/*
 * Copyright (c) 2019-2020 GeyserMC. http://geysermc.org
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @author GeyserMC
 * @link https://github.com/GeyserMC/Geyser
 */

package org.geysermc.connector.metrics;

import com.google.gson.JsonArray;
import com.google.gson.JsonObject;
import org.geysermc.api.Geyser;
import org.geysermc.connector.GeyserConnector;

import javax.net.ssl.HttpsURLConnection;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.zip.GZIPOutputStream;

/**
 * bStats collects some data for plugin authors.
 *
 * Check out https://bStats.org/ to learn more about bStats!
 */
public class Metrics {

    // 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/server-implementation";

    // Should failed requests be logged?
    private static boolean logFailedRequests = false;

    // The logger for the failed requests
    private static Logger logger = Logger.getLogger("bStats");

    // The name of the server software
    private final String name;

    // The uuid of the server
    private final String serverUUID;

    // A list with all custom charts
    private final List<CustomChart> charts = new ArrayList<>();

    /**
     * Class constructor.
     *
     * @param name The name of the server software.
     * @param serverUUID The uuid of the server.
     * @param logFailedRequests Whether failed requests should be logged or not.
     * @param logger The logger for the failed requests.
     */
    public Metrics(String name, String serverUUID, boolean logFailedRequests, Logger logger) {
        this.name = name;
        this.serverUUID = serverUUID;
        Metrics.logFailedRequests = logFailedRequests;
        Metrics.logger = logger;

        // Start submitting the data
        startSubmitting();
    }

    /**
     * Adds a custom chart.
     *
     * @param chart The chart to add.
     */
    public void addCustomChart(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() {
        Geyser.getGeneralThreadPool().scheduleAtFixedRate(this::submitData, 1, 30, TimeUnit.MINUTES);
        // Submit the data every 30 minutes, first time after 5 minutes to give other plugins enough time to start
        // WARNING: Changing the frequency has no effect but your plugin WILL be blocked/deleted!
        // WARNING: Just don't do it!
    }

    /**
     * Gets the plugin specific data.
     *
     * @return The plugin specific data.
     */
    private JsonObject getPluginData() {
        JsonObject data = new JsonObject();

        data.addProperty("pluginName", name); // Append the name of the server software
        data.addProperty("pluginVersion", GeyserConnector.VERSION); // Append the name of the server software

        JsonArray customCharts = new JsonArray();
        for (CustomChart customChart : charts) {
            // Add the data of the custom charts
            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() {
        // OS specific data
        int playerAmount = Geyser.getPlayerCount();

        String osName = System.getProperty("os.name");
        String osArch = System.getProperty("os.arch");
        String osVersion = System.getProperty("os.version");
        int coreCount = Runtime.getRuntime().availableProcessors();

        JsonObject data = new JsonObject();

        data.addProperty("serverUUID", serverUUID);

        data.addProperty("playerAmount", playerAmount);
        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();

        JsonArray pluginData = new JsonArray();
        pluginData.add(getPluginData());
        data.add("plugins", pluginData);

        new Thread(() -> {
            try {
                // We are still in the Thread of the timer, so nothing get blocked :)
                sendData(data);
            } catch (Exception e) {
                // Something went wrong! :(
                if (logFailedRequests) {
                    logger.log(Level.WARNING, "Could not submit stats of " + name, e);
                }
            }
        }).start();
    }

    /**
     * Sends the data to the bStats server.
     *
     * @param data The data to send.
     * @throws Exception If the request failed.
     */
    private static void sendData(JsonObject data) throws Exception {
        if (data == null) {
            throw new IllegalArgumentException("Data cannot be null!");
        }
        HttpsURLConnection connection = (HttpsURLConnection) new URL(URL).openConnection();

        // Compress the data to save bandwidth
        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);
        DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
        outputStream.write(compressedData);
        outputStream.flush();
        outputStream.close();

        connection.getInputStream().close(); // We don't care about the response - Just send our data :)
    }

    /**
     * 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;
        }
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        GZIPOutputStream gzip = new GZIPOutputStream(outputStream);
        gzip.write(str.getBytes("UTF-8"));
        gzip.close();
        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(String chartId) {
            if (chartId == null || chartId.isEmpty()) {
                throw new IllegalArgumentException("ChartId cannot be null or empty!");
            }
            this.chartId = chartId;
        }

        private JsonObject getRequestJsonObject() {
            JsonObject chart = new JsonObject();
            chart.addProperty("chartId", chartId);
            try {
                JsonObject data = getChartData();
                if (data == null) {
                    // If the data is null we don't send the chart.
                    return null;
                }
                chart.add("data", data);
            } catch (Throwable t) {
                if (logFailedRequests) {
                    logger.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(String chartId, Callable<String> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            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(String chartId, Callable<Map<String, Integer>> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            JsonObject values = new JsonObject();
            Map<String, Integer> map = callable.call();
            if (map == null || map.isEmpty()) {
                // Null = skip the chart
                return null;
            }
            boolean allSkipped = true;
            for (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(String chartId, Callable<Map<String, Map<String, Integer>>> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        public JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            JsonObject values = new JsonObject();
            Map<String, Map<String, Integer>> map = callable.call();
            if (map == null || map.isEmpty()) {
                // Null = skip the chart
                return null;
            }
            boolean reallyAllSkipped = true;
            for (Map.Entry<String, Map<String, Integer>> entryValues : map.entrySet()) {
                JsonObject value = new JsonObject();
                boolean allSkipped = true;
                for (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(String chartId, Callable<Integer> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            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(String chartId, Callable<Map<String, Integer>> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            JsonObject values = new JsonObject();
            Map<String, Integer> map = callable.call();
            if (map == null || map.isEmpty()) {
                // Null = skip the chart
                return null;
            }
            boolean allSkipped = true;
            for (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(String chartId, Callable<Map<String, Integer>> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            JsonObject values = new JsonObject();
            Map<String, Integer> map = callable.call();
            if (map == null || map.isEmpty()) {
                // Null = skip the chart
                return null;
            }
            for (Map.Entry<String, Integer> entry : map.entrySet()) {
                JsonArray categoryValues = new JsonArray();
                categoryValues.add(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(String chartId, Callable<Map<String, int[]>> callable) {
            super(chartId);
            this.callable = callable;
        }

        @Override
        protected JsonObject getChartData() throws Exception {
            JsonObject data = new JsonObject();
            JsonObject values = new JsonObject();
            Map<String, int[]> map = callable.call();
            if (map == null || map.isEmpty()) {
                // Null = skip the chart
                return null;
            }
            boolean allSkipped = true;
            for (Map.Entry<String, int[]> entry : map.entrySet()) {
                if (entry.getValue().length == 0) {
                    continue; // Skip this invalid
                }
                allSkipped = false;
                JsonArray categoryValues = new JsonArray();
                for (int categoryValue : entry.getValue()) {
                    categoryValues.add(categoryValue);
                }
                values.add(entry.getKey(), categoryValues);
            }
            if (allSkipped) {
                // Null = skip the chart
                return null;
            }
            data.add("values", values);
            return data;
        }

    }
}