Add BattleSession events.

src/main/java/com/gmail/goosius/siegewar/events/BattleSessionEndedEvent.java

@@ -0,0 +1,23 @@
+package com.gmail.goosius.siegewar.events;
+
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.NotNull;
+
+public class BattleSessionEndedEvent extends Event {
+
+	private static final HandlerList handlers = new HandlerList();
+
+	public BattleSessionEndedEvent() {
+	}
+
+	@NotNull
+	@Override
+	public HandlerList getHandlers() {
+		return handlers;
+	}
+
+	public static HandlerList getHandlerList() {
+		return handlers;
+	}
+}

src/main/java/com/gmail/goosius/siegewar/events/BattleSessionPreStartEvent.java

@@ -0,0 +1,44 @@
+package com.gmail.goosius.siegewar.events;
+
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.NotNull;
+
+public class BattleSessionPreStartEvent extends Event implements Cancellable {
+
+	private static final HandlerList handlers = new HandlerList();
+	private boolean cancelled;
+	private String cancellationMsg = "Battle Session prevented by another plugin.";
+
+	public BattleSessionPreStartEvent() {
+	}
+
+	@NotNull
+	@Override
+	public HandlerList getHandlers() {
+		return handlers;
+	}
+
+	public static HandlerList getHandlerList() {
+		return handlers;
+	}
+
+	@Override
+	public boolean isCancelled() {
+		return cancelled;
+	}
+
+	@Override
+	public void setCancelled(boolean cancel) {
+		cancelled = cancel;
+	}
+
+	public String getCancellationMsg() {
+		return cancellationMsg;
+	}
+
+	public void setCancellationMsg(String cancellationMsg) {
+		this.cancellationMsg = cancellationMsg;
+	}
+}

src/main/java/com/gmail/goosius/siegewar/events/BattleSessionStartedEvent.java

@@ -0,0 +1,24 @@
+package com.gmail.goosius.siegewar.events;
+
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.NotNull;
+
+public class BattleSessionStartedEvent extends Event {
+
+	private static final HandlerList handlers = new HandlerList();
+
+	public BattleSessionStartedEvent() {
+	}
+
+	@NotNull
+	@Override
+	public HandlerList getHandlers() {
+		return handlers;
+	}
+
+	public static HandlerList getHandlerList() {
+		return handlers;
+	}
+
+}

src/main/java/com/gmail/goosius/siegewar/utils/SiegeWarBattleSessionUtil.java

@@ -5,6 +5,9 @@
 import com.gmail.goosius.siegewar.SiegeWar;
 import com.gmail.goosius.siegewar.enums.SiegeSide;
 import com.gmail.goosius.siegewar.enums.SiegeStatus;
+import com.gmail.goosius.siegewar.events.BattleSessionEndedEvent;
+import com.gmail.goosius.siegewar.events.BattleSessionPreStartEvent;
+import com.gmail.goosius.siegewar.events.BattleSessionStartedEvent;
 import com.gmail.goosius.siegewar.objects.BattleSession;
 import com.gmail.goosius.siegewar.objects.Siege;
 import com.gmail.goosius.siegewar.settings.SiegeWarSettings;
@@ -41,6 +44,8 @@ public static void startBattleSession() {
 		battleSession.setScheduledEndTime(System.currentTimeMillis() + (SiegeWarSettings.getWarSiegeBattleSessionDurationMinutes() * 60000));
 		//Clear the scheduled start time
 		battleSession.setScheduledStartTime(null);
+		//Send up the Bukkit event for other plugins to listen for.
+		Bukkit.getPluginManager().callEvent(new BattleSessionStartedEvent());	
 		//Send global message to let the server know that the battle session started
 		Messaging.sendGlobalMessage(Translation.of("msg_war_siege_battle_session_started"));
 	}
@@ -108,7 +113,9 @@ public void run() {
 				t.printStackTrace();
 			}
 		}
-
+
+		Bukkit.getPluginManager().callEvent(new BattleSessionEndedEvent());
+
 		//Send message
 		sendBattleSessionEndedMessage(battleResults);
 	}
@@ -125,7 +132,7 @@ public static void evaluateBattleSessions() {
 			}
 
 		} else {
-		    //Battle session is inactive.
+			//Battle session is inactive.
 
 			//If there is no battle session scheduled, attempt to schedule session now.
 			if(battleSession.getScheduledStartTime() == null) {
@@ -135,6 +142,18 @@ public static void evaluateBattleSessions() {
 			//If a battle session is scheduled, start it if we hit the scheduled time
 			if(battleSession.getScheduledStartTime() != null) {
 				if (System.currentTimeMillis() > battleSession.getScheduledStartTime()) {
+
+					//Send up the Bukkit event for other plugins to listen for and potentially cancel.
+					BattleSessionPreStartEvent event = new BattleSessionPreStartEvent();
+					Bukkit.getPluginManager().callEvent(event);
+					if (event.isCancelled()) {
+						//Null the next scheduled time, so it can be reset on the next ShortTime.
+						battleSession.setScheduledStartTime(null);
+						//Broadcast a cancelled BatterlSession message.
+						Messaging.sendGlobalMessage(event.getCancellationMsg());
+						return;
+					}
+
 					//Activate the session
 					startBattleSession();
 				}