package com.smtscript.lib.file;

import java.io.File;
import java.io.RandomAccessFile;
import java.nio.channels.FileLock;
import java.nio.charset.Charset;

public class JSFileLock 
{
	protected File				_file;
	protected FileLock			_fileLock;
	protected RandomAccessFile 	_randomAccessFile;
	protected Charset			_charset;
	
	public JSFileLock(String fileName) throws Exception
	{
		_charset = Charset.forName("UTF-8");
		_file = new File(fileName);
		_randomAccessFile = new RandomAccessFile(_file, "rw");
	}
	
	public boolean tryLockWrite() throws Exception
	{
		if(_fileLock != null)
			throw new Exception("file has been locked");
		_fileLock = _randomAccessFile.getChannel().tryLock();
		return _fileLock != null;
	}
	
	public void waitLockWrite() throws Exception
	{
		if(_fileLock != null)
			throw new Exception("file has been locked");
		_fileLock = _randomAccessFile.getChannel().lock();
	}
	
	public void setFileLength(int length) throws Exception
	{
		_randomAccessFile.setLength((long)length);
	}
	
	public void setFilePos(int pos) throws Exception
	{
		_randomAccessFile.seek((long)pos);
	}
	
	public int getFilePos() throws Exception
	{
		return (int)_randomAccessFile.getFilePointer();
	}
	
	public int getFileSize() throws Exception
	{
		return (int)_randomAccessFile.length();
	}
	
	public void writeAllText(String text) throws Exception
	{
		_randomAccessFile.setLength(0);
		_randomAccessFile.write(text.getBytes(_charset));
	}
	
	public String readAllText() throws Exception
	{
		_randomAccessFile.seek(0);
		int size = (int)_randomAccessFile.length();
		byte[] data = new byte[size];
		_randomAccessFile.read(data);
		
		return new String(data, _charset);
	}
	
	public void unlock() throws Exception
	{
		if(_fileLock != null)
		{
			_fileLock.release();
			_fileLock = null;
		}
	}
	
	public void close(boolean deleteFile) throws Exception
	{
		unlock();
		if(_randomAccessFile != null)
		{
			_randomAccessFile.close();
			_randomAccessFile = null;
		}
		if(_file != null && deleteFile)
		{
			_file.delete();
			_file = null;
		}
	}
}