Some magic changes and added multi-gem interactions

src/main/java/com/minelittlepony/unicopia/command/DisguiseCommand.java

@@ -83,7 +83,7 @@ public class DisguiseCommand {
     static int reveal(ServerCommandSource source, PlayerEntity player) {
         Pony iplayer = Pony.of(player);
         iplayer.getEffect(DisguiseSpell.class).ifPresent(disguise -> {
-            disguise.setDead();
+            disguise.onDestroyed(iplayer);
         });
 
         if (player.getEntityWorld().getGameRules().getBoolean(GameRules.SEND_COMMAND_FEEDBACK)) {

src/main/java/com/minelittlepony/unicopia/entity/Creature.java

@@ -53,7 +53,7 @@ public class Creature implements Ponylike<LivingEntity>, Caster<LivingEntity> {
     }
 
     @Override
-    public <T extends MagicEffect> T getEffect(Class<T> type, boolean update) {
+    public <T> T getEffect(Class<T> type, boolean update) {
         return effectDelegate.get(type, update);
     }
 

src/main/java/com/minelittlepony/unicopia/entity/ProjectileEntity.java

@@ -4,6 +4,7 @@ import java.util.UUID;
 
 import com.minelittlepony.unicopia.magic.Affinity;
 import com.minelittlepony.unicopia.magic.Caster;
+import com.minelittlepony.unicopia.magic.EtherialListener;
 import com.minelittlepony.unicopia.magic.MagicEffect;
 import com.minelittlepony.unicopia.magic.TossedMagicEffect;
 import com.minelittlepony.unicopia.magic.spell.SpellRegistry;
@@ -34,6 +35,7 @@ import net.minecraft.server.world.ServerWorld;
 import net.minecraft.util.hit.BlockHitResult;
 import net.minecraft.util.hit.EntityHitResult;
 import net.minecraft.util.hit.HitResult;
+import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 
@@ -52,6 +54,8 @@ public class ProjectileEntity extends ThrownItemEntity implements IMagicals, Adv
 
     private UUID ownerUuid;
 
+    private BlockPos lastBlockPos;
+
     public ProjectileEntity(EntityType<ProjectileEntity> type, World world) {
         super(type, world);
     }
@@ -133,7 +137,7 @@ public class ProjectileEntity extends ThrownItemEntity implements IMagicals, Adv
     }
 
     @Override
-    public <T extends MagicEffect> T getEffect(Class<T> type, boolean update) {
+    public <T> T getEffect(Class<T> type, boolean update) {
         return effectDelegate.get(type, update);
     }
 
@@ -178,6 +182,12 @@ public class ProjectileEntity extends ThrownItemEntity implements IMagicals, Adv
         }
 
         if (hasEffect()) {
+            if (lastBlockPos == null || !lastBlockPos.equals(getBlockPos())) {
+                notifyNearbySpells(getEffect(), lastBlockPos, 6, EtherialListener.REMOVED);
+                lastBlockPos = getBlockPos();
+                notifyNearbySpells(getEffect(), 6, EtherialListener.ADDED);
+            }
+
             if (getEffect().isDead()) {
                 remove();
             } else {

src/main/java/com/minelittlepony/unicopia/entity/SpellcastEntity.java

@@ -12,6 +12,7 @@ import com.minelittlepony.unicopia.item.UItems;
 import com.minelittlepony.unicopia.magic.Affinity;
 import com.minelittlepony.unicopia.magic.Castable;
 import com.minelittlepony.unicopia.magic.Caster;
+import com.minelittlepony.unicopia.magic.EtherialListener;
 import com.minelittlepony.unicopia.magic.MagicEffect;
 import com.minelittlepony.unicopia.magic.spell.SpellRegistry;
 import com.minelittlepony.unicopia.network.EffectSync;
@@ -44,7 +45,7 @@ import net.minecraft.world.GameRules;
 import net.minecraft.world.World;
 import net.minecraft.world.explosion.Explosion.DestructionType;
 
-public class SpellcastEntity extends MobEntityWithAi implements IMagicals, Caster<LivingEntity>, InAnimate, PickedItemSupplier {
+public class SpellcastEntity extends MobEntityWithAi implements IMagicals, Caster<LivingEntity>, EtherialListener, InAnimate, PickedItemSupplier {
 
     private static final TrackedData<Integer> LEVEL = DataTracker.registerData(SpellcastEntity.class, TrackedDataHandlerRegistry.INTEGER);
     private static final TrackedData<Optional<UUID>> OWNER = DataTracker.registerData(SpellcastEntity.class, TrackedDataHandlerRegistry.OPTIONAL_UUID);
@@ -110,7 +111,7 @@ public class SpellcastEntity extends MobEntityWithAi implements IMagicals, Caste
 
