package org.daisy.pipeline.nlp;
   
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.Comparator;
   
   import org.daisy.pipeline.nlp.impl.MatchRule;
   
   public abstract class RuleBasedTextCategorizer extends TextCategorizer {
  
  	@Override
  	public CategorizedWord categorize(String fullcase, String lowercase) {
  		CategorizedWord res = null;
  		int k;
  		// find the first match in the priority-sorted list
  		for (k = 0; res == null && k < mRules.size(); ++k) {
  			// k < mRules.size() is not tested because raising an exception
  			// is the best we can do here
  			res = mRules.get(k).match(fullcase, lowercase);
  		}
  
  		if (res == null) {
  			res = new CategorizedWord();
  			res.category = Category.UNKNOWN;
  			res.word = fullcase.substring(0, 1);
  			return res;
  		}
  
  		// select the longest match with the same priority
  		int priority = mRules.get(k - 1).getPriority();
  		for (; k < mRules.size() && mRules.get(k).getPriority() == priority; ++k) {
  			CategorizedWord m = mRules.get(k).match(fullcase, lowercase);
  			if (m != null && m.word.length() > res.word.length()) {
  				res = m;
  			}
  		}
  
  		return res;
  	}
  
  	@Override
  	public void resetContext() {
  		// this categorizer does not need any context
  	}
  
  	@Override
  	public boolean threadsafe() {
  		return mThreadsafe;
  	}
  
  	// ///// internal helpers //////
  	protected ArrayList<MatchRule> mRules = new ArrayList<MatchRule>();
  
  	protected void addRule(MatchRule rule) {
  		mRules.add(rule);
  	}
  
  	/**
  	 * Should only be called once.
  	 */
  	@Override
  	public void compile() {
  		Collections.sort(mRules, new Comparator<MatchRule>() {
  			@Override
  			public int compare(MatchRule r1, MatchRule r2) {
  				if (r1.getPriority() == r2.getPriority())
  					return (r1 == r2 ? 0 : -1);
  				return (r1.getPriority() > r2.getPriority() ? -1 : 1);
  			}
  		});
  		for (MatchRule rule : mRules) {
  			if (!rule.threadsafe()) {
  				return;
  			}
  		}
  		mThreadsafe = true;
  	}
  
  	private boolean mThreadsafe = false;
  }