/*****************************************************************
/ In recitation today, we developed a class hierarchy for a      /
/ file system.  I've done a little bit of prettying it up and    /
/ have created a compilable version, below.  Most of the method  /
/ method code is left out, but in a few places where I thought   /
/ it helped to illustrate something, I put in a couple of lines. /
/        -- Alan Frank, 4 January 2001                           /
*****************************************************************/

import java.io.*;   // for System.out.println
import java.util.*; // for Date

/**
A file system; may or may not be hierarchical
*/
public class FileSystem {
	protected int	capacity;
	protected int	fileNameMaxLength;
	protected boolean readOnly;
	protected Device	location;
	protected Directory rootDirectory;

	/* constructor & accessor methods are omitted from the listings
	   of this and other classes.
	*/

	public void DeleteFile (File goner) {}
	File FindFile (String fileName)
	{
		return rootDirectory.FindFile (fileName);
	}

	public static File FindFileAnywhere (String fileName)
	{
		// loops through all FileSystems to find file
		return null; // so we can compile this
	}
} // end class FileSystem

/**
A hierarchical file system; that means that directories can have
subdirectories, <I>ad infinitum</I>
*/
public class HierarchicalFileSystem extends FileSystem {
	protected Directory currentDirectory;

	public void changeDirectory (String directoryName)
	{
		currentDirectory = (Directory) FindFile (directoryName);
	}
	public void changeDirectoryRelative (String subdirectoryName) {}
	public void changeDirectory (Directory destinationDirectory)
	{
		currentDirectory = destinationDirectory;
	}
	/* void AddFile (File newFile, Directory parentDirectory)
	   This isn't implemented; instead, use
		parentDirectory.AddFile(newFile);

	   CreateDirectory (String name) isn't implemented either; use
		parentDirectory.AddFile (new Directory (name, fileSystem));
	*/
} // end class HierarchicalFileSystem

/**
A file, but we can't do anything with it
*/
public abstract class File {
	protected String 	name;
	protected Date	updatedDate;
	protected int	size;
	private BunchOfBlocks blocks [];

	abstract public void Edit ();
	abstract public void Display ();
	static void Edit (String fileName)
	{
		FileSystem.FindFileAnywhere (fileName).Edit();
	}
	/**
	This inner class allows us to keep together all the
	information about the blocks that make up this file.
	*/
	private class BunchOfBlocks {
		private int startingBlock;
		private int numberOfBlocks;
		BunchOfBlocks (int position, int sb, int nob)
		{
			startingBlock = sb;
			numberOfBlocks = nob;
			blocks [position] = this;
		}
	}
}

public interface Executable {
	public void Execute ();
}

public class Directory extends File {
	File	fileList [];
	FileSystem fileSystem;

	public void Edit ()
	{
		System.out.println ("I don't know how to edit a directory.");
	}
	public void Display ()
	{
		// Run ("ls " + name);
	}
	public File FindFile (String name)
	{
		return null;
	}
} // end class Directory
	
public class TextFile extends File {
	public void Edit ()
	{
		// Run ("emacs " + name);
	}
	public void Display ()
	{
		// Run ("cat " + name);
	}
}

public class HTML extends TextFile implements Executable {
	public void Execute ()
	{
		// put code here to call browser
	}
}

public class ShellScript extends TextFile implements Executable {
	public void Execute ()
	{
		// Code here to run a shell script
	}
}

public class BinaryFile extends File {
	public void Edit ()
	{
		// Put some code here to edit a binary file
	}
	public void Display ()
	{
		// Put some code here to display a binary file
	}
}

public class JavaClassFile extends BinaryFile implements Executable {
	public HTML FindJavadoc ()
	{
		// left as an exercise
		return null; // if not found
	}
	public void Display ()
	{
		HTML	javadoc;
		javadoc = FindJavadoc();
		if (javadoc == null)
			super.Display ();
		else
			javadoc.Execute();
	}
	public void Execute ()
	{
		// Run ("java " + name);
	}
} // end class JavaClassFile

public class Device {} // dummy