     @Nullable
     @Override
-    public <T extends MagicEffect> T getEffect(@Nullable Class<T> type, boolean update) {
+    public <T> T getEffect(@Nullable Class<T> type, boolean update) {
         return effectDelegate.get(type, update);
     }
 
@@ -267,7 +268,7 @@ public class SpellcastEntity extends MobEntityWithAi implements IMagicals, Caste
     @Override
     public void remove() {
         if (hasEffect()) {
-            getEffect().setDead();
+            getEffect().onDestroyed(this);
         }
         super.remove();
     }
@@ -362,4 +363,14 @@ public class SpellcastEntity extends MobEntityWithAi implements IMagicals, Caste
             compound.put("effect", SpellRegistry.instance().serializeEffectToNBT(getEffect()));
         }
     }
+
+    @Override
+    public void onNearbySpellChange(Caster<?> source, MagicEffect effect, int newState) {
+        if (hasEffect()) {
+            EtherialListener listener = getEffect(EtherialListener.class, true);
+            if (listener != null) {
+                listener.onNearbySpellChange(source, effect, newState);
+            }
+        }
+    }
 }

src/main/java/com/minelittlepony/unicopia/entity/player/Pony.java

@@ -382,7 +382,7 @@ public class Pony implements Caster<PlayerEntity>, Ponylike<PlayerEntity>, Trans
 
     @Nullable
     @Override
-    public <T extends MagicEffect> T getEffect(@Nullable Class<T> type, boolean update) {
+    public <T> T getEffect(@Nullable Class<T> type, boolean update) {
         return effectDelegate.get(type, update);
     }
 

src/main/java/com/minelittlepony/unicopia/magic/Caster.java

@@ -6,6 +6,7 @@ import java.util.stream.Stream;
 
 import javax.annotation.Nullable;
 
+import com.minelittlepony.unicopia.AwaitTickQueue;
 import com.minelittlepony.unicopia.entity.IMagicals;
 import com.minelittlepony.unicopia.entity.Owned;
 import com.minelittlepony.unicopia.particles.ParticleSource;
@@ -39,7 +40,7 @@ public interface Caster<E extends LivingEntity> extends Owned<E>, Levelled, Affi
      * Returns null if no such effect exists for this caster.
      */
     @Nullable
-    <T extends MagicEffect> T getEffect(@Nullable Class<T> type, boolean update);
+    <T> T getEffect(@Nullable Class<T> type, boolean update);
 
     /**
      * Gets the active effect for this caster updating it if needed.
@@ -134,4 +135,16 @@ public interface Caster<E extends LivingEntity> extends Owned<E>, Levelled, Affi
     default Stream<Entity> findAllEntitiesInRange(double radius) {
         return VecHelper.findAllEntitiesInRange(getEntity(), getWorld(), getOrigin(), radius);
     }
+
+    default void notifyNearbySpells(MagicEffect sender, BlockPos origin, double radius, int newState) {
+        AwaitTickQueue.enqueueTask(w -> {
+            VecHelper.findAllEntitiesInRange(getEntity(), getWorld(), origin, radius).filter(i -> i instanceof EtherialListener).forEach(i -> {
+                ((EtherialListener)i).onNearbySpellChange(this, sender, newState);
+            });
+        });
+    }
+
+    default void notifyNearbySpells(MagicEffect sender, double radius, int newState) {
+        notifyNearbySpells(sender, getOrigin(), radius, newState);
+    }
 }

src/main/java/com/minelittlepony/unicopia/magic/EtherialListener.java

@@ -0,0 +1,18 @@
+package com.minelittlepony.unicopia.magic;
+
+/**
+ * A change listener for when a magic spell is either placed or destroyed in the world.
+ */
+public interface EtherialListener {
+    int REMOVED = 0x0;
+    int ADDED =   0x1;
+
+    /**
+     * Called when a nearby spell is added or removed.
+     *
+     * @param source The casting source of the sending spell
+     * @param effect The spell that dispatched the event
+     * @param state  The new state
+     */
+    void onNearbySpellChange(Caster<?> source, MagicEffect effect, int state);
+}

src/main/java/com/minelittlepony/unicopia/magic/MagicEffect.java

@@ -65,6 +65,13 @@ public interface MagicEffect extends NbtSerialisable, Affine {
 
