Include bStats metrics. Not enabled yet

main/src/main/java/me/blackvein/quests/Quests.java

@@ -162,6 +162,8 @@ public class Quests extends JavaPlugin implements ConversationAbandonedListener
         conditionFactory = new ConditionFactory(this);
         depends = new Dependencies(this);
         trigger = new DenizenTrigger(this);
+        /*final Metrics metrics = new Metrics(this);
+        metrics.addCustomChart(new Metrics.SimplePie("language", () -> Lang.getISO()));*/
 
         // 2 - Load main config
         settings.init();

main/src/main/java/me/blackvein/quests/statistics/Metrics.java

@@ -0,0 +1,755 @@
+/*******************************************************************************************************
+ * Continued by PikaMug (formerly HappyPikachu) with permission from _Blackvein_. All rights reserved.
+ * 
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
+ * NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *******************************************************************************************************/
+
+package me.blackvein.quests.statistics;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayOutputStream;
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Level;
+import java.util.zip.GZIPOutputStream;
+
+import javax.net.ssl.HttpsURLConnection;
+
+import org.bukkit.Bukkit;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.RegisteredServiceProvider;
+import org.bukkit.plugin.ServicePriority;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.JsonPrimitive;
+
+/**
+ * bStats collects some data for plugin authors.
+ * <p>
+ * Check out https://bStats.org/ to learn more about bStats!
+ */
+//@SuppressWarnings({"WeakerAccess", "unused"})
+public class Metrics {
+
+    static {
+        // You can use the property to disable the check in your test environment
+        if (System.getProperty("bstats.relocatecheck") == null || !System.getProperty("bstats.relocatecheck").equals("false")) {
+            // Maven's Relocate is clever and changes strings, too. So we have to use this little "trick" ... :D
+            final String defaultPackage = new String(
+                    new byte[]{'o', 'r', 'g', '.', 'b', 's', 't', 'a', 't', 's', '.', 'b', 'u', 'k', 'k', 'i', 't'});
+            final String examplePackage = new String(new byte[]{'y', 'o', 'u', 'r', '.', 'p', 'a', 'c', 'k', 'a', 'g', 'e'});
+            // We want to make sure nobody just copy & pastes the example and use the wrong package names
+            if (Metrics.class.getPackage().getName().equals(defaultPackage) || Metrics.class.getPackage().getName().equals(examplePackage)) {
+                throw new IllegalStateException("bStats Metrics class has not been relocated correctly!");
+            }
+        }
+    }
+
+    // This ThreadFactory enforces the naming convention for our Threads
+    private final ThreadFactory threadFactory = task -> new Thread(task, "bStats-Metrics");
+
+    // Executor service for requests
+    // We use an executor service because the Bukkit scheduler is affected by server lags
+    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1, threadFactory);
+
+    // The version of this bStats class
+    public static final int B_STATS_VERSION = 1;
+
+    // The url to which the data is sent
+    private static final String URL = "https://bStats.org/submitData/bukkit";
+
+    // Is bStats enabled on this server?
+    private final boolean enabled;
+
+    // Should failed requests be logged?
+    private static boolean logFailedRequests;
+
+    // Should the sent data be logged?
+    private static boolean logSentData;
+
+    // Should the response text be logged?
+    private static boolean logResponseStatusText;
+
+    // The uuid of the server
+    private static String serverUUID;
+
+    // The plugin
+    private final Plugin plugin;
+
+    // The plugin id
+    private final int pluginId;
+
+    // A list with all custom charts
+    private final List<CustomChart> charts = new ArrayList<>();
+
+    /**
+     * Class constructor.
+     *
+     * @param plugin The plugin which stats should be submitted.
+     * @param pluginId The id of the plugin.
+     *                 It can be found at <a href="https://bstats.org/what-is-my-plugin-id">What is my plugin id?</a>
+     */
+    public Metrics(final Plugin plugin) {
+        if (plugin == null) {
+            throw new IllegalArgumentException("Plugin cannot be null!");
+        }
+        this.plugin = plugin;
+        this.pluginId = 9528;
+
+        // Get the config file
+        final File bStatsFolder = new File(plugin.getDataFolder().getParentFile(), "bStats");
+        final File configFile = new File(bStatsFolder, "config.yml");
+        final YamlConfiguration config = YamlConfiguration.loadConfiguration(configFile);
+
+        // Check if the config file exists
+        if (!config.isSet("serverUuid")) {
+
+            // Add default values
+            config.addDefault("enabled", true);
+            // Every server gets it's unique random id.
