[#845] Added an event that is called when Plan enables.

This includes, but might not be limited to:
- First time the plugin enables successfully
- Plan is reloaded
- Bukkit-BungeeCord setup updates settings
- Plan is enabled after it was disabled

Following events are available:
Bukkit: PlanBukkitEnableEvent
Sponge: PlanSpongeEnableEvent
BungeeCord: PlanBungeeEnableEvent
Velocity: PlanVelocityEnableEvent

Plan/bukkit/src/main/java/com/djrapitops/plan/Plan.java

@@ -73,6 +73,9 @@ public class Plan extends BukkitPlugin implements PlanPlugin {
         command.registerCommands();
         registerCommand("plan", command);
         new RegisterCommandFilter().registerFilter();
+        if (system != null) {
+            system.getListenerSystem().callEnableEvent(this);
+        }
     }
 
     @Override

Plan/bukkit/src/main/java/com/djrapitops/plan/api/events/PlanBukkitEnableEvent.java

@@ -0,0 +1,58 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.api.events;
+
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+
+/**
+ * Event that is called when Plan is enabled.
+ * <p>
+ * This includes, but might not be limited to:
+ * - First time the plugin enables successfully
+ * - Plan is reloaded
+ * - Bukkit-BungeeCord setup updates settings
+ * - Plan is enabled after it was disabled
+ * <p>
+ * {@code event.isPlanSystemEnabled()} can be called to determine if the enable was successful.
+ * It is not guaranteed that this event is called when the plugin fails to enable properly.
+ *
+ * @author Rsl1122
+ */
+public class PlanBukkitEnableEvent extends Event {
+    private static final HandlerList handlers = new HandlerList();
+
+    private final boolean enabled;
+
+    public PlanBukkitEnableEvent(boolean enabled) {
+        super(true);
+        this.enabled = enabled;
+    }
+
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+
+    public boolean isPlanSystemEnabled() {
+        return enabled;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+}

Plan/bukkit/src/main/java/com/djrapitops/plan/system/listeners/BukkitListenerSystem.java

@@ -17,8 +17,11 @@
 package com.djrapitops.plan.system.listeners;
 
 import com.djrapitops.plan.Plan;
+import com.djrapitops.plan.PlanPlugin;
+import com.djrapitops.plan.api.events.PlanBukkitEnableEvent;
 import com.djrapitops.plan.system.listeners.bukkit.*;
 import com.djrapitops.plan.system.status.Status;
+import org.bukkit.Bukkit;
 import org.bukkit.event.HandlerList;
 
 import javax.inject.Inject;
@@ -77,4 +80,10 @@ public class BukkitListenerSystem extends ListenerSystem {
     protected void unregisterListeners() {
         HandlerList.unregisterAll(plugin);
     }
+
+    @Override
+    public void callEnableEvent(PlanPlugin plugin) {
+        PlanBukkitEnableEvent event = new PlanBukkitEnableEvent(plugin.isSystemEnabled());
+        Bukkit.getServer().getPluginManager().callEvent(event);
+    }
 }

Plan/bungeecord/src/main/java/com/djrapitops/plan/PlanBungee.java

@@ -70,6 +70,9 @@ public class PlanBungee extends BungeePlugin implements PlanPlugin {
         PlanProxyCommand command = component.planCommand();
         command.registerCommands();
         registerCommand("planbungee", command);
+        if (system != null) {
+            system.getListenerSystem().callEnableEvent(this);
+        }
     }
 
     @Override

Plan/bungeecord/src/main/java/com/djrapitops/plan/api/events/PlanBungeeEnableEvent.java

@@ -0,0 +1,46 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.api.events;
+
+import net.md_5.bungee.api.plugin.Event;
+
+/**
+ * Event that is called when Plan is enabled.
+ * <p>
+ * This includes, but might not be limited to:
+ * - First time the plugin enables successfully
+ * - Plan is reloaded
+ * - Plan is enabled after it was disabled
+ * <p>
+ * {@code event.isPlanSystemEnabled()} can be called to determine if the enable was successful.
+ * It is not guaranteed that this event is called when the plugin fails to enable properly.
+ *
+ * @author Rsl1122
+ */
+public class PlanBungeeEnableEvent extends Event {
+
+    private final boolean enabled;
+
+    public PlanBungeeEnableEvent(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    public boolean isPlanSystemEnabled() {
+        return enabled;
+    }
+
+}

Plan/bungeecord/src/main/java/com/djrapitops/plan/system/listeners/BungeeListenerSystem.java

