import { extractErrorMessage } from "../http-error";

function jsonResponse(body: unknown): Response {
  return new Response(JSON.stringify(body), {
    status: 400,
    headers: { "Content-Type": "application/json" },
  });
}

describe("extractErrorMessage", () => {
  it("returns the top-level message when no details are supplied", async () => {
    const r = jsonResponse({ error: { message: "Bad request" } });
    expect(await extractErrorMessage(r, "fb")).toBe("Bad request");
  });

  it("joins details with commas", async () => {
    const r = jsonResponse({ error: { message: "ignored", details: ["a", "b", "c"] } });
    expect(await extractErrorMessage(r, "fb")).toBe("a, b, c");
  });

  it("caps the number of details rendered and marks the truncation", async () => {
    const details = Array.from({ length: 20 }, (_, i) => `e${i}`);
    const r = jsonResponse({ error: { message: "ignored", details } });
    const out = await extractErrorMessage(r, "fb");
    expect(out.endsWith(", …")).toBe(true);
    expect(out.split(", ").length).toBe(6); // 5 entries + the ellipsis marker
  });

  it("returns fallback for unparseable bodies", async () => {
    const r = new Response("not json", { status: 500 });
    expect(await extractErrorMessage(r, "fallback")).toBe("fallback");
  });
});