+            config.addDefault("serverUuid", UUID.randomUUID().toString());
+            // Should failed request be logged?
+            config.addDefault("logFailedRequests", false);
+            // Should the sent data be logged?
+            config.addDefault("logSentData", false);
+            // Should the response text be logged?
+            config.addDefault("logResponseStatusText", false);
+
+            // Inform the server owners about bStats
+            config.options().header(
+                    "bStats collects some data for plugin authors like how many servers are using their plugins.\n" +
+                            "To honor their work, you should not disable it.\n" +
+                            "This has nearly no effect on the server performance!\n" +
+                            "Check out https://bStats.org/ to learn more :)"
+            ).copyDefaults(true);
+            try {
+                config.save(configFile);
+            } catch (final IOException ignored) { }
+        }
+
+        // Load the data
+        enabled = config.getBoolean("enabled", true);
+        serverUUID = config.getString("serverUuid");
+        logFailedRequests = config.getBoolean("logFailedRequests", false);
+        logSentData = config.getBoolean("logSentData", false);
+        logResponseStatusText = config.getBoolean("logResponseStatusText", false);
+
+        if (enabled) {
+            boolean found = false;
+            // Search for all other bStats Metrics classes to see if we are the first one
+            for (final Class<?> service : Bukkit.getServicesManager().getKnownServices()) {
+                try {
+                    service.getField("B_STATS_VERSION"); // Our identifier :)
+                    found = true; // We aren't the first
+                    break;
+                } catch (final NoSuchFieldException ignored) { }
+            }
+            // Register our service
+            Bukkit.getServicesManager().register(Metrics.class, this, plugin, ServicePriority.Normal);
+            if (!found) {
+                // We are the first!
+                startSubmitting();
+            }
+        }
+    }
+
+    /**
+     * Checks if bStats is enabled.
+     *
+     * @return Whether bStats is enabled or not.
+     */
+    public boolean isEnabled() {
+        return enabled;
+    }
+
+    /**
+     * Adds a custom chart.
+     *
+     * @param chart The chart to add.
+     */
+    public void addCustomChart(final CustomChart chart) {
+        if (chart == null) {
+            throw new IllegalArgumentException("Chart cannot be null!");
+        }
+        charts.add(chart);
+    }
+
+    /**
+     * Starts the Scheduler which submits our data every 30 minutes.
+     */
+    private void startSubmitting() {
+        final Runnable submitTask = () -> {
+            if (!plugin.isEnabled()) { // Plugin was disabled
+                scheduler.shutdown();
+                return;
+            }
+            // Nevertheless we want our code to run in the Bukkit main thread, so we have to use the Bukkit scheduler
+            // Don't be afraid! The connection to the bStats server is still async, only the stats collection is sync ;)
+            Bukkit.getScheduler().runTask(plugin, this::submitData);
+        };
+
+        // Many servers tend to restart at a fixed time at xx:00 which causes an uneven distribution of requests on the
+        // bStats backend. To circumvent this problem, we introduce some randomness into the initial and second delay.
+        // WARNING: You must not modify and part of this Metrics class, including the submit delay or frequency!
+        // WARNING: Modifying this code will get your plugin banned on bStats. Just don't do it!
+        final long initialDelay = (long) (1000 * 60 * (3 + Math.random() * 3));
+        final long secondDelay = (long) (1000 * 60 * (Math.random() * 30));
+        scheduler.schedule(submitTask, initialDelay, TimeUnit.MILLISECONDS);
+        scheduler.scheduleAtFixedRate(submitTask, initialDelay + secondDelay, 1000 * 60 * 30, TimeUnit.MILLISECONDS);
+    }
+
+    /**
+     * Gets the plugin specific data.
+     * This method is called using Reflection.
+     *
+     * @return The plugin specific data.
+     */
+    public JsonObject getPluginData() {
+        final JsonObject data = new JsonObject();
+
+        final String pluginName = plugin.getDescription().getName();
+        final String pluginVersion = plugin.getDescription().getVersion();
+
+        data.addProperty("pluginName", pluginName); // Append the name of the plugin
+        data.addProperty("id", pluginId); // Append the id of the plugin
+        data.addProperty("pluginVersion", pluginVersion); // Append the version of the plugin
+        final JsonArray customCharts = new JsonArray();
+        for (final CustomChart customChart : charts) {
+            // Add the data of the custom charts
+            final JsonObject chart = customChart.getRequestJsonObject();
+            if (chart == null) { // If the chart is null, we skip it
+                continue;
+            }
+            customCharts.add(chart);
+        }
+        data.add("customCharts", customCharts);
+
+        return data;
+    }
+
+    /**
+     * Gets the server specific data.
