/*
 * Copyright 2008-2019 by Emeric Vernat
 *
 *     This file is part of Java Melody.
 *
 * 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 net.bull.javamelody.internal.model;

import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Paint;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Timer;

import javax.imageio.ImageIO;

import org.jrobin.core.ConsolFuns;
import org.jrobin.core.FetchRequest;
import org.jrobin.core.RrdBackendFactory;
import org.jrobin.core.RrdDb;
import org.jrobin.core.RrdDbPool;
import org.jrobin.core.RrdDef;
import org.jrobin.core.RrdException;
import org.jrobin.core.Sample;
import org.jrobin.core.Util;
import org.jrobin.data.DataProcessor;
import org.jrobin.data.Plottable;
import org.jrobin.graph.RrdGraph;
import org.jrobin.graph.RrdGraphDef;

import net.bull.javamelody.Parameter;
import net.bull.javamelody.internal.common.I18N;
import net.bull.javamelody.internal.common.LOG;
import net.bull.javamelody.internal.common.Parameters;

/**
 * Stockage RRD et graphiques statistiques.
 * Cette classe utilise <a href='http://www.jrobin.org/index.php/Main_Page'>JRobin</a>
 * qui est une librairie Java opensource (LGPL) similaire à <a href='http://oss.oetiker.ch/rrdtool/'>RRDTool</a>.
 * L'API et le tutorial JRobin sont à http://oldwww.jrobin.org/api/index.html
 * @author Emeric Vernat
 */
public final class JRobin {
	public static final int SMALL_HEIGHT = 50;
	private static final Color PERCENTILE_COLOR = new Color(200, 50, 50);
	private static final Color LIGHT_RED = Color.RED.brighter().brighter();
	private static final Paint SMALL_GRADIENT = new GradientPaint(0, 0, LIGHT_RED, 0, SMALL_HEIGHT,
			Color.GREEN, false);
	private static final int HOUR = 60 * 60;
	private static final int DAY = 24 * HOUR;
	private static final int DEFAULT_OBSOLETE_GRAPHS_DAYS = 90;
	private static final int DEFAULT_MAX_RRD_DISK_USAGE_MB = 20;

	// pool of open RRD files
	private final RrdDbPool rrdPool = getRrdDbPool();
	private final String application;
	private final String name;
	private final String rrdFileName;
	private final int step;
	private final String requestName;

	private static final class AppContextClassLoaderLeakPrevention {
		private AppContextClassLoaderLeakPrevention() {
			super();
		}

		static {
			// issue 476: appContextProtection is disabled by default in JreMemoryLeakPreventionListener since Tomcat 7.0.42,
			// so protect from sun.awt.AppContext ourselves
			final ClassLoader loader = Thread.currentThread().getContextClassLoader();
			try {
				// Use the system classloader as the victim for this ClassLoader pinning we're about to do.
				Thread.currentThread().setContextClassLoader(ClassLoader.getSystemClassLoader());

				// Trigger a call to sun.awt.AppContext.getAppContext().
				// This will pin the system class loader in memory but that shouldn't be an issue.
				ImageIO.getCacheDirectory();
			} catch (final Throwable t) { // NOPMD
				LOG.info("prevention of AppContext ClassLoader leak failed, skipping");
			} finally {
				Thread.currentThread().setContextClassLoader(loader);
			}
		}

		static void dummy() {
			// just to initialize the class
		}
	}

	private JRobin(String application, String name, File rrdFile, int step, String requestName)
			throws RrdException, IOException {
		super();
		assert application != null;
		assert name != null;
		assert rrdFile != null;
		assert step > 0;
		// requestName est null pour un compteur

		this.application = application;
		this.name = name;
		this.rrdFileName = rrdFile.getPath();
		this.step = step;
		this.requestName = requestName;

		init();
	}

	public static void stop() {
		if (RrdNioBackend.getFileSyncTimer() != null) {
			RrdNioBackend.getFileSyncTimer().cancel();
		}
	}

