/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community 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://opensource.org/licenses/ecl2.txt
   *
   * 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 org.opencastproject.adminui.util;
  
  import static org.opencastproject.adminui.endpoint.AbstractEventEndpoint.SCHEDULING_AGENT_ID_KEY;
  import static org.opencastproject.adminui.endpoint.AbstractEventEndpoint.SCHEDULING_END_KEY;
  import static org.opencastproject.adminui.endpoint.AbstractEventEndpoint.SCHEDULING_START_KEY;
  
  import org.opencastproject.elasticsearch.api.SearchIndexException;
  import org.opencastproject.elasticsearch.index.ElasticsearchIndex;
  import org.opencastproject.elasticsearch.index.objects.event.Event;
  import org.opencastproject.index.service.api.IndexService;
  import org.opencastproject.index.service.catalog.adapter.events.CommonEventCatalogUIAdapter;
  import org.opencastproject.mediapackage.MediaPackageElements;
  
  import org.json.simple.JSONArray;
  import org.json.simple.JSONObject;
  import org.json.simple.parser.JSONParser;
  import org.json.simple.parser.ParseException;
  
  import java.time.DayOfWeek;
  import java.time.Duration;
  import java.time.Instant;
  import java.time.ZoneId;
  import java.time.ZoneOffset;
  import java.time.ZonedDateTime;
  import java.time.format.DateTimeFormatter;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.List;
  import java.util.Optional;
  
  
  /**
   * This class holds utility functions which are related to the bulk update feature for events.
   */
  public final class BulkUpdateUtil {
  
    private static final JSONParser parser = new JSONParser();
  
    private BulkUpdateUtil() {
    }
  
    /**
     * Wraps the IndexService.getEvent() method to convert SearchIndexExceptions into RuntimeExceptions. Useful when
     * using Java's functional programming features.
     *
     * @param indexSvc The IndexService instance.
     * @param index The index to get the event from.
     * @param id The id of the event to get.
     * @return An optional holding the event or nothing, if not found.
     */
    public static Optional<Event> getEvent(
      final IndexService indexSvc,
      final ElasticsearchIndex index,
      final String id) {
      try {
        return indexSvc.getEvent(id, index);
      } catch (SearchIndexException e) {
        throw new RuntimeException(e);
      }
    }
  
    /**
     * Takes the given scheduling information and completes the event start and end dates as well as the duration for the
     * given event. If the weekday shall be changed, the start and end dates are adjusted accordingly.
     *
     * @param event The event to complete the scheduling information for.
     * @param scheduling The (yet incomplete) scheduling information to complete.
     * @return The completed scheduling information, adjusted for the given event.
     */
    @SuppressWarnings("unchecked")
    public static JSONObject addSchedulingDates(final Event event, final JSONObject scheduling) {
      final JSONObject result = deepCopy(scheduling);
      ZonedDateTime startDate = ZonedDateTime.parse(event.getRecordingStartDate());
      ZonedDateTime endDate = ZonedDateTime.parse(event.getRecordingEndDate());
      final InternalDuration oldDuration = InternalDuration.of(startDate.toInstant(), endDate.toInstant());
      final ZoneId timezone = ZoneId.of((String) result.get("timezone"));
  
     // The client only sends start time hours and/or minutes. We have to apply this to each event to get a full date.
     if (result.containsKey(SCHEDULING_START_KEY)) {
       startDate = adjustedSchedulingDate(result, SCHEDULING_START_KEY, startDate, timezone);
     }
     // The client only sends end time hours and/or minutes. We have to apply this to each event to get a full date.
     if (result.containsKey(SCHEDULING_END_KEY)) {
       endDate = adjustedSchedulingDate(result, SCHEDULING_END_KEY, endDate, timezone);
     }
     if (endDate.isBefore(startDate)) {
       endDate = endDate.plusDays(1);
     }
 
