package u7;

import java.io.*;
import utils.*;

public class ESortUtils {

  /** 
   * Converts file of Item objects into file that stores numbered lines 
   * of the string representation of that objects.
   */
  public static void convertToText(String fname, String nName) {
    try {
        FileInputStream istream = new FileInputStream(fname);
        ObjectInputStream p = new ObjectInputStream(istream);
        
        FileOutputStream ostream = new FileOutputStream(nName);
        OutputStreamWriter w = new OutputStreamWriter(ostream);  
        
        Item item;
        
        item = readObject(p);
        
        int i = 0;
        while(item != null) {
          w.write("Item[" + i + "]  ==  " + item + "\r\n");
          i++;
          item = readObject(p);
        }
        istream.close();
        w.flush();
        ostream.close();
        System.out.println("Items saved to file " + nName);
    } catch (Exception ex) {
        System.out.println("[printFile] Exception in pritnFile caught:");
        ex.printStackTrace();
        throw new RuntimeException("Exception in [ESortUtils][printFile] " + ex.getMessage());
    }
  } 

  /** Reads an Item object from the object input stream */
  public static Item readObject(ObjectInputStream ois) {
    Item result;
    try {
        result = (Item) ois.readObject();
    } catch (IOException ex) {
        System.out.println("[readObject] IOException caught: " + ex.getMessage());
        result = null;
    } catch (ClassNotFoundException ex) {
        System.out.println("[readObject] ClassNotFoundException caught: " + ex.getMessage());
        throw new RuntimeException("Exception in [ESortUtils][readObject] " + ex.getMessage());
    }
    return result;
  }
  
    
  /** 
   * Reads elements from the input stream into the buffer 'items'.
   * Returns the number of elements that were loaded.
   */
  public static int load(Item[] items, ObjectInputStream ois) {
      int iSize = 0;
      while (iSize < items.length) {
        try {
            items[iSize] = (Item) ois.readObject();
            iSize++;
        } catch (IOException ex) {
            break;
        } catch (ClassNotFoundException ex) {
            System.out.println("[readObject] ClassNotFoundExceptioncaught: " + ex.getMessage());
            throw new RuntimeException("Exception in [ESortUtils][load] " + ex.getMessage());
        }
      }
      return iSize;
  }
  
  /**
   * Saves the elements from the buffer 'items'.
   * @param iSize the number of elements to be saved.
   */
  public static void writeBuffer(ObjectOutputStream p, Item[] items, int iSize) {
    try {
      for (int i=0; i < iSize; i++) {        
        p.writeObject(items[i]);
      }
    } catch (IOException ex) {
        System.out.println("[writeBuffer] exception caught:");
        ex.printStackTrace();
        throw new RuntimeException("Exception in [ESortUtils][writeBuffer] " + ex.getMessage());
    }
  }

}