feat: ProxySpell

core/src/main/java/com/nisovin/magicspells/spells/buff/ProxySpell.java

@@ -0,0 +1,135 @@
+package com.nisovin.magicspells.spells.buff;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+
+import org.jetbrains.annotations.NotNull;
+
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.event.Listener;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.entity.EntityDamageByEntityEvent;
+
+import com.nisovin.magicspells.events.SpellTargetEvent;
+import com.nisovin.magicspells.events.SpellPreImpactEvent;
+import com.nisovin.magicspells.events.MagicSpellsEntityDamageByEntityEvent;
+import com.nisovin.magicspells.spells.BuffSpell;
+import com.nisovin.magicspells.spelleffects.EffectPosition;
+import com.nisovin.magicspells.util.MagicConfig;
+import com.nisovin.magicspells.util.SpellData;
+
+public class ProxySpell extends BuffSpell implements Listener {
+
+	private final Map<UUID, SpellData> proxies;
+	private final Set<UUID> redirecting;
+
+	public ProxySpell(MagicConfig config, String spellName) {
+		super(config, spellName);
+
+		proxies = new HashMap<>();
+		redirecting = new HashSet<>();
+	}
+
+	@Override
+	public boolean castBuff(SpellData data) {
+		proxies.put(data.target().getUniqueId(), data);
+		return true;
+	}
+
+	@Override
+	public boolean recastBuff(SpellData data) {
+		stopEffects(data.target());
+		return castBuff(data);
+	}
+
+	@Override
+	public boolean isActive(LivingEntity entity) {
+		return proxies.containsKey(entity.getUniqueId());
+	}
+
+	@Override
+	public void turnOffBuff(LivingEntity entity) {
+		proxies.remove(entity.getUniqueId());
+	}
+
+	@Override
+	protected @NotNull Collection<UUID> getActiveEntities() {
+		return proxies.keySet();
+	}
+
+	@EventHandler(ignoreCancelled = true)
+	public void onSpellTarget(SpellTargetEvent event) {
+		LivingEntity target = event.getTarget();
+		if (target == null || !target.isValid()) return;
+
+		LivingEntity proxyTarget = getProxyTarget(target);
+		if (proxyTarget == null) return;
+
+		SpellData subData = event.getSpellData().target(proxyTarget);
+		playRedirectEffects(target, proxyTarget, subData);
+
+		event.setTarget(proxyTarget);
+		addUseAndChargeCost(target);
+	}
+
+	@EventHandler(ignoreCancelled = true)
+	public void onSpellPreImpact(SpellPreImpactEvent event) {
+		LivingEntity target = event.getTarget();
+		if (target == null || !target.isValid()) return;
+
+		LivingEntity proxyTarget = getProxyTarget(target);
+		if (proxyTarget == null) return;
+
+		SpellData subData = new SpellData(event.getCaster(), proxyTarget, event.getPower());
+		playRedirectEffects(target, proxyTarget, subData);
+
+		event.setRedirected(true);
+		addUseAndChargeCost(target);
+	}
+
+	@EventHandler(ignoreCancelled = true)
+	public void onEntityDamage(EntityDamageByEntityEvent event) {
+		if (!(event.getEntity() instanceof LivingEntity target) || !target.isValid()) return;
+
+		LivingEntity proxyTarget = getProxyTarget(target);
+		if (proxyTarget == null) return;
+		if (!redirecting.add(proxyTarget.getUniqueId())) return;
+
+		SpellData subData = new SpellData(event.getDamager() instanceof LivingEntity damager ? damager : null, proxyTarget);
+		playRedirectEffects(target, proxyTarget, subData);
+
+		event.setCancelled(true);
+		try {
+			proxyTarget.damage(event.getDamage(), event.getDamager());
+			addUseAndChargeCost(target);
+		} finally {
+			redirecting.remove(proxyTarget.getUniqueId());
+		}
+	}
+
+	@EventHandler(ignoreCancelled = true)
+	public void onLegacyDamage(MagicSpellsEntityDamageByEntityEvent event) {
+		onEntityDamage(event);
+	}
+
+	private LivingEntity getProxyTarget(LivingEntity target) {
+		SpellData proxyData = proxies.get(target.getUniqueId());
+		if (proxyData == null) return null;
+
+		LivingEntity proxyTarget = proxyData.caster();
+		if (proxyTarget != null && proxyTarget.isValid()) return proxyTarget;
+
+		turnOff(target);
+		return null;
+	}
+
+	private void playRedirectEffects(LivingEntity target, LivingEntity proxyTarget, SpellData data) {
+		playSpellEffects(EffectPosition.TARGET, target, data);
+		playSpellEffects(EffectPosition.END_POSITION, proxyTarget, data);
+	}
+
+}