import java.io.*;

/*********************************************************
 *A class to build files of species records and to display
 *the file contents on the screen. Uses the class Species.
 *********************************************************/
public class SpeciesFiler
{
   private String fileName = null;
   private DataInputStream inputStream = null;
   private DataOutputStream outputStream = null;

   /**************************************************************************
    *Obtains a file name from the user and fills the file with species records.
    **************************************************************************/
   public void buildAFile()
   {
      System.out.println("This program will record the species records");
      System.out.println("you enter and store them in a file.");
      fileName = getFileName("Enter name of file to hold records:");
      System.out.println("If there already exists a file");
      System.out.println("with that name, the data will be lost.");
      System.out.println("OK to continue with the file "
                                        + fileName + "? (y/n)");
      char ans = SavitchIn.readLineNonwhiteChar();
      if ((ans == 'n') && (ans == 'N'))
          System.out.println("File " + fileName + " not changed.");
      else
      {
         try
         {
             outputStream =
                 new DataOutputStream(new FileOutputStream(fileName));

             Species oneSpecies = new Species();
             System.out.println("Ready to start entering?(y/n)");
             ans = SavitchIn.readLineNonwhiteChar();
             while ((ans == 'y') || (ans == 'Y'))
             {
                 oneSpecies.readInput();
                 oneSpecies.writeOutput(outputStream);
                 System.out.println("Enter another species?(y/n)");
                 ans = SavitchIn.readLineNonwhiteChar();
             }
             outputStream.close();
             System.out.println("Species records written to the file "
                                                         + fileName);
         }
         catch(FileNotFoundException e)
         {
             System.out.println("Error opening file " + fileName);
         }
         catch(IOException e)
         {
             System.out.println("Error writing to file " + fileName);
         }
      }
   }

   //Throws a FileNotFoundException if there is no file with the given name.
   private void viewAFileNoProblems() throws IOException
   {
      System.out.println("This program will display all the species");
      System.out.println("records contained in the file you specify.");
      fileName = getFileName("Enter name of file with records:");
      inputStream = new DataInputStream(new FileInputStream(fileName));
      Species oneSpecies = new Species();
      System.out.println("Records from the file " + fileName + ":");
      try
      {
         while (true)
         {
            oneSpecies.readInput(inputStream);
            oneSpecies.writeOutput();
            System.out.println("Press Enter to see more.");
            String junk = SavitchIn.readLine();
         }
      }
      catch(EOFException e)
      {
         System.out.println("No more records in the file "
                                                  + fileName);
      }
      inputStream.close();
      System.out.println("File " + fileName + " put away.");
   }

   /**************************************************
    *Obtains a file name from the user and displays the
    *file contents to the screen.
    *Precondition: The file must be a binary file of
    *the kind created by buildAFile.
    **************************************************/
   public void viewAFile()
   {

       try
       {
          viewAFileNoProblems();
       }
       catch(FileNotFoundException e)
       {
          System.out.println("Cannot find a file named "
                                                + fileName);
       }
       catch(IOException e)
       {
          System.out.println("Error reading from file "
                                               + fileName);
       }

   }

   private String getFileName(String prompt)
   {
       String nameString = null;
       System.out.println(prompt);
       nameString = SavitchIn.readLineWord();
       return nameString;
   }
}