package com.acumenvelocity.ath.steps;
   
   import java.util.ArrayList;
   import java.util.List;
   
   import net.sf.okapi.common.Event;
   import net.sf.okapi.common.EventType;
   import net.sf.okapi.common.Util;
   import net.sf.okapi.common.pipeline.BasePipelineStep;
  import net.sf.okapi.common.resource.ITextUnit;
  import net.sf.okapi.common.resource.MultiEvent;
  import net.sf.okapi.common.resource.Property;
  
  public abstract class BaseTuBatchProcessingStep extends BasePipelineStep {
  
    private long numProcessedTus;
  
    // TU events to be processed together
    private final List<Event> tuEvents = new ArrayList<>();
  
    // We need to buffer all the events, not only TU ones, or the events sequence will be broken
    private final List<Event> allEvents = new ArrayList<>();
  
    protected abstract void clear();
  
    protected abstract void processTuEvents(List<Event> tuEvents);
  
    @Override
    protected Event handleStartDocument(Event event) {
      numProcessedTus = 0;
      return super.handleStartDocument(event);
    }
  
    private void clearEvents() {
      clear(); // Let subclasses clear their stuff
      allEvents.clear();
      tuEvents.clear();
    }
  
    @Override
    public Event handleEvent(Event event) {
      // Collect the original events
      allEvents.add(event);
  
      Event e = super.handleEvent(event); // Call handleXX(), ignore the results
      return event.isEndDocument() ? e : Event.createNoopEvent();
    }
  
    @Override
    protected Event handleTextUnit(Event event) {
      ITextUnit tu = event.getTextUnit();
  
      // Exclude non-translatable TUs from MT
      if (!tu.isTranslatable()) {
        return event;
      }
  
      // Exclude approved TUs from MT
      Property prop = tu.getTargetProperty(getTargetLocale(), Property.APPROVED);
  
      if (prop != null) {
        if ("yes".equals(prop.getValue()))
          return event;
      }
  
      numProcessedTus++;
      tuEvents.add(event);
      return Event.createNoopEvent(); // Can return event, ignored in the handleEvent() caller
    }
  
    @Override
    protected Event handleEndDocument(Event event) {
      if (Util.isEmpty(allEvents)) {
        // We get here from the END_DOCUMENT of exploded MULTI_EVENT
        return event;
      }
      
      // TU events are also part of allEvents in the right positions
      processTuEvents(tuEvents);
  
      // We create a copy of the list, the events themselves are alive after we clean the list
      MultiEvent me = new MultiEvent(List.copyOf(allEvents));
      clearEvents(); // Release memory
  
      return new Event(EventType.MULTI_EVENT, me);
    }
  
    public long getNumProcessedTus() {
      return numProcessedTus;
    }
  }