// Programmer:    Kasia Trapszo
// Course:        CS 152 
// Project:       Project 1
// Program:       od
// Description:   Unix od utility (octal dump)
// Files:         User specified input file


import java.io.*;

public class od {

   // Defines the end of file 
   public final static int EOF = -1;

   // Proper usage message
   private final static String usageMessage[] =
      { " ",
        "The Usage is:",
        " ",
        "   java od -h             Printout this message",
        " ",
        "   java od -b [FileName]  Printout the contents of a file as octal",
        " ",
        "   java od -c [FileName]  Printout all printable characters in a file",
        "                          as ASCII, all control characters as corresponding",
        "                          letter preceded by a backslash and rest in octal." };
                                 
   
   
   public static void main(String args[]) {

      od o = new od();

      // If the number of arguments is 0, program prints out usage message
      // and exits
      if (args.length == 0) {
         System.out.println("Error:  Invalid number of arguments");
         o.printStringArray(usageMessage);
         return;
      }   
      
      // If the number of arguments is higher than 2, program prints out
      // usage message and exits
      if (args.length > 2) {
         System.out.println("Error:  Invalid number of arguments");
         o.printStringArray(usageMessage);
         return;
      }
      
      // Option -h, prints out usage message
      if (args[0].equals("-h")) {
         o.printStringArray(usageMessage);
      }
      
      // option -b prints out the octal representation of a user
      // specified file
      else if (args[0].equals("-b")) {
         
         
         // If the number of arguments is less than 2, program exits with
         // an error message
         if (args.length < 2) {
            System.out.println("Error:  Invalid number of arguments");
            return;
         }
         
         // If the procedure worked succesfully, program prints out 
         // a success message
         if(o.optionB(args[1])) {
            System.out.println();
            System.out.println("Command completed succesfully");
         }
         
         // If the procedure did not work properly, program prints
         // out an error message
         else {
            System.out.println("Fatal error");
            return;
         }   
      }   
         
      // Option -c, all printable and control characters printed 
      // rest in octal representation 
      else if (args[0].equals("-c")) {      
      
         // If the number of arguments is less than 2, program prints
         // out an error message and exits
         if (args.length < 2) {
            System.out.println("Error:  Invalid number of arguments");
            return;
         }
         
         // If the procedure worked properly, program prints out a
         // success message
         if (o.optionC(args[1])) {
            System.out.println();
            System.out.println("Command completed succesfully");
         }
         
         // If the procedure did not work properly, program prints
         // out an error message
         else {
            System.out.println("Fatal error");
            return;
         }
      }
      
      // If none of the valid options were chosen, program prints out the 
      // usage message and exits
      else {
      
         System.out.println("Error:  Invalid argument");
         o.printStringArray(usageMessage);
      }
      
      
   } // main   
      
   // Option -b, octal representation of a user specified file   
   // returns true when succesfull and false when there's an error,
   // accepts file name as argument
   private boolean optionB(String fName) {
      
      int i;      // used for reading from the file
      int c = 0;  // used for output formatting
      String b;   // used for output
         
      FileInputStream inStream;
        
      try {
         inStream = new FileInputStream(fName);
      }
      
      // If file not found, prints an error message and exits
      catch (FileNotFoundException e) {
         System.out.println("Error: File '" + fName + "' not found");
         return false;   
      }
     
      // If unable to access the file for security reasons, prints out
      // an error message and exits
      catch (SecurityException e) {
         System.out.println("Error: You do not have sufficient privileges to complete this operation");
         return false;
      }
   
      // Buffered file reader
      BufferedInputStream inBufStream = new BufferedInputStream(inStream);
             
      try {
         
         System.out.println();
         System.out.println("Octal representation of '" + fName + "':");
         System.out.println();
        
         while((i = inBufStream.read()) != EOF) {
            b = Integer.toString(i, 8); // converts to octal
            printOctal(b);
                 