     }
 
+    /**
+     * Called when a gem is destroyed.
+     */
+    default void onDestroyed(Caster<?> caster) {
+        setDead();
+    }
+
     default boolean handleProjectileImpact(ProjectileEntity projectile) {
         return false;
     }

src/main/java/com/minelittlepony/unicopia/magic/Suppressable.java

@@ -3,7 +3,7 @@ package com.minelittlepony.unicopia.magic;
 /**
  * Magic effects that can be suppressed by other nearby effects.
  */
-public interface SuppressableEffect extends MagicEffect {
+public interface Suppressable {
 
     /**
      * Returns true if this spell is currently still suppressed.

src/main/java/com/minelittlepony/unicopia/magic/spell/AbstractLinkedSpell.java

@@ -7,14 +7,13 @@ import javax.annotation.Nullable;
 
 import com.minelittlepony.unicopia.entity.SpellcastEntity;
 import com.minelittlepony.unicopia.magic.Caster;
-
 import net.minecraft.entity.Entity;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.server.world.ServerWorld;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Box;
 
-public abstract class AbstractAttachableSpell extends AbstractSpell {
+public abstract class AbstractLinkedSpell extends AbstractSpell {
 
     protected boolean searching = true;
 

src/main/java/com/minelittlepony/unicopia/magic/spell/AttractiveSpell.java

@@ -1,18 +1,33 @@
 package com.minelittlepony.unicopia.magic.spell;
 
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.annotation.Nullable;
+
 import com.minelittlepony.unicopia.entity.player.Pony;
 import com.minelittlepony.unicopia.magic.Affinity;
 import com.minelittlepony.unicopia.magic.Caster;
+import com.minelittlepony.unicopia.magic.EtherialListener;
+import com.minelittlepony.unicopia.magic.MagicEffect;
 import com.minelittlepony.unicopia.particles.MagicParticleEffect;
 import com.minelittlepony.unicopia.util.MagicalDamageSource;
+import com.minelittlepony.unicopia.util.NbtSerialisable;
+import com.minelittlepony.unicopia.util.VecHelper;
 import com.minelittlepony.unicopia.util.shape.Sphere;
 
 import net.minecraft.entity.Entity;
+import net.minecraft.entity.ItemEntity;
 import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 
-public class AttractiveSpell extends ShieldSpell {
+public class AttractiveSpell extends ShieldSpell implements EtherialListener {
+
+    @Nullable
+    private BlockPos homingPos;
 
     @Override
     public String getName() {
@@ -44,9 +59,21 @@ public class AttractiveSpell extends ShieldSpell {
         return 10 + (caster.getCurrentLevel() * 2);
     }
 
+    @Override
+    protected List<Entity> getTargets(Caster<?> source, double radius) {
+
+        if (homingPos != null) {
+            return VecHelper.findAllEntitiesInRange(source.getEntity(), source.getWorld(), source.getOrigin(), radius)
+                .filter(i -> i instanceof ItemEntity)
+                .collect(Collectors.toList());
+        }
+
+        return super.getTargets(source, radius);
+    }
+
     @Override
     protected void applyRadialEffect(Caster<?> source, Entity target, double distance, double radius) {
-        Vec3d pos = source.getOriginVector();
+        Vec3d pos = homingPos == null ? source.getOriginVector() : new Vec3d(homingPos);
 
         double force = 2.5F / distance;
 
@@ -74,4 +101,37 @@ public class AttractiveSpell extends ShieldSpell {
 
         target.setVelocity(x, y, z);
     }
+
+    @Override
+    public void onNearbySpellChange(Caster<?> source, MagicEffect effect, int newState) {
+        if (effect instanceof ChargingSpell && !isDead()) {
+            if (newState == ADDED) {
+                if (homingPos == null) {
+                    homingPos = source.getOrigin();
+                }
+                setDirty(true);
+            } else if (homingPos.equals(source.getOrigin())) {
+                setDead();
+                setDirty(true);
+                source.notifyNearbySpells(this, 5, REMOVED);
+            }
+        }
+    }
+
+    @Override
+    public void toNBT(CompoundTag compound) {
+        super.toNBT(compound);
+        if (homingPos != null) {
+            compound.put("homingPos", NbtSerialisable.writeBlockPos(homingPos));
+        }
+    }
+
+    @Override
+    public void fromNBT(CompoundTag compound) {
+        super.fromNBT(compound);
+        if (compound.contains("homingPos")) {
+            homingPos = NbtSerialisable.readBlockPos(compound.getCompound("homingPos"));
+        }
+    }
+
 }

