generalize buff damage multipliers

src/buff.js

@@ -5,6 +5,7 @@ export default class Buff {
 
   name = 'Buff'
 
+  damageMultiplier = null
   duration = 0
 
   #effect = null
@@ -22,5 +23,6 @@ export default class Buff {
     id: 'exposed',
     name: 'Exposed',
     duration: 4,
+    onHitMultiplier: 3,
   })
 }

src/entity.js

@@ -324,15 +324,21 @@ export default class Entity {
   damage(amount, source = null) {
     if (this.dead) { return }
 
-    let damage = amount
+    let customMultipliers = 0
     if (this.hasBuff(Buff.exposed.id)) {
       const buff = this.getBuff(Buff.exposed.id)
       if (buff.source == source.id) {
-        damage *= 3 // TODO: move to Buff class to make generic
+        customMultipliers += (buff.onHitMultiplier - 1)
         this.removeBuff(Buff.exposed.id)
       }
     }
 
+    const damageMultiplerBuffs = source.buffs.map((it) => it.getBuff).filter((it) => it != null && it.damageMultiplier != null)
+    const buffPassiveDamageMultiplier = damageMultiplerBuffs.reduce((it) => it.damageMultiplier - 1, 0)
+
+    const damageMultipler = 1 + buffPassiveDamageMultiplier + customMultipliers
+    const damage = amount * damageMultipler
+
     this.health = Math.min(Math.max(0, this.health - damage), this.maxHealth)
   }