	/**
	 * JavaMelody uses a custom RrdNioBackendFactory,
	 * in order to use its own and cancelable file sync timer.
	 * @param timer Timer
	 * @throws IOException e
	 */
	public static void initBackendFactory(Timer timer) throws IOException {
		RrdNioBackend.setFileSyncTimer(timer);

		try {
			if (!RrdBackendFactory.getDefaultFactory().getFactoryName()
					.equals(RrdNioBackendFactory.FACTORY_NAME)) {
				RrdBackendFactory.registerAndSetAsDefaultFactory(new RrdNioBackendFactory());
			}
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	static JRobin createInstance(String application, String name, String requestName)
			throws IOException {
		final File rrdFile = getRrdFile(application, name);
		final int step = Parameters.getResolutionSeconds();
		try {
			return new JRobin(application, name, rrdFile, step, requestName);
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	static JRobin createInstanceIfFileExists(String application, String name, String requestName)
			throws IOException {
		final File rrdFile = getRrdFile(application, name);
		if (rrdFile.exists()) {
			final int step = Parameters.getResolutionSeconds();
			try {
				return new JRobin(application, name, rrdFile, step, requestName);
			} catch (final RrdException e) {
				throw createIOException(e);
			}
		}
		return null;
	}

	private static File getRrdFile(String application, String name) {
		final File dir = Parameters.getStorageDirectory(application);
		return new File(dir, name + ".rrd");
	}

	private void init() throws IOException, RrdException {
		final File rrdFile = new File(rrdFileName);
		final File rrdDirectory = rrdFile.getParentFile();
		if (!rrdDirectory.mkdirs() && !rrdDirectory.exists()) {
			throw new IOException(
					"JavaMelody directory can't be created: " + rrdDirectory.getPath());
		}
		// cf issue 41: rrdFile could have been created with length 0 if out of disk space
		// (fix IOException: Read failed, file xxx.rrd not mapped for I/O)
		if (!rrdFile.exists() || rrdFile.length() == 0) {
			// create RRD file since it does not exist (or is empty)
			final RrdDef rrdDef = new RrdDef(rrdFileName, step);
			// "startTime" décalé de "step" pour éviter que addValue appelée juste
			// après ne lance l'exception suivante la première fois
			// "Bad sample timestamp x. Last update time was x, at least one second step is required"
			rrdDef.setStartTime(Util.getTime() - step);
			// single gauge datasource
			final String dsType = "GAUGE";
			// max time before "unknown value"
			final int heartbeat = step * 2;
			rrdDef.addDatasource(getDataSourceName(), dsType, heartbeat, 0, Double.NaN);
			// several archives
			final String average = ConsolFuns.CF_AVERAGE;
			final String max = ConsolFuns.CF_MAX;
			// 1 jour
			rrdDef.addArchive(average, 0.25, 1, DAY / step);
			rrdDef.addArchive(max, 0.25, 1, DAY / step);
			// 1 semaine
			rrdDef.addArchive(average, 0.25, HOUR / step, 7 * 24);
			rrdDef.addArchive(max, 0.25, HOUR / step, 7 * 24);
			// 1 mois
			rrdDef.addArchive(average, 0.25, 6 * HOUR / step, 31 * 4);
			rrdDef.addArchive(max, 0.25, 6 * HOUR / step, 31 * 4);
			// 2 ans (1 an pour période "1 an" et 2 ans pour période "tout")
			rrdDef.addArchive(average, 0.25, 8 * 6 * HOUR / step, 2 * 12 * 15);
			rrdDef.addArchive(max, 0.25, 8 * 6 * HOUR / step, 2 * 12 * 15);
			// create RRD file in the pool
			final RrdDb rrdDb = rrdPool.requestRrdDb(rrdDef);
			rrdPool.release(rrdDb);
		}
	}

	private void resetFile() throws IOException {
		deleteFile();
		try {
			init();
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	public byte[] graph(Range range, int width, int height) throws IOException {
		return graph(range, width, height, false);
	}

	public byte[] graph(Range range, int width, int height, boolean maxHidden) throws IOException {
		// static init of the AppContext ClassLoader
		AppContextClassLoaderLeakPrevention.dummy();

		try {
			// Rq : il pourrait être envisagé de récupérer les données dans les fichiers rrd ou autre stockage
			// puis de faire des courbes en sparklines html (écrites dans la page html) ou jfreechart

