/*
    * Copyright (C) 2024 B3Partners B.V.
    *
    * SPDX-License-Identifier: MIT
    */
   package org.tailormap.api.repository.events;
   
   import java.lang.invoke.MethodHandles;
   import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  import java.util.UUID;
  import org.quartz.JobDataMap;
  import org.quartz.JobKey;
  import org.quartz.Scheduler;
  import org.quartz.SchedulerException;
  import org.quartz.impl.matchers.GroupMatcher;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.data.rest.core.annotation.HandleAfterDelete;
  import org.springframework.data.rest.core.annotation.HandleBeforeSave;
  import org.springframework.data.rest.core.annotation.RepositoryEventHandler;
  import org.springframework.stereotype.Component;
  import org.tailormap.api.persistence.SearchIndex;
  import org.tailormap.api.scheduling.IndexTask;
  import org.tailormap.api.scheduling.TMJobDataMap;
  import org.tailormap.api.scheduling.Task;
  import org.tailormap.api.scheduling.TaskManagerService;
  import org.tailormap.api.scheduling.TaskType;
  
  /**
   * Event handler for Solr indexes; when a {@code SearchIndex} is created, updated or deleted a {@code Task} is
   * associated.
   */
  @Component
  @RepositoryEventHandler
  public class SearchIndexEventHandler {
    private static final Logger logger =
        LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
  
    private final Scheduler scheduler;
    private final TaskManagerService taskManagerService;
  
    public SearchIndexEventHandler(@Autowired Scheduler scheduler, @Autowired TaskManagerService taskManagerService) {
      this.scheduler = scheduler;
      this.taskManagerService = taskManagerService;
    }
  
    /**
     * Handle after delete. Delete any associated task.
     *
     * @param searchIndex the search index that was deleted
     */
    @HandleAfterDelete
    public void afterDeleteSearchIndexEventHandler(SearchIndex searchIndex) throws SchedulerException {
      if (null != searchIndex.getSchedule()) {
        JobKey jobKey = taskManagerService.getJobKey(
            TaskType.INDEX, searchIndex.getSchedule().getUuid());
  
        if (null != jobKey && scheduler.checkExists(jobKey)) {
          logger.info(
              "Deleting index task {} associated with search index: {}",
              searchIndex.getSchedule().getUuid(),
              searchIndex.getName());
          boolean succes = scheduler.deleteJob(jobKey);
          logger.info(
              "Task {}:{} deletion {}",
              jobKey.getGroup(),
              jobKey.getName(),
              (succes ? "succeeded" : "failed"));
        }
      }
    }
  
    /**
     * Handle before save. Create or update the associated task.
     *
     * @param searchIndex the search index that was saved
     * @throws SchedulerException if the task could not be created or updated
     */
    @HandleBeforeSave
    public void beforeSaveSearchIndexEventHandler(SearchIndex searchIndex) throws SchedulerException {
      // TODO we don't handle the case where the schedule is null here; we would need to determine if
      //   a task exists that was associated with the search index before;
      //   this case can already be handled requesting a delete of the scheduled task instead
      if (null != searchIndex.getSchedule()) {
        if (null == searchIndex.getSchedule().getUuid()) {
          validateNoTaskExistsForIndex(searchIndex);
          // no task exists yet, create one
          logger.info("Creating new task associated with search index: {}", searchIndex.getName());
          TMJobDataMap jobDataMap = new TMJobDataMap(Map.of(
              Task.TYPE_KEY,
              TaskType.INDEX,
              Task.DESCRIPTION_KEY,
              searchIndex.getSchedule().getDescription(),
              IndexTask.INDEX_KEY,
              searchIndex.getId().toString()));
          if (null != searchIndex.getSchedule().getPriority()
             && searchIndex.getSchedule().getPriority() > 0) {
           jobDataMap.put(Task.PRIORITY_KEY, searchIndex.getSchedule().getPriority());
         }
         final UUID uuid = taskManagerService.createTask(
             IndexTask.class, jobDataMap, searchIndex.getSchedule().getCronExpression());
         searchIndex.getSchedule().setUuid(uuid);
       } else {
         // UUID given, task should exist; update it
         logger.info(
             "Updating task {} associated with search index: {}",
             searchIndex.getSchedule().getUuid(),
             searchIndex.getName());
 
         JobKey jobKey = taskManagerService.getJobKey(
             TaskType.INDEX, searchIndex.getSchedule().getUuid());
         if (null != jobKey && scheduler.checkExists(jobKey)) {
           // the only things that may have changed are the cron expression, priority and description
           JobDataMap jobDataMap = scheduler.getJobDetail(jobKey).getJobDataMap();
           jobDataMap.put(
               Task.DESCRIPTION_KEY, searchIndex.getSchedule().getDescription());
           jobDataMap.put(
               Task.CRON_EXPRESSION_KEY, searchIndex.getSchedule().getCronExpression());
           if (null != searchIndex.getSchedule().getPriority()
               && searchIndex.getSchedule().getPriority() > 0) {
             jobDataMap.put(
                 Task.PRIORITY_KEY, searchIndex.getSchedule().getPriority());
           }
 
           taskManagerService.updateTask(jobKey, new TMJobDataMap(jobDataMap));
         }
       }
     }
   }
 
   /**
    * Validate that no scheduled task exists for the given index.
    *
    * @param searchIndex the search index to validate for scheduling a task
    * @throws SchedulerException if there is a task that is already associated with the given index
    */
   private void validateNoTaskExistsForIndex(SearchIndex searchIndex) throws SchedulerException {
     Optional<JobDataMap> jobDataMapOptional =
         scheduler.getJobKeys(GroupMatcher.groupEquals(TaskType.INDEX.getValue())).stream()
             .map(jobKey -> {
               try {
                 return scheduler.getJobDetail(jobKey).getJobDataMap();
               } catch (SchedulerException e) {
                 logger.error("Error getting task detail", e);
                 return null;
               }
             })
             .filter(Objects::nonNull)
             .filter(jobDataMap -> searchIndex.getId().equals(jobDataMap.getLongValue(IndexTask.INDEX_KEY)))
             .findFirst();
 
     if (jobDataMapOptional.isPresent()) {
       logger.warn("A scheduled task already exists for search index: {}", searchIndex.getName());
       throw new SchedulerException(
           "A scheduled task already exists for search index: '%s'".formatted(searchIndex.getName()));
     }
   }
 }