/*

 *

 * Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.

 * 

 * This software is the proprietary information of Sun Microsystems, Inc.  

 * Use is subject to license terms.

 * 

 */



import java.util.*;

import javax.ejb.*;

import java.sql.*;

import javax.sql.*;

import java.util.*;

import javax.naming.*;





public class StockEJB implements EntityBean {



   private String productId;

   private int quantityOnHand;

   private int reorderLevel;

   private EntityContext context;

   private Connection con;

   private String dbName = "java:comp/env/jdbc/StockDB";





   public void updateOnHand(int quantity) {



      System.out.println("StockEJB: updateOnHand()");

      quantityOnHand -= quantity; 

   }



   public boolean reorderNeeded() {



      System.out.println("StockEJB: reorderNeeded()");

      return (quantityOnHand <= reorderLevel);

   }





   public String ejbCreate(String productId, int quantityOnHand, 

      int reorderLevel) {



      System.out.println("StockEJB: ejbCreate()");

      try {

         insertRow(productId, quantityOnHand, reorderLevel);

      } catch (Exception ex) {

          throw new EJBException("ejbCreate: " + 

             ex.getMessage());

      }



      this.productId  = productId;

      this.quantityOnHand = quantityOnHand;

      this.reorderLevel = reorderLevel;

      return productId;

   }



   public String ejbFindByPrimaryKey(String primaryKey) 

      throws FinderException {



      productId = primaryKey;

      boolean result;



      try {

         result = selectByPrimaryKey();

       } catch (Exception ex) {

           throw new EJBException("ejbFindByPrimaryKey: " + 

              ex.getMessage());

       }



      if (result) {

         try {

            loadRow();

          } catch (SQLException ex) {

              throw new EJBException("ejbFindByPrimaryKey: " +

                 ex.getMessage());

          }

         return productId;

      }

      else {

         throw new ObjectNotFoundException

            ("ejbFindByPrimaryKey: Row for primaryKey " + primaryKey + " not found.");

      }

   }



   public void ejbRemove() {



      try {

         deleteRow(productId);

       } catch (Exception ex) {

           throw new EJBException("ejbRemove: " +

              ex.getMessage());

       }

   }



   public void ejbActivate() {



      productId = (String)context.getPrimaryKey();

   }



   public void ejbPassivate() {



      productId = null;

   }



   public void setEntityContext(EntityContext context) {



      this.context = context;

      try {

         makeConnection();

      } catch (Exception ex) {

          throw new EJBException("Unable to connect to database. " +

             ex.getMessage());

      }

   }



   public void unsetEntityContext() {



      try {

         con.close();

      } catch (SQLException ex) {

          throw new EJBException("unsetEntityContext: " + ex.getMessage());

      }

   }



   public void ejbLoad() {



      try {

         loadRow();

       } catch (Exception ex) {

           throw new EJBException("ejbLoad: " +

              ex.getMessage());

       }

   }



   public void ejbStore() {



      try {

         storeRow();

       } catch (Exception ex) {

           throw new EJBException("ejbLoad: " +

              ex.getMessage());

       }

   }



   public void ejbPostCreate(String productId, int quantityOnHand,

      int reorderLevel) { }



   private void debugState() {

      System.out.println("  productId = " + this.productId + " quantityOnHand = " + this.quantityOnHand + " reorderLevel = " + this.reorderLevel);

   }



/*********************** Database Routines **********************/





   private void makeConnection() throws NamingException, SQLException {



      InitialContext ic = new InitialContext();

      DataSource ds = (DataSource) ic.lookup(dbName);

      con =  ds.getConnection();

   }



   private void insertRow (String productId, int quantityOnHand, 

                           int reorderLevel) throws SQLException {



          String insertStatement =

                "insert into stock values ( ? , ? , ? )";

          PreparedStatement prepStmt = 

                con.prepareStatement(insertStatement);



          prepStmt.setString(1, productId);

          prepStmt.setInt(2, quantityOnHand);

          prepStmt.setInt(3, reorderLevel);



          prepStmt.executeUpdate();

          prepStmt.close();

   }



   private void deleteRow(String id) throws SQLException {



      String deleteStatement =

            "delete from stock where product_id = ? ";

      PreparedStatement prepStmt =

            con.prepareStatement(deleteStatement);



      prepStmt.setString(1, id);

      prepStmt.executeUpdate();

      prepStmt.close();

   }



   private boolean selectByPrimaryKey() 

      throws SQLException {



      String selectStatement =

            "select product_id " +

            "from stock where product_id = ? ";

      PreparedStatement prepStmt =

            con.prepareStatement(selectStatement);

      prepStmt.setString(1, productId);



      ResultSet rs = prepStmt.executeQuery();

      boolean result = rs.next();

      prepStmt.close();

      return result;

   }



   private void loadRow() throws SQLException {



      String selectStatement =

            "select quantity_on_hand, reorder_level " +

            "from stock where product_id = ? ";

      PreparedStatement prepStmt = 

            con.prepareStatement(selectStatement);



      prepStmt.setString(1, productId);



      ResultSet rs = prepStmt.executeQuery();



      if (rs.next()) {

         quantityOnHand = rs.getInt(1);

         reorderLevel = rs.getInt(2);

         prepStmt.close();

      }

      else {

         prepStmt.close();

         throw new NoSuchEntityException("loadRow: Row for productId " + productId +

            " not found in database.");

      }

   }



   private void storeRow() throws SQLException {



      String updateStatement =

            "update stock set quantity_on_hand =  ? ," +

            "reorder_level = ? " +

            "where product_id = ? ";

      PreparedStatement prepStmt = 

            con.prepareStatement(updateStatement);



      prepStmt.setInt(1, quantityOnHand);

      prepStmt.setInt(2, reorderLevel);

      prepStmt.setString(3, productId);

      int rowCount = prepStmt.executeUpdate();

      prepStmt.close();



      if (rowCount == 0) {

         throw new EJBException("Storing row for productId " + productId + 

            " failed.");

      }

   }



} // StockEJB