// File: Disk.java
//
// Author: Andrew H. Fagg
// 11/15/2
//
// Class that simulates the disk.  The disk is a randomaccess file
//  that contains the bytes necessary to represent all blocks.
//
// To Do: nothing
//

import java.util.*;
import java.lang.*;
import java.io.*;


class Disk {
    public int numBlocks;               // Number of blocks
    public int blockSize;               // Number of bytes within each block
    public RandomAccessFile fp;         // Reference to the file
    public boolean debug_flag;          // Set if in debuggin mode

    //
    // public Disk(String fname, int bs, int nb) {
    //
    // Disk interface constructor
    //  <fname> = the name of the disk file on the base file system
    //  <bs> = size of the blocks
    //  <nb> = number of blocks
    //
    // Exits if there is a file error
    //

    public Disk(String fname, int bs, int nb) {
	// Remember the disk parameters
	blockSize = bs;
	numBlocks = nb;
	debug_flag = false;
	try {
	    // Open the disk file in r/w mode
	    fp = new RandomAccessFile(fname, "rw");
	}catch(FileNotFoundException e) {
	    System.out.println("Disk(): FileNotFoundException " + e);
	    System.exit(1);
	};
    };

    // public void debug(String strg) 
    //
    // Generic debugging logger.
    //  <strg> = String to be written to System.out
    //
    // The string is only written if <debug_flag> has been set.
    //

    public void debug(String strg) {
	if(debug_flag) {
	    System.out.println(strg);
	};
    };

    
    // public void format() throws FileSystemException
    //
    // Format the disk.
    //
    // Effects:
    //  1. Initializes the first block (block 0) as the free block
    //       (the first two blocks are marked as not free)
    //  2. Initializes block 1 as the root directory; it is empty
    //  3. Clears the remaining blocks
    //
    // throws FileSystemException if:
    //  1. There is a disk write error
    //

    public void format() throws FileSystemException {
	int i;

	// Master free space record
	FreeBlock fb = new FreeBlock(this);
	// Initialize free space
	fb.buffer[0] = (byte) 0xfc;
	for(i = 1; i < blockSize; ++i) {
	    fb.buffer[i] = (byte) 0xff;
	};
	fb.write(0);

	// Root directory.
	DirectoryBlock dir = new DirectoryBlock(this);
	dir.write(1);

	// Empty data block for remaining blocks.
	DataBlock db = new DataBlock(this);
  	for(i = 2; i < numBlocks; ++i) {
  	    db.write(i);
	};
    };
};