added double jump and mysql support for the most part

pom.xml

@@ -36,30 +36,6 @@
                     </execution>
                 </executions>
             </plugin>
-            <plugin>
-                <groupId>org.jetbrains.kotlin</groupId>
-                <artifactId>kotlin-maven-plugin</artifactId>
-                <version>${kotlin.version}</version>
-                <executions>
-                    <execution>
-                        <id>compile</id>
-                        <phase>process-sources</phase>
-                        <goals>
-                            <goal>compile</goal>
-                        </goals>
-                    </execution>
-                    <execution>
-                        <id>test-compile</id>
-                        <phase>test-compile</phase>
-                        <goals>
-                            <goal>test-compile</goal>
-                        </goals>
-                    </execution>
-                </executions>
-                <configuration>
-                    <jvmTarget>1.8</jvmTarget>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>

src/main/java/me/fivevl/doublejump/Database.java

@@ -0,0 +1,17 @@
+package me.fivevl.doublejump;
+
+import javax.sql.rowset.CachedRowSet;
+import java.sql.SQLException;
+
+public interface Database {
+    void connect() throws SQLException;
+    void disconnect() throws SQLException;
+    boolean isConnected() throws SQLException;
+    void setUsername(String username);
+    void setPassword(String password);
+    void setHost(String host);
+    void setDatabase(String database);
+    void setPort(String port);
+    CachedRowSet query(String query) throws SQLException;
+    void execute(String query) throws SQLException;
+}

src/main/java/me/fivevl/doublejump/Main.java

@@ -1,15 +1,72 @@
 package me.fivevl.doublejump;
 
+import me.fivevl.doublejump.events.OnFly;
+import me.fivevl.doublejump.events.OnJump;
+import org.bukkit.Bukkit;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.entity.Player;
 import org.bukkit.plugin.java.JavaPlugin;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
 
 public class Main extends JavaPlugin {
+    public static List<Player> doDoubleJump = new ArrayList<>();
+    private static Main instance;
+    public static Main getInstance() {
+        return instance;
+    }
+    private static MySQL sql;
+    public static MySQL getMySQL() {
+        return sql;
+    }
     @Override
     public void onEnable() {
+        instance = this;
+        sql = new MySQL();
+        try {
+            setupDatabase();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        Bukkit.getPluginManager().registerEvents(new OnFly(), this);
+        Bukkit.getPluginManager().registerEvents(new OnJump(), this);
         getLogger().info("DoubleJump enabled!");
     }
 
     @Override
     public void onDisable() {
+        try {
+            sql.disconnect();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
         getLogger().info("DoubleJump disabled!");
     }
+
+    private void setupDatabase() throws SQLException {
+        ConfigurationSection config = getConfig().getConfigurationSection("database");
+        if (config == null) {
+            getLogger().severe("Database configuration not found!");
+            return;
+        }
+        String[] credentials = {config.getString("host"), config.getString("port"), config.getString("database"), config.getString("username"), config.getString("password")};
+        for (String s : credentials) {
+            if (s == null) {
+                getLogger().severe("Correct database configuration not found!");
+                return;
+            }
+        }
+        if (credentials[0].equalsIgnoreCase("12.34.56.78")) {
+            getLogger().severe("Please set the database credentials in the config.yml!");
+            return;
+        }
+        sql.setUsername(credentials[3]);
+        sql.setPassword(credentials[4]);
+        sql.setHost(credentials[0]);
+        sql.setPort(credentials[1]);
+        sql.setDatabase(credentials[2]);
+        sql.connect();
+        sql.execute("CREATE TABLE IF NOT EXISTS `settings` (`uuid` VARCHAR(36) NOT NULL, `strength` DOUBLE NOT NULL DEFAULT '1', PRIMARY KEY (`uuid`))");
+    }
 }

src/main/java/me/fivevl/doublejump/MySQL.java

@@ -0,0 +1,66 @@
+package me.fivevl.doublejump;
+
+import javax.sql.rowset.CachedRowSet;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+public class MySQL implements Database {
+    private Connection connection;
+    private String username;
+    private String password;
+    private String database;
+    private String host;
+    private String port;
+    @Override
+    public void connect() throws SQLException {
+        connection = DriverManager.getConnection("jdbc:mysql://" + host + ":" + port + "/" + database + "?autoReconnect=true", username, password);
+    }
+
+    @Override
+    public void disconnect() throws SQLException {
+        connection.close();
+    }
+
+    @Override
+    public boolean isConnected() throws SQLException {
+        return !connection.isClosed();
+    }
+
+    @Override
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    @Override
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    @Override
+    public void setDatabase(String database) {
+        this.database = database;
+    }
+
+    @Override
+    public void setPort(String port) {
+        this.port = port;
+    }
+
+    @Override
+    public CachedRowSet query(String query) throws SQLException{
+        CachedRowSet cachedRowSet = new com.sun.rowset.CachedRowSetImpl();
+        cachedRowSet.populate(connection.prepareStatement(query).executeQuery());
+        return cachedRowSet;
+    }
+
+    @Override
+    public void execute(String query) throws SQLException {
+        connection.prepareStatement(query).execute();
+    }
+}

src/main/java/me/fivevl/doublejump/events/OnFly.java

@@ -0,0 +1,21 @@
+package me.fivevl.doublejump.events;
+
+import me.fivevl.doublejump.Main;
+import org.bukkit.GameMode;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerToggleFlightEvent;
+
+public class OnFly implements Listener {
+    @EventHandler
+    public void onFly(PlayerToggleFlightEvent e) {
+        Player p = e.getPlayer();
+        if (p.hasPermission("doublejump.use") && Main.doDoubleJump.contains(p) && (p.getGameMode() == GameMode.ADVENTURE || p.getGameMode() == GameMode.SURVIVAL)) {
+            e.setCancelled(true);
+            p.setAllowFlight(false);
+            p.setVelocity(p.getLocation().getDirection().multiply(2.0D));
+            p.setFallDistance(0);
+        }
+    }
+}

src/main/java/me/fivevl/doublejump/events/OnJump.java

@@ -0,0 +1,24 @@
+package me.fivevl.doublejump.events;
+
+import com.destroystokyo.paper.event.player.PlayerJumpEvent;
+import me.fivevl.doublejump.Main;
+import org.bukkit.Bukkit;
+import org.bukkit.GameMode;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+
+public class OnJump implements Listener {
+    @EventHandler
+    public void onJump(PlayerJumpEvent e) {
+        Player p = e.getPlayer();
+        if (p.hasPermission("doublejump.use") && (p.getGameMode() == GameMode.ADVENTURE || p.getGameMode() == GameMode.SURVIVAL)) {
+            p.setAllowFlight(true);
+            Main.doDoubleJump.add(p);
+            Bukkit.getScheduler().scheduleSyncDelayedTask(Main.getInstance(), () -> {
+                p.setAllowFlight(false);
+                Main.doDoubleJump.remove(p);
+            }, 20L);
+        }
+    }
+}

src/main/resources/config.yml

@@ -0,0 +1,6 @@
+database: # Database configuration, please change it to a valid one.
+  host: "12.34.56.78"
+  port: 3306
+  username: "admin"
+  password: "password"
+  database: "database"

src/main/resources/plugin.yml

@@ -4,3 +4,6 @@ main: me.fivevl.doublejump.Main
 api-version: 1.18
 authors: [ 5vl ]
 description: A trial project for DevRoom.
+commands:
+  jump:
+    description: Opens the main GUI