import { describe, it, expect, beforeAll } from "vitest";

// The façade guard: lib/api.ts is a spread-only façade over per-domain slice modules. These tests
// mechanise the two invariants that make that structure safe — so a future edit that reintroduces
// the interleave (a method dropped into two slices → a silent last-wins spread override) or bloats
// the barrel (a method defined inline instead of in a domain module) fails CI instead of shipping.
//
// Scope, on purpose: this covers RUNTIME method-key collisions — the only *silent* failure mode,
// since tsc does not flag overlapping spread keys. It deliberately does NOT cover exported-TYPE-name
// clashes across slices (two slices exporting the same interface name): types are erased at runtime
// so they're invisible here, and that case is already build-caught — the barrel's `export type *`
// makes the ambiguous name a downstream tsc "no exported member" error, so nothing ships. Left to
// tsc rather than re-checked by a fragile source parse.

type Slice = Record<string, unknown>;

// Names line up with the modules below; kept as a list so the wiring stays a single source.
const SLICE_MODULES = [
  ["accountApi", () => import("./account")],
  ["authApi", () => import("./auth")],
  ["setupApi", () => import("./setup")],
  ["feedApi", () => import("./feed")],
  ["discoverApi", () => import("./discover")],
  ["channelsApi", () => import("./channels")],
  ["syncApi", () => import("./sync")],
  ["playlistsApi", () => import("./playlists")],
  ["tagsApi", () => import("./tags")],
  ["notificationsApi", () => import("./notifications")],
  ["savedViewsApi", () => import("./savedViews")],
  ["quotaApi", () => import("./quota")],
  ["adminApi", () => import("./admin")],
  ["plexApi", () => import("./plex")],
  ["downloadsApi", () => import("./downloads")],
  ["diagnosticsApi", () => import("./diagnostics")],
  ["debugSessionsApi", () => import("./diagnostics")],
] as const;

let api: Slice;
const slices: Record<string, Slice> = {};

beforeAll(async () => {
  // The runtime api graph pulls i18n at module-load, which reads localStorage/navigator. Under
  // vitest's node env (no jsdom — see vitest.config.ts) stub the minimum so the import succeeds.
  if (typeof globalThis.localStorage === "undefined") {
    const store = new Map<string, string>();
    globalThis.localStorage = {
      getItem: (k: string) => store.get(k) ?? null,
      setItem: (k: string, v: string) => void store.set(k, String(v)),
      removeItem: (k: string) => void store.delete(k),
      clear: () => store.clear(),
      key: (i: number) => [...store.keys()][i] ?? null,
      get length() {
        return store.size;
      },
    } as Storage;
  }
  if (typeof globalThis.navigator === "undefined") {
    globalThis.navigator = { language: "en" } as Navigator;
  }
  if (typeof globalThis.document === "undefined") {
    globalThis.document = { documentElement: {} } as Document;
  }

  for (const [name, load] of SLICE_MODULES) {
    const mod = (await load()) as Record<string, Slice>;
    const slice = mod[name];
    if (!slice) throw new Error(`slice module did not export ${name}`);
    slices[name] = slice;
  }
  api = ((await import("../api")) as { api: Slice }).api;
});

describe("api façade is a collision-free spread of domain slices", () => {
  it("defines no method name in more than one slice (object spread would silently drop one)", () => {
    const owner = new Map<string, string>();
    const collisions: string[] = [];
    for (const [sliceName, slice] of Object.entries(slices)) {
      for (const key of Object.keys(slice)) {
        const prev = owner.get(key);
        if (prev) collisions.push(`"${key}" is defined in both ${prev} and ${sliceName}`);
        else owner.set(key, sliceName);
      }
    }
    expect(collisions).toEqual([]);
  });

  it("exposes exactly the union of the slices — nothing added inline in the barrel, nothing lost", () => {
    const union = new Set<string>();
    for (const slice of Object.values(slices)) {
      for (const key of Object.keys(slice)) union.add(key);
    }
    expect(new Set(Object.keys(api))).toEqual(union);
  });
});