feat: add extensive test suite

app/api/card/[sub]/handler.ts

@@ -0,0 +1,46 @@
+export type CardSubmission = { uid: string; char: string | null };
+export type CardCharacter = { amber: string };
+
+type CardDependencies = {
+  findSubmission: (id: string) => Promise<CardSubmission | undefined>;
+  findImage: (id: string) => Promise<Uint8Array<ArrayBuffer> | undefined>;
+  findCharacter: (name: string) => Promise<CardCharacter | undefined>;
+  fetch: (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;
+  persistImage: (id: string, image: ArrayBuffer) => Promise<unknown>;
+  after: (task: () => Promise<void>) => void;
+};
+
+export function createCardHandler(dependencies: CardDependencies) {
+  return async function GET(
+    _request: Request,
+    { params }: { params: Promise<{ sub: string }> },
+  ) {
+    const { sub: subId } = await params;
+    const [sub, image] = await Promise.all([
+      dependencies.findSubmission(subId),
+      dependencies.findImage(subId),
+    ]);
+    if (image) return new Response(image);
+    if (!sub)
+      return new Response(`Unknown submission: ${subId}`, { status: 404 });
+    if (!sub.char)
+      return new Response("This submission isn't character-specific.", {
+        status: 422,
+      });
+
+    const character = await dependencies.findCharacter(sub.char);
+    if (!character)
+      return new Response(`Unknown character: ${sub.char}`, { status: 500 });
+
+    const card = await dependencies.fetch(
+      `https://api.astrxl.dev/v1/card/genshin/${encodeURIComponent(sub.uid)}/${encodeURIComponent(character.amber.split("-")[0])}?lang=th&substat=true&quality=true`,
+    );
+    if (!card.ok) return card;
+
+    const fresh = await card.arrayBuffer();
+    dependencies.after(async () => {
+      await dependencies.persistImage(subId, fresh);
+    });
+    return new Response(fresh);
+  };
+}