import { afterEach, expect, test, rs } from "@rstest/core";

import {
  clearReconnectRun,
  getAPIClient,
  isInactiveRunStreamError,
  isRunNotCancellableError,
  StreamReplayGapError,
} from "@/core/api/api-client";

function makeSessionStorage() {
  const values = new Map<string, string>();
  return {
    getItem: rs.fn((key: string) => values.get(key) ?? null),
    removeItem: rs.fn((key: string) => {
      values.delete(key);
    }),
    setItem: rs.fn((key: string, value: string) => {
      values.set(key, value);
    }),
  };
}

function makeSSEResponse(body: string, headers?: HeadersInit) {
  return new Response(body, {
    status: 200,
    headers: {
      "Content-Type": "text/event-stream",
      ...headers,
    },
  });
}

afterEach(() => {
  rs.unstubAllGlobals();
});

test("identifies inactive run stream errors", () => {
  const error = Object.assign(
    new Error(
      'HTTP 409: {"detail":"Run run-1 is not active on this worker and cannot be streamed"}',
    ),
    { status: 409 },
  );

  expect(isInactiveRunStreamError(error)).toBe(true);
});

test("does not classify unrelated conflict errors as inactive streams", () => {
  const error = Object.assign(new Error("HTTP 409: run is still active"), {
    status: 409,
  });

  expect(isInactiveRunStreamError(error)).toBe(false);
});

test("clears matching reconnect metadata", () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  rs.stubGlobal("window", { sessionStorage });

  clearReconnectRun("thread-1", "run-1");

  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("keeps newer reconnect metadata", () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "newer-run");
  rs.stubGlobal("window", { sessionStorage });

  clearReconnectRun("thread-1", "stale-run");

  expect(sessionStorage.removeItem).not.toHaveBeenCalled();
});

test("ignores reconnect metadata storage access failures", () => {
  rs.stubGlobal("window", {
    get sessionStorage() {
      throw new DOMException("Blocked", "SecurityError");
    },
  });

  expect(() => clearReconnectRun("thread-1", "run-1")).not.toThrow();
});

test("clears stale reconnect metadata when join stream cannot be resumed", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal(
    "fetch",
    rs.fn(async () => {
      return new Response(
        JSON.stringify({
          detail:
            "Run run-1 is not active on this worker and cannot be streamed",
        }),
        { status: 409 },
      );
    }),
  );

  await expect(
    getAPIClient(true).runs.joinStream("thread-1", "run-1").next(),
  ).resolves.toMatchObject({ done: true });

  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("rethrows unrelated streaming errors", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal(
    "fetch",
    rs.fn(async () => {
      return new Response(JSON.stringify({ detail: "run is still active" }), {
        status: 409,
      });
    }),
  );

  await expect(
    getAPIClient(true).runs.joinStream("thread-1", "run-1").next(),
  ).rejects.toThrow("HTTP 409");

  expect(sessionStorage.removeItem).not.toHaveBeenCalled();
});

test("identifies terminal-state cancel conflicts", () => {
  const error = Object.assign(
    new Error(
      'HTTP 409: {"detail":"Run run-1 is not cancellable (status: success)"}',
    ),
    { status: 409 },
  );

  expect(isRunNotCancellableError(error)).toBe(true);
});

test("does not classify not-active-on-worker cancel as terminal", () => {
  // A run still pending/running on another worker is a real cancel failure —
  // it must stay visible and must NOT be swallowed.
  const error = Object.assign(
    new Error(
      'HTTP 409: {"detail":"Run run-1 is not active on this worker and cannot be cancelled"}',
    ),
    { status: 409 },
  );

  expect(isRunNotCancellableError(error)).toBe(false);
});

test("swallows terminal-state cancel 409 and clears stale key", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal(
    "fetch",
    rs.fn(async () => {
      return new Response(
        JSON.stringify({
          detail: "Run run-1 is not cancellable (status: success)",
        }),
        { status: 409 },
      );
    }),
  );

  // Resolves (no throw) — cancelling an already-finished run is a no-op.
  await expect(
    getAPIClient(true).runs.cancel("thread-1", "run-1"),
  ).resolves.toBeUndefined();