+     *
+     * @return The server specific data.
+     */
+    private JsonObject getServerData() {
+        // Minecraft specific data
+        int playerAmount;
+        try {
+            // Around MC 1.8 the return type was changed to a collection from an array,
+            // This fixes java.lang.NoSuchMethodError: org.bukkit.Bukkit.getOnlinePlayers()Ljava/util/Collection;
+            final Method onlinePlayersMethod = Class.forName("org.bukkit.Server").getMethod("getOnlinePlayers");
+            playerAmount = onlinePlayersMethod.getReturnType().equals(Collection.class)
+                    ? ((Collection<?>) onlinePlayersMethod.invoke(Bukkit.getServer())).size()
+                    : ((Player[]) onlinePlayersMethod.invoke(Bukkit.getServer())).length;
+        } catch (final Exception e) {
+            playerAmount = Bukkit.getOnlinePlayers().size(); // Just use the new method if the Reflection failed
+        }
+        final int onlineMode = Bukkit.getOnlineMode() ? 1 : 0;
+        final String bukkitVersion = Bukkit.getVersion();
+        final String bukkitName = Bukkit.getName();
+
+        // OS/Java specific data
+        final String javaVersion = System.getProperty("java.version");
+        final String osName = System.getProperty("os.name");
+        final String osArch = System.getProperty("os.arch");
+        final String osVersion = System.getProperty("os.version");
+        final int coreCount = Runtime.getRuntime().availableProcessors();
+
+        final JsonObject data = new JsonObject();
+
+        data.addProperty("serverUUID", serverUUID);
+
+        data.addProperty("playerAmount", playerAmount);
+        data.addProperty("onlineMode", onlineMode);
+        data.addProperty("bukkitVersion", bukkitVersion);
+        data.addProperty("bukkitName", bukkitName);
+
+        data.addProperty("javaVersion", javaVersion);
+        data.addProperty("osName", osName);
+        data.addProperty("osArch", osArch);
+        data.addProperty("osVersion", osVersion);
+        data.addProperty("coreCount", coreCount);
+
+        return data;
+    }
+
+    /**
+     * Collects the data and sends it afterwards.
+     */
+    private void submitData() {
+        final JsonObject data = getServerData();
+
+        final JsonArray pluginData = new JsonArray();
+        // Search for all other bStats Metrics classes to get their plugin data
+        for (final Class<?> service : Bukkit.getServicesManager().getKnownServices()) {
+            try {
+                service.getField("B_STATS_VERSION"); // Our identifier :)
+
+                for (final RegisteredServiceProvider<?> provider : Bukkit.getServicesManager().getRegistrations(service)) {
+                    try {
+                        final Object plugin = provider.getService().getMethod("getPluginData").invoke(provider.getProvider());
+                        if (plugin instanceof JsonObject) {
+                            pluginData.add((JsonObject) plugin);
+                        } else { // old bstats version compatibility
+                            try {
+                                final Class<?> jsonObjectJsonSimple = Class.forName("org.json.simple.JSONObject");
+                                if (plugin.getClass().isAssignableFrom(jsonObjectJsonSimple)) {
+                                    final Method jsonStringGetter = jsonObjectJsonSimple.getDeclaredMethod("toJSONString");
+                                    jsonStringGetter.setAccessible(true);
+                                    final String jsonString = (String) jsonStringGetter.invoke(plugin);
+                                    final JsonObject object = new JsonParser().parse(jsonString).getAsJsonObject();
+                                    pluginData.add(object);
+                                }
+                            } catch (final ClassNotFoundException e) {
+                                // minecraft version 1.14+
+                                if (logFailedRequests) {
+                                    this.plugin.getLogger().log(Level.SEVERE, "Encountered unexpected exception", e);
+                                }
+                            }
+                        }
+                    } catch (NullPointerException | NoSuchMethodException | IllegalAccessException | InvocationTargetException ignored) { }
+                }
+            } catch (final NoSuchFieldException ignored) { }
+        }
+
+        data.add("plugins", pluginData);
+
+        // Create a new thread for the connection to the bStats server
+        new Thread(() -> {
+            try {
+                // Send the data
+                sendData(plugin, data);
+            } catch (final Exception e) {
+                // Something went wrong! :(
+                if (logFailedRequests) {
+                    plugin.getLogger().log(Level.WARNING, "Could not submit plugin stats of " + plugin.getName(), e);
+                }
+            }
+        }).start();
+    }
+
+    /**
+     * Sends the data to the bStats server.
