Add starting changes for a new flag

src/main/java/com/ryderbelserion/simpleflags/SimpleFlags.java

@@ -6,6 +6,7 @@ import com.ryderbelserion.simpleflags.commands.types.CommandHelp;
 import com.ryderbelserion.simpleflags.commands.types.CommandReload;
 import com.ryderbelserion.simpleflags.config.ConfigManager;
 import com.ryderbelserion.simpleflags.flags.FlagManager;
+import com.ryderbelserion.simpleflags.flags.types.CapacityFlag;
 import com.ryderbelserion.simpleflags.flags.types.DrownFlag;
 import com.ryderbelserion.simpleflags.flags.types.NaturalFlag;
 import com.ryderbelserion.simpleflags.listeners.DrowningListener;
@@ -34,7 +35,9 @@ public class SimpleFlags extends Vital {
 
         List.of(
                 new DrownFlag(),
-                new NaturalFlag()
+                new NaturalFlag(),
+
+                new CapacityFlag()
         ).forEach(this.flagManager::addFlag);
     }
 

src/main/java/com/ryderbelserion/simpleflags/config/impl/Config.java

@@ -13,6 +13,9 @@ public class Config implements SettingsHolder {
     @Comment("The flag prevent_drowning as you guessed it, it prevents drowning if enabled.")
     public static final Property<Boolean> drowning_flag = newProperty("flags.drowning-flag", false);
 
+    @Comment("The flag max_players only allows a set amount of players in a region.")
+    public static final Property<Boolean> max_players_flag = newProperty("flags.max-players-flag", false);
+
     @Comment("The flag prevent_natural_spawning prevents natural mob spawns in regions.")
     public static final Property<Boolean> natural_spawning_flag = newProperty("flags.natural-spawning-flag", false);
 

src/main/java/com/ryderbelserion/simpleflags/flags/FlagBuilder.java

@@ -8,7 +8,7 @@ import com.sk89q.worldguard.protection.flags.registry.FlagRegistry;
 import com.sk89q.worldguard.protection.regions.RegionQuery;
 import org.bukkit.plugin.java.JavaPlugin;
 
-public abstract class FlagBuilder<T extends Flag> {
+public abstract class FlagBuilder<F extends Flag> {
 
     protected SimpleFlags plugin = JavaPlugin.getPlugin(SimpleFlags.class);
 
@@ -18,14 +18,14 @@ public abstract class FlagBuilder<T extends Flag> {
 
     public abstract String getName();
 
-    public abstract T getFlag();
+    public abstract F getFlag();
 
     public abstract boolean isEnabled();
 
     /**
      * @return A query of regions.
      */
-    protected RegionQuery getQuery() {
+    public RegionQuery getQuery() {
         return this.plugin.getRegions().createQuery();
     }
 
@@ -35,5 +35,4 @@ public abstract class FlagBuilder<T extends Flag> {
     protected FlagRegistry getRegistry() {
         return this.plugin.getWorldGuard().getFlagRegistry();
     }
-
 }

src/main/java/com/ryderbelserion/simpleflags/flags/types/CapacityFlag.java

@@ -0,0 +1,54 @@
+package com.ryderbelserion.simpleflags.flags.types;
+
+import com.ryderbelserion.simpleflags.config.impl.Config;
+import com.ryderbelserion.simpleflags.flags.builders.IntegerFlagBuilder;
+import com.ryderbelserion.simpleflags.flags.enums.CustomFlags;
+import com.sk89q.worldguard.protection.flags.Flag;
+import com.sk89q.worldguard.protection.flags.IntegerFlag;
+import com.sk89q.worldguard.protection.flags.registry.FlagConflictException;
+import java.util.logging.Level;
+
+public class CapacityFlag extends IntegerFlagBuilder {
+
+    private static final Number[] values = {0, 5, 10, 20};
+
+    private IntegerFlag flag;
+
+    @Override
+    public void register() {
+        if (!isEnabled()) return;
+
+        try {
+            this.flag = new IntegerFlag("max-players");
+
+            this.flag.setSuggestedValues(values); //todo() might break in the future
+
+            getRegistry().register(this.flag);
+        } catch (FlagConflictException exception) {
+            Flag<?> existingFlag = getRegistry().get("max-players");
+
+            if (existingFlag instanceof IntegerFlag integerFlag) {
+                this.flag = integerFlag;
+
+                return;
+            }
+
+            this.plugin.getLogger().log(Level.WARNING, "An error has occurred registering " + getName() + " flag.", exception);
+        }
+    }
+
+    @Override
+    public String getName() {
+        return CustomFlags.CAPACITY_FLAG.getName();
+    }
+
+    @Override
+    public IntegerFlag getFlag() {
+        return this.flag;
+    }
+
+    @Override
+    public boolean isEnabled() {
+        return this.config.getProperty(Config.max_players_flag);
+    }
+}

src/main/java/com/ryderbelserion/simpleflags/listeners/CapacityListener.java

@@ -0,0 +1,43 @@
+package com.ryderbelserion.simpleflags.listeners;
+
+import com.ryderbelserion.simpleflags.SimpleFlags;
+import com.ryderbelserion.simpleflags.flags.builders.IntegerFlagBuilder;
+import com.ryderbelserion.simpleflags.flags.FlagManager;
+import com.ryderbelserion.simpleflags.flags.enums.CustomFlags;
+import com.sk89q.worldguard.protection.flags.IntegerFlag;
+import org.bukkit.Location;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerMoveEvent;
+import org.bukkit.plugin.java.JavaPlugin;
+
+public class CapacityListener implements Listener {
+
+    private final SimpleFlags plugin = JavaPlugin.getPlugin(SimpleFlags.class);
+
+    private final FlagManager flagManager = this.plugin.getFlagManager();
+
+    @EventHandler
+    public void onPlayerMove(PlayerMoveEvent event) {
+        final Location location = event.getTo();
+
+        if (location == event.getFrom()) return; // don't run if they didn't move.
+
+        final String flagName = CustomFlags.CAPACITY_FLAG.getName();
+
+        if (!this.flagManager.hasFlag(flagName)) return;
+
+        final IntegerFlagBuilder flag = (IntegerFlagBuilder) this.flagManager.getFlag(flagName);
+
+        if (!flag.isEnabled()) return;
+
+        final IntegerFlag integerFlag = flag.getFlag();
+
+        if (integerFlag == null) return;
+
+        final Player player = event.getPlayer();
+
+        final String query = flag.getQuery().queryValue(location, player, integerFlag);
+    }
+}