  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("rethrows not-active-on-worker cancel 409", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal(
    "fetch",
    rs.fn(async () => {
      return new Response(
        JSON.stringify({
          detail:
            "Run run-1 is not active on this worker and cannot be cancelled",
        }),
        { status: 409 },
      );
    }),
  );

  await expect(
    getAPIClient(true).runs.cancel("thread-1", "run-1"),
  ).rejects.toThrow("HTTP 409");

  expect(sessionStorage.removeItem).not.toHaveBeenCalled();
});

test("short-circuits reconnect to a terminal run", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    // Preflight GET /threads/{tid}/runs/{runId} reports a finished run.
    if (path.endsWith("/runs/run-1")) {
      return new Response(JSON.stringify({ status: "success" }), {
        status: 200,
      });
    }
    // If join were attempted it must never run; fail loudly if it does.
    return new Response(JSON.stringify({ detail: "unexpected join" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const gen = getAPIClient(true).runs.joinStream("thread-1", "run-1");
  await expect(gen.next()).resolves.toMatchObject({ done: true });

  // Preflight only — no stream/join request beyond the GET.
  expect(fetchFn).toHaveBeenCalledTimes(1);
  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("falls back to join when preflight cannot resolve the run", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    // Preflight GET 404s (record evicted) — must fall back to join.
    if (path.endsWith("/runs/run-1")) {
      return new Response(JSON.stringify({ detail: "Run run-1 not found" }), {
        status: 404,
      });
    }
    // Join then surfaces the inactive-stream 409 and clears the key.
    return new Response(
      JSON.stringify({
        detail: "Run run-1 is not active on this worker and cannot be streamed",
      }),
      { status: 409 },
    );
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  await expect(
    getAPIClient(true).runs.joinStream("thread-1", "run-1").next(),
  ).resolves.toMatchObject({ done: true });

  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("proceeds to join when the run is still active", async () => {
  // Positive path: a running/pending run must NOT be short-circuited — the
  // preflight must let the real join through so an in-flight stream can be
  // rejoined. Proves the guard does not over-eagerly skip active runs.
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    // Preflight GET reports an active run.
    if (path.endsWith("/runs/run-1")) {
      return new Response(JSON.stringify({ status: "running" }), {
        status: 200,
      });
    }
    // The real join is attempted (here it surfaces the inactive-stream 409,
    // which the wrapper catches and clears the key — same path as production).
    return new Response(
      JSON.stringify({
        detail: "Run run-1 is not active on this worker and cannot be streamed",
      }),
      { status: 409 },
    );
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  await expect(
    getAPIClient(true).runs.joinStream("thread-1", "run-1").next(),
  ).resolves.toMatchObject({ done: true });

  // Two requests: preflight GET + the real join. A short-circuit would be one.
  expect(fetchFn).toHaveBeenCalledTimes(2);
  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});

test("recovers a join stream gap from durable state and resumes after the retained tail", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  const gap = {
    code: "stream_replay_gap",
    run_id: "run-1",
    requested_event_id: "1-0",
    earliest_available_event_id: "2-0",
    latest_available_event_id: "3-0",
    recovery: "reload_durable_state",
  };
  const recoveryRequests: RequestInit[] = [];
  const fetchFn = rs.fn(async (url: string | URL, init?: RequestInit) => {
    const path = url.toString();
    if (path.endsWith("/runs/run-1")) {
      return new Response(JSON.stringify({ status: "running" }), {
        status: 200,
      });
    }
    if (path.includes("/runs/run-1/stream")) {
      recoveryRequests.push(init ?? {});
      if (recoveryRequests.length === 1) {
        return makeSSEResponse(`event: gap\ndata: ${JSON.stringify(gap)}\n\n`);
      }
      return makeSSEResponse("event: end\ndata: null\n\n");
    }
    if (path.includes("/threads/thread-1/state")) {
      return new Response(
        JSON.stringify({
          values: { messages: [{ type: "ai", content: "durable" }] },
          next: [],
          tasks: [],
          metadata: {},
          created_at: null,
          checkpoint: {},
          parent_checkpoint: null,
        }),
        { status: 200 },
      );
    }
    return new Response(JSON.stringify({ detail: "unexpected request" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const received: Array<{ id?: string; event: string; data: unknown }> = [];
  for await (const entry of getAPIClient(true).runs.joinStream(
    "thread-1",
    "run-1",
    { lastEventId: "1-0" },
  )) {
    received.push(entry);
  }