			// create common part of graph definition
			final RrdGraphDef graphDef = new RrdGraphDef();
			if (Locale.CHINESE.getLanguage()
					.equals(I18N.getResourceBundle().getLocale().getLanguage())) {
				graphDef.setSmallFont(new Font(Font.MONOSPACED, Font.PLAIN, 10));
				graphDef.setLargeFont(new Font(Font.MONOSPACED, Font.BOLD, 12));
			}

			initGraphSource(graphDef, height, maxHidden, range);

			initGraphPeriodAndSize(range, width, height, graphDef);

			graphDef.setImageFormat("png");
			graphDef.setFilename("-");
			// il faut utiliser le pool pour les performances
			// et pour éviter des erreurs d'accès concurrents sur les fichiers
			// entre différentes générations de graphs et aussi avec l'écriture des données
			graphDef.setPoolUsed(true);
			return new RrdGraph(graphDef).getRrdGraphInfo().getBytes();
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	private void initGraphPeriodAndSize(Range range, int width, int height, RrdGraphDef graphDef) {
		// ending timestamp is the (current) timestamp in seconds
		// starting timestamp will be adjusted for each graph
		final long endTime = range.getJRobinEndTime();
		final long startTime = range.getJRobinStartTime();
		final String label = getLabel();
		final String titleStart;
		if (label.length() > 31 && width <= 200) {
			// si le label est trop long, on raccourci le titre sinon il ne rentre pas
			titleStart = label;
		} else {
			titleStart = label + " - " + range.getLabel();
		}
		final String titleEnd;
		if (width > 400) {
			if (range.getPeriod() == null) {
				titleEnd = " - " + I18N.getFormattedString("sur", getApplication());
			} else {
				titleEnd = " - " + I18N.getCurrentDate() + ' '
						+ I18N.getFormattedString("sur", getApplication());
			}
		} else {
			titleEnd = "";
			if (range.getPeriod() == null) {
				// si période entre 2 dates et si pas de zoom,
				// alors on réduit de 2 point la fonte du titre pour qu'il rentre dans le cadre
				graphDef.setLargeFont(graphDef.getLargeFont()
						.deriveFont(graphDef.getLargeFont().getSize2D() - 2f));
			}
		}
		graphDef.setStartTime(startTime);
		graphDef.setEndTime(endTime);
		graphDef.setTitle(titleStart + titleEnd);
		graphDef.setFirstDayOfWeek(
				Calendar.getInstance(I18N.getCurrentLocale()).getFirstDayOfWeek());
		// or if the user locale patch is merged we should do:
		// (https://sourceforge.net/tracker/?func=detail&aid=3403733&group_id=82668&atid=566807)
		//graphDef.setLocale(I18N.getCurrentLocale());

		// rq : la largeur et la hauteur de l'image sont plus grandes que celles fournies
		// car jrobin ajoute la largeur et la hauteur des textes et autres
		graphDef.setWidth(width);
		graphDef.setHeight(height);
		if (width <= 100) {
			graphDef.setNoLegend(true);
			graphDef.setUnitsLength(0);
			graphDef.setShowSignature(false);
			graphDef.setTitle(null);
		}
		//		graphDef.setColor(RrdGraphConstants.COLOR_BACK, new GradientPaint(0, 0,
		//				RrdGraphConstants.DEFAULT_BACK_COLOR.brighter(), 0, height,
		//				RrdGraphConstants.DEFAULT_BACK_COLOR));
	}