            // output formatting
            c += 1;
            if (c == 16) {
               System.out.println();
               c = 0;
            }                  
               
         }
         inBufStream.close(); // close in-file
         System.out.println();
      }

      // if there's an IO error, prints out an error message and exits
      catch (IOException e){
         System.out.println("Error reading from file");
         return false;
      }
      // Procedure complete succesfully      
      return true;   
   } // optionB

   // Option -c, prints out control characters and printable characters
   // and converts everything else to octal.
   // Returns true when succesfull and false when failed
   // Accepts file name as argument
   private boolean optionC(String fName) {
      
      int i;      // used for reading from file
      int c = 0;  // used for formatting output
      String b;   // used for output
         
      FileInputStream inStream;
        
      try {
         inStream = new FileInputStream(fName);
      }
      
      // If file not found, print out an error message and exit
      catch (FileNotFoundException e) {
         System.out.println("Error: File '" + fName + "' not found");
         return false;   
      }
     
      // If file unaccessible for security reasons, print out an error
      // message and exit
      catch (SecurityException e) {
         System.out.println("Error: You do not have sufficient privileges to complete this operation");
         return false;
      }
   
      // Buffered file reader
      BufferedInputStream inBufStream = new BufferedInputStream(inStream);
   
      try {
         
         System.out.println();
         while((i = inBufStream.read()) != EOF) {
            
            // If decimal 0, then print out the null character ^@
            if (i == 0) {
               System.out.print(" ^@ ");
            }
            
            // if decimal 10, the print out the end of line character \n
            else if (i == 10) {
               System.out.print(" \\n ");
            }
            
            // if decimal 13, then print out the carriage return character
            // \r
            else if (i == 13) {
               System.out.print(" \\r ");
            }
            
            // if decimal 0 - 10, print out the appropriate control
            // characters
            else if ((i > 0) && (i < 10)) {
               System.out.print(" ^" + (char)(i + 64) + " ");
            }
            
            // if decimal 10 - 13, print out the appropriate control
            // characters
            else if ((i > 10) && (i < 13)) {
               System.out.print(" ^" + (char)(i + 64) + " ");
            }
            
            // if decimal 12 - 27, print out the appropriate
            // control characters
            else if ((i > 13) && (i < 27)) {
               System.out.print(" ^" + (char)(i + 64) + " ");
            }
            
            // decimal 27 - 127 print out the printable
            // characters
            else if ((i >= 27) && (i <127)) {
               System.out.print("  " + (char)i + " ");
            }
            
            // decimal 127, print out "del"
            else if ( i == 127 ) {
               System.out.print("del ");
            }
            
            // Convert everything else to octal
            else {
                       
               b = Integer.toString(i, 8);
               printOctal(b);
            }
                 
            // Output formatting
            c += 1;
            if (c == 16) {
               System.out.println();
               c = 0;
            }                  
               
         }
         inBufStream.close(); // close the in file
         System.out.println();
      }

      // File reading error, print out an error message and exit
      catch (IOException e){
         System.out.println("Error reading from file");
         return false;
      }
      
      // Procedure completed succesfully      
      return true;   
   } // optionC

   // Prints out properly formatted octal representations
   // Returns no value and accepts String b as argument
   private void printOctal(String b) {
      
              
      // if the length of b is 1 character, add two 0s
      if (b.length() == 1) {
         System.out.print("00");                     
         System.out.print(b);
      }
      
      // if the length of b is 2 characters, add 1 0
      else if (b.length() == 2) {
         System.out.print("0");
         System.out.print(b);
      }
         
      // else just print out b
      else 
         System.out.print(b);
                 
      // print out a blank space to seperate octal numbers
      System.out.print(" ");
                      
   } // printOctal  
        
   // Procedure to print out an array of strings
   // Returns no value and accepts an array of strings as argument
   private void printStringArray(String s[]) {
      
      for(int i = 0; i < s.length; i++)
         System.out.println(s[i]);
        
   } // printStringArray     
} //class od