TipsManager.java

/*
 * Copyright (C) 2009-2012 Geometer Plus <contact@geometerplus.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */

package org.geometerplus.fbreader.tips;

import java.util.*;
import java.io.File;

import org.geometerplus.zlibrary.core.filesystem.ZLFile;
import org.geometerplus.zlibrary.core.options.ZLBooleanOption;
import org.geometerplus.zlibrary.core.options.ZLIntegerOption;
import org.geometerplus.zlibrary.core.network.ZLNetworkManager;
import org.geometerplus.zlibrary.core.network.ZLNetworkException;

import org.geometerplus.fbreader.Paths;
import org.geometerplus.fbreader.network.atom.ATOMXMLReader;

public class TipsManager {
	private static TipsManager ourInstance;

	public static TipsManager Instance() {
		if (ourInstance == null) {
			ourInstance = new TipsManager();
		}
		return ourInstance;
	}

	public ZLBooleanOption TipsAreInitializedOption =
		new ZLBooleanOption("tips", "tipsAreInitialized", false);
	public ZLBooleanOption ShowTipsOption =
		new ZLBooleanOption("tips", "showTips", false);

	// time when last tip was shown, 2^16 milliseconds
	private final ZLIntegerOption myLastShownOption =
		new ZLIntegerOption("tips", "shownAt", 0);
	// index of next tip to show
	private final ZLIntegerOption myIndexOption =
		new ZLIntegerOption("tips", "index", 0);

	private volatile boolean myDownloadInProgress;

	private TipsManager() {
	}

	private String getUrl() {
		return "https://data.fbreader.org/tips/tips.php";
	}

	private String getLocalFilePath() {
		return Paths.networkCacheDirectory() + "/tips/tips.xml";
	}

	private List<Tip> myTips;
	private List<Tip> getTips() {
		if (myTips == null) {
			final ZLFile file = ZLFile.createFileByPath(getLocalFilePath());
			if (file.exists()) {
				final TipsFeedHandler handler = new TipsFeedHandler();
				new ATOMXMLReader(handler, false).readQuietly(file);
				final List<Tip> tips = Collections.unmodifiableList(handler.Tips);
				if (tips.size() > 0) {
					myTips = tips;
				}
			}
		}
		return myTips;
	}

	public boolean hasNextTip() {
		final List<Tip> tips = getTips();
		if (tips == null) {
			return false;
		}

		final int index = myIndexOption.getValue();
		if (index >= tips.size()) {
			new File(getLocalFilePath()).delete();
			myIndexOption.setValue(0);
			return false;
		}

		return true;
	}

	public Tip getNextTip() {
		final List<Tip> tips = getTips();
		if (tips == null) {
			return null;
		}

		final int index = myIndexOption.getValue();
		if (index >= tips.size()) {
			new File(getLocalFilePath()).delete();
			myIndexOption.setValue(0);
			return null;
		}

		myIndexOption.setValue(index + 1);
		myLastShownOption.setValue(currentTime());
		return tips.get(index);
	}

	private final int DELAY = (24 * 60 * 60 * 1000) >> 16; // 1 day

	private int currentTime() {
		return (int)(new Date().getTime() >> 16);
	}

	public static enum Action {
		Initialize,
		Show,
		Download,
		None
	}

	public Action requiredAction() {
		if (ShowTipsOption.getValue()) {
			if (hasNextTip()) {
				return myLastShownOption.getValue() + DELAY < currentTime()
					? Action.Show : Action.None;
			} else {
				return myDownloadInProgress
					? Action.None : Action.Download;
			}
		} else if (!TipsAreInitializedOption.getValue()) {
			return Action.Initialize;
		}
		return Action.None;
	}

	public synchronized void startDownloading() {
		if (requiredAction() != Action.Download) {
			return;
		}

		myDownloadInProgress = true;

		new File(Paths.networkCacheDirectory() + "/tips").mkdirs();
		new Thread(new Runnable() {
			public void run() {
				try {
					ZLNetworkManager.Instance().downloadToFile(
						getUrl(), new File(getLocalFilePath())
					);
				} catch (ZLNetworkException e) {
					e.printStackTrace();
				} finally {
					myDownloadInProgress = false;
				}
			}
		}).start();
	}
}