src/main/java/com/minelittlepony/unicopia/magic/spell/ChangelingTrapSpell.java

@@ -132,7 +132,7 @@ public class ChangelingTrapSpell extends AbstractSpell implements TossedMagicEff
 
         if (caster.isLocal()) {
             if (struggleCounter <= 0) {
-                setDead();
+                onDestroyed(caster);
                 setDirty(true);
 
                 WorldEvent.DESTROY_BLOCK.play(caster.getWorld(), origin, Blocks.SLIME_BLOCK.getDefaultState());
@@ -166,7 +166,7 @@ public class ChangelingTrapSpell extends AbstractSpell implements TossedMagicEff
         struggleCounter = 10;
 
         if (caster.isLocal() && caster.getWorld().random.nextInt(3) == 0) {
-            setDead();
+            onDestroyed(caster);
 
             CuccoonEntity cuccoon = UEntities.CUCCOON.create(caster.getWorld());
             cuccoon.copyPositionAndRotation(caster.getEntity());

src/main/java/com/minelittlepony/unicopia/magic/spell/ChargingSpell.java

@@ -3,6 +3,8 @@ package com.minelittlepony.unicopia.magic.spell;
 import com.minelittlepony.unicopia.entity.SpellcastEntity;
 import com.minelittlepony.unicopia.magic.Affinity;
 import com.minelittlepony.unicopia.magic.Caster;
+import com.minelittlepony.unicopia.magic.EtherialListener;
+import com.minelittlepony.unicopia.magic.MagicEffect;
 import com.minelittlepony.unicopia.particles.MagicParticleEffect;
 import com.minelittlepony.unicopia.util.shape.Shape;
 import com.minelittlepony.unicopia.util.shape.Line;
@@ -10,7 +12,7 @@ import com.minelittlepony.unicopia.util.shape.Line;
 import net.minecraft.util.math.Box;
 import net.minecraft.util.math.Vec3d;
 
-public class ChargingSpell extends AbstractAttachableSpell {
+public class ChargingSpell extends AbstractLinkedSpell implements EtherialListener {
 
     private static final Box searchArea = new Box(-15, -15, -15, 15, 15, 15);
 
@@ -71,4 +73,24 @@ public class ChargingSpell extends AbstractAttachableSpell {
 
         return !isDead();
     }
+
+    @Override
+    public void onPlaced(Caster<?> caster) {
+        caster.notifyNearbySpells(this, 12, ADDED);
+    }
+
+    @Override
+    public void onDestroyed(Caster<?> caster) {
+        super.onDestroyed(caster);
+        caster.notifyNearbySpells(this, 12, REMOVED);
+    }
+
+    @Override
+    public void onNearbySpellChange(Caster<?> source, MagicEffect effect, int newState) {
+        if (effect instanceof AttractiveSpell && !isDead()) {
+            setDead();
+            setDirty(true);
+            source.notifyNearbySpells(this, 12, newState);
+        }
+    }
 }

src/main/java/com/minelittlepony/unicopia/magic/spell/DarknessSpell.java

@@ -29,7 +29,7 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Box;
 import net.minecraft.util.math.Vec3d;
 
-public class DarknessSpell extends AbstractAttachableSpell {
+public class DarknessSpell extends AbstractLinkedSpell {
 
     private static final Box searchArea = new Box(-5, -5, -5, 5, 5, 5);
 

src/main/java/com/minelittlepony/unicopia/magic/spell/DisguiseSpell.java

@@ -16,7 +16,7 @@ import com.minelittlepony.unicopia.magic.CasterUtils;
 import com.minelittlepony.unicopia.magic.AttachedMagicEffect;
 import com.minelittlepony.unicopia.magic.Caster;
 import com.minelittlepony.unicopia.magic.MagicEffect;
-import com.minelittlepony.unicopia.magic.SuppressableEffect;
+import com.minelittlepony.unicopia.magic.Suppressable;
 import com.minelittlepony.unicopia.particles.MagicParticleEffect;
 import com.minelittlepony.unicopia.particles.UParticles;
 import com.minelittlepony.unicopia.util.projectile.ProjectileUtil;
@@ -45,7 +45,7 @@ import net.minecraft.entity.vehicle.MinecartEntity;
 import net.minecraft.item.ItemStack;
 import net.minecraft.nbt.CompoundTag;
 