+     *
+     * @param plugin Any plugin. It's just used to get a logger instance.
+     * @param data The data to send.
+     * @throws Exception If the request failed.
+     */
+    private static void sendData(final Plugin plugin, final JsonObject data) throws Exception {
+        if (data == null) {
+            throw new IllegalArgumentException("Data cannot be null!");
+        }
+        if (Bukkit.isPrimaryThread()) {
+            throw new IllegalAccessException("This method must not be called from the main thread!");
+        }
+        if (logSentData) {
+            plugin.getLogger().info("Sending data to bStats: " + data);
+        }
+        final HttpsURLConnection connection = (HttpsURLConnection) new URL(URL).openConnection();
+
+        // Compress the data to save bandwidth
+        final byte[] compressedData = compress(data.toString());
+
+        // Add headers
+        connection.setRequestMethod("POST");
+        connection.addRequestProperty("Accept", "application/json");
+        connection.addRequestProperty("Connection", "close");
+        connection.addRequestProperty("Content-Encoding", "gzip"); // We gzip our request
+        connection.addRequestProperty("Content-Length", String.valueOf(compressedData.length));
+        connection.setRequestProperty("Content-Type", "application/json"); // We send our data in JSON format
+        connection.setRequestProperty("User-Agent", "MC-Server/" + B_STATS_VERSION);
+
+        // Send data
+        connection.setDoOutput(true);
+        try (DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream())) {
+            outputStream.write(compressedData);
+        }
+
+        final StringBuilder builder = new StringBuilder();
+        try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(connection.getInputStream()))) {
+            String line;
+            while ((line = bufferedReader.readLine()) != null) {
+                builder.append(line);
+            }
+        }
+
+        if (logResponseStatusText) {
+            plugin.getLogger().info("Sent data to bStats and received response: " + builder);
+        }
+    }
+
+    /**
+     * Gzips the given String.
+     *
+     * @param str The string to gzip.
+     * @return The gzipped String.
+     * @throws IOException If the compression failed.
+     */
+    private static byte[] compress(final String str) throws IOException {
+        if (str == null) {
+            return null;
+        }
+        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        try (GZIPOutputStream gzip = new GZIPOutputStream(outputStream)) {
+            gzip.write(str.getBytes(StandardCharsets.UTF_8));
+        }
+        return outputStream.toByteArray();
+    }
+
+    /**
+     * Represents a custom chart.
+     */
+    public static abstract class CustomChart {
+
+        // The id of the chart
+        final String chartId;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         */
+        CustomChart(final String chartId) {
+            if (chartId == null || chartId.isEmpty()) {
+                throw new IllegalArgumentException("ChartId cannot be null or empty!");
+            }
+            this.chartId = chartId;
+        }
+
+        private JsonObject getRequestJsonObject() {
+            final JsonObject chart = new JsonObject();
+            chart.addProperty("chartId", chartId);
+            try {
+                final JsonObject data = getChartData();
+                if (data == null) {
+                    // If the data is null we don't send the chart.
+                    return null;
+                }
+                chart.add("data", data);
+            } catch (final Throwable t) {
+                if (logFailedRequests) {
+                    Bukkit.getLogger().log(Level.WARNING, "Failed to get data for custom chart with id " + chartId, t);
+                }
+                return null;
+            }
+            return chart;
+        }
+
+        protected abstract JsonObject getChartData() throws Exception;
+
+    }
+
+    /**
+     * Represents a custom simple pie.
+     */
+    public static class SimplePie extends CustomChart {
+
+        private final Callable<String> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public SimplePie(final String chartId, final Callable<String> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final String value = callable.call();
+            if (value == null || value.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            data.addProperty("value", value);
+            return data;
+        }
+    }
+
+    /**
+     * Represents a custom advanced pie.
+     */
+    public static class AdvancedPie extends CustomChart {
+
+        private final Callable<Map<String, Integer>> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public AdvancedPie(final String chartId, final Callable<Map<String, Integer>> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final JsonObject values = new JsonObject();
+            final Map<String, Integer> map = callable.call();
+            if (map == null || map.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            boolean allSkipped = true;
+            for (final Map.Entry<String, Integer> entry : map.entrySet()) {
+                if (entry.getValue() == 0) {
+                    continue; // Skip this invalid
+                }
+                allSkipped = false;
+                values.addProperty(entry.getKey(), entry.getValue());
+            }
+            if (allSkipped) {
+                // Null = skip the chart
+                return null;
+            }
+            data.add("values", values);
+            return data;
+        }
+    }
+
+    /**
+     * Represents a custom drilldown pie.