	private void initGraphSource(RrdGraphDef graphDef, int height, boolean maxHidden, Range range)
			throws IOException {
		final String dataSourceName = getDataSourceName();
		final String average = "average";
		graphDef.datasource(average, rrdFileName, dataSourceName, ConsolFuns.CF_AVERAGE);
		graphDef.setMinValue(0);
		final String moyenneLabel = I18N.getString("Moyenne");
		graphDef.area(average, getPaint(height), moyenneLabel);
		graphDef.gprint(average, ConsolFuns.CF_AVERAGE, moyenneLabel + ": %9.0f %S\\r");
		//graphDef.gprint(average, ConsolFuns.CF_MIN, "Minimum: %9.0f %S\\r");
		if (!maxHidden) {
			final String max = "max";
			graphDef.datasource(max, rrdFileName, dataSourceName, ConsolFuns.CF_MAX);
			final String maximumLabel = I18N.getString("Maximum");
			graphDef.line(max, Color.BLUE, maximumLabel);
			graphDef.gprint(max, ConsolFuns.CF_MAX, maximumLabel + ": %9.0f %S\\r");
		}
		if (height > 200) {
			final double percentileValue = get95PercentileValue(range);
			final Plottable constantDataSource = new Plottable() {
				@Override
				public double getValue(long timestamp) {
					return percentileValue;
				}
			};
			final String percentile = "percentile";
			graphDef.datasource(percentile, constantDataSource);
			final String percentileLabel = I18N.getString("95percentile");
			graphDef.line(percentile, PERCENTILE_COLOR, percentileLabel);
			graphDef.gprint(percentile, ConsolFuns.CF_MAX, ":%9.0f %S\\r");
		}
		// graphDef.comment("JRobin :: RRDTool Choice for the Java World");
	}

	private static Paint getPaint(int height) {
		// si on avait la moyenne globale/glissante des valeurs et l'écart type
		// on pourrait mettre vert si < moyenne + 1 écart type puis orange puis rouge si > moyenne + 2 écarts types,
		// en utilisant LinearGradientPaint par exemple, ou bien selon paramètres de plages de couleurs par graphe
		if (height == SMALL_HEIGHT) {
			// design pattern fly-weight (poids-mouche) pour le cas des 9 ou 12 graphs
			// dans la page html de départ
			return SMALL_GRADIENT;
		}
		return new GradientPaint(0, 0, LIGHT_RED, 0, height, Color.GREEN, false);
	}

	void addValue(double value) throws IOException {
		try {
			// request RRD database reference from the pool
			final RrdDb rrdDb = rrdPool.requestRrdDb(rrdFileName);
			synchronized (rrdDb) {
				try {
					// create sample with the current timestamp
					final Sample sample = rrdDb.createSample();
					// test pour éviter l'erreur suivante au redéploiement par exemple:
					// org.jrobin.core.RrdException:
					// Bad sample timestamp x. Last update time was x, at least one second step is required
					if (sample.getTime() > rrdDb.getLastUpdateTime()) {
						// set value for load datasource
						sample.setValue(getDataSourceName(), value);
						// update database
						sample.update();
					}
				} finally {
					// release RRD database reference
					rrdPool.release(rrdDb);
				}
			}
		} catch (final FileNotFoundException e) {
			if (e.getMessage() != null && e.getMessage().endsWith("[non existent]")) {
				// cf issue 255
				LOG.debug("A JRobin file was deleted and created again: "
						+ new File(rrdFileName).getPath());
				resetFile();
				addValue(value);
			}
		} catch (final RrdException e) {
			if (e.getMessage() != null && e.getMessage().startsWith("Invalid file header")) {
				// le fichier RRD a été corrompu, par exemple en tuant le process java au milieu
				// d'un write, donc on efface le fichier corrompu et on le recrée pour corriger
				// le problème
				LOG.debug("A JRobin file was found corrupted and was reset: "
						+ new File(rrdFileName).getPath());
				resetFile();
				addValue(value);
			}
			throw createIOException(e);
		} catch (final IllegalArgumentException | ArithmeticException e) {
			// catch IllegalArgumentException for issue 533:
			//			java.lang.IllegalArgumentException
			//			at java.nio.Buffer.position(Buffer.java:244)
			//			at net.bull.javamelody.RrdNioBackend.read(RrdNioBackend.java:147)
			//          ...
			//			at org.jrobin.core.RrdDbPool.requestRrdDb(RrdDbPool.java:103)
			//			at net.bull.javamelody.JRobin.addValue(JRobin.java:334)

