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

class Disk 
{
  public final static int BLOCK_SIZE = 512;       // blobk size in bytes
  public final static int NUM_BLOCKS = 1000;      // # of disk blocks
  public final static int POINTERS_PER_BLOCK = (BLOCK_SIZE/4);
  private int readCount = 0;                      // # or reads/writes
  private int writeCount = 0;                     // to filesystem

	// the file representing the simulated  disk
  private File fileName;                     
  private RandomAccessFile disk;

	// read in the file representing the simulated disk
  public Disk() 
  {
    try 
    {
      fileName = new File("DISK");
      disk = new RandomAccessFile(fileName, "rw");
    }
    catch (IOException e) 
    {
      System.err.println ("Unable to start the disk");
      System.exit(1);
    }
  }

  private void seek(int blocknum) throws IOException 
  {
    if (blocknum < 0 || blocknum >= NUM_BLOCKS) 
      throw new RuntimeException ("Attempt to read block " +
					       blocknum + " is out of range");
    disk.seek((long)(blocknum * BLOCK_SIZE));
  }

  public void read(int blocknum, byte[] buffer) // read block into buffer
  {
    if (buffer.length != BLOCK_SIZE) 
      throw new RuntimeException("Read: bad buffer size " + buffer.length);
    try 
    {
      seek(blocknum);
      disk.read(buffer);
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    readCount++;
  } 

  public void read(int blocknum, SuperBlock block) 
  {
    try 
    {
      seek(blocknum);
      block.size = disk.readInt();
      block.iSize = disk.readInt();
      block.freeList = disk.readInt();
    }
    catch (EOFException e) 
    {
      if (blocknum != 0) 
      {
        System.err.println(e);
        System.exit(1);
      }
      block.size = block.iSize = block.freeList = 0;
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    readCount++;
  } 

  public void read(int blocknum, InodeBlock block) 
  {
    try 
    {
      seek(blocknum);
      for (int i=0; i<block.node.length; i++) 
      {
        block.node[i].flags = disk.readInt();
        block.node[i].owner = disk.readInt();
        block.node[i].fileSize = disk.readInt();
        for (int j=0; j<13; j++)
          block.node[i].pointer[j] = disk.readInt();
      }
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    readCount++;
  } 
		
  public void read(int blocknum, IndirectBlock block) 
  {
    try 
    {
      seek(blocknum);
      for (int i=0; i<block.pointer.length; i++)
        block.pointer[i] = disk.readInt();
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    readCount++;
  } 

  public void write(int blocknum, byte[] buffer)  // write block
  {
    if (buffer.length != BLOCK_SIZE) 
      throw new RuntimeException("Write: bad buffer size " + buffer.length);
    try 
    {
      seek(blocknum);
      disk.write(buffer);
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    writeCount++;
  }

  public void write(int blocknum, SuperBlock block) 
  {
    try 
    {
      seek(blocknum);
      disk.writeInt(block.size);
      disk.writeInt(block.iSize);
      disk.writeInt(block.freeList);
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    writeCount++;
  } 

  public void write(int blocknum, InodeBlock block) 
  {
    try 
    {
      seek(blocknum);
      for (int i=0; i<block.node.length; i++) 
      {
        disk.writeInt(block.node[i].flags);
        disk.writeInt(block.node[i].owner);
        disk.writeInt(block.node[i].fileSize);
        for (int j=0; j<13; j++)
          disk.writeInt(block.node[i].pointer[j]);
      }
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    writeCount++;
  } 
		
  public void write(int blocknum, IndirectBlock block) 
  {
    try 
    {
      seek(blocknum);
      for (int i=0; i<block.pointer.length; i++)
        disk.writeInt(block.pointer[i]);
    }
    catch (IOException e) 
    {
      System.err.println(e);
      System.exit(1);
    }
    writeCount++;
  } 

  public void stop(boolean removeFile)           // stop FS simulation
  {
    System.out.println (generateStats());
    if (removeFile)
      fileName.delete();
  }

  public void stop() 
  {
    stop(true);
  }

  public String generateStats()                 // report stats
  {
    return ("DISK: Read count: " + readCount + " Write count: " + writeCount);
  }
}