//Dstl (c) Crown Copyright 2017
package uk.gov.dstl.baleen.annotators.regex;

import java.util.Collections;
import java.util.regex.Matcher;

import org.apache.commons.lang.StringUtils;
import org.apache.uima.jcas.JCas;

import com.google.common.collect.ImmutableSet;

import uk.gov.dstl.baleen.annotators.regex.helpers.AbstractRegexAnnotator;
import uk.gov.dstl.baleen.core.pipelines.orderers.AnalysisEngineAction;
import uk.gov.dstl.baleen.types.common.Chemical;

/**
 * Identify chemicals by looking for CAS numbers and checking the check digit
 */
public class CasRegistryNumber extends AbstractRegexAnnotator<Chemical> {
	private static final String CAS_REGEX = "\\b(\\d{2,7})-(\\d{2})-(\\d{1})\\b";
	
	/**
	 * New instance.
	 */
	public CasRegistryNumber() {
		super(CAS_REGEX, false, 1.0f);
	}

	@Override
	protected Chemical create(JCas jCas, Matcher matcher) {
		//Check checksum
		Integer checkDigit = Integer.valueOf(matcher.group(3));
		
		String part1 = matcher.group(1);
		String part2 = matcher.group(2);
		
		part1 = StringUtils.reverse(part1);
		
		Integer sum = Integer.valueOf(part2.substring(1, 2)) + (2*Integer.valueOf(part2.substring(0, 1)));
		Integer pos = 0;
		while(pos < part1.length()){
			Integer x = Integer.valueOf(part1.substring(pos, pos + 1));
			sum += (pos + 3)*x;
			
			pos++;
		}
		
		if(sum % 10 != checkDigit){
			getMonitor().debug("Pattern matching CAS format found, but check digit is incorrect");
			return null;
		}
		
		Chemical c = new Chemical(jCas);
		c.setSubType("CAS");
		return c;
	}

	@Override
	public AnalysisEngineAction getAction() {
		return new AnalysisEngineAction(Collections.emptySet(), ImmutableSet.of(Chemical.class));
	}
}