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

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.apache.uima.resource.Resource;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;

import uk.gov.dstl.baleen.exceptions.BaleenException;

/**
 * An abstract class to implement a gazetteer using a MultiMap as the backend.
 * 
 * Developers should provide a reloadValues() method, and override any existing methods they wish to extend.
 * 
 * The following configuration parameters are expected/allowed:
 * <ul>
 * <li><b>caseSensitive</b> - If false, then all values are lower cased; otherwise the original casing is kept and comparisons are done case sensitively. Defaults to false</li>
 * </ul>
 * 
 * 
 * @param <T> The type used for the ID of terms
 */
public abstract class AbstractMultiMapGazetteer<T> implements IGazetteer {
	private Multimap<T, String> idToValues = ArrayListMultimap.create();
	private Map<String, T> valueToId = new HashMap<>();
	
	public static final String CONFIG_CASE_SENSITIVE = "caseSensitive";
	public static final Boolean DEFAULT_CASE_SENSITIVE = false;

	protected boolean caseSensitive = DEFAULT_CASE_SENSITIVE;
	
	@Override
	public void init(Resource connection, Map<String, Object> config) throws BaleenException {
		caseSensitive = false;
		if (config.containsKey(CONFIG_CASE_SENSITIVE) && "true".equalsIgnoreCase(config.get(CONFIG_CASE_SENSITIVE).toString())) {
			caseSensitive = true;
		}

		reloadValues();
	}

	@Override
	public String[] getValues() {
		return valueToId.keySet().toArray(new String[0]);
	}

	@Override
	public boolean hasValue(String key) {
		return valueToId.containsKey(caseSensitive ? key : key.toLowerCase());
	}

	@Override
	public String[] getAliases(String key) {
		String val = caseSensitive ? key : key.toLowerCase();
		T id = valueToId.get(val);
		
		return idToValues.get(id).stream().filter(s -> !s.equals(val)).toArray(size -> new String[size]);
	}

	@Override
	public Map<String, Object> getAdditionalData(String key) {
		return Collections.emptyMap();
	}

	@Override
	public void destroy() {
		idToValues = null;
		valueToId = null;
	}
	
	protected void reset(){
		valueToId.clear();
		idToValues.clear();
	}
	
	protected void addTerm(T id, String value){
		String val = value;
		if(!caseSensitive){
			val = value.toLowerCase();
		}

		valueToId.put(val, id);
		idToValues.put(id, val);
	}
	
	protected T getId(String value){
		return valueToId.get(caseSensitive ? value : value.toLowerCase());
	}
}