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

public class collection { 

   private Vector CDS;                           // Vector for holding collection of cd objects 
   private Vector theOutput; 
   private static String default_file = "cd_url.txt";
                        
   public collection() {                         // constructor.
      CDS = new Vector();
   }
   
   public Vector processInput(String theInput) {
      String command = null;
      String restOfLine = null;
      theOutput = new Vector();                  // packaging Vector
      
      if (CDS.size() < 1) {                      // automatically loads default collection on start-up  
         try {
            loadCollectionText(default_file);
         }
         catch (FileNotFoundException e) {       // to handle wrong file name. 
            System.out.println("\n++ERROR - File not found.");
            System.exit(0);
         }              
         catch (IOException e) {                 // to handle IO exceptions.
            System.out.println("\n++ERROR - Failure to load specified file.");
            System.exit(0);
         }
         catch (NullPointerException e) {      // handle file without markers '*'. 
            System.out.println("++ERROR - Default collection may be corrupted.");
            System.exit(0);
         }   
      }
      else {                                     // client requests processed here
         try {
            StringTokenizer st = new StringTokenizer(theInput);
            command = st.nextToken();      
            restOfLine = theInput.substring(theInput.indexOf(' ')+1, theInput.length());  
            System.out.println("Heard: " + command + " " + restOfLine); // displays client request
         
            if (command.equalsIgnoreCase("LIST")) List();
            else if (command.equalsIgnoreCase("ARTIST")) Search(1, restOfLine);
            else if (command.equalsIgnoreCase("COMPOSER")) Search(2, restOfLine);
            else if (command.equalsIgnoreCase("TITLE")) Search(3, restOfLine);
            else if (command.equalsIgnoreCase("TRACK")) Search(4, restOfLine);
            else if (command.equalsIgnoreCase("LOAD")) loadCollection(restOfLine);
            else if (command.equalsIgnoreCase("SAVE")) saveCollection(restOfLine);
            else if (command.equalsIgnoreCase("REMOVE")) Search(5, restOfLine); 
         }     
         catch (IOException e)  {              // to hanlde IO exceptions. 
            System.out.println("IOException");
         }       
         catch (NoSuchElementException e) {    // to handle empty Strings.
            System.out.println("NoSuchElementException");
         }
      }
      return theOutput;                     // packaging Vector used to return cd objects (if any)
   }                               
   
   //======================================= addCD() =============================================
   
   public void addCD(cd inputCD) {
      System.out.println("Adding CD.");
      CDS.addElement(inputCD);              // cd object added to CDS (collection) Vector     
   }
     
   //================================ Search() and Remove() =======================================
  
   private void Search(int command, String r_o_l) {
      boolean found = false;
            
      for (int i = 0; i < CDS.size(); ++i) {
         found = false;                                // resets boolean each loop.
         cd element = (cd)CDS.elementAt(i);
         switch (command) {
            case 1: if (element.getArtist().equalsIgnoreCase(r_o_l)) found = true; break;
            case 2: if (element.getComposer().equalsIgnoreCase(r_o_l)) found = true; break;
            case 3: if (element.getTitle().equalsIgnoreCase(r_o_l)) found = true; break;
            case 4: {
               Vector TR = new Vector();
               TR = element.getTracks();
               for (int j = 0; j < TR.size(); ++j) {
                  String track = (String)TR.elementAt(j);
                  if (track.equalsIgnoreCase(r_o_l)) found = true;
               }
               break;
            }
            case 5: if (element.getTitle().equalsIgnoreCase(r_o_l)) {  
               CDS.removeElementAt(i);
            }    
         }   
         if (found) {
            theOutput.addElement(element);  // adds the cd object containing the found 
         }                                  // object to packaging Vector (theOutput)
      }
   }
   
   //==================================== List() ==============================================
  
   private void List() {
      theOutput = CDS;                      // fills packaging Vector with current collection
   }
   
   //=============================== loadCollection() ==========================================
      
   private void loadCollection(String f) throws IOException {
      FileInputStream in = new FileInputStream(f);
      ObjectInputStream s = new ObjectInputStream(in);
      CDS.removeAllElements();              // clears old collection from the CDS Vector
      
      try {
         CDS = (Vector)s.readObject();      // fills CDS vector with new collection
      }
      catch (ClassNotFoundException e) {
         System.out.println("Error - ClassNotFoundException !");
      }   
      theOutput = CDS;                      // fills packaging Vector with current collection
      in.close();
   } 
   
   //=============================== loadCollectionText() ====================================
   
   // This method reads the default text file and constructs CD objects adding them to the Vector CDS. 
       
   private void loadCollectionText(String f) throws IOException {
      BufferedReader in = new BufferedReader(new FileReader(f));
      String track;
  
      while (in.ready()) { 
         
         Vector TR = new Vector();
         String A = in.readLine();                       // 1st 5 lines of text file are read into tempory Strings.  
         String C = in.readLine();   
         String T = in.readLine();
         String U = in.readLine();
         
         while (!(track = in.readLine()).equals("*")) {  // rest of data set is read into tempory Vector containing Tracks.
            TR.addElement(track);
         }
         
         cd element = new cd(A, C, T, TR, U);            // CD instance constructed using the tempory objects above.
        
         CDS.addElement(element);                        // CD instance added to CD Vector (CDS).
      }
      theOutput = CDS;                                   // fills packaging Vector with current collection
      System.out.println("\n++OK - FILE " + f + " LOADED SUCCESSFULLY.");  // confirm to the user the method is finished.
   } 
   
   //=============================== saveCollection() ====================================
   
   private void saveCollection (String f) throws IOException {
      
      FileOutputStream out = new FileOutputStream(f);
      ObjectOutputStream s = new ObjectOutputStream(out);
      s.writeObject(CDS);
      s.flush();
      out.close();
      s.close();
   }
}