package com.nostra13.universalimageloader.cache.disc.impl;



import java.io.File;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;



import com.nostra13.universalimageloader.cache.disc.BaseDiscCache;

import com.nostra13.universalimageloader.cache.disc.naming.FileNameGenerator;

import com.nostra13.universalimageloader.cache.disc.naming.HashCodeFileNameGenerator;



/**

 * Cache which deletes files which were loaded more than defined time. Cache size is unlimited.

 * 

 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)

 * @see BaseDiscCache

 */

public class LimitedAgeDiscCache extends BaseDiscCache {



	private final long maxFileAge;



	private final Map<File, Long> loadingDates = Collections.synchronizedMap(new HashMap<File, Long>());



	/**

	 * @param cacheDir

	 *            Directory for file caching

	 * @param maxAge

	 *            Max file age (in seconds). If file age will exceed this value then it'll be removed on next treatment

	 *            (and therefore be reloaded).

	 */

	public LimitedAgeDiscCache(File cacheDir, long maxAge) {

		this(cacheDir, new HashCodeFileNameGenerator(), maxAge);

	}



	/**

	 * @param cacheDir

	 *            Directory for file caching

	 * @param fileNameGenerator

	 *            Name generator for cached files

	 * @param maxAge

	 *            Max file age (in seconds). If file age will exceed this value then it'll be removed on next treatment

	 *            (and therefore be reloaded).

	 */

	public LimitedAgeDiscCache(File cacheDir, FileNameGenerator fileNameGenerator, long maxAge) {

		super(cacheDir, fileNameGenerator);

		this.maxFileAge = maxAge * 1000; // to milliseconds

		readLoadingDates();

	}



	private void readLoadingDates() {

		File[] cachedFiles = getCacheDir().listFiles();

		for (File cachedFile : cachedFiles) {

			loadingDates.put(cachedFile, cachedFile.lastModified());

		}

	}



	@Override

	public void put(String key, File file) {

		long currentTime = System.currentTimeMillis();

		file.setLastModified(currentTime);

		loadingDates.put(file, currentTime);

	}



	@Override

	public File get(String key) {

		File file = super.get(key);

		if (file.exists()) {

			Long loadingDate = loadingDates.get(file);

			if (loadingDate == null) {

				loadingDate = file.lastModified();

			}

			if (System.currentTimeMillis() - loadingDate > maxFileAge) {

				file.delete();

				loadingDates.remove(file);

			}

		}

		return file;

	}

}