package util;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.HashMap;

import java.util.LinkedHashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import java.util.Set;

/**

 * Provides additional methods for collection operation

 * @author zhengc

 *

 */

public class CollectionsEx {

    @SuppressWarnings("hiding")

    /**

     * Returns sorted HashMap by descend Value

     * @param map the original HashMap 

     * @return sorted HashMap by descend Value

     */

    public static <String, Double extends Comparable<? super Double>> Map<String, Double> sortByValueR( Map<String, Double> map ) {

        /* sort map by value reversed*/

        List<Map.Entry<String, Double>> list = new LinkedList<>(map.entrySet());

        Collections.sort(list, Collections.reverseOrder(new Comparator<Map.Entry<String, Double>>() {

            public int compare( Map.Entry<String, Double> o1, Map.Entry<String, Double> o2 ) {

                return ( o1.getValue() ).compareTo( o2.getValue() );

            }

        }) );

        Map<String, Double> result = new LinkedHashMap<>();

        for (Map.Entry<String, Double> entry : list){

            result.put( entry.getKey(), entry.getValue() );

        }

        return result;

    }

    @SuppressWarnings("hiding")

    /**

     * Returns sorted HashMap by Value

     * @param map the original HashMap 

     * @return sorted HashMap by Value

     */

    public static <String, Double extends Comparable<? super Double>> Map<String, Double> sortByValue( Map<String, Double> map ) {

        /* sort map by value*/

        List<Map.Entry<String, Double>> list = new LinkedList<>(map.entrySet());

        Collections.sort(list, new Comparator<Map.Entry<String, Double>>() {

            public int compare( Map.Entry<String, Double> o1, Map.Entry<String, Double> o2 ) {

                return ( o1.getValue() ).compareTo( o2.getValue() );

            }

        } );

        Map<String, Double> result = new LinkedHashMap<>();

        for (Map.Entry<String, Double> entry : list){

            result.put( entry.getKey(), entry.getValue() );

        }

        return result;

    }

//  public static Map<String, String> sortByKey(Map<String, String> map ) {

//      /* sort map by key*/

//      Map<String, String> sortedmap = new HashMap<String, String>();

//      Set<String> keys = map.keySet();

//      List<String> key_list = setToList(keys);

//      Collections.sort(key_list);

//      

//      for(String key : key_list) {

//          System.out.println(key);

//          sortedmap.put(key, map.get(key));

//      }

//      return sortedmap;

//  }

    /**

     * Creates a list from a set

     * @param set a set

     * @return a list

     */

    public static List<String> setToList(Set<String> set) {

        List<String> list = new ArrayList<String>();

        for (String s: set) {

            list.add(s);

        }

        Collections.sort(list);

        return list;

    }

}