots implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
  private static final Logger logger = LogManager.getLogger(CreateSlots.class);
  private static final MetricsLogger metricsLogger = MetricsUtils.metricsLogger();
  private final SlotService slotService;
  private final SlotParser slotParser;

  /**
   * Constructor called by AWS Lambda.
   */
  @SuppressWarnings("unused")
  public CreateSlots() {
    this(new SlotService(), new SlotParser());
    metricsLogger.putDimensions(DimensionSet.of("FunctionName", "CreateSlots"));
  }

  /**
   * Constructor for unit testing. Allow test code to inject mocked SlotService.
   *
   * @param slotService the mocked SlotService instance
   */
  CreateSlots(SlotService slotService, SlotParser slotParser) {
    this.slotService = slotService;
    this.slotParser = slotParser;
  }

  /**
   * Handle create-slots POST via Api Gateway.
   * pathParameters expected: {farm-id=Integer}
   * <pre>
   * POST Body expected: {
      slots: [
          {
              numDeliveries: "2",
              from: "2020-01-01T10:00:00",
              to: "2020-01-01T10:00:00"
          }
      ]
   }
   * </pre>
   *
   * @return 200: success<br/>
   *        4xx: if request doesn't come from authenticated client app<br/>
   *        5xx: if slot can't be persisted
   */
  @Logging(correlationIdPath = API_GATEWAY_REST)
  @Tracing
  @Metrics(captureColdStart = true)
  public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent input, Context context) {
    String returnVal = "";
    int httpStatus = 200;
    List<Slot> slotList = new ArrayList<>();

    try {
      String farmIdStr = input.getPathParameters().get("farm-id");
      LoggingUtils.appendKey("farmId", farmIdStr);
      String body = input.getBody();
      slotList = slotParser.parseAndCreateSlotList(body, farmIdStr);

    } catch (Exception e) {
      returnVal = "The data received is incomplete or invalid";
      httpStatus = 400;
      logger.error(e.getMessage(), e);

      metricsLogger.putMetric("InvalidSlotList", 1, Unit.COUNT);
    }

    logger.info("{} slots created", slotList.size());
    if (!slotList.isEmpty()) {
      try {
        int rowsUpdated = slotService.insertSlotList(slotList);

        logger.info("{} slots inserted", rowsUpdated);

        if (rowsUpdated == 0) {
          returnVal = "There was an error and the data could not be saved";
          httpStatus = 500;

          metricsLogger.putMetric("FailedToSaveSlots", 1, Unit.COUNT);
        } else {
          returnVal = "Slot data (" + rowsUpdated + ") was saved successfully";
        }

        metricsLogger.putMetric("SlotsCreated", rowsUpdated, Unit.COUNT);
      } catch (Exception e) {
        returnVal = "Error encountered while inserting the slot list";
        httpStatus = 500;
        logger.error(e.getMessage(), e);

        metricsLogger.putMetric("CreateSlotsException", 1, Unit.COUNT);
      }
    }

    return ApiUtil.generateReturnData(httpStatus, returnVal);
  }
}