// Copyright 2016 The Nomulus Authors. 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 google.registry.export;

import static com.google.appengine.api.taskqueue.QueueFactory.getQueue;
import static com.google.appengine.api.taskqueue.TaskOptions.Builder.withUrl;
import static google.registry.bigquery.BigqueryUtils.toJobReferenceString;

import com.google.api.services.bigquery.Bigquery;
import com.google.api.services.bigquery.model.Job;
import com.google.api.services.bigquery.model.JobReference;
import com.google.appengine.api.taskqueue.Queue;
import com.google.appengine.api.taskqueue.TaskHandle;
import com.google.appengine.api.taskqueue.TaskOptions;
import com.google.appengine.api.taskqueue.TaskOptions.Method;
import dagger.Lazy;
import google.registry.request.Action;
import google.registry.request.Header;
import google.registry.request.HttpException.BadRequestException;
import google.registry.request.HttpException.NotModifiedException;
import google.registry.request.Payload;
import google.registry.util.FormattingLogger;
import google.registry.util.TaskEnqueuer;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import javax.inject.Inject;
import org.joda.time.Duration;

/**
 * An action which polls the state of a bigquery job. If it is completed then it will log its
 * completion state; otherwise it will return a failure code so that the task will be retried.
 */
@Action(
    path = BigqueryPollJobAction.PATH,
    method = {Action.Method.GET, Action.Method.POST},
    automaticallyPrintOk = true)
public class BigqueryPollJobAction implements Runnable {

  private static final FormattingLogger logger = FormattingLogger.getLoggerForCallerClass();

  static final String QUEUE = "export-bigquery-poll";  // See queue.xml
  static final String PATH = "/_dr/task/pollBigqueryJob";  // See web.xml
  static final String CHAINED_TASK_QUEUE_HEADER = "X-DomainRegistry-ChainedTaskQueue";
  static final String PROJECT_ID_HEADER = "X-DomainRegistry-ProjectId";
  static final String JOB_ID_HEADER = "X-DomainRegistry-JobId";
  static final Duration POLL_COUNTDOWN = Duration.standardSeconds(20);

  @Inject Bigquery bigquery;
  @Inject TaskEnqueuer enqueuer;
  @Inject @Header(CHAINED_TASK_QUEUE_HEADER) Lazy<String> chainedQueueName;
  @Inject @Header(PROJECT_ID_HEADER) String projectId;
  @Inject @Header(JOB_ID_HEADER) String jobId;
  @Inject @Payload byte[] payload;
  @Inject BigqueryPollJobAction() {}

  @Override
  public void run() {
    checkJobOutcome();  // Throws a NotModifiedException if the job hasn't completed.
    if (payload == null || payload.length == 0) {
      return;
    }
    // If there is a payload, it's a chained task, so enqueue it.
    TaskOptions task;
    try {
      task = (TaskOptions) new ObjectInputStream(new ByteArrayInputStream(payload)).readObject();
    } catch (ClassNotFoundException | IOException e) {
      logger.severe(e, e.toString());
      throw new BadRequestException("Cannot deserialize task from payload", e);
    }
    String taskName = enqueuer.enqueue(getQueue(chainedQueueName.get()), task).getName();
    logger.infofmt(
        "Added chained task %s for %s to queue %s: %s",
        taskName,
        task.getUrl(),
        chainedQueueName.get(),
        task.toString());
  }

  /**
   * Returns true if the provided job succeeded, false if it failed, and throws an exception if it
   * is still pending.
   */
  private boolean checkJobOutcome() {
    Job job = null;
    String jobRefString =
        toJobReferenceString(new JobReference().setProjectId(projectId).setJobId(jobId));

    try {
      job = bigquery.jobs().get(projectId, jobId).execute();
    } catch (IOException e) {
      // We will throw a new exception because done==false, but first log this exception.
      logger.warning(e, e.getMessage());
    }
    // If job is not yet done, then throw an exception so that we'll return a failing HTTP status
    // code and the task will be retried.
    if (job == null || !job.getStatus().getState().equals("DONE")) {
      throw new NotModifiedException(jobRefString);
    }

    // Check if the job ended with an error.
    if (job.getStatus().getErrorResult() != null) {
      logger.severefmt("Bigquery job failed - %s - %s", jobRefString, job);
      return false;
    }
    logger.infofmt("Bigquery job succeeded - %s", jobRefString);
    return true;
  }


  /** Helper class to enqueue a bigquery poll job. */
  public static class BigqueryPollJobEnqueuer {

    private final TaskEnqueuer enqueuer;

    @Inject
    BigqueryPollJobEnqueuer(TaskEnqueuer enqueuer) {
      this.enqueuer = enqueuer;
    }

    /** Enqueue a task to poll for the success or failure of the referenced BigQuery job. */
    public TaskHandle enqueuePollTask(JobReference jobRef) {
      return enqueuer.enqueue(getQueue(QUEUE), createCommonPollTask(jobRef).method(Method.GET));
    }

    /**
     * Enqueue a task to poll for the success or failure of the referenced BigQuery job and to
     * launch the provided task in the specified queue if the job succeeds.
     */
    public TaskHandle enqueuePollTask(
        JobReference jobRef, TaskOptions chainedTask, Queue chainedTaskQueue) throws IOException {
      // Serialize the chainedTask into a byte array to put in the task payload.
      ByteArrayOutputStream taskBytes = new ByteArrayOutputStream();
      new ObjectOutputStream(taskBytes).writeObject(chainedTask);
      return enqueuer.enqueue(
          getQueue(QUEUE),
          createCommonPollTask(jobRef)
              .method(Method.POST)
              .header(CHAINED_TASK_QUEUE_HEADER, chainedTaskQueue.getQueueName())
              .payload(taskBytes.toByteArray()));
    }

    /**
     * Enqueue a task to poll for the success or failure of the referenced BigQuery job and to
     * launch the provided task in the specified queue if the job succeeds.
     */
    private static TaskOptions createCommonPollTask(JobReference jobRef) {
      // Omit host header so that task will be run on the current backend/module.
      return withUrl(PATH)
          .countdownMillis(POLL_COUNTDOWN.getMillis())
          .header(PROJECT_ID_HEADER, jobRef.getProjectId())
          .header(JOB_ID_HEADER, jobRef.getJobId());
    }
  }
}