Minecraft-Server-Launcher/src/main/java/net/knarcraft/minecraftserverlauncher/utility/Updater.java

package net.knarcraft.minecraftserverlauncher.utility;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import net.knarcraft.minecraftserverlauncher.Main;
import net.knarcraft.minecraftserverlauncher.userinterface.GUI;

import javax.swing.*;
import java.io.*;
import java.nio.file.Paths;
import java.util.Scanner;

import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.downloadFile;
import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.getResourceAsScanner;
import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.readFile;

/**
 * A utility used for updating the software
 */
public final class Updater {

    private static final String updaterFile = Main.getApplicationWorkDirectory() + File.separator + "Updater.jar";
    private static final String updaterURL = "https://jenkins.knarcraft.net/job/KnarCraft/job/Jar-Updater/job/master/" +
            "lastSuccessfulBuild/artifact/target/jar-updater-1.0-SNAPSHOT.jar";
    private static final String targetFile = "minecraft-server-launcher.jar";

    /**
     * Checks if a newer version is available
     *
     * @param updateURL     <p>The URL used for checking for updates</p>
     * @param updateChannel <p>The release channel to use</p>
     * @throws IOException <p>If the update data cannot be read</p>
     */
    public static void checkForUpdate(String updateURL, String updateChannel) throws IOException {
        Scanner file = getResourceAsScanner("currentversion.csv");
        if (!file.hasNextLine()) {
            throw new FileNotFoundException("File currentversion.csv is invalid");
        }
        String oldType = file.nextLine();
        if (!file.hasNextLine()) {
            throw new FileNotFoundException("File currentversion.csv is invalid");
        }
        String oldVer = file.nextLine();
        file.close();

        String data = readFile(updateURL);
        JsonObject jsonObject = new JsonParser().parse(data).getAsJsonObject();
        String latest = jsonObject.getAsJsonObject("latest").get(updateChannel).getAsString();

        if (!oldType.equals(updateChannel) || !oldVer.equals(latest)) {
            JsonArray versionList = jsonObject.getAsJsonArray("versions");
            String url = "";
            for (JsonElement elem : versionList) {
                JsonObject obj = elem.getAsJsonObject();
                String ver = obj.get("id").getAsString();
                String type = obj.get("type").getAsString();
                if (ver.equals(latest) && type.equals(updateChannel)) {
                    url = obj.get("url").getAsString();
                    break;
                }
            }
            if (!new File(updaterFile).exists()) {
                downloadFile(updaterURL, Paths.get(updaterFile));
            }

            int answer = JOptionPane.showConfirmDialog(null,
                    "An update is available. Do you want to update?", "Update available",
                    JOptionPane.YES_NO_OPTION
            );
            if (answer == JOptionPane.YES_NO_OPTION) {
                runUpdater(url);
            }
        }
    }

    /**
     * Updates the software
     *
     * @param url <p>The URL of the new file to download</p>
     * @throws IOException <p>If unable to run the updater</p>
     */
    private static void runUpdater(String url) throws IOException {
        ProcessBuilder builder;
        builder = new ProcessBuilder("java", "-jar", "Updater.jar", url, "yes", targetFile, "5", "nogui");
        builder.directory(new File(Main.getApplicationWorkDirectory()));
        builder.redirectErrorStream(true);
        builder.start();
        System.exit(1);
    }
}