From 624059ef025b9051bfb47d269d48419e7875020d Mon Sep 17 00:00:00 2001
From: Johannes Loher <johannes.loher@fg4f.de>
Date: Tue, 16 Feb 2021 15:39:18 +0100
Subject: [PATCH] Always derive hitPoints.max from the final hitPoints.total

---
 src/module/actor/actor.ts | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/src/module/actor/actor.ts b/src/module/actor/actor.ts
index c912316..f6ef187 100644
--- a/src/module/actor/actor.ts
+++ b/src/module/actor/actor.ts
@@ -18,6 +18,7 @@ export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
         this.applyActiveEffectsToNonDerivedData();
         this.prepareDerivedData();
         this.applyActiveEffectsToDerivedData();
+        this.prepareFinalDerivedData();
     }
 
     /** @override */
@@ -33,11 +34,17 @@ export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
     }
 
     applyActiveEffectsToNonDerivedData(): void {
-        this.applyActiveEffectsFiltered((change) => !this.derivedDataProperties.includes(change.key));
+        this.applyActiveEffectsFiltered(
+            (change) =>
+                !this.derivedDataProperties.includes(change.key) && !this.finalDerivedProperties.includes(change.key),
+        );
     }
 
     applyActiveEffectsToDerivedData(): void {
-        this.applyActiveEffectsFiltered((change) => this.derivedDataProperties.includes(change.key));
+        this.applyActiveEffectsFiltered(
+            (change) =>
+                this.derivedDataProperties.includes(change.key) && !this.finalDerivedProperties.includes(change.key),
+        );
     }
 
     /**
@@ -87,18 +94,38 @@ export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
         return item ?? undefined;
     }
 
-    /** @override */
+    /**
+     * Apply transformations to the Actor data after effects have been applied to the base data.
+     * @override
+     */
     prepareDerivedData(): void {
         this._prepareCombatValues();
     }
 
-    /** The list of properties that are derived from others, given in dot notation */
+    /**
+     * The list of properties that are derived from others, given in dot notation.
+     */
     get derivedDataProperties(): Array<string> {
         return Object.keys(DS4.i18n.combatValues)
             .map((combatValue) => `data.combatValues.${combatValue}.total`)
             .concat("data.combatValues.hitPoints.max");
     }
 
+    /**
+     * Apply final transformations to the Actor data after all effects have been applied.
+     */
+    prepareFinalDerivedData(): void {
+        this.data.data.combatValues.hitPoints.max = this.data.data.combatValues.hitPoints.total;
+    }
+
+    /**
+     * The list of properties that are completely derived (i.e. {@link ActiveEffect}s cannot be applied to them), given in dot
+     * notation.
+     */
+    get finalDerivedProperties(): string[] {
+        return ["data.combatValues.hitPoints.max"];
+    }
+
     /**
      * The list of item types that can be owned by this actor.
      */
@@ -156,8 +183,6 @@ export class DS4Actor extends Actor<DS4ActorData, DS4Item> {
         Object.values(data.combatValues).forEach(
             (combatValue: ModifiableData<number>) => (combatValue.total = combatValue.base + combatValue.mod),
         );
-
-        data.combatValues.hitPoints.max = data.combatValues.hitPoints.total;
     }
 
     /**