/*
* ====================================================================
*
* TORPEDO
* A Testbed of Object Relational Products for Enterprise Distributed Objects
* Copyright (c) 2004 The Middleware Company All Rights Reserved
* @version 7.19.04
*
* ====================================================================
*/



package com.middleware_company.torpedo.auction.toplink;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import javax.naming.NamingException;
import oracle.toplink.expressions.*;
import oracle.toplink.queryframework.*;
import oracle.toplink.threetier.Server;
import oracle.toplink.tools.sessionconfiguration.*;
import oracle.toplink.tools.sessionmanagement.*;
import oracle.toplink.sessions.*;
import oracle.toplink.publicinterface.Descriptor;

import com.middleware_company.torpedo.auction.AuctionServiceException;

/**
 * Torpedo Persistence implementation for OracleAS TopLink 9.0.4.
 * This persists the Torpedo POJO Auction object model through the TopLink API.
 * This implementation uses several TopLink optimizations including,
 * - joining
 * - batch reading
 * - partial object reading
 * - batch writing
 * - parameterized SQL
 * - unit of work
 */
public class Persistence
        extends com.middleware_company.torpedo.auction.Persistence {

	protected Server serverSession;

	/**
	 * Load the tunned TopLink session from the sessions.xml configuration file.
	 */
	public Server getServerSession() {
		if (serverSession == null) {
			serverSession = (Server) SessionManager.getManager().getSession(new XMLLoader("com/middleware_company/torpedo/auction/toplink/sessions.xml"), "TorpedoSession", getClass().getClassLoader());
		}
		return serverSession;
	}

	/**
	 * Return a unit of work if in a JTA transaction, otherwise a client session.
	 */
	public Session getActiveSession() {
		Session session = getServerSession().getActiveUnitOfWork();
		if (session == null) {
			session = getServerSession().acquireClientSession();
		}
		return session;
	}

	/**
	 * Create a new bid, set the aution and buyer.
	 */
    public com.middleware_company.torpedo.auction.Bid createBid(
            String ID,
            com.middleware_company.torpedo.auction.Auction auction,
            com.middleware_company.torpedo.auction.User buyer,
            Float amount,
            Float maxAmount) throws AuctionServiceException,NamingException {

        List result = null;
        UnitOfWork unitOfWork = getServerSession().getActiveUnitOfWork();
        Bid bid= new Bid(ID, auction, buyer, amount, maxAmount);
        unitOfWork.registerNewObject(bid);
        return bid;
    }

	/**
	 * Find all auctions.
	 * This uses joining to optimize the loading of the auction's item.
	 * This uses batch reading to optimize the loading of the auction's bid's,
	 * note that batch reading is used instead of joining because even though it causes an extra line of SQL,
	 * it reads in the minimal amount of data and does not require an inefficient outerjoin,
	 * joining would read a lot of duplicate data which is much less efficient for large reads.
	 * This benifits joining in the bid's buyer's mapping to optimize the loading of the bid's buyer.
	 */
    public Collection findAllAuctions()
            throws AuctionServiceException, NamingException {

        Session session = getServerSession().getActiveSession();
		ExpressionBuilder builder = new ExpressionBuilder();
        ReadAllQuery auctionsQuery = new ReadAllQuery(Auction.class, builder);
		auctionsQuery.addJoinedAttribute(builder.getAllowingNull("item"));
		auctionsQuery.addBatchReadAttribute(builder.anyOfAllowingNone("bids"));
        List auctions = (List)session.executeQuery(auctionsQuery);
        return auctions;
    }

	/**
	 * Find the high bid(s) for an auction.
	 * If there are several bids at the same price, this may be multiple bids.
	 * This uses a sub-select to find the max bid amout.
	 * This benifits from joining in the bid's buyer's mapping to optimize the loading of the bid's buyer.
	 */
    public Collection findHighBids(String auctionID)
            throws AuctionServiceException, NamingException {

        Session session = getServerSession().getActiveSession();
		// Max amount sub-query.
        ExpressionBuilder maxBid = new ExpressionBuilder(Bid.class);
        ReportQuery subQuery = new ReportQuery(Bid.class, maxBid);
        subQuery.addMaximum("amount");
        subQuery.setSelectionCriteria(maxBid.get("auction").get("id").equal(auctionID));
		// High bid query.
        ExpressionBuilder builder = new ExpressionBuilder();
        ReadAllQuery bidsQuery = new ReadAllQuery(Bid.class, builder);
        bidsQuery.setSelectionCriteria(builder.get("auction").get("id").equal(auctionID).and(builder.get("amount").equal(subQuery)));

        List bids = (List)session.executeQuery(bidsQuery);
        return bids;
    }

	/**
	 * Return the auction for the id.
	 * This uses joining to optimize the loading of the auction's item.
	 */
    public com.middleware_company.torpedo.auction.Auction getAuction(String auctionID)
            throws AuctionServiceException, NamingException {

        Session session = getServerSession().getActiveSession();
		ExpressionBuilder builder = new ExpressionBuilder();
        ReadObjectQuery readAuctionQuery = new ReadObjectQuery(Auction.class, builder);
		readAuctionQuery.addJoinedAttribute(builder.getAllowingNull("item"));
        readAuctionQuery.setSelectionCriteria(builder.get("id").equal(auctionID));
        Auction result = (Auction)session.executeQuery(readAuctionQuery);
        return result;
    }

	/**
	 * Return an auction with only the required data.
	 * This uses a partial object query.
	 */
    public com.middleware_company.torpedo.auction.Auction getPartialAuction(String auctionID)
			throws AuctionServiceException,NamingException {

        Session session = getServerSession().getActiveSession();
		ExpressionBuilder builder = new ExpressionBuilder();
        ReadObjectQuery readAuctionQuery = new ReadObjectQuery(Auction.class, builder);
        readAuctionQuery.addPartialAttribute("lowPrice");
        readAuctionQuery.addPartialAttribute("id");
        readAuctionQuery.addPartialAttribute("item");
        readAuctionQuery.addPartialAttribute(builder.get("item").get("itemName"));
        readAuctionQuery.dontMaintainCache();
		readAuctionQuery.setSelectionCriteria(builder.get("id").equal(auctionID));
        Auction result = (Auction)session.executeQuery(readAuctionQuery);
        return result;
    }

	/**
	 * Return the user for the id.
	 */
    public com.middleware_company.torpedo.auction.User getUser(String userID)
            throws AuctionServiceException, NamingException {

        Session session = getServerSession().getActiveSession();
		ExpressionBuilder builder = new ExpressionBuilder();
        ReadObjectQuery userQuery = new ReadObjectQuery(User.class, builder);
        userQuery.setSelectionCriteria(builder.get("id").equal(userID));
        User result = (User)session.executeQuery(userQuery);
        return result;
    }

}