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

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.uima.UimaContext;
import org.apache.uima.analysis_engine.AnalysisEngineProcessException;
import org.apache.uima.fit.descriptor.ConfigurationParameter;
import org.apache.uima.resource.ResourceInitializationException;

import uk.gov.dstl.baleen.exceptions.BaleenException;
import uk.gov.dstl.baleen.resources.gazetteer.IGazetteer;
import uk.gov.dstl.baleen.types.BaleenAnnotation;
import uk.gov.dstl.baleen.uima.data.TextBlock;

/**
 * Abstract class that builds on AbstractAhoCorasickAnnotator, but rather than searching the entire
 * document for gazetteer matches, it uses a regular expression to find potential matches and then
 * checks to see whether they appear in the Gazetteer.
 *
 *
 * @baleen.javadoc
 */
public abstract class AbstractRegexAhoCorasickAnnotator extends AbstractAhoCorasickAnnotator {

	/**
	 * The regular expression to check against
	 *
	 * @baleen.config \\b\\w*\\b
	 */
	public static final String PARAM_REGEX = "regex";
	@ConfigurationParameter(name = PARAM_REGEX, defaultValue = "\\b\\w*\\b")
	protected String regex;

	Pattern regexPattern;

	/**
	 * Constructor
	 */
	public AbstractRegexAhoCorasickAnnotator() {
		// Do nothing
	}

	@Override
	public abstract IGazetteer configureGazetteer() throws BaleenException;

	@Override
	public void doInitialize(UimaContext aContext) throws ResourceInitializationException {
		super.doInitialize(aContext);

		if (caseSensitive) {
			regexPattern = Pattern.compile(regex);
		} else {
			regexPattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);
		}
	}

	@Override
	public void doProcessTextBlock(TextBlock block) throws AnalysisEngineProcessException {
		Map<String, List<BaleenAnnotation>> entities = new HashMap<>();

		Matcher m = regexPattern.matcher(block.getCoveredText());
		while (m.find()) {
			String csValue = caseSensitive ? m.group() : m.group().toLowerCase();
			if (gazetteer.hasValue(csValue)) {
				try {
					BaleenAnnotation ent = createEntity(block, m.start(), m.end(), m.group(), csValue);

					List<String> aliases = new ArrayList<>(Arrays.asList(gazetteer.getAliases(csValue)));
					aliases.add(csValue);

					String key = generateKey(aliases);

					List<BaleenAnnotation> groupEntities = entities.containsKey(key) ? entities.get(key)
							: new ArrayList<>();
					groupEntities.add(ent);
					entities.put(key, groupEntities);
				} catch (Exception e) {
					getMonitor().error("Unable to create entity of type '{}' for value '{}'", entityType.getName(),
							m.group(), e);
					continue;
				}
			}
		}

		createReferenceTargets(block, entities.values());
	}
}