import { describe, expect, it } from "vitest";
import { createChatScope } from "./chat-utils";

function deferred<T>() {
  let resolve!: (value: T) => void;
  let reject!: (error: Error) => void;
  const promise = new Promise<T>((yes, no) => {
    resolve = yes;
    reject = no;
  });
  return { promise, resolve, reject };
}

describe("chat async scope", () => {
  it("ignores a send resolved after a channel switch", async () => {
    const scope = createChatScope("acme", "first");
    const request = deferred<string>();
    const result: string[] = [];
    const valid = scope.capture();
    const completion = request.promise.then((message) => {
      if (valid()) result.push(message);
    });
    scope.select("acme", "second");
    request.resolve("first-channel message");
    await completion;
    expect(result).toEqual([]);
  });

  it("ignores a late failed send, including a permission error", async () => {
    const scope = createChatScope("acme", "first");
    const request = deferred<string>();
    const result: string[] = [];
    const valid = scope.capture();
    const completion = request.promise.catch((error: Error) => {
      if (valid()) result.push(error.message);
    });
    scope.select("acme", "second");
    request.reject(new Error("FORBIDDEN"));
    await completion;
    expect(result).toEqual([]);
  });

  it("ignores a stale mutation result and its subsequent refresh", async () => {
    const scope = createChatScope("acme", "first");
    const mutation = deferred<string>();
    const refresh = deferred<string>();
    const result: string[] = [];
    const valid = scope.capture();
    const completion = mutation.promise.then(async (value) => {
      if (!valid()) return;
      result.push(value);
      const page = await refresh.promise;
      if (valid()) result.push(page);
    });
    mutation.resolve("edited");
    await Promise.resolve();
    scope.select("acme", "second");
    refresh.resolve("old page");
    await completion;
    expect(result).toEqual(["edited"]);
  });

  it("invalidates pending work on purge before redirect and cannot remove a new channel's cache", async () => {
    const scope = createChatScope("acme", "first");
    const cancellation = deferred<void>();
    const result: string[] = [];
    const valid = scope.capture();
    scope.revoke();
    result.push("redirect");
    const cleanup = cancellation.promise.then(() => {
      if (valid()) result.push("remove queries");
    });
    scope.select("acme", "second");
    cancellation.resolve();
    await cleanup;
    expect(result).toEqual(["redirect"]);
    expect(scope.capture()()).toBe(true);
  });
});