//Dstl (c) Crown Copyright 2017
package uk.gov.dstl.baleen.uima.utils;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import org.apache.uima.cas.CAS;
import org.apache.uima.cas.CommonArrayFS;
import org.apache.uima.cas.Feature;
import org.apache.uima.jcas.tcas.Annotation;
import org.slf4j.LoggerFactory;

/**
 * Some commonly used functions to handle CAS Features
 *
 * 
 */
public class FeatureUtils {

	private FeatureUtils() {
		// Singleton
	}

	/**
	 * Convert a UIMA feature to a Java object of the correct type
	 *
	 * @param f UIMA CAS Feature
	 * @param a UIMA CAS Annotation
	 * @return Java object, or null if unable to convert
	 */
	public static Object featureToObject(Feature f, Annotation a){
		Object ret = null;
		
		switch(f.getRange().getName()){
		case CAS.TYPE_NAME_STRING:
			ret = StringToObject.convertStringToObject(a.getStringValue(f));
			break;
		case CAS.TYPE_NAME_INTEGER:
			ret = a.getIntValue(f);
			break;
		case CAS.TYPE_NAME_FLOAT:
			ret = a.getFloatValue(f);
			break;
		case CAS.TYPE_NAME_BOOLEAN:
			ret = a.getBooleanValue(f);
			break;
		case CAS.TYPE_NAME_BYTE:
			ret = a.getByteValue(f);
			break;
		case CAS.TYPE_NAME_SHORT:
			ret = a.getShortValue(f);
			break;
		case CAS.TYPE_NAME_LONG:
			ret = a.getLongValue(f);
			break;
		case CAS.TYPE_NAME_DOUBLE:
			ret = a.getDoubleValue(f);
			break;
		default:
			ret = null;
		}
		
		return ret;
	}

	/**
	 * Convert a UIMA feature array to an array of Java objects of the correct type, parsing Strings to objects where possible
	 *
	 * @param f UIMA CAS Feature
	 * @param a UIMA CAS Annotation
	 * @return Array of Java objects, or null if unable to convert
	 */
	public static Object[] featureToArray(Feature f, Annotation a){
		Object[] ret;
		
		if(a.getFeatureValue(f) == null){
			ret = new Object[0];
		}else{
			ret = toArray(f, a);
		}
		
		return ret;
	}
	
	/**
	 * Convert a UIMA feature array to a List of Java objects of the correct type, parsing Strings to objects where possible
	 *
	 * @param f UIMA CAS Feature
	 * @param a UIMA CAS Annotation
	 * @return List of Java objects, or empty if unable to convert
	 */
	public static List<Object> featureToList(Feature f, Annotation a){
		if(a.getFeatureValue(f) == null){
			return Collections.emptyList();
		}

		return Arrays.asList(toArray(f, a));
	}
	
	private static Object[] toArray(Feature f, Annotation a){
		Object[] ret;
		
		try{
			CommonArrayFS array = (CommonArrayFS) a.getFeatureValue(f);
			ret = new Object[array.size()];
			int index = 0;
			for(String s : array.toStringArray()){
				ret[index] = StringToObject.convertStringToObject(s);
				index++;
			}
			
			return ret;
		}catch(ClassCastException cce){
			LoggerFactory.getLogger(FeatureUtils.class).debug("Couldn't cast feature value to array", cce);
			return new Object[0];
		}
	}
}