  expect(received).toEqual([
    {
      event: "custom",
      data: { type: "stream_replay_gap", ...gap },
    },
    {
      event: "values",
      data: { messages: [{ type: "ai", content: "durable" }] },
    },
    { event: "end", data: null },
  ]);
  expect(new Headers(recoveryRequests[1]?.headers).get("Last-Event-ID")).toBe(
    "3-0",
  );
});

test("recovers a gap emitted by the initial run stream", async () => {
  const sessionStorage = makeSessionStorage();
  const gap = {
    code: "stream_replay_gap",
    run_id: "run-2",
    requested_event_id: null,
    earliest_available_event_id: "4-0",
    latest_available_event_id: "5-0",
    recovery: "reload_durable_state",
  };
  const recoveryHeaders: Headers[] = [];
  const fetchFn = rs.fn(async (url: string | URL, init?: RequestInit) => {
    const path = url.toString();
    if (path.endsWith("/threads/thread-2/runs/stream")) {
      return makeSSEResponse(`event: gap\ndata: ${JSON.stringify(gap)}\n\n`, {
        "Content-Location": "/threads/thread-2/runs/run-2",
      });
    }
    if (path.includes("/threads/thread-2/state")) {
      return new Response(
        JSON.stringify({
          values: { messages: [{ type: "ai", content: "checkpoint" }] },
        }),
        { status: 200 },
      );
    }
    if (path.includes("/runs/run-2/stream")) {
      recoveryHeaders.push(new Headers(init?.headers));
      return makeSSEResponse("event: end\ndata: null\n\n");
    }
    return new Response(JSON.stringify({ detail: "unexpected request" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const received: Array<{ id?: string; event: string; data: unknown }> = [];
  for await (const entry of getAPIClient(true).runs.stream(
    "thread-2",
    "lead_agent",
    { streamResumable: true },
  )) {
    received.push(entry);
  }

  expect(received).toEqual([
    {
      event: "custom",
      data: { type: "stream_replay_gap", ...gap },
    },
    {
      event: "values",
      data: { messages: [{ type: "ai", content: "checkpoint" }] },
    },
    { event: "end", data: null },
  ]);
  expect(recoveryHeaders[0]?.get("Last-Event-ID")).toBe("5-0");
});

test("clears reconnect metadata when an initial stream gap resume is inactive", async () => {
  const sessionStorage = makeSessionStorage();
  const gap = {
    code: "stream_replay_gap",
    run_id: "run-inactive-resume",
    requested_event_id: null,
    earliest_available_event_id: "4-0",
    latest_available_event_id: "5-0",
    recovery: "reload_durable_state",
  };
  let recoveryRequests = 0;
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    if (path.endsWith("/threads/thread-inactive-resume/runs/stream")) {
      return makeSSEResponse(`event: gap\ndata: ${JSON.stringify(gap)}\n\n`, {
        "Content-Location":
          "/threads/thread-inactive-resume/runs/run-inactive-resume",
      });
    }
    if (path.includes("/threads/thread-inactive-resume/state")) {
      return new Response(
        JSON.stringify({
          values: { messages: [{ type: "ai", content: "checkpoint" }] },
        }),
        { status: 200 },
      );
    }
    if (path.includes("/runs/run-inactive-resume/stream")) {
      recoveryRequests += 1;
      return new Response(
        JSON.stringify({
          detail:
            "Run run-inactive-resume is not active on this worker and cannot be streamed",
        }),
        { status: 409 },
      );
    }
    return new Response(JSON.stringify({ detail: "unexpected request" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const stream = getAPIClient(true).runs.stream(
    "thread-inactive-resume",
    "lead_agent",
    { streamResumable: true },
  );

  await expect(stream.next()).resolves.toMatchObject({
    done: false,
    value: {
      event: "custom",
      data: { type: "stream_replay_gap", ...gap },
    },
  });
  await expect(stream.next()).resolves.toMatchObject({
    done: false,
    value: {
      event: "values",
      data: { messages: [{ type: "ai", content: "checkpoint" }] },
    },
  });
  await expect(stream.next()).resolves.toMatchObject({ done: true });

  expect(recoveryRequests).toBe(1);
  expect(sessionStorage.getItem("lg:stream:thread-inactive-resume")).toBeNull();
});

