/**
 * Tests for the error-classification behaviour of `checkAgentName`.
 *
 * Issue #3041: when the backend returns a non-200 response (e.g. a 500 with
 * a database error, a 422 from misbehaving routing, or any other 4xx/5xx
 * not in the 502/503/504 set), the UI used to swallow the backend detail
 * into a generic "Could not verify name availability" fallback because the
 * page-level catch block only handled `reason === "backend_unreachable"`.
 *
 * The fix carries the raw backend detail as `AgentNameCheckError.detail`
 * (distinct from `message`, which always has a non-empty value because
 * `checkAgentName` substitutes a generated fallback when the backend sent
 * no detail). The UI uses `detail` to decide whether to surface a real
 * backend string or fall back to the localised "could not verify" copy.
 *
 * These tests pin both halves of the contract so a future refactor doesn't
 * silently drop the detail or leak the generated fallback into the UI.
 */
import { beforeEach, describe, expect, test, rs } from "@rstest/core";

rs.mock("@/core/api/fetcher", () => ({
  fetch: rs.fn(),
}));

rs.mock("@/core/config", () => ({
  getBackendBaseURL: () => "",
}));

import { AgentsApiDisabledError, checkAgentName } from "@/core/agents/api";
import { fetch as fetcher } from "@/core/api/fetcher";

const mockedFetch = rs.mocked(fetcher);

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

beforeEach(() => {
  mockedFetch.mockReset();
});

describe("checkAgentName", () => {
  test("returns availability payload on 200", async () => {
    mockedFetch.mockResolvedValueOnce(
      jsonResponse(200, { available: true, name: "dealagent" }),
    );
    const result = await checkAgentName("dealagent");
    expect(result).toEqual({ available: true, name: "dealagent" });
  });

  test("treats network-layer fetch rejection as backend_unreachable", async () => {
    mockedFetch.mockRejectedValueOnce(new TypeError("Failed to fetch"));
    await expect(checkAgentName("dealagent")).rejects.toMatchObject({
      name: "AgentNameCheckError",
      reason: "backend_unreachable",
    });
  });

  test.each([502, 503, 504])(
    "treats HTTP %i as backend_unreachable",
    async (status) => {
      mockedFetch.mockResolvedValueOnce(
        jsonResponse(status, { detail: "Bad Gateway" }),
      );
      await expect(checkAgentName("dealagent")).rejects.toMatchObject({
        name: "AgentNameCheckError",
        reason: "backend_unreachable",
      });
    },
  );

  test("recognises agents_api disabled detail and throws AgentsApiDisabledError", async () => {
    const detail =
      "Custom-agent management API is disabled. Set agents_api.enabled=true to expose agent and user-profile routes over HTTP.";
    mockedFetch.mockResolvedValueOnce(jsonResponse(403, { detail }));
    await expect(checkAgentName("dealagent")).rejects.toBeInstanceOf(
      AgentsApiDisabledError,
    );
  });

  test("carries backend 422 detail through AgentNameCheckError.detail (issue #3041)", async () => {
    // This is the exact response shape produced by `_validate_agent_name`
    // when the user submits a name with disallowed characters — e.g. a
    // trailing space, a dot, a Chinese character, or invisible whitespace
    // pasted in from another window.
    const detail =
      "Invalid agent name 'deal agent'. Must match ^[A-Za-z0-9-]+$ (letters, digits, and hyphens only).";
    mockedFetch.mockResolvedValueOnce(jsonResponse(422, { detail }));

    await expect(checkAgentName("deal agent")).rejects.toMatchObject({
      name: "AgentNameCheckError",
      reason: "request_failed",
      // The full detail is preserved on both `detail` (for the UI to
      // recognise "real backend detail vs generated fallback") and
      // `message` (for stack traces / logs).
      detail,
      message: detail,
    });
  });

  test("falls back to statusText in message but leaves detail null when backend returns no detail", async () => {
    // The fallback message must NOT mask the absence of a real backend
    // detail — the page-level catch relies on `detail === null` to choose
    // the localised generic fallback rather than rendering the bare
    // "Failed to check agent name: Internal Server Error" string.
    mockedFetch.mockResolvedValueOnce(
      new Response("", { status: 500, statusText: "Internal Server Error" }),
    );
    await expect(checkAgentName("dealagent")).rejects.toMatchObject({
      name: "AgentNameCheckError",
      reason: "request_failed",
      detail: null,
      message: expect.stringContaining("Internal Server Error"),
    });
  });

  test("treats non-string detail as null (defence against future schema drift)", async () => {
    // If the backend ever returns `{detail: {code, message}}` (the shape
    // used by auth errors today) on this endpoint, we must not surface a
    // `[object Object]` string. `detail` should fall back to null so the
    // page uses its localised fallback.
    mockedFetch.mockResolvedValueOnce(
      jsonResponse(500, { detail: { code: "x", message: "y" } }),
    );
    await expect(checkAgentName("dealagent")).rejects.toMatchObject({
      name: "AgentNameCheckError",
      reason: "request_failed",
      detail: null,
    });
  });

  test("does not misclassify a 422 with unrelated detail as agents_api disabled", async () => {
    // Defence-in-depth: the disabled detector matches on the substring
    // "agents_api.enabled", so a 422 whose detail accidentally contains
    // the same substring would be misclassified. The validation detail
    // produced by `_validate_agent_name` never contains it; this test
    // simply asserts that "Invalid agent name ..." stays in the
    // request_failed branch, which is where the page now surfaces it.
    const detail =
      "Invalid agent name 'deal.agent'. Must match ^[A-Za-z0-9-]+$ (letters, digits, and hyphens only).";
    mockedFetch.mockResolvedValueOnce(jsonResponse(422, { detail }));
    await expect(checkAgentName("deal.agent")).rejects.not.toBeInstanceOf(
      AgentsApiDisabledError,
    );
  });
});