     // If duration is set, we have to adjust the end or start date.
     if (result.containsKey("duration")) {
       final JSONObject time = (JSONObject) result.get("duration");
       final InternalDuration newDuration = new InternalDuration(oldDuration);
       if (time.containsKey("hour")) {
         newDuration.hours = (Long) time.get("hour");
       }
       if (time.containsKey("minute")) {
         newDuration.minutes = (Long) time.get("minute");
       }
       if (time.containsKey("second")) {
         newDuration.seconds = (Long) time.get("second");
       }
       if (result.containsKey(SCHEDULING_END_KEY)) {
         startDate = endDate.minusHours(newDuration.hours)
           .minusMinutes(newDuration.minutes)
           .minusSeconds(newDuration.seconds);
       } else {
         endDate = startDate.plusHours(newDuration.hours)
           .plusMinutes(newDuration.minutes)
           .plusSeconds(newDuration.seconds);
       }
     }
 
     // Setting the weekday means that the event should be moved to the new weekday within the same week
     if (result.containsKey("weekday")) {
       final String weekdayAbbrev = ((String) result.get("weekday"));
       if (weekdayAbbrev != null) {
         final DayOfWeek newWeekDay = Arrays.stream(DayOfWeek.values())
           .filter(d -> d.name().startsWith(weekdayAbbrev.toUpperCase()))
           .findAny()
           .orElseThrow(() -> new IllegalArgumentException("Cannot parse weekday: " + weekdayAbbrev));
         final int daysDiff = newWeekDay.getValue() - startDate.getDayOfWeek().getValue();
         startDate = startDate.plusDays(daysDiff);
         endDate = endDate.plusDays(daysDiff);
       }
     }
 
     result.put(SCHEDULING_START_KEY, startDate.format(DateTimeFormatter.ISO_INSTANT));
     result.put(SCHEDULING_END_KEY, endDate.format(DateTimeFormatter.ISO_INSTANT));
     return result;
   }
 
   /**
    * Creates a json object containing meta data based on the given scheduling information.
    *
    * @param scheduling The scheduling information to extract meta data from.
    * @return The meta data, consisting of location, startDate, and duration.
    */
   @SuppressWarnings("unchecked")
   public static JSONObject toNonTechnicalMetadataJson(final JSONObject scheduling) {
     final List<JSONObject> fields = new ArrayList<>();
     if (scheduling.containsKey(SCHEDULING_AGENT_ID_KEY)) {
       final JSONObject locationJson = new JSONObject();
       locationJson.put("id", "location");
       locationJson.put("value", scheduling.get(SCHEDULING_AGENT_ID_KEY));
       fields.add(locationJson);
     }
     if (scheduling.containsKey(SCHEDULING_START_KEY) && scheduling.containsKey(SCHEDULING_END_KEY)) {
       final JSONObject startDateJson = new JSONObject();
       startDateJson.put("id", "startDate");
       final String startDate = Instant.parse((String) scheduling.get(SCHEDULING_START_KEY))
         .atOffset(ZoneOffset.UTC)
         .format(DateTimeFormatter.ISO_LOCAL_DATE_TIME) + ".000Z";
       startDateJson.put("value", startDate);
       fields.add(startDateJson);
 
       final JSONObject durationJson = new JSONObject();
       durationJson.put("id", "duration");
       final Instant start = Instant.parse((String) scheduling.get(SCHEDULING_START_KEY));
       final Instant end = Instant.parse((String) scheduling.get(SCHEDULING_END_KEY));
       final InternalDuration duration = InternalDuration.of(start, end);
       durationJson.put("value", duration.toString());
       fields.add(durationJson);
     }
 
     final JSONObject result = new JSONObject();
     result.put("flavor", MediaPackageElements.EPISODE.toString());
     result.put("title", CommonEventCatalogUIAdapter.EPISODE_TITLE);
     result.put("fields", fields);
     return result;
   }
 
   /**
    * Merges all fields of the given meta data json objects into one object.
    *
    * @param first The first meta data json object.
    * @param second The second meta data json object.
    * @return A new json meta data object, containing the field of both input objects.
    */
   @SuppressWarnings("unchecked")
   public static JSONObject mergeMetadataFields(final JSONObject first, final JSONObject second) {
     if (first == null) {
       return second;
     }
     if (second == null) {
       return first;
     }
     final JSONObject result = deepCopy(first);
     final Collection fields = (Collection) result.get("fields");
     fields.addAll((Collection) second.get("fields"));
     return result;
   }
 
   private static JSONObject deepCopy(final JSONObject o) {
     try {
       return (JSONObject) parser.parse(o.toJSONString());
     } catch (ParseException e) {
       throw new IllegalArgumentException(e);
     }
   }
 
   private static class InternalDuration {
     private long hours;
     private long minutes;
     private long seconds;
 
