/*
 * Copyright 2016 John Grosh (jagrosh).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.jagrosh.jmusicbot.queue;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 *
 * @author John Grosh (jagrosh)
 * @param <T>
 */
public class FairQueue<T extends Queueable> 
{
    private final List<T> list = new ArrayList<>();
    private final Set<Long> set = new HashSet<>();
    
    public int add(T item)
    {
        int lastIndex;
        for(lastIndex=list.size()-1; lastIndex>-1; lastIndex--)
            if(list.get(lastIndex).getIdentifier() == item.getIdentifier())
                break;
        lastIndex++;
        set.clear();
        for(; lastIndex<list.size(); lastIndex++)
        {
            if(set.contains(list.get(lastIndex).getIdentifier()))
                break;
            set.add(list.get(lastIndex).getIdentifier());
        }
        list.add(lastIndex, item);
        return lastIndex;
    }
    
    public void addAt(int index, T item)
    {
        if(index >= list.size())
            list.add(item);
        else
            list.add(index, item);
    }
    
    public int size()
    {
        return list.size();
    }
    
    public T pull()
    {
        return list.remove(0);
    }
    
    public boolean isEmpty()
    {
        return list.isEmpty();
    }
    
    public List<T> getList()
    {
        return list;
    }
    
    public T get(int index)
    {
        return list.get(index);
    }
    
    public T remove(int index)
    {
        return list.remove(index);
    }
    
    public int removeAll(long identifier)
    {
        int count = 0;
        for(int i=list.size()-1; i>=0; i--)
        {
            if(list.get(i).getIdentifier()==identifier)
            {
                list.remove(i);
                count++;
            }
        }
        return count;
    }
    
    public void clear()
    {
        list.clear();
    }
    
    public int shuffle(long identifier)
    {
        List<Integer> iset = new ArrayList<>();
        for(int i=0; i<list.size(); i++)
        {
            if(list.get(i).getIdentifier()==identifier)
                iset.add(i);
        }
        for(int j=0; j<iset.size(); j++)
        {
            int first = iset.get(j);
            int second = iset.get((int)(Math.random()*iset.size()));
            T temp = list.get(first);
            list.set(first, list.get(second));
            list.set(second, temp);
        }
        return iset.size();
    }
    
    public void skip(int number)
    {
        for(int i=0; i<number; i++)
            list.remove(0);
    }

    /**
     * Move an item to a different position in the list
     * @param from The position of the item
     * @param to The new position of the item
     * @return the moved item
     */
    public T moveItem(int from, int to)
    {
        T item = list.remove(from);
        list.add(to, item);
        return item;
    }
}