			// ou catch ArithmeticException for issue 139 / JENKINS-51590:
			//		java.lang.ArithmeticException : / by zero
			//		at org.jrobin.core.Archive.archive(Archive.java:129)
			//		at org.jrobin.core.RrdDb.archive(RrdDb.java:720)
			//		at org.jrobin.core.Datasource.process(Datasource.java:201)
			//		at org.jrobin.core.RrdDb.store(RrdDb.java:593)
			//		at org.jrobin.core.Sample.update(Sample.java:228)
			//		at net.bull.javamelody.internal.model.JRobin.addValue(JRobin.java:374)

			// le fichier RRD a été corrompu, par exemple en tuant le process java au milieu
			// d'un write, donc on efface le fichier corrompu et on le recrée pour corriger
			// le problème
			LOG.debug("A JRobin file was found corrupted and was reset: "
					+ new File(rrdFileName).getPath());
			resetFile();
			addValue(value);
			throw createIOException(e);
		}
	}

	public double getLastValue() throws IOException {
		try {
			// request RRD database reference from the pool
			final RrdDb rrdDb = rrdPool.requestRrdDb(rrdFileName);
			try {
				return rrdDb.getLastDatasourceValue(getDataSourceName());
			} finally {
				// release RRD database reference
				rrdPool.release(rrdDb);
			}
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	public void dumpXml(OutputStream output, Range range) throws IOException {
		try {
			// request RRD database reference from the pool
			final RrdDb rrdDb = rrdPool.requestRrdDb(rrdFileName);
			try {
				if (range.getPeriod() == Period.TOUT) {
					rrdDb.exportXml(output);
				} else {
					final FetchRequest fetchRequest = rrdDb.createFetchRequest(
							ConsolFuns.CF_AVERAGE, range.getJRobinStartTime(),
							range.getJRobinEndTime());
					final String xml = fetchRequest.fetchData().exportXml()
							.replaceFirst("<file>.*</file>", "");
					output.write(xml.getBytes(StandardCharsets.UTF_8));
				}
			} finally {
				// release RRD database reference
				rrdPool.release(rrdDb);
			}
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	public String dumpTxt(Range range) throws IOException {
		try {
			// request RRD database reference from the pool
			final RrdDb rrdDb = rrdPool.requestRrdDb(rrdFileName);
			try {
				if (range.getPeriod() == Period.TOUT) {
					return rrdDb.dump();
				}
				final FetchRequest fetchRequest = rrdDb.createFetchRequest(ConsolFuns.CF_AVERAGE,
						range.getJRobinStartTime(), range.getJRobinEndTime());
				return fetchRequest.fetchData().dump();
			} finally {
				// release RRD database reference
				rrdPool.release(rrdDb);
			}
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	double getMeanValue(Range range) throws IOException {
		assert range.getPeriod() == null;
		try {
			final DataProcessor dproc = processData(range);
			return dproc.getAggregate("average", ConsolFuns.CF_AVERAGE);
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	private double get95PercentileValue(Range range) throws IOException {
		try {
			final DataProcessor dproc = processData(range);
			// 95th percentile et non un autre percentile par choix
			return dproc.get95Percentile("average");
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	private DataProcessor processData(Range range) throws IOException, RrdException {
		final String dataSourceName = getDataSourceName();
		final long endTime = range.getJRobinEndTime();
		final long startTime = range.getJRobinStartTime();
		final DataProcessor dproc = new DataProcessor(startTime, endTime);
		dproc.addDatasource("average", rrdFileName, dataSourceName, ConsolFuns.CF_AVERAGE);
		dproc.setPoolUsed(true);
		dproc.processData();
		return dproc;
	}

