// Copyright (c) 1999, 2000 Oracle Corporation
package oracle.jbo.common.ampool;

import java.util.Vector;
import java.util.Hashtable;
import javax.naming.*;
import oracle.jbo.*;

/**
 ** This class provides the default implementation of the ApplicationPool interface.
 **
 ** <a HREF="ApplicationPool.txt">View definition of ApplicationPool</a>
 ** <a HREF="ApplicationPoolImpl.txt">View Implementation of ApplicationPoolImpl</a>
 ** <P>
 ** @author Juan Oropeza
 **/
public class ApplicationPoolImpl extends Object implements ApplicationPool
{
  static final String     IS_CHECKED_OUT = "Yes";
  static final String     IS_NOT_CHECKED_OUT = "No";

  Hashtable               env;
  String                  poolName;
  Vector                  instances = new Vector(10);
  Context                 initialContext;
  ApplicationModuleHome   home;
  Hashtable               userData;
  String                  sConnectString;
  String                  sApplicationModule;
  Hashtable               instanceInfo = new Hashtable(10);
  
  /**
   * Constructor
   */
  public ApplicationPoolImpl()
  {

  }

  public void initialize(String sPoolName , String sApplicationModule, String sConnectString, Hashtable env) throws Exception
  {
      this.poolName = sPoolName;
      this.env = env;
      this.sConnectString = sConnectString;
      this.sApplicationModule = sApplicationModule;
      
      initialContext = new InitialContext(env);

      home = (ApplicationModuleHome) initialContext.lookup(sApplicationModule);
  }

  public String getApplicationModuleClass()
  {
     return this.sApplicationModule;
  }

  public String getConnectString()
  {
     return this.sConnectString;
  }

  public Hashtable getEnvironment()
  {
     return this.env;
  }

  public synchronized void checkin(ApplicationModule instance)
  {
    setAvailable(instance , true);
  }

  public boolean isAvailable(ApplicationModule instance)
  {
      Object obj = instanceInfo.get(instance.toString());
      if(obj != null && obj.toString().equalsIgnoreCase(this.IS_CHECKED_OUT))
         return false;
         
      return true;
  }

  public void setAvailable(ApplicationModule instance, boolean bSet)
  {
      if(bSet)
      {
            instanceInfo.put(instance.toString(),this.IS_NOT_CHECKED_OUT);
      }
      else
      {
            instanceInfo.put(instance.toString(),this.IS_CHECKED_OUT);
      }
  }

  public synchronized ApplicationModule createNewInstance()
  {
    // create a new instance using the connect info
    ApplicationModule am = home.create();

    am.getTransaction().connect(this.sConnectString);

    instanceInfo.put(am.toString(),this.IS_NOT_CHECKED_OUT);
    
    // add instance to collection
    instances.addElement(am);

    return am;
  }
  
  public synchronized ApplicationModule checkout()
  {
    ApplicationModule available = null;
    ApplicationModule current = null;
    
    for(int i = 0 ; i < instances.size(); i ++)
    {
      current = (ApplicationModule)instances.elementAt(i);
      if(isAvailable(current))
      {
        setAvailable(current , false);
        available = current;
        return available;
      }
    }

    if(available == null)
    {
      available = createNewInstance();
      setAvailable(available, false);
    }
    
    return available;
  }

  public synchronized void releaseInstances()
  {
    int nSize = instances.size();

    for(int i = 0; i < nSize; i++)
    {
      ApplicationModule instance = (ApplicationModule)instances.elementAt(i);

      instance.remove();
    }

    for(int i = nSize - 1; i >= 0; i--)
    {
      instances.removeElementAt(i);
    }
    instanceInfo.clear();
  }

  public synchronized int  getInstanceCount()
  {
    return instances.size();
  }

  public synchronized ApplicationModule getInstance(int nIndex)
  {
    return (ApplicationModule)instances.elementAt(nIndex);
  }
  
  public synchronized String getPoolName()
  {
    return poolName;
  }
  
   /**
  **  returns the User Data hashtable. This is a generic container for
  **  any settings the user would like to associate with this application instance.
  **/
  public Hashtable getUserData()
  {
    return userData;
  }

  /**
  ** Replaces the userData with the new Hashtable.
  **/
  public void setUserData(Hashtable data)
  {
    this.userData = data;
  }
}