@@ -17,6 +17,8 @@
 package com.djrapitops.plan.system.listeners;
 
 import com.djrapitops.plan.PlanBungee;
+import com.djrapitops.plan.PlanPlugin;
+import com.djrapitops.plan.api.events.PlanBungeeEnableEvent;
 import com.djrapitops.plan.system.listeners.bungee.PlayerOnlineListener;
 
 import javax.inject.Inject;
@@ -41,4 +43,10 @@ public class BungeeListenerSystem extends ListenerSystem {
     protected void unregisterListeners() {
         plugin.getProxy().getPluginManager().unregisterListeners(plugin);
     }
+
+    @Override
+    public void callEnableEvent(PlanPlugin plugin) {
+        PlanBungeeEnableEvent event = new PlanBungeeEnableEvent(plugin.isSystemEnabled());
+        ((PlanBungee) plugin).getProxy().getPluginManager().callEvent(event);
+    }
 }

Plan/common/src/main/java/com/djrapitops/plan/PlanPlugin.java

@@ -41,4 +41,8 @@ public interface PlanPlugin extends IPlugin {
     boolean isReloading();
 
     PlanSystem getSystem();
+
+    default boolean isSystemEnabled() {
+        return getSystem().isEnabled();
+    }
 }

Plan/common/src/main/java/com/djrapitops/plan/data/plugin/HookHandler.java

@@ -93,6 +93,10 @@ public class HookHandler implements SubSystem {
                 configHandler.createSection(dataSource);
             }
             if (configHandler.isEnabled(dataSource)) {
+                additionalDataSources.stream()
+                        .filter(pluginData -> pluginData.getSourcePlugin().equals(dataSource.getSourcePlugin()))
+                        .findAny()
+                        .ifPresent(additionalDataSources::remove);
                 logger.debug("Registered a new datasource: " + dataSource.getSourcePlugin());
                 additionalDataSources.add(dataSource);
             }

Plan/common/src/main/java/com/djrapitops/plan/system/PlanSystem.java

@@ -49,6 +49,8 @@ import javax.inject.Singleton;
 @Singleton
 public class PlanSystem implements SubSystem {
 
+    private boolean enabled = false;
+
     private final PlanFiles files;
     private final ConfigSystem configSystem;
     private final VersionCheckSystem versionCheckSystem;
@@ -130,6 +132,7 @@ public class PlanSystem implements SubSystem {
                 taskSystem,
                 hookHandler
         );
+        enabled = true;
     }
 
     private void enableSystems(SubSystem... systems) throws EnableException {
@@ -140,6 +143,7 @@ public class PlanSystem implements SubSystem {
 
     @Override
     public void disable() {
+        enabled = false;
         disableSystems(
                 taskSystem,
                 hookHandler,
@@ -240,4 +244,8 @@ public class PlanSystem implements SubSystem {
     public HtmlUtilities getHtmlUtilities() {
         return htmlUtilities;
     }
+
+    public boolean isEnabled() {
+        return false;
+    }
 }

Plan/common/src/main/java/com/djrapitops/plan/system/listeners/ListenerSystem.java

@@ -16,6 +16,7 @@
  */
 package com.djrapitops.plan.system.listeners;
 
+import com.djrapitops.plan.PlanPlugin;
 import com.djrapitops.plan.system.SubSystem;
 
 public abstract class ListenerSystem implements SubSystem {
@@ -34,4 +35,6 @@ public abstract class ListenerSystem implements SubSystem {
 
     protected abstract void unregisterListeners();
 
+    public abstract void callEnableEvent(PlanPlugin plugin);
+
 }

Plan/sponge/src/main/java/com/djrapitops/plan/PlanSponge.java

@@ -105,6 +105,9 @@ public class PlanSponge extends SpongePlugin implements PlanPlugin {
         PlanCommand command = component.planCommand();
         command.registerCommands();
         registerCommand("plan", command);
+        if (system != null) {
+            system.getListenerSystem().callEnableEvent(this);
+        }
     }
 
     @Override

Plan/sponge/src/main/java/com/djrapitops/plan/api/events/PlanSpongeEnableEvent.java

