/**
 * 
 */
package org.mpi.openmind.repository.utils;

import java.io.IOException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.csv.QuoteMode;
import org.apache.commons.lang.ArrayUtils;
import org.mpi.openmind.repository.bo.Attribute;
import org.mpi.openmind.repository.bo.Entity;

/**
 * Class that creates a CSV file from a List of Entities.
 * 
 * Creates columns for all Attributes.
 * 
 * @author casties
 *
 */
public class CsvEntityListWriter {

    public static void writeEntities(List<Entity> entities, Appendable output) throws IOException {
        Set<String> attNameSet = new HashSet<String>();
        /*
         * create a list of all attribute names
         */
        for (Entity entity : entities) {
            for (Attribute att : entity.getAttributes()) {
                attNameSet.add(att.getName());
            }
        }
        String[] attNames = attNameSet.toArray(new String[attNameSet.size()]);
        String[] entProps = new String[] {"id", "object_class", "own_value"};
        String[] headers = (String[]) ArrayUtils.addAll(entProps, attNames);
        // create CSV format with header
        CSVFormat format = CSVFormat.DEFAULT.withHeader(headers).withQuoteMode(QuoteMode.NON_NUMERIC);
        // create CSVPrinter
        CSVPrinter printer = new CSVPrinter(output, format);
        
        /*
         * print all Entities
         */
        for (Entity entity : entities) {
            for (String field : headers) {
                if (field.equals("id")) {
                    printer.print(entity.getId());
                    
                } else if (field.equals("object_class")) {
                    printer.print(entity.getObjectClass());
                    
                } else if (field.equals("own_value")) {
                    printer.print(entity.getOwnValue());
                    
                } else {
                    // print attribute
                    Attribute att = entity.getAttributeByName(field);
                    if (att != null) {
                        printer.print(att.getOwnValue());
                    } else {
                        printer.print(null);
                    }
                }
            }
            printer.println();
        }
        printer.flush();
        printer.close();
    }
}