Began the great TypeScript Migration

It's helping a lot to move to the new parenting system

app/imports/api/engine/computation/buildComputation/computeInactiveStatus.ts

@@ -0,0 +1,44 @@
+import { CreatureProperty } from '/imports/api/creature/creatureProperties/CreatureProperties';
+import walkDown from '/imports/api/engine/computation/utility/walkdown.js';
+import { TreeNode } from '/imports/api/parenting/parentingFunctions';
+import { isSpell } from '/imports/api/properties/Spells';
+
+export default function computeInactiveStatus(node: TreeNode<CreatureProperty>): void {
+  const prop = node.doc;
+  if (!isActive(prop)) {
+    // Mark prop inactive due to self
+    prop.inactive = true;
+    prop.deactivatedBySelf = true;
+  }
+  if (!childrenActive(prop)) {
+    // Mark children as inactive due to ancestor
+    walkDown(node.children, child => {
+      child.node.inactive = true;
+      child.node.deactivatedByAncestor = true;
+    });
+  }
+}
+
+function isActive(prop: CreatureProperty): boolean {
+  if (prop.disabled) return false;
+  if (isSpell(prop)) {
+    return !!prop.prepared || !!prop.alwaysPrepared;
+  } else {
+    return true;
+  }
+}
+
+function childrenActive(prop): boolean {
+  // Children of disabled properties are always inactive
+  if (prop.disabled) return false;
+  switch (prop.type) {
+    // Only equipped items with non-zero quantity have active children
+    case 'item': return !!prop.equipped && prop.quantity !== 0;
+    // The children of actions, spells, and triggers are always inactive
+    case 'action': return false;
+    case 'spell': return false;
+    case 'trigger': return false;
+    // Other children are active
+    default: return true;
+  }
+}