package cn.twinkling.stream.util;

import java.io.Closeable;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;

import cn.twinkling.stream.servlet.FormDataServlet;
import cn.twinkling.stream.servlet.Range;
import cn.twinkling.stream.servlet.StreamServlet;

/**
 * IO--closing, getting file name ... main function method
 */
public class IoUtil {
	static final Pattern RANGE_PATTERN = Pattern.compile("bytes \\d+-\\d+/\\d+");
	/** where the file should be put on. */
	public static final String REPOSITORY = System.getProperty("java.io.tmpdir", "/tmp/upload-repository");
	
	/**
	 * According the key, generate a file (if not exist, then create
	 * a new file).
	 * @param key
	 * @return
	 * @throws IOException
	 */
	public static File getFile(String key) throws IOException {
		return getFile(key, null);
	}
	
	/**
	 * According the key, generate a file (if not exist, then create
	 * a new file).
	 * @param key
	 * @param fullPath the file relative path(something like `a../bxx/wenjian.txt`)
	 * @return
	 * @throws IOException
	 */
	public static File getFile(String key, String fullPath) throws IOException {
		if (key == null || key.isEmpty())
			return null;
		String folder = "";
		if (fullPath != null && !fullPath.isEmpty()
				&& fullPath.indexOf("/") > 0) {
			int index = fullPath.lastIndexOf("/");
			folder = fullPath.substring(0, index).replaceAll("/", File.separator);
		}
		File f = new File(REPOSITORY + File.separator + folder + File.separator + key);
		if (!f.getParentFile().exists())
			f.getParentFile().mkdirs();
		if (!f.exists())
			f.createNewFile();
		
		return f;
	}

	/**
	 * Acquired the file.
	 * @param key
	 * @return
	 * @throws FileNotFoundException If key not found, will throws this.
	 */
	public static File getTokenedFile(String key) throws FileNotFoundException {
		if (key == null || key.isEmpty())
			return null;

		File f = new File(REPOSITORY + File.separator + key);
		if (!f.getParentFile().exists())
			f.getParentFile().mkdirs();
		if (!f.exists())
			throw new FileNotFoundException("File `" +f + "` not exist.");
		
		return f;
	}
	
	/**
	 * close the IO stream.
	 * @param stream
	 */
	public static void close(Closeable stream) {
		try {
			if (stream != null)
				stream.close();
		} catch (IOException e) {
		}
	}
	
	/**
	 * 获取Range参数
	 * @param req
	 * @return
	 * @throws IOException
	 */
	public static Range parseRange(HttpServletRequest req) throws IOException {
		String range = req.getHeader(StreamServlet.CONTENT_RANGE_HEADER);
		Matcher m = RANGE_PATTERN.matcher(range);
		if (m.find()) {
			range = m.group().replace("bytes ", "");
			String[] rangeSize = range.split("/");
			String[] fromTo = rangeSize[0].split("-");

			long from = Long.parseLong(fromTo[0]);
			long to = Long.parseLong(fromTo[1]);
			long size = Long.parseLong(rangeSize[1]);

			return new Range(from, to, size);
		}
		throw new IOException("Illegal Access!");
	}

	/**
	 * From the InputStream, write its data to the given file.
	 */
	public static long streaming(InputStream in, String key, String fileName) throws IOException {
		OutputStream out = null;
		long size = 0;
		try {
			File f = getFile(key);
			out = new FileOutputStream(f);

			int read = 0;
			final byte[] bytes = new byte[FormDataServlet.BUFFER_LENGTH];
			while ((read = in.read(bytes)) != -1) {
				out.write(bytes, 0, read);
			}
			out.flush();
			/** rename the file */
			f.renameTo(getFile(fileName));
			
			size = getFile(fileName).length();
		} finally {
			close(out);
		}
		return size;
	}
}