package com.acumenvelocity.ath.steps;
   
   import net.sf.okapi.common.Event;
   import net.sf.okapi.common.IResource;
   import net.sf.okapi.common.pipeline.BasePipelineStep;
   import net.sf.okapi.common.resource.ISegments;
   import net.sf.okapi.common.resource.ITextUnit;
   import net.sf.okapi.common.resource.Segment;
   import net.sf.okapi.common.resource.TextContainer;
  
  public abstract class BaseMergerStep extends BasePipelineStep {
  
    private long position;
  
    protected abstract void setTargetSegment(ITextUnit tu, Segment sseg, Segment tseg,
        long position);
  
    @Override
    protected Event handleStartDocument(Event event) {
      // Reset the position within the document
      position = 0;
      return super.handleStartDocument(event);
    }
  
    public static boolean checkTu(ITextUnit tu) {
      if (!tu.isTranslatable()) {
        return false;
      }
  
      TextContainer source = tu.getSource();
  
      if (source == null) {
        return false;
      }
  
      return source.hasText();
    }
  
    /**
     * Override to handle TU in a different way
     * @param tu
     */
    protected void processTu(ITextUnit tu) {
      TextContainer source = tu.getSource();
      TextContainer target = tu.getTarget(getTargetLocale());
  
      if (target == null) {
        target = tu.createTarget(getTargetLocale(), true, IResource.COPY_ALL);
      }
  
      ISegments ssegs = source.getSegments();
      ISegments tsegs = target.getSegments();
  
      for (Segment sseg : ssegs) {
        if (sseg == null) {
          continue;
        }
  
        position++;      
        Segment tseg = tsegs.get(sseg.getId());
        
        if (tseg == null) {
          continue;
        }
        
        setTargetSegment(tu, sseg, tseg, position);
      }
    }
  
    @Override
    protected Event handleTextUnit(Event event) {
      ITextUnit tu = event.getTextUnit();
  
      if (checkTu(tu)) {
        processTu(tu);
      }
  
      return super.handleTextUnit(event);
    }
  }