/*
 * Copyright 2020 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://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

package com.amazon.aoc.services;

import com.amazonaws.services.cloudwatch.AmazonCloudWatch;
import com.amazonaws.services.cloudwatch.AmazonCloudWatchClientBuilder;
import com.amazonaws.services.cloudwatch.model.Datapoint;
import com.amazonaws.services.cloudwatch.model.Dimension;
import com.amazonaws.services.cloudwatch.model.GetMetricDataRequest;
import com.amazonaws.services.cloudwatch.model.GetMetricDataResult;
import com.amazonaws.services.cloudwatch.model.GetMetricStatisticsRequest;
import com.amazonaws.services.cloudwatch.model.ListMetricsRequest;
import com.amazonaws.services.cloudwatch.model.Metric;
import com.amazonaws.services.cloudwatch.model.MetricDataQuery;
import com.amazonaws.services.cloudwatch.model.MetricDataResult;
import com.amazonaws.services.cloudwatch.model.MetricDatum;
import com.amazonaws.services.cloudwatch.model.MetricStat;
import com.amazonaws.services.cloudwatch.model.PutMetricDataRequest;
import com.amazonaws.services.cloudwatch.model.PutMetricDataResult;
import com.amazonaws.services.cloudwatch.model.StandardUnit;
import com.amazonaws.services.logs.AWSLogs;
import com.amazonaws.services.logs.AWSLogsClientBuilder;
import com.amazonaws.services.logs.model.FilterLogEventsRequest;
import com.amazonaws.services.logs.model.FilterLogEventsResult;
import com.amazonaws.services.logs.model.FilteredLogEvent;
import com.amazonaws.services.logs.model.GetLogEventsRequest;
import com.amazonaws.services.logs.model.GetLogEventsResult;
import com.amazonaws.services.logs.model.OutputLogEvent;
import java.util.Date;
import java.util.List;
import lombok.extern.log4j.Log4j2;

/** a wrapper of cloudwatch client. */
@Log4j2
public class CloudWatchService {
  private static final int MAX_QUERY_PERIOD = 60;
  private static final String REQUESTER = "integrationTest";

  private AmazonCloudWatch amazonCloudWatch;
  private AWSLogs awsLogs;

  /**
   * Construct CloudWatch Service with region.
   *
   * @param region the region for CloudWatch
   */
  public CloudWatchService(String region) {
    amazonCloudWatch = AmazonCloudWatchClientBuilder.standard().withRegion(region).build();
    awsLogs = AWSLogsClientBuilder.standard().withRegion(region).build();
  }

  /**
   * listMetrics fetches metrics from CloudWatch.
   *
   * @param namespace the metric namespace on CloudWatch
   * @param metricName the metric name on CloudWatch
   * @return List of Metrics
   */
  public List<Metric> listMetrics(final String namespace, final String metricName) {
    final ListMetricsRequest listMetricsRequest =
        new ListMetricsRequest().withNamespace(namespace).withMetricName(metricName);
    return amazonCloudWatch.listMetrics(listMetricsRequest).getMetrics();
  }

  /**
   * getMetricData fetches the history data of the given metric from CloudWatch.
   *
   * @param metric metric query object
   * @param startTime the start timestamp
   * @param endTime the end timestamp
   * @return List of MetricDataResult
   */
  public List<MetricDataResult> getMetricData(Metric metric, Date startTime, Date endTime) {
    MetricStat stat =
        new MetricStat().withMetric(metric).withStat("Average").withPeriod(MAX_QUERY_PERIOD);
    MetricDataQuery query = new MetricDataQuery().withMetricStat(stat).withId(REQUESTER);
    final GetMetricDataRequest request =
        new GetMetricDataRequest()
            .withMetricDataQueries(query)
            .withStartTime(startTime)
            .withEndTime(endTime);

    GetMetricDataResult result = amazonCloudWatch.getMetricData(request);
    return result.getMetricDataResults();
  }

  /**
   * putMetricData publish metric to CloudWatch.
   *
   * @param namespace the metric namespace on CloudWatch
   * @param metricName the metric name on CloudWatch
   * @param value the metric value on CloudWatch
   * @param dimensions the dimensions of metric
   * @return Response of PMD call
   */
  public PutMetricDataResult putMetricData(
      final String namespace,
      final String metricName,
      final Double value,
      final Dimension... dimensions) {
    MetricDatum datum =
        new MetricDatum()
            .withMetricName(metricName)
            .withUnit(StandardUnit.None)
            .withDimensions(dimensions)
            .withValue(value);
    PutMetricDataRequest request =
        new PutMetricDataRequest().withNamespace(namespace).withMetricData(datum);
    return amazonCloudWatch.putMetricData(request);
  }

  /**
   * getDatapoints fetches datapoints from CloudWatch using the given request.
   *
   * @param request request for datapoint
   * @return List of Datapoints
   */
  public List<Datapoint> getDatapoints(GetMetricStatisticsRequest request) {
    return amazonCloudWatch.getMetricStatistics(request).getDatapoints();
  }

  /**
   * getLogs fetches log entries from CloudWatch.
   *
   * @param logGroupName the log group name
   * @param logStreamName the log stream name
   * @param startFromTimestamp the start timestamp
   * @param limit the maximum number of log events to be returned in a single query
   * @return List of OutputLogEvent
   */
  public List<OutputLogEvent> getLogs(
      String logGroupName, String logStreamName, long startFromTimestamp, int limit) {
    GetLogEventsRequest request =
        new GetLogEventsRequest()
            .withLogGroupName(logGroupName)
            .withLogStreamName(logStreamName)
            .withStartTime(startFromTimestamp)
            .withLimit(limit);

    GetLogEventsResult result = awsLogs.getLogEvents(request);
    return result.getEvents();
  }

  /**
   * filterLogs filters log entries from CloudWatch.
   *
   * @param logGroupName the log group name
   * @param filterPattern the filter pattern, see
   *     https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/FilterAndPatternSyntax.html
   * @param startFromTimestamp the start timestamp
   * @param limit the maximum number of log events to be returned in a single query
   * @return List of FilteredLogEvent
   */
  public List<FilteredLogEvent> filterLogs(
      String logGroupName, String filterPattern, long startFromTimestamp, int limit) {
    FilterLogEventsRequest request =
        new FilterLogEventsRequest()
            .withLogGroupName(logGroupName)
            .withStartTime(startFromTimestamp)
            .withFilterPattern(filterPattern)
            .withLimit(limit);

    FilterLogEventsResult result = awsLogs.filterLogEvents(request);
    return result.getEvents();
  }
}