add pigs to event categories, fallback to those

web/src/lib/event.ts

@@ -11,6 +11,7 @@ import {
 import { toLocalTime, formatDate } from "./date";
 import { graphql } from "@/gql";
 import { EventFragment, EventCategory, EventOccurrence } from "@/gql/graphql";
+import { PIG_NAMES, PigName, randomElement } from "@/lib/common";
 
 export type {
   EventFragment,
@@ -51,6 +52,7 @@ const EventFragmentDefinition = graphql(`
       ... on EventCategory {
         name
         slug
+        pig
       }
     }
     occurrences {
@@ -181,3 +183,20 @@ export function getClosestOccurrence(event: EventFragment) {
 
   return futureOccurrences[0];
 }
+
+export function getEventPig(event: EventFragment): string | null {
+  if (event.pig === "" || typeof event.pig !== "string") {
+    return null;
+  }
+  if (PIG_NAMES.includes(event.pig)) {
+    return event.pig;
+  }
+  if (event.pig === "automatic") {
+    const categoryPigs = event.categories
+      ?.map((category) => category.pig)
+      .filter((pig) => PIG_NAMES.includes(pig));
+    const chosenPig = randomElement(categoryPigs ?? []);
+    return typeof chosenPig === "string" ? chosenPig : null;
+  }
+  return null;
+}