/*
 * Copyright 2018 John Grosh (john.a.grosh@gmail.com).
 *
 * 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.vortex.utils;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

/**
 *
 * @author John Grosh (john.a.grosh@gmail.com)
 * @param <K> key type
 * @param <V> cache item type
 */
public class FixedCache<K, V>
{
    private final Map<K, V> map;
    private final K[] keys;
    private int currIndex = 0;

    public FixedCache(int size)
    {
        this.map = new HashMap<>();
        if(size < 1)
            throw new IllegalArgumentException("Cache size must be at least 1!");
        this.keys = (K[]) new Object[size];
    }

    public V put(K key, V value)
    {
        if(map.containsKey(key))
        {
            return map.put(key, value);
        }
        if(keys[currIndex] != null)
        {
            map.remove(keys[currIndex]);
        }
        keys[currIndex] = key;
        currIndex = (currIndex + 1) % keys.length;
        return map.put(key, value);
    }

    public V pull(K key)
    {
        return map.remove(key);
    }
    
    public V get(K key)
    {
        return map.get(key);
    }
    
    public boolean contains(K key)
    {
        return map.containsKey(key);
    }
    
    public Collection<V> getValues()
    {
        return map.values();
    }
}