     InternalDuration() {
     }
 
     InternalDuration(final InternalDuration other) {
       this.hours = other.hours;
       this.minutes = other.minutes;
       this.seconds = other.seconds;
     }
 
     public static InternalDuration of(final Instant start, final Instant end) {
       final InternalDuration result = new InternalDuration();
       final Duration duration = Duration.between(start, end);
       result.hours = duration.toHours();
       result.minutes = duration.minusHours(result.hours).toMinutes();
       result.seconds = duration.minusHours(result.hours).minusMinutes(result.minutes).getSeconds();
       return result;
     }
 
     @Override
     public String toString() {
       return String.format("%02d:%02d:%02d", hours, minutes, seconds);
     }
   }
 
   private static ZonedDateTime adjustedSchedulingDate(
     final JSONObject scheduling,
     final String dateKey,
     final ZonedDateTime date,
     final ZoneId timezone) {
     final JSONObject time = (JSONObject) scheduling.get(dateKey);
     ZonedDateTime result = date.withZoneSameInstant(timezone);
     if (time.containsKey("hour")) {
       final int hour = Math.toIntExact((Long) time.get("hour"));
       result = result.withHour(hour);
     }
     if (time.containsKey("minute")) {
       final int minute = Math.toIntExact((Long) time.get("minute"));
       result = result.withMinute(minute);
     }
     return result.withZoneSameInstant(ZoneOffset.UTC);
   }
 
   /**
    * Model class for one group of update instructions
    */
   public static class BulkUpdateInstructionGroup {
     private final List<String> eventIds;
     private final JSONObject metadata;
     private final JSONObject scheduling;
 
     /**
      * Create a new group from parsed JSON data
      *
      * @param eventIds Event IDs in this group
      * @param metadata Metadata for this group
      * @param scheduling Scheduling for this group
      */
     public BulkUpdateInstructionGroup(final List<String> eventIds, final JSONObject metadata, final JSONObject scheduling) {
       this.eventIds = eventIds;
       this.metadata = metadata;
       this.scheduling = scheduling;
     }
 
     /**
      * Get the list of IDs of events to apply the bulk update to.
      *
      * @return The list of IDs of the events to apply the bulk update to.
      */
     public List<String> getEventIds() {
       return eventIds;
     }
 
     /**
      * Get the meta data update to apply.
      *
      * @return The meta data update to apply.
      */
     public JSONObject getMetadata() {
       return metadata;
     }
 
     /**
      *  Get the scheduling information update to apply.
      *
      * @return The scheduling information update to apply.
      */
     public JSONObject getScheduling() {
       return scheduling;
     }
   }
 
   /**
    * Model class for the bulk update instructions which are sent by the UI.
    */
   public static class BulkUpdateInstructions {
     private static final String KEY_EVENTS = "events";
     private static final String KEY_METADATA = "metadata";
     private static final String KEY_SCHEDULING = "scheduling";
 
     private final List<BulkUpdateInstructionGroup> groups;
 
     /**
      * Create a new instance by parsing the given json String.
      *
      * @param json The json serialized version of the bulk update instructions sent by the UI.
      *
      * @throws IllegalArgumentException If the json string cannot be parsed.
      */
     @SuppressWarnings("unchecked")
     public BulkUpdateInstructions(final String json) throws IllegalArgumentException {
       try {
         final JSONArray root = (JSONArray) parser.parse(json);
         groups = new ArrayList<>(root.size());
         for (final Object jsonGroup : root) {
           final JSONObject jsonObject = (JSONObject) jsonGroup;
           final JSONArray eventIds = (JSONArray) jsonObject.get(KEY_EVENTS);
           final JSONObject metadata = (JSONObject) jsonObject.get(KEY_METADATA);
           final JSONObject scheduling = (JSONObject) jsonObject.get(KEY_SCHEDULING);
           groups.add(new BulkUpdateInstructionGroup(eventIds, metadata, scheduling));
         }
       } catch (final ParseException e) {
         throw new IllegalArgumentException(e);
       }
     }
 
     public List<BulkUpdateInstructionGroup> getGroups() {
       return groups;
     }
   }
 
 }