test("stops after five consecutive stream gap recoveries", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-gap-loop", "run-gap-loop");
  let streamCalls = 0;
  let stateCalls = 0;
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    if (path.endsWith("/runs/run-gap-loop")) {
      return new Response(JSON.stringify({ status: "running" }), {
        status: 200,
      });
    }
    if (path.includes("/runs/run-gap-loop/stream")) {
      streamCalls += 1;
      const gap = {
        code: "stream_replay_gap",
        run_id: "run-gap-loop",
        requested_event_id: `${streamCalls}-0`,
        earliest_available_event_id: `${streamCalls + 1}-0`,
        latest_available_event_id: `${streamCalls + 2}-0`,
        recovery: "reload_durable_state",
      };
      return makeSSEResponse(`event: gap\ndata: ${JSON.stringify(gap)}\n\n`);
    }
    if (path.includes("/threads/thread-gap-loop/state")) {
      stateCalls += 1;
      return new Response(JSON.stringify({ values: { messages: [] } }), {
        status: 200,
      });
    }
    return new Response(JSON.stringify({ detail: "unexpected request" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const consume = async () => {
    for await (const entry of getAPIClient(true).runs.joinStream(
      "thread-gap-loop",
      "run-gap-loop",
      { lastEventId: "1-0" },
    )) {
      // Drain until the recovery budget is exhausted.
      void entry;
    }
  };

  await expect(consume()).rejects.toBeInstanceOf(StreamReplayGapError);
  expect(streamCalls).toBe(6);
  expect(stateCalls).toBe(5);
});

test("surfaces durable-state recovery failures as a structured gap error", async () => {
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-gap-state", "run-gap-state");
  sessionStorage.setItem.mockClear();
  const gap = {
    code: "stream_replay_gap",
    run_id: "run-gap-state",
    requested_event_id: "1-0",
    earliest_available_event_id: "2-0",
    latest_available_event_id: "3-0",
    recovery: "reload_durable_state",
  };
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    if (path.endsWith("/runs/run-gap-state")) {
      return new Response(JSON.stringify({ status: "running" }), {
        status: 200,
      });
    }
    if (path.includes("/runs/run-gap-state/stream")) {
      return makeSSEResponse(`event: gap\ndata: ${JSON.stringify(gap)}\n\n`);
    }
    if (path.includes("/threads/thread-gap-state/state")) {
      return new Response(JSON.stringify({ detail: "state unavailable" }), {
        status: 404,
      });
    }
    return new Response(JSON.stringify({ detail: "unexpected request" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const consume = async () => {
    for await (const entry of getAPIClient(true).runs.joinStream(
      "thread-gap-state",
      "run-gap-state",
      { lastEventId: "1-0" },
    )) {
      void entry;
    }
  };

  const error = await consume().catch((cause: unknown) => cause);
  expect(error).toBeInstanceOf(StreamReplayGapError);
  expect(error).toMatchObject({
    gap,
    recoveryAttempts: 1,
    recoveryCause: expect.any(Error),
  });
  expect(sessionStorage.removeItem).toHaveBeenCalledWith(
    "lg:stream:thread-gap-state",
  );
  expect(sessionStorage.setItem).not.toHaveBeenCalledWith(
    "lg:stream:thread-gap-state",
    "run-gap-state",
  );
});

test("short-circuits reconnect to an interrupted (user-cancelled) run", async () => {
  // Regression: interrupted is a persisted terminal status written by
  // RunManager.cancel(). Reconnecting to it must short-circuit like other
  // terminal states, otherwise — once the bridge is reaped — joinStream blocks
  // forever and isLoading sticks. Keeps the frontend status set aligned with
  // the backend RunStatus contract.
  const sessionStorage = makeSessionStorage();
  sessionStorage.setItem("lg:stream:thread-1", "run-1");
  const fetchFn = rs.fn(async (url: string | URL) => {
    const path = url.toString();
    if (path.endsWith("/runs/run-1")) {
      return new Response(JSON.stringify({ status: "interrupted" }), {
        status: 200,
      });
    }
    return new Response(JSON.stringify({ detail: "unexpected join" }), {
      status: 500,
    });
  });
  rs.stubGlobal("window", {
    location: { origin: "http://localhost:2026" },
    sessionStorage,
  });
  rs.stubGlobal("fetch", fetchFn);

  const gen = getAPIClient(true).runs.joinStream("thread-1", "run-1");
  await expect(gen.next()).resolves.toMatchObject({ done: true });

  expect(fetchFn).toHaveBeenCalledTimes(1);
  expect(sessionStorage.removeItem).toHaveBeenCalledWith("lg:stream:thread-1");
});