package com.fengxing.ams.tvclient.videomedia;

import com.fengxing.ams.tvclient.intf.IPageMediaDataSource;

import org.apache.commons.io.IOUtils;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.nio.ByteBuffer;

import java.util.HashSet;

import java.util.Set;

import java.util.concurrent.locks.Lock;

import java.util.concurrent.locks.ReentrantLock;

/**

* Created by Administrator on 2016/6/4.

*/

public abstract class AbstractMediaDataSource implements IPageMediaDataSource {

protected static final String TAG = "CacheDataSource";

private final Lock lock = new ReentrantLock();

//一次申明重复利用，子类不能直接操作cache

private ByteBuffer cacheBuffer = ByteBuffer.allocate((int) PAGE_MAX_SIZE);

protected String url;

private long currentPage = -1;

protected long videoId;

protected File rootDisk;

private int zeroBackTime = 0;

@Override

public abstract int readAt(long position, byte[] buffer, int offset, int size) throws IOException;

@Override

public void desctory() {

lock.lock();

try {

cacheBuffer.clear();

cacheBuffer = null;

currentPage = -1;

} finally {

lock.unlock();

}

}

public int readFormBuffer(long position, byte[] buffer, int offset, int size) {

lock.lock();

try {

cacheBuffer.rewind();

int exceptPosition = (int) (position % PAGE_MAX_SIZE);

if (exceptPosition >= cacheBuffer.limit())

return -1;

cacheBuffer.position(exceptPosition);

//如果没有元素则返回0

if (!cacheBuffer.hasRemaining()) {

zeroBackTime++;

if (zeroBackTime > 3) {

return -1;

}

return 0;

} else {

zeroBackTime = 0;

}

int exceptSize = size > cacheBuffer.remaining() ? cacheBuffer.remaining() : size;

cacheBuffer.get(buffer, offset, exceptSize);

return exceptSize;

} finally {

lock.unlock();

}

}

public long getPageForPosition(long position) {

return position / PAGE_MAX_SIZE;

}

public long getCurrentPage() {

return this.currentPage;

}

public long getStartPosition(long page) {

return page * PAGE_MAX_SIZE;

}

public long getEndPosition(long page, int size) {

return ((page + 1L) * PAGE_MAX_SIZE) - 1L;

}

public void write(long position, byte[] b) {

lock.lock();

try {

//清理缓存数据，将位置设置为 0，将限制设置为容量

if (cacheBuffer != null) {

cacheBuffer.clear();

//放入数据

cacheBuffer.put(b).position(0).limit(b.length);

this.currentPage = this.getPageForPosition(position);

}

} finally {

lock.unlock();

}

}

}