package btl;

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

/** 
 * BT Library Item Database using a text file.
 * Uses the Singleton Design Pattern! 
 */

/** 
 * Item Database using a text file.
 * Uses the Singleton Design Pattern!
 */    
public class FileItemDB implements ItemDB {

   // The database filename.
   private static String datafile = "btl\\Items\\Items.txt";

   // The hashmap used to store the Item objects, keyed by the Item id.
   private HashMap map;
   
   // The private reference to the one and only instance of the database.
   private static ItemDB uniqueInstance = null;
  
   /**
    * Returns a reference to the single instance.
    * Creates the instance if it does not yet exist.
    * (This is called lazy instantiation.)
    */
   public static ItemDB instance()
   {
     if(uniqueInstance == null)
       uniqueInstance = new FileItemDB();
     return uniqueInstance;
   }
 
    /**
     * The private constructor!
    */
   private FileItemDB() {
     map = new HashMap();
     open();
   }
  
   /*
    * Opens the database.
    * In this case, opens the text data file.  Parses each
    * line and adds an entry to the hash map using the id as
    * the key and the Item object as the value.
    */
   public void open () {
      try {
	 FileReader fr = new FileReader (datafile);
	 BufferedReader br = new BufferedReader (fr);
            
	 String line;
         // Skip header line!
         line = br.readLine();
	 while ((line = br.readLine()) != null) {
	    Item Item = parseItemRecord (line);
	    map.put(Item.getId(), Item);
	 }
	 fr.close();
      } catch (Exception e) {
	 System.err.println (e);
      } 
   }
    
   /**
    * Closes the database.
    * In this case, does nothing.
    */
   public void close() {
   }

   /**
    * Parses the text file record.
    * Fields are tab separated.
    */
   private Item parseItemRecord (String str) throws IOException {
      StringTokenizer st = new StringTokenizer (str, "\t");        
      String id = st.nextToken();
      String title = st.nextToken();
      String author = st.nextToken();
      String genre = st.nextToken();
      String binding = st.nextToken();
      String strPrice = st.nextToken();
      double price = Double.parseDouble(strPrice);
      String availability = st.nextToken();

      return new Item (id, title, author, genre, binding,
	 price, availability);
   }

   /**
    * Search by key.
    */   
   public Item searchByKey(String key) {
      return (Item) map.get(key);
   }

   /**
    * Search by title.
    */   
   public Item[] searchTitle(String ss) {
      ArrayList l = new ArrayList();
      Set s = map.keySet();
      Iterator iter = s.iterator();
      while (iter.hasNext()) {
	 Item b = (Item) map.get((String)iter.next());
	 String title = b.getTitle();
	 if (title.indexOf(ss) != -1)
	    l.add(b);
      }
      Item[] b = new Item[l.size()];
      return (Item[]) l.toArray(b);
   }
   
   /**
    * Search by author.
    */   
   public Item[] searchAuthor(String ss) {
      ArrayList l = new ArrayList();
      Set s = map.keySet();
      Iterator iter = s.iterator();
      while (iter.hasNext()) {
	 Item b = (Item) map.get((String)iter.next());
	 String author = b.getAuthor();
	 if (author.indexOf(ss) != -1)
	    l.add(b);
      }
      Item[] b = new Item[l.size()];
      return (Item[]) l.toArray(b);
   }
   
   /**
    * Search by genre.
    */   
   public Item[] searchGenre(String ss) {
      ArrayList l = new ArrayList();
      Set s = map.keySet();
      Iterator iter = s.iterator();
      while (iter.hasNext()) {
	 Item b = (Item) map.get((String)iter.next());
	 String genre = b.getGenre();
	 if (genre.equalsIgnoreCase(ss))
	    l.add(b);
      }
      Item[] b = new Item[l.size()];
      return (Item[]) l.toArray(b);
   }
   
}