/*
 * Copyright (c) 2001 Matthew Feldt. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided the copyright notice above is
 * retained.
 *
 * THIS SOFTWARE IS PROVIDED ''AS IS'' AND WITHOUT ANY EXPRESSED OR
 * IMPLIED WARRANTIES.
 */

/**
 * DirectoryDiskUsage.java
 *
 * Java Examples In A Nutshell Copyright (c) 2000 David Flanagan
 * Exercise 3-4:
 * Write a program that adds up and reports the size of all files in a
 * specified directory. It should recursively scan any subdirectories,
 * summing and reporting the size of the files that they contain, and
 * incorporate those directory sizes into its final output.
 *
 * @author Matthew Feldt <developer@feldt.com>
 * @version 1.0, 01/30/2001 10:56
 */

package com.feldt.examples.io;
import java.io.*;

class DirectoryDiskUsage {
	/**
	 * Static method to recursively compute the amount of storage used
	 * in a specified directory.
	 */
	public static long getDiskUsage(File dir) throws IllegalArgumentException {
		long total = 0;
		if (! dir.exists())
			throw new IllegalArgumentException(dir + " does not exist.");
		if (! dir.canRead())
			throw new IllegalArgumentException(dir + " read protected.");

		File[] entries = dir.listFiles();
		for (int i = 0; i < entries.length; i++) {
			if (entries[i].isFile())
				total += entries[i].length();
			else if (entries[i].isDirectory()) // recurse
				total += getDiskUsage(entries[i]);
		}

		return total;
	}

	/** test class */
	static class Test {
		public static void main (String args[]) {
			final String usage = "Usage: java DirectoryDiskUsage$Test dir";

			if (args.length != 1) {
				System.err.println(usage);
				System.exit(-1);
			}

			File dir = new File(args[0]);
			System.out.println(dir + " " +
				DirectoryDiskUsage.getDiskUsage(dir));
		}
	}
}