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

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.apache.uima.UimaContext;
import org.apache.uima.analysis_engine.AnalysisEngineProcessException;
import org.apache.uima.fit.descriptor.ConfigurationParameter;
import org.apache.uima.fit.util.JCasUtil;
import org.apache.uima.jcas.JCas;
import org.apache.uima.resource.ResourceInitializationException;

import com.google.common.collect.ImmutableSet;

import uk.gov.dstl.baleen.core.pipelines.orderers.AnalysisEngineAction;
import uk.gov.dstl.baleen.core.utils.ConfigUtils;
import uk.gov.dstl.baleen.types.semantic.Entity;
import uk.gov.dstl.baleen.types.semantic.Temporal;
import uk.gov.dstl.baleen.uima.BaleenAnnotator;

/**
 * This cleaner performs the following actions on all Temporal entitites:
 * <ul>
 * <li>For any Temporal entity with timestamps set, checks to see if the timestamp refers to a date more than x years in the past/future and if so removes it.</li>
 * <li>Removes any Temporal entity that begins with a currency sign (this seems to be a common error in the OpenNLP NER model for dates).</li>
 * <li>Optionally removes any timestamp with a value of 0L (generally this means the timestamp has not been set)
 * </ul>
 * 
 * @baleen.javadoc
 */
public class CleanTemporal extends BaleenAnnotator {
	LocalDateTime start = null;
	LocalDateTime end = null;
	
	/**
	 * The number of years before or after the current date that we consider to be valid 
	 * 
	 * @baleen.config 50
	 */
	public static final String PARAM_YEARS = "years";
	@ConfigurationParameter(name = PARAM_YEARS, defaultValue="50")
	private String yearsString;
	
	//Parse the years config parameter into this variable to avoid issues with parameter types
	private int years;
	
	/**
	 * Remove entities with a timestamp set to 0L.
	 * 
	 * Generally, a timestamp will be 0L if it hasn't been set,
	 * but it will also be 0L if the timestamp represents 1970-01-01 00:00:00
	 * and therefore valid data may be removed.
	 * 
	 * @baleen.config removeZeroTimestamp true
	 */
	public static final String PARAM_REMOVE_ZERO_TIMESTAMP = "removeZeroTimestamp";
	@ConfigurationParameter(name = PARAM_REMOVE_ZERO_TIMESTAMP, defaultValue="false")
	private Boolean removeZeroTimestamp;
	
	@Override
	public void doInitialize(UimaContext aContext) throws ResourceInitializationException {
		years = ConfigUtils.stringToInteger(yearsString, 50);
		start = LocalDateTime.now().minusYears(years);
		end = LocalDateTime.now().plusYears(years);
	}
	
	@Override
	public void doProcess(JCas jCas) throws AnalysisEngineProcessException{
		Collection<Temporal> tempora = JCasUtil.select(jCas, Temporal.class);
		List<Entity> toRemove = new ArrayList<>();
		
		for(Temporal t : tempora){
			if(zeroTimestamp(t) || (isMoney(t.getValue()) || isMoney(t.getCoveredText())) || isOutsideRange(t)){
				toRemove.add(t);
				continue;
			}
		}
		
		removeFromJCasIndex(toRemove);
	}
	
	private boolean zeroTimestamp(Temporal t){
		return removeZeroTimestamp && (t.getTimestampStart() == 0L || t.getTimestampStop() == 0L);
	}
	
	private boolean isOutsideRange(Temporal t){
		if(t.getTimestampStart() != 0L && t.getTimestampStart() < start.toEpochSecond(ZoneOffset.UTC))
			return true;
		
		if(t.getTimestampStop() != 0L && t.getTimestampStop() > end.toEpochSecond(ZoneOffset.UTC))
			return true;
		
		return false;
	}
	
	private boolean isMoney(String text){
		return text.startsWith("£") || text.startsWith("$") || text.startsWith("€");
	}
	
	@Override
	public AnalysisEngineAction getAction() {
		return new AnalysisEngineAction(ImmutableSet.of(Temporal.class), Collections.emptySet());
	}
}