package com.novelbook.android.utils;

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * 按照插入顺序排序的Map，当超出容量时，将最早插入的对象移除。
 *
 * @param <K>
 * @param <V>
 */
public class FIFOMap<K, V> extends LinkedHashMap<K, V> {
	private static final long serialVersionUID = 27034646516234314L;

	protected int maxSize;
	public FIFOMap(int maxSize) {
		super(maxSize, 0.75f, false);
		this.maxSize = maxSize;
	}
	
	@Override
	protected boolean removeEldestEntry(Entry<K, V> eldest) {
		return maxSize < size();
	}

	@Override
	public synchronized V put(K key, V value) {
		return super.put(key, value);
	}

	@Override
	public synchronized void putAll(Map<? extends K, ? extends V> m) {
		super.putAll(m);
	}

	@Override
	public synchronized V remove(Object key) {
		return super.remove(key);
	}

	public void setCapacity(int size) {
		maxSize = size;
	}
	public int getCapacity() {
		return maxSize;
	}
	
	public static void main(String[] args) {
		int maxSize = 100;
		FIFOMap<Integer, Integer> map = new FIFOMap<Integer, Integer>(maxSize);
		for (int i = 1; i <= maxSize; i++) {
			map.put(i, i);
			assertTrue(map.size() == i);
		}
		
		for (int i = 1; i <= maxSize; i++) {
			map.put(i, i);
			assertTrue(map.size() == maxSize);
		}

		for (int i = 101; i <= 100 + maxSize; i++) {
			map.put(i, i);
			assertTrue(map.size() == maxSize);
		}
		for (int i = 191; i <= 100 + maxSize; i++) {
			map.remove(i);
			assertTrue(map.size()== maxSize + 190 - i );
		}

		for (int i = 101; i <= 100 + maxSize; i++) {
			map.put(i, i);
		}

		for (int i = 1; i <= 10000 + maxSize; i++) {
			map.put(i, i);
		}
		assertTrue(map.size() == maxSize);
	}
	
	private static void assertTrue(boolean flag) {
		if ( !flag )  System.out.println("should be true. but is false.");
	}
}