+     */
+    public static class DrilldownPie extends CustomChart {
+
+        private final Callable<Map<String, Map<String, Integer>>> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public DrilldownPie(final String chartId, final Callable<Map<String, Map<String, Integer>>> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        public JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final JsonObject values = new JsonObject();
+            final Map<String, Map<String, Integer>> map = callable.call();
+            if (map == null || map.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            boolean reallyAllSkipped = true;
+            for (final Map.Entry<String, Map<String, Integer>> entryValues : map.entrySet()) {
+                final JsonObject value = new JsonObject();
+                boolean allSkipped = true;
+                for (final Map.Entry<String, Integer> valueEntry : map.get(entryValues.getKey()).entrySet()) {
+                    value.addProperty(valueEntry.getKey(), valueEntry.getValue());
+                    allSkipped = false;
+                }
+                if (!allSkipped) {
+                    reallyAllSkipped = false;
+                    values.add(entryValues.getKey(), value);
+                }
+            }
+            if (reallyAllSkipped) {
+                // Null = skip the chart
+                return null;
+            }
+            data.add("values", values);
+            return data;
+        }
+    }
+
+    /**
+     * Represents a custom single line chart.
+     */
+    public static class SingleLineChart extends CustomChart {
+
+        private final Callable<Integer> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public SingleLineChart(final String chartId, final Callable<Integer> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final int value = callable.call();
+            if (value == 0) {
+                // Null = skip the chart
+                return null;
+            }
+            data.addProperty("value", value);
+            return data;
+        }
+
+    }
+
+    /**
+     * Represents a custom multi line chart.
+     */
+    public static class MultiLineChart extends CustomChart {
+
+        private final Callable<Map<String, Integer>> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public MultiLineChart(final String chartId, final Callable<Map<String, Integer>> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final JsonObject values = new JsonObject();
+            final Map<String, Integer> map = callable.call();
+            if (map == null || map.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            boolean allSkipped = true;
+            for (final Map.Entry<String, Integer> entry : map.entrySet()) {
+                if (entry.getValue() == 0) {
+                    continue; // Skip this invalid
+                }
+                allSkipped = false;
+                values.addProperty(entry.getKey(), entry.getValue());
+            }
+            if (allSkipped) {
+                // Null = skip the chart
+                return null;
+            }
+            data.add("values", values);
+            return data;
+        }
+
+    }
+
+    /**
+     * Represents a custom simple bar chart.
+     */
+    public static class SimpleBarChart extends CustomChart {
+
+        private final Callable<Map<String, Integer>> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public SimpleBarChart(final String chartId, final Callable<Map<String, Integer>> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final JsonObject values = new JsonObject();
+            final Map<String, Integer> map = callable.call();
+            if (map == null || map.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            for (final Map.Entry<String, Integer> entry : map.entrySet()) {
+                final JsonArray categoryValues = new JsonArray();
+                categoryValues.add(new JsonPrimitive(entry.getValue()));
+                values.add(entry.getKey(), categoryValues);
+            }
+            data.add("values", values);
+            return data;
+        }
+
+    }
+
+    /**
+     * Represents a custom advanced bar chart.
+     */
+    public static class AdvancedBarChart extends CustomChart {
+
+        private final Callable<Map<String, int[]>> callable;
+
+        /**
+         * Class constructor.
+         *
+         * @param chartId The id of the chart.
+         * @param callable The callable which is used to request the chart data.
+         */
+        public AdvancedBarChart(final String chartId, final Callable<Map<String, int[]>> callable) {
+            super(chartId);
+            this.callable = callable;
+        }
+
+        @Override
+        protected JsonObject getChartData() throws Exception {
+            final JsonObject data = new JsonObject();
+            final JsonObject values = new JsonObject();
+            final Map<String, int[]> map = callable.call();
+            if (map == null || map.isEmpty()) {
+                // Null = skip the chart
+                return null;
+            }
+            boolean allSkipped = true;
+            for (final Map.Entry<String, int[]> entry : map.entrySet()) {
+                if (entry.getValue().length == 0) {
+                    continue; // Skip this invalid
+                }
+                allSkipped = false;
+                final JsonArray categoryValues = new JsonArray();
+                for (final int categoryValue : entry.getValue()) {
+                    categoryValues.add(new JsonPrimitive(categoryValue));
+                }
+                values.add(entry.getKey(), categoryValues);
+            }
+            if (allSkipped) {
+                // Null = skip the chart
+                return null;
+            }
+            data.add("values", values);
+            return data;
+        }
+    }
+}