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

   public class BookList
   {
   /* **************************
   PROGRAMMER: 			Chris Eason 
   PROGRAMMING LANGUAGE: 	jdk 1.2.2
   PROJECT: 			Puddleville Library
   COURSE:			CS 1302
   DATE:			8 February 2001
   
   PURPOSE: This class models a collection of books.
   
   METHODS:
   		The constructor is overloaded to create the collection using either
   		a file containing information about the books, or an array of Book objects.
   		
   			BookList(String fileName)
   			Booklist(Book[] books)
   			
   		The look up method finds a book in the collection and returns a reference
   		to it. If the requested book is not in the collection, null is returned.
   		
   			Book lookUp(String ISBN)
   
   INPUT: 
   	The input for the BookList constructor that accepts a file name will have
   	the following format: 
   
   		The file will list the books one per line. Each line will contain all the 
   		information for one book with the caret ^ symbol separating each piece of data.
   		The format for a book that is checked out will be as follows: 
   
   			ISBN^PatronNumber^month^day^year
   
   		The format for a Book that is not checked out will be as follows: 
   		
   			ISBN^ ^^^
   
   OUTPUT:	This class produces no direct output.
   
   LIMITATIONS:
   		Assumes all input has been checked and is error free.
   		NO ERROR CHECKING is done.
   
   
   ************************** */
   
   
   /* **************************
   CONSTRUCTORS
   ************************** */
   
      public BookList(String fileName) throws Exception
      {
      /* **************************
      PURPOSE: 	Creates the collection of books 
      PARAMETERS:	String filename -- the name of the file containing the book data 
      INPUT: 		A text file containing information about books in the format specified
      				in the opening documentation of this class.
      OUTPUT: 		Produces no direct output.
      
      LIMITATIONS:	Does no error checking on the input. 
      			All Exceptions are thrown
      ************************** */
      
         BufferedReader bookFile = new BufferedReader( new FileReader(fileName) );
      
         // Count the number of books in the file NOTE: one book per line
         int count = 0;
         while (bookFile.readLine() != null)
            count++;
      
         // Create the instance variable theBooks with the appropriate size
         theBooks = new Book[count];
      
         // Read the data from the file and fill the array
         int pos = 0; // the position in the array to be filled
         bookFile = new BufferedReader( new FileReader(fileName) );
         String bookDataLine = bookFile.readLine();
         while (bookDataLine != null)
         {
            // parse the input and create the book
            StringTokenizer stok = new StringTokenizer(bookDataLine, "^");
            // the first token is the ISBN
            Book thisBook = new Book(stok.nextToken());
            // the next token is either blank (not checked out) or the patron (checked out)
            String tok = stok.nextToken();
            if ( ! tok.equals(" ") ) // the token is not blank, so the book is checked out
            {
               thisBook.setPatron(tok);
               // take care of the due date
               int month = Integer.parseInt(stok.nextToken());
               int day = Integer.parseInt(stok.nextToken());
               int year = Integer.parseInt(stok.nextToken());
               thisBook.setDueDate(new Date(year-1900, month-1, day));
            }
         
            // add the book to the array
            theBooks[pos++] = thisBook;
         
            // get the next input line from the file
            bookDataLine = bookFile.readLine();
         } // while (bookDataLine != null)
      
      
      } // BookList(String)
   
      public BookList(Book[] books)
      {
      /* **************************
      PURPOSE: 	Creates the collection of books 
      PARAMETERS:	Book[] books -- an array of books that are to be in the collection 
      INPUT: 		No direct input.
      OUTPUT: 		Produces no direct output.
      
      LIMITATIONS:	 Assumes the books passed in are error free.
      ************************** */
      
         theBooks = books;
      
      } // BookList(Book[])
   
   /* **************************
   PUBLIC METHODS
   ************************** */
   
   
      public Book lookUp(String ISBN)
      {
      /* **************************
      PURPOSE: 	 Find a book in the collection.
      PARAMETERS:	 String ISBN -- the ISBN of the book that is being searched for.
      RETURNS:		If the requested book is in the collection -- A reference to the Book
      				If the requested book is NOT in the collection -- null
      INPUT: 		No direct input.
      OUTPUT: 		Produces no direct output.
      
      LIMITATIONS: 
      ************************** */
      
         // Search the array for the requested ISBN and return the book
         for (int i = 0; i < theBooks.length; i++)
            if ( theBooks[i].getISBN().equals(ISBN) )
               return theBooks[i];
      
         // If we get past the loop, the ISBN wasn't found
         return null;
      
      } // lookUp(String)
   
   
   /* **************************
   INSTANCE VARIABLES
   ************************** */
   
      Book[] theBooks;
   
   } // BookList class