@@ -0,0 +1,66 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.api.events;
+
+import com.djrapitops.plan.PlanSponge;
+import org.spongepowered.api.event.cause.Cause;
+import org.spongepowered.api.event.cause.EventContext;
+import org.spongepowered.api.event.impl.AbstractEvent;
+
+/**
+ * Event that is called when Plan is enabled.
+ * <p>
+ * This includes, but might not be limited to:
+ * - First time the plugin enables successfully
+ * - Plan is reloaded
+ * - Sponge-BungeeCord setup updates settings
+ * - Plan is enabled after it was disabled
+ * <p>
+ * {@code event.isPlanSystemEnabled()} can be called to determine if the enable was successful.
+ * It is not guaranteed that this event is called when the plugin fails to enable properly.
+ *
+ * @author Rsl1122
+ */
+public class PlanSpongeEnableEvent extends AbstractEvent {
+
+    private final PlanSponge plugin;
+    private final boolean enabled;
+
+    public PlanSpongeEnableEvent(PlanSponge plugin) {
+        this.plugin = plugin;
+        this.enabled = plugin.isSystemEnabled();
+    }
+
+    public boolean isPlanSystemEnabled() {
+        return enabled;
+    }
+
+    @Override
+    public Cause getCause() {
+        return Cause.builder().append(plugin.getSystem()).build(EventContext.empty());
+    }
+
+    @Override
+    public Object getSource() {
+        return plugin.getSystem();
+    }
+
+    @Override
+    public EventContext getContext() {
+        return EventContext.empty();
+    }
+}

Plan/sponge/src/main/java/com/djrapitops/plan/system/listeners/SpongeListenerSystem.java

@@ -16,9 +16,12 @@
  */
 package com.djrapitops.plan.system.listeners;
 
+import com.djrapitops.plan.PlanPlugin;
 import com.djrapitops.plan.PlanSponge;
+import com.djrapitops.plan.api.events.PlanSpongeEnableEvent;
 import com.djrapitops.plan.system.listeners.sponge.*;
 import org.spongepowered.api.Sponge;
+import org.spongepowered.api.event.Event;
 
 import javax.inject.Inject;
 
@@ -72,4 +75,10 @@ public class SpongeListenerSystem extends ListenerSystem {
     protected void unregisterListeners() {
         Sponge.getEventManager().unregisterPluginListeners(plugin);
     }
+
+    @Override
+    public void callEnableEvent(PlanPlugin plugin) {
+        Event event = new PlanSpongeEnableEvent((PlanSponge) plugin);
+        Sponge.getEventManager().post(event);
+    }
 }

Plan/velocity/src/main/java/com/djrapitops/plan/PlanVelocity.java

@@ -96,6 +96,9 @@ public class PlanVelocity extends VelocityPlugin implements PlanPlugin {
         PlanProxyCommand command = component.planCommand();
         command.registerCommands();
         registerCommand("planvelocity", command);
+        if (system != null) {
+            system.getListenerSystem().callEnableEvent(this);
+        }
     }
 
     @Override

Plan/velocity/src/main/java/com/djrapitops/plan/api/events/PlanVelocityEnableEvent.java

@@ -0,0 +1,45 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.api.events;
+
+/**
+ * Event that is called when Plan is enabled.
+ * <p>
+ * This includes, but might not be limited to:
+ * - First time the plugin enables successfully
+ * - Plan is reloaded
+ * - Bukkit-BungeeCord setup updates settings
+ * - Plan is enabled after it was disabled
+ * <p>
+ * {@code event.isPlanSystemEnabled()} can be called to determine if the enable was successful.
+ * It is not guaranteed that this event is called when the plugin fails to enable properly.
+ *
+ * @author Rsl1122
+ */
+public class PlanVelocityEnableEvent {
+
+    private final boolean enabled;
+
+    public PlanVelocityEnableEvent(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    public boolean isPlanSystemEnabled() {
+        return enabled;
+    }
+
+}

Plan/velocity/src/main/java/com/djrapitops/plan/system/listeners/VelocityListenerSystem.java

@@ -16,7 +16,9 @@
  */
 package com.djrapitops.plan.system.listeners;
 
+import com.djrapitops.plan.PlanPlugin;
 import com.djrapitops.plan.PlanVelocity;
+import com.djrapitops.plan.api.events.PlanVelocityEnableEvent;
 import com.djrapitops.plan.system.listeners.velocity.PlayerOnlineListener;
 
 import javax.inject.Inject;
@@ -47,4 +49,10 @@ public class VelocityListenerSystem extends ListenerSystem {
     protected void unregisterListeners() {
         plugin.getProxy().getEventManager().unregisterListeners(plugin);
     }
+
+    @Override
+    public void callEnableEvent(PlanPlugin plugin) {
+        PlanVelocityEnableEvent event = new PlanVelocityEnableEvent(plugin.isSystemEnabled());
+        ((PlanVelocity) plugin).getProxy().getEventManager().fireAndForget(event);
+    }
 }