/*
 * Copyright (c) 2017 Google Inc. 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.android.vts.job;

import static com.googlecode.objectify.ObjectifyService.ofy;

import com.android.vts.entity.CodeCoverageEntity;
import com.android.vts.entity.DeviceInfoEntity;
import com.android.vts.entity.TestCoverageStatusEntity;
import com.android.vts.entity.TestRunEntity;
import com.android.vts.util.EmailHelper;
import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.EntityNotFoundException;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;
import com.google.appengine.api.datastore.Query;
import com.google.appengine.api.taskqueue.Queue;
import com.google.appengine.api.taskqueue.QueueFactory;
import com.google.appengine.api.taskqueue.TaskOptions;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.RoundingMode;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.lang.StringUtils;

/**
 * Coverage notification job.
 */
public class VtsCoverageAlertJobServlet extends BaseJobServlet {

  private static final String COVERAGE_ALERT_URL = "/task/vts_coverage_job";
  protected static final Logger logger =
      Logger.getLogger(VtsCoverageAlertJobServlet.class.getName());
  protected static final double CHANGE_ALERT_THRESHOLD = 0.05;
  protected static final double GOOD_THRESHOLD = 0.7;
  protected static final double BAD_THRESHOLD = 0.3;

  protected static final DecimalFormat FORMATTER;

  /** Initialize the decimal formatter. */
  static {
    FORMATTER = new DecimalFormat("#.#");
    FORMATTER.setRoundingMode(RoundingMode.HALF_UP);
  }

  /**
   * Gets a new coverage status and adds notification emails to the messages list.
   *
   * Send an email to notify subscribers in the event that a test goes up or down by more than 5%,
   * becomes higher or lower than 70%, or becomes higher or lower than 30%.
   *
   * @param status The TestCoverageStatusEntity object for the test.
   * @param testRunKey The key for TestRunEntity whose data to process and reflect in the state.
   * @param link The string URL linking to the test's status table.
   * @param emailAddresses The list of email addresses to send notifications to.
   * @param messages The email Message queue.
   * @returns TestCoverageStatusEntity or null if no update is available.
   */
  public static TestCoverageStatusEntity getTestCoverageStatus(
      TestCoverageStatusEntity status,
      Key testRunKey,
      String link,
      List<String> emailAddresses,
      List<Message> messages)
      throws IOException {
    DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

    String testName = status.getTestName();

    double previousPct;
    double coveragePct;
    if (status == null || status.getTotalLineCount() <= 0 || status.getCoveredLineCount() < 0) {
      previousPct = 0;
    } else {
      previousPct = ((double) status.getCoveredLineCount()) / status.getTotalLineCount();
    }

    Entity testRun;
    try {
      testRun = datastore.get(testRunKey);
    } catch (EntityNotFoundException e) {
      logger.log(Level.WARNING, "Test run not found: " + testRunKey);
      return null;
    }

    TestRunEntity testRunEntity = TestRunEntity.fromEntity(testRun);
        if (testRunEntity == null || !testRunEntity.getHasCodeCoverage()) {
      return null;
    }
    CodeCoverageEntity codeCoverageEntity = testRunEntity.getCodeCoverageEntity();

    if (codeCoverageEntity.getTotalLineCount() <= 0
            || codeCoverageEntity.getCoveredLineCount() < 0) {
        coveragePct = 0;
    } else {
        coveragePct =
                ((double) codeCoverageEntity.getCoveredLineCount())
                        / codeCoverageEntity.getTotalLineCount();
    }

    Set<String> buildIdList = new HashSet<>();
    Query deviceQuery = new Query(DeviceInfoEntity.KIND).setAncestor(testRun.getKey());
    List<DeviceInfoEntity> devices = new ArrayList<>();
    for (Entity device : datastore.prepare(deviceQuery).asIterable()) {
      DeviceInfoEntity deviceEntity = DeviceInfoEntity.fromEntity(device);
      if (deviceEntity == null) {
        continue;
      }
      devices.add(deviceEntity);
      buildIdList.add(deviceEntity.getBuildId());
    }
    String deviceBuild = StringUtils.join(buildIdList, ", ");
    String footer = EmailHelper.getEmailFooter(testRunEntity, devices, link);