	boolean deleteFile() {
		return new File(rrdFileName).delete();
	}

	private String getApplication() {
		return application;
	}

	public String getName() {
		return name;
	}

	private String getDataSourceName() {
		// RrdDef.addDatasource n'accepte pas un nom de datasource supérieur à 20 caractères
		return name.substring(0, Math.min(20, name.length()));
	}

	public String getLabel() {
		if (requestName == null) {
			// c'est un jrobin global issu soit de JavaInformations soit d'un Counter dans le Collector
			return I18N.getString(getName());
		}
		// c'est un jrobin issu d'un CounterRequest dans le Collector
		final String shortRequestName = requestName.substring(0,
				Math.min(30, requestName.length()));
		// plus nécessaire:  if (getName().startsWith("error")) {
		// c'est un jrobin issu d'un CounterRequest du Counter "error"
		// return I18N.getString("Erreurs_par_minute_pour") + ' ' + shortRequestName; }
		return I18N.getFormattedString("Temps_moyens_de", shortRequestName);
	}

	private static IOException createIOException(Exception e) {
		// Rq: le constructeur de IOException avec message et cause n'existe qu'en jdk 1.6
		return new IOException(e.getMessage(), e);
	}

	static long deleteObsoleteJRobinFiles(String application) {
		final Calendar nowMinusThreeMonthsAndADay = Calendar.getInstance();
		nowMinusThreeMonthsAndADay.add(Calendar.DAY_OF_YEAR, -getObsoleteGraphsDays());
		nowMinusThreeMonthsAndADay.add(Calendar.DAY_OF_YEAR, -1);
		final long timestamp = Util.getTimestamp(nowMinusThreeMonthsAndADay);
		final int counterRequestIdLength = new CounterRequest("", "").getId().length();
		long diskUsage = 0;
		final Map<String, Long> lastUpdateTimesByPath = new HashMap<>();
		final List<File> rrdFiles = new ArrayList<>(listRrdFiles(application));
		for (final File file : rrdFiles) {
			// on ne supprime que les fichiers rrd de requêtes (les autres sont peu nombreux)
			if (file.getName().length() > counterRequestIdLength
					&& file.lastModified() < nowMinusThreeMonthsAndADay.getTimeInMillis()) {
				final long lastUpdateTime = getLastUpdateTime(file);
				lastUpdateTimesByPath.put(file.getPath(), lastUpdateTime);
				final boolean obsolete = lastUpdateTime < timestamp;
				boolean deleted = false;
				if (obsolete) {
					deleted = file.delete();
				}
				if (!deleted) {
					diskUsage += file.length();
				}
			} else {
				diskUsage += file.length();
			}
		}
		final long maxRrdDiskUsage = getMaxRrdDiskUsageMb() * 1024L * 1024L;
		if (diskUsage > maxRrdDiskUsage) {
			// sort rrd files from least to most recently used
			for (final File file : rrdFiles) {
				if (lastUpdateTimesByPath.get(file.getPath()) == null) {
					lastUpdateTimesByPath.put(file.getPath(), getLastUpdateTime(file));
				}
			}
			final Comparator<File> comparatorByLastUpdateTime = new Comparator<File>() {
				@Override
				public int compare(File o1, File o2) {
					return lastUpdateTimesByPath.get(o1.getPath())
							.compareTo(lastUpdateTimesByPath.get(o2.getPath()));
				}
			};
			Collections.sort(rrdFiles, comparatorByLastUpdateTime);
			// delete least recently used rrd files until rrd disk usage < 20 MB
			for (final File file : rrdFiles) {
				if (diskUsage < maxRrdDiskUsage) {
					break;
				}
				if (file.getName().length() > counterRequestIdLength) {
					final long length = file.length();
					if (file.delete()) {
						diskUsage -= length;
					}
				}
			}
		}

