package cz.muni.fi.pb162.task5;

import java.util.Map;
import java.util.HashMap;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import java.util.HashSet;
import java.util.Collections;

/**
 * Write a description of class ContinentsImpl here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class ContinentsImpl implements Continents
{
    private Map<Continent,Set<Country>> map;
    /**
     * Constructor for objects of class ContinentsImpl
     */
    public ContinentsImpl()
    {
        map=new HashMap<Continent,Set<Country>>();
    }

    /**
     * Adds a country to the continent.
     *
     * @param continent Continent
     * @param country Country to be added
     * @return false if the contitent or country arguments are null or if the continent
     *         already contained the specified country
     */
   public boolean add(Continent continent, Country country){
       if(continent != null && country != null){
           if (map.containsKey(continent)&&!map.get(continent).contains(country)){
            Set set = map.get(continent);
            set.add(country);
            map.put(continent, set);
            return true;
          } else{return false;}
        }
          else{
           return false;
           }

        }

    /**
     * Removes country from the continent.
     *
     * @param continent Continent
     * @param country Country to be removed
     * @return false if the continent does not exist or does not contain specified country
     */
    public boolean remove(Continent continent, Country country){
        if (continent==null||country==null||map.get(continent)==null){
           return false;
        }else{
            return (map.get(continent)).remove(country);
        }
    }

    /**
     * Computes population of the continent.
     *
     * @param continent Continent
     * @return population, 0  if the continent does not exist
     */
    public int getPopulation(Continent continent){
        int count=0;
        if (!(map.containsKey(continent))) { return 0; }

        for (Country c: map.get(continent)) {
            count+= c.getPopulation();
        }
        return count;
    }

    /**
     * @param continent Continent
     * @return All countries of the continent.
     *         If the continent does not exist or has no country then empty
     *         collection is returned.
     */
    public Collection<Country> getCountries(Continent continent){

        if(continent==null||map.containsKey(continent)){
            return Collections.unmodifiableSet(Collections.EMPTY_SET );
        } else{
           return Collections.unmodifiableSet(map.get(continent));
        }

    }

    /**
     * Returns all countries of all continent WITHOUT DUPLICITIES
     * (one country can by located in multiple continets, i.e. Russia).
     *
     * @return all countries of all continents (without duplicities)
     */
    public Collection<Country> getAllCountries(){
        Set<Country> set = new HashSet<Country>();
        for (Continent k: map.keySet()){

            for (Country c: map.get(k)) {
                set.add(c);
            }
        }
        return set;
    }

    /**
     * Searches for the countries with the highest population.
     * Because there can exist multiple most populated countries then a collection is returned.
     *
     * @return Collection of the most populated countries. Never returns null.
     */
    public Collection<Country> getMostPopulatedCountries(){
       double mostPeople = 0;
        Collection<Country> biggest = new HashSet<Country>();

        for (Country c: getAllCountries()){
            if (c.getPopulation()>mostPeople){
                mostPeople=c.getPopulation();
            }
        }

        for (Country c: getAllCountries()){
            if (c.getPopulation()==mostPeople){
                biggest.add(c);
            }
        }

        return biggest;
    }

    /**
     * @return list of continents and their countries. For the format see listings
     *         in the homework assignment
     */
    public String toString(){
        //String countries = new String();
        String continent = new String();
        continent=" ";
        for (Continent k: map.keySet()){
            continent += k.toString();
             continent+="= [";
            for (Country c: map.get(k)) {
                continent+=c.getName() + " ,";
            }
           continent+=" ]";
        }
        return continent;
    }
}