    String subject = null;
    String body = null;
    String subjectSuffix = " @ " + deviceBuild;
    if (coveragePct >= GOOD_THRESHOLD && previousPct < GOOD_THRESHOLD) {
      // Coverage entered the good zone
      subject =
          "Congratulations! "
              + testName
              + " has exceeded "
              + FORMATTER.format(GOOD_THRESHOLD * 100)
              + "% coverage"
              + subjectSuffix;
      body =
          "Hello,<br><br>The "
              + testName
              + " has achieved "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    } else if (coveragePct < GOOD_THRESHOLD && previousPct >= GOOD_THRESHOLD) {
      // Coverage dropped out of the good zone
      subject =
          "Warning! "
              + testName
              + " has dropped below "
              + FORMATTER.format(GOOD_THRESHOLD * 100)
              + "% coverage"
              + subjectSuffix;
      ;
      body =
          "Hello,<br><br>The test "
              + testName
              + " has dropped to "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    } else if (coveragePct <= BAD_THRESHOLD && previousPct > BAD_THRESHOLD) {
      // Coverage entered into the bad zone
      subject =
          "Warning! "
              + testName
              + " has dropped below "
              + FORMATTER.format(BAD_THRESHOLD * 100)
              + "% coverage"
              + subjectSuffix;
      body =
          "Hello,<br><br>The test "
              + testName
              + " has dropped to "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    } else if (coveragePct > BAD_THRESHOLD && previousPct <= BAD_THRESHOLD) {
      // Coverage emerged from the bad zone
      subject =
          "Congratulations! "
              + testName
              + " has exceeded "
              + FORMATTER.format(BAD_THRESHOLD * 100)
              + "% coverage"
              + subjectSuffix;
      body =
          "Hello,<br><br>The test "
              + testName
              + " has achived "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    } else if (coveragePct - previousPct < -CHANGE_ALERT_THRESHOLD) {
      // Send a coverage drop alert
      subject =
          "Warning! "
              + testName
              + "'s code coverage has decreased by more than "
              + FORMATTER.format(CHANGE_ALERT_THRESHOLD * 100)
              + "%"
              + subjectSuffix;
      body =
          "Hello,<br><br>The test "
              + testName
              + " has dropped from "
              + FORMATTER.format(previousPct * 100)
              + "% code coverage to "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    } else if (coveragePct - previousPct > CHANGE_ALERT_THRESHOLD) {
      // Send a coverage improvement alert
      subject =
          testName
              + "'s code coverage has increased by more than "
              + FORMATTER.format(CHANGE_ALERT_THRESHOLD * 100)
              + "%"
              + subjectSuffix;
      body =
          "Hello,<br><br>The test "
              + testName
              + " has increased from "
              + FORMATTER.format(previousPct * 100)
              + "% code coverage to "
              + FORMATTER.format(coveragePct * 100)
              + "% code coverage on device build ID(s): "
              + deviceBuild
              + "."
              + footer;
    }
    if (subject != null && body != null) {
      try {
        messages.add(EmailHelper.composeEmail(emailAddresses, subject, body));
      } catch (MessagingException | UnsupportedEncodingException e) {
        logger.log(Level.WARNING, "Error composing email : ", e);
      }
    }
        return new TestCoverageStatusEntity(
                testName,
                testRunEntity.getStartTimestamp(),
                codeCoverageEntity.getCoveredLineCount(),
                codeCoverageEntity.getTotalLineCount(),
                devices.size() > 0 ? devices.get(0).getId() : 0);
  }

  /**
   * Add a task to process coverage data
   *
   * @param testRunKey The key of the test run whose data process.
   */
  public static void addTask(Key testRunKey) {
    Queue queue = QueueFactory.getDefaultQueue();
    String keyString = KeyFactory.keyToString(testRunKey);
    queue.add(
        TaskOptions.Builder.withUrl(COVERAGE_ALERT_URL)
            .param("runKey", keyString)
            .method(TaskOptions.Method.POST));
  }

  @Override
  public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws IOException {
    String runKeyString = request.getParameter("runKey");

    Key testRunKey;
    try {
      testRunKey = KeyFactory.stringToKey(runKeyString);
    } catch (IllegalArgumentException e) {
      logger.log(Level.WARNING, "Invalid key specified: " + runKeyString);
      return;
    }
    String testName = testRunKey.getParent().getName();

    TestCoverageStatusEntity status = ofy().load().type(TestCoverageStatusEntity.class).id(testName)
        .now();
    if (status == null) {
            status = new TestCoverageStatusEntity(testName, 0, -1, -1, 0);
    }

    StringBuffer fullUrl = request.getRequestURL();
    String baseUrl = fullUrl.substring(0, fullUrl.indexOf(request.getRequestURI()));
    String link = baseUrl + "/show_tree?testName=" + testName;
    TestCoverageStatusEntity newStatus;
    List<Message> messageQueue = new ArrayList<>();
    try {
      List<String> emails = EmailHelper.getSubscriberEmails(testRunKey.getParent());
      newStatus = getTestCoverageStatus(status, testRunKey, link, emails, messageQueue);
    } catch (IOException e) {
      logger.log(Level.SEVERE, e.toString());
      return;
    }

    if (newStatus == null) {
      return;
    } else {
      if (status == null || status.getUpdatedTimestamp() < newStatus.getUpdatedTimestamp()) {
        newStatus.save();
        EmailHelper.sendAll(messageQueue);
      }
    }
  }
}