		return diskUsage;
	}

	private static long getLastUpdateTime(File file) {
		try {
			final RrdDbPool rrdPool = getRrdDbPool();
			final RrdDb rrdDb = rrdPool.requestRrdDb(file.getPath());
			final long lastUpdateTime = rrdDb.getLastUpdateTime();
			rrdPool.release(rrdDb);
			return lastUpdateTime;
		} catch (final IOException | RrdException e) {
			return file.lastModified() / 1000L;
		}
	}

	private static long getMaxRrdDiskUsageMb() {
		final String param = Parameters.getParameterValue(Parameter.MAX_RRD_DISK_USAGE_MB);
		if (param != null) {
			// lance une NumberFormatException si ce n'est pas un nombre
			final int result = Integer.parseInt(param);
			if (result <= 0) {
				throw new IllegalStateException(
						"The parameter max-rrd-disk-usage-mb should be > 0 (20 recommended)");
			}
			return result;
		}
		return DEFAULT_MAX_RRD_DISK_USAGE_MB;
	}

	/**
	 * @return Nombre de jours avant qu'un fichier de graphique JRobin (extension .rrd) qui n'est plus utilisé,
	 * soit considéré comme obsolète et soit supprimé automatiquement, à minuit (90 par défaut, soit 3 mois).
	 */
	private static int getObsoleteGraphsDays() {
		final String param = Parameter.OBSOLETE_GRAPHS_DAYS.getValue();
		if (param != null) {
			// lance une NumberFormatException si ce n'est pas un nombre
			final int result = Integer.parseInt(param);
			if (result <= 0) {
				throw new IllegalStateException(
						"The parameter obsolete-graphs-days should be > 0 (90 recommended)");
			}
			return result;
		}
		return DEFAULT_OBSOLETE_GRAPHS_DAYS;
	}

	private static List<File> listRrdFiles(String application) {
		final File storageDir = Parameters.getStorageDirectory(application);
		// filtre pour ne garder que les fichiers d'extension .rrd et pour éviter d'instancier des File inutiles
		final FilenameFilter filenameFilter = new FilenameFilter() {
			/** {@inheritDoc} */
			@Override
			public boolean accept(File dir, String fileName) {
				return fileName.endsWith(".rrd");
			}
		};
		final File[] files = storageDir.listFiles(filenameFilter);
		if (files == null) {
			return Collections.emptyList();
		}
		return Arrays.asList(files);
	}

	private static RrdDbPool getRrdDbPool() throws IOException {
		try {
			return RrdDbPool.getInstance();
		} catch (final RrdException e) {
			throw createIOException(e);
		}
	}

	@Override
	public String toString() {
		return getClass().getSimpleName() + "[application=" + getApplication() + ", name="
				+ getName() + ']';
	}

	//  public void test() throws RrdException, IOException {
	//    for (int i = 1000; i > 0; i--) {
	//      // request RRD database reference from the pool
	//      RrdDb rrdDb = rrdPool.requestRrdDb(rrdFileName);
	//      // create sample with the current timestamp
	//      Sample sample = rrdDb.createSample(Util.getTime() - 120 * i);
	//      // set value for load datasource
	//      // println(i + " " + new byte[5000]);
	//      sample.setValue(name, Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory());
	//      // update database
	//      sample.update();
	//      // release RRD database reference
	//      rrdPool.release(rrdDb);
	//    }
	//
	//    graph(Period.JOUR);
	//    graph(Period.SEMAINE);
	//    graph(Period.MOIS);
	//    graph(Period.ANNEE);
	//  }
	//
	//  public static void main(String[] args) throws IOException, RrdException {
	//    new JRobin("Mémoire", "jrobin", 120).test();
	//  }
}
