tapestry/tapestry-examples/Vlib/src/java/org/apache/tapestry/vlib/components/BookLink.java

// Copyright 2004, 2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry.vlib.components;

import java.sql.Timestamp;

import org.apache.tapestry.BaseComponent;
import org.apache.tapestry.annotations.InjectState;
import org.apache.tapestry.annotations.InjectStateFlag;
import org.apache.tapestry.annotations.Parameter;
import org.apache.tapestry.vlib.Visit;
import org.apache.tapestry.vlib.ejb.Book;

/**
 * Creates a link to the {@link org.apache.tapestry.vlib.pages.ViewBook} page using the external
 * service. <table border=1>
 * <tr>
 * <th>Parameter</th>
 * <th>Type</th>
 * <th>Direction</th>
 * <th>Required</th>
 * <th>Default</th>
 * <th>Description</th>
 * </tr>
 * <tr>
 * <td>book</td>
 * <td>{@link Book}</td>
 * <td>in</td>
 * <td>yes</td>
 * <td>&nbsp;</td>
 * <td>The {@link Book} to create a link to.</td>
 * </tr>
 * </table>
 * <p>
 * Informal parameters are allowed.
 * 
 * @author Howard Lewis Ship
 */

public abstract class BookLink extends BaseComponent
{
    /**
     * One week, in milliseconds (1/1000 second). Books that have been added in the last week are
     * marked new, until the user logs in, at which point, its books added since the user last
     * logged in.
     */

    private static final long ONE_WEEK_MILLIS = 1000L * 60L * 60L * 24L * 7L;

    @Parameter(required = true)
    public abstract Book getBook();

    @InjectState("visit")
    public abstract Visit getVisitState();

    @InjectStateFlag("visit")
    public abstract boolean getVisitExists();

    public boolean isNewlyAdded()
    {
        Timestamp lastAccess = null;

        if (getVisitExists())
            lastAccess = getVisitState().getLastAccess();

        Book book = getBook();

        Timestamp dateAdded = book.getDateAdded();

        // Some old records may not contain a value for dateAdded

        if (dateAdded == null)
            return false;

        // If don't know the last access time (because the user
        // hasn't logged in yet), then show anything newer
        // than a week.

        if (lastAccess == null)
        {
            long now = System.currentTimeMillis();

            return (now - dateAdded.getTime()) <= ONE_WEEK_MILLIS;
        }

        // Return true if lastAccess is earlier than date added.

        return lastAccess.compareTo(dateAdded) <= 0;
    }

}