-public class DisguiseSpell extends AbstractSpell implements AttachedMagicEffect, SuppressableEffect, FlightPredicate, HeightPredicate {
+public class DisguiseSpell extends AbstractSpell implements AttachedMagicEffect, Suppressable, FlightPredicate, HeightPredicate {
 
     @Nonnull
     private String entityId = "";

src/main/java/com/minelittlepony/unicopia/magic/spell/RevealingSpell.java

@@ -2,7 +2,7 @@ package com.minelittlepony.unicopia.magic.spell;
 
 import com.minelittlepony.unicopia.magic.Affinity;
 import com.minelittlepony.unicopia.magic.Caster;
-import com.minelittlepony.unicopia.magic.SuppressableEffect;
+import com.minelittlepony.unicopia.magic.Suppressable;
 import com.minelittlepony.unicopia.particles.MagicParticleEffect;
 import com.minelittlepony.unicopia.util.shape.Shape;
 import com.minelittlepony.unicopia.util.shape.Sphere;
@@ -32,7 +32,7 @@ public class RevealingSpell extends AbstractSpell {
     @Override
     public boolean update(Caster<?> source) {
         source.findAllSpellsInRange(15).forEach(e -> {
-            SuppressableEffect spell = e.getEffect(SuppressableEffect.class, false);
+            Suppressable spell = e.getEffect(Suppressable.class, false);
 
             if (spell != null && spell.isVulnerable(source, this)) {
                 spell.onSuppressed(source);

src/main/java/com/minelittlepony/unicopia/magic/spell/ShieldSpell.java

@@ -66,7 +66,7 @@ public class ShieldSpell extends AbstractRangedAreaSpell implements AttachedMagi
                 cost *= costMultiplier / 5F;
 
                 if (!source.subtractEnergyCost(cost)) {
-                    setDead();
+                    onDestroyed(source);
                 }
             }
         }
@@ -84,21 +84,25 @@ public class ShieldSpell extends AbstractRangedAreaSpell implements AttachedMagi
         return true;
     }
 
-    protected int applyEntities(Caster<?> source) {
+    protected List<Entity> getTargets(Caster<?> source, double radius) {
-        double radius = getDrawDropOffRange(source);
 
         Entity owner = source.getOwner();
 
         boolean ownerIsValid = source.getAffinity() != Affinity.BAD && EquinePredicates.PLAYER_UNICORN.test(owner);
 
-        Vec3d origin = source.getOriginVector();
+        return source.findAllEntitiesInRange(radius)
-
-        List<Entity> targets = source.findAllEntitiesInRange(radius)
             .filter(entity -> !(ownerIsValid && (
                     entity.equals(owner)
                     || (entity instanceof PlayerEntity && owner instanceof PlayerEntity && Pony.equal((PlayerEntity)entity, (PlayerEntity)owner)))))
             .collect(Collectors.toList());
+    }
 
+    protected int applyEntities(Caster<?> source) {
+        double radius = getDrawDropOffRange(source);
+
+        Vec3d origin = source.getOriginVector();
+
+        List<Entity> targets = getTargets(source, radius);
         targets.forEach(i -> {
             try {
                 double dist = i.getPos().distanceTo(origin);

src/main/java/com/minelittlepony/unicopia/magic/spell/SiphoningSpell.java

@@ -84,7 +84,7 @@ public class SiphoningSpell extends AbstractRangedAreaSpell {
 
                 if (maxHealthGain <= 0) {
                     if (source.getWorld().random.nextInt(30) == 0) {
-                        setDead();
+                        onDestroyed(source);
                     } else {
                         e.damage(damage, e.getHealth() / 4);
                     }

src/main/java/com/minelittlepony/unicopia/network/EffectSync.java

@@ -55,7 +55,7 @@ public class EffectSync {
     }
 
     @SuppressWarnings("unchecked")
-    public <E extends MagicEffect> E get(Class<E> type, boolean update) {
+    public <E> E get(Class<E> type, boolean update) {
         if (!update) {
             if (effect == null || type == null || type.isAssignableFrom(effect.getClass())) {
                 return (E)effect;