// 不自动运行（需要 npm i -D vitest vue 后执行 npx vitest run）
import { describe, expect, it } from "vitest";
import { effectScope } from "vue";
import { useChatStream } from "./useChatStream.ts";

function sseResponse(chunks: string[], failAfter?: number): Response {
  let i = 0;
  const body = new ReadableStream<Uint8Array>({
    pull(ctrl) {
      if (failAfter !== undefined && i === failAfter) return ctrl.error(new Error("network down"));
      if (i >= chunks.length) return ctrl.close();
      ctrl.enqueue(new TextEncoder().encode(chunks[i++]));
    },
  });
  return new Response(body, { status: 200, headers: { "Content-Type": "text/event-stream" } });
}

const FINAL = 'id: 3\nevent: final\ndata: {"answer":"好","citations":[{"id":1,"title":"政策"}]}\n\n';

describe("useChatStream", () => {
  it("拼接 token 并解析 final", async () => {
    const scope = effectScope();
    const chat = scope.run(() =>
      useChatStream({ url: "/chat", fetchImpl: async () => sseResponse(["id: 1\nevent: token\ndata: 你", "好\n\n", FINAL]) }),
    )!;
    await chat.send("hi");
    expect(chat.status.value).toBe("done");
    expect(chat.text.value).toBe("你好");
    expect(chat.final.value?.citations[0]?.title).toBe("政策");
    scope.stop();
  });

  it("断线后带 Last-Event-ID 重试", async () => {
    const seen: (string | null)[] = [];
    let n = 0;
    const fetchImpl = async (_: RequestInfo | URL, init?: RequestInit) => {
      seen.push(new Headers(init?.headers).get("Last-Event-ID"));
      return n++ === 0 ? sseResponse(["id: 1\nevent: token\ndata: 你\n\n", "x"], 1) : sseResponse([FINAL]);
    };
    const chat = useChatStream({ url: "/chat", fetchImpl, maxRetries: 1 });
    await chat.send("hi");
    expect(seen).toEqual([null, "1"]);
    expect(chat.status.value).toBe("done");
  });

  it("stop 之后状态为 aborted", async () => {
    const fetchImpl = (_: RequestInfo | URL, init?: RequestInit) =>
      new Promise<Response>((_, reject) =>
        init?.signal?.addEventListener("abort", () => reject(new DOMException("aborted", "AbortError"))),
      );
    const chat = useChatStream({ url: "/chat", fetchImpl });
    const p = chat.send("hi");
    chat.stop();
    await p;
    expect(chat.status.value).toBe("aborted");
  });
});