/**
 * Admin API client. Talks to the same Go BFF as the main app, reusing its
 * cookie session: auth uses the shared /auth/* endpoints, and every admin
 * action lives under /admin/* (gated server-side by RequireAdmin). All
 * requests send credentials so the httpOnly session cookie travels.
 *
 * For this to work cross-origin, the BFF must list this app's origin in CORS
 * via the ADMIN_URL env var (see .env.example).
 */

const BFF = process.env.NEXT_PUBLIC_BFF_URL || "http://localhost:8080";

export class AdminError extends Error {
  constructor(
    public status: number,
    message: string,
  ) {
    super(message);
    this.name = "AdminError";
  }
}

type Envelope<T> = {
  success: boolean;
  data?: T;
  error?: { code: number; message: string };
  meta?: { total?: number; page?: number; limit?: number; total_pages?: number };
};

async function call<T>(
  path: string,
  init?: RequestInit,
): Promise<{ data: T; meta?: Envelope<T>["meta"] }> {
  const res = await fetch(`${BFF}/api/v1${path}`, {
    credentials: "include",
    headers: { "Content-Type": "application/json", ...(init?.headers ?? {}) },
    ...init,
  });
  // 204 No Content (archive, delete, reset…) is success with no body —
  // there's no JSON to parse.
  if (res.status === 204) return { data: undefined as T };
  let body: Envelope<T>;
  try {
    body = (await res.json()) as Envelope<T>;
  } catch {
    throw new AdminError(res.status, res.statusText || "Request failed");
  }
  if (!res.ok || body.success === false) {
    throw new AdminError(
      res.status,
      body.error?.message || res.statusText || "Request failed",
    );
  }
  return { data: body.data as T, meta: body.meta };
}

export type Paged<T> = { items: T[]; total: number };

async function listed<T>(path: string): Promise<Paged<T>> {
  const { data, meta } = await call<T[]>(path);
  const items = data ?? [];
  return { items, total: meta?.total ?? items.length };
}

function qs(params: Record<string, string | number | undefined>): string {
  const u = new URLSearchParams();
  for (const [k, v] of Object.entries(params)) {
    if (v !== undefined && v !== "") u.set(k, String(v));
  }
  const s = u.toString();
  return s ? `?${s}` : "";
}

// ─── Types (mirror the BFF admin DTOs) ──────────────────────────────────────

export type Me = {
  id: string;
  email: string | null;
  handle: string;
  name: string;
  role: string;
};

export type Stats = {
  users: number;
  users_last_7_days: number;
  posts: number;
  posts_last_7_days: number;
  collections: number;
  public_collections: number;
  bookmarks: number;
  reshares: number;
  feedback: number;
  feedback_last_7_days: number;
  feedback_by_category: { category: string; count: number }[];
};

export type AdminShortUrl = {
  id: number;
  code: string;
  long_url: string;
  content_type: string;
  click_count: number;
  human_click_count: number;
  disabled: boolean;
  created_at: string;
};

export type ShortUrlRangeStat = { created: number; clicks: number };

export type ShortUrlStats = {
  today: ShortUrlRangeStat;
  week: ShortUrlRangeStat;
  month: ShortUrlRangeStat;
  total_urls: number;
  total_clicks: number;
  range?: ShortUrlRangeStat; // present only when a custom from/to is requested
};

export type AdminUser = {
  id: string;
  email: string | null;
  handle: string;
  name: string;
  avatar_url: string | null;
  role: string;
  /** Staff role key (superadmin/admin/moderator/custom), absent for users. */
  admin_role?: string | null;
  plan: string;
  email_verified_at: string | null;
  banned_at: string | null;
  post_count: number;
  created_at: string;
  has_password: boolean;
  providers: string[];
  /** Effective save limits in force (plan default merged with any override);
   *  -1 means unlimited. */
  bookmark_limit: number;
  public_collection_limit: number;
  private_collection_limit: number;
  /** Direct-disciple link: the Mongo disciple id this account is linked to,
   *  and that disciple's name (hydrated server-side). Both null when the
   *  account isn't one of Śrīla Prabhupāda's direct disciples. */
  disciple_id: string | null;
  disciple_name: string | null;
};

/** One option in the direct-disciple picker. `linked_handle` is the @handle of
 *  the account already linked to this disciple — non-null means "taken". */
export type AdminDisciple = {
  id: string;
  initiated_name: string;
  suffix: string;
  initiation_date: string | null;
  initiation_place: string | null;
  linked_handle: string | null;
};

/** Per-user save-limit override payload. null = reset that limit to the plan
 *  default; a number caps it for this user. */
export type UserLimitsInput = {
  bookmark_limit: number | null;
  public_collection_limit: number | null;
  private_collection_limit: number | null;
};

export type AdminPost = {
  id: string;
  user_id: string;
  caption: string;
  source_title: string;
  source_url: string;
  is_hidden: boolean;
  deleted_at: string | null;
  created_at: string;
  author_name: string;
  author_handle: string;
  likes_count: number;
  comments_count: number;
};

export type AdminCollection = {
  id: string;
  user_id: string;
  title: string;
  description: string | null;
  is_public: boolean;
  item_count: number;
  created_at: string;
  owner_name: string;
  owner_handle: string;
};

export type AdminFeedback = {
  id: string;
  category: string;
  /** The category's current display name. */
  category_label?: string;
  message: string;
  contact_email: string | null;
  created_at: string;
  acknowledged_at: string | null;
  resolved_at: string | null;
  replied_at: string | null;
  reply_message: string | null;
  author_handle: string | null;
  author_name: string | null;
  author_email: string | null;
};

export type ReportType = "post" | "comment" | "user";

export type AdminReport = {
  id: string;
  type: ReportType;
  category: string;
  reason: string;
  created_at: string;
  resolved_at: string | null;
  reporter_handle: string | null;
  reporter_name: string | null;
  resolution_note: string | null;
  target_removed: boolean;
  target_id: string;
  target_text: string | null;
  target_author_handle: string | null;
};

// Login can complete immediately (session) or require an emailed OTP (the
// BFF's 30-day-stale gate). The admin login form handles both.
export type LoginResult =
  | { kind: "session"; user: Me }
  | { kind: "otp_required" };

// ─── API surface ────────────────────────────────────────────────────────────

export const api = {
  // Auth (shared endpoints). The BFF returns the bare User on a completed
  // login (200), or { otp_required: true } (202) when an emailed code is
  // needed — there's no { kind } wrapper, so we derive it here.
  async login(email: string, password: string): Promise<LoginResult> {
    const { data } = await call<Me | { otp_required?: boolean }>("/auth/login", {
      method: "POST",
      body: JSON.stringify({ email, password }),
    });
    if (data && (data as { otp_required?: boolean }).otp_required) {
      return { kind: "otp_required" };
    }
    return { kind: "session", user: data as Me };
  },
  async verifyLoginOtp(
    email: string,
    password: string,
    otp: string,
  ): Promise<Me> {
    const { data } = await call<Me>("/auth/verify-login-otp", {
      method: "POST",
      body: JSON.stringify({ email, password, otp }),
    });
    return data;
  },
  async me(): Promise<Me | null> {
    try {
      const { data } = await call<Me>("/auth/me");
      return data;
    } catch (e) {
      if (e instanceof AdminError && e.status === 401) return null;
      throw e;
    }
  },
  async logout(): Promise<void> {
    await call("/auth/logout", { method: "POST" });
  },
  async forgotPassword(email: string): Promise<void> {
    await call("/auth/forgot-password", {
      method: "POST",
      body: JSON.stringify({ email }),
    });
  },
  async resetPassword(token: string, password: string): Promise<void> {
    await call("/auth/reset-password", {
      method: "POST",
      body: JSON.stringify({ token, password }),
    });
  },

  // Admin resources
  async stats(): Promise<Stats> {
    const { data } = await call<Stats>("/admin/stats");
    return data;
  },
  users(q: string, limit: number, offset: number) {
    return listed<AdminUser>(`/admin/users${qs({ q, limit, offset })}`);
  },
  notifyUser(id: string, title: string, body: string) {
    return call(`/admin/users/${id}/notify`, {
      method: "POST",
      body: JSON.stringify({ title, body }),
    });
  },
  banUser(id: string) {
    return call(`/admin/users/${id}/ban`, { method: "POST" });
  },
  unbanUser(id: string) {
    return call(`/admin/users/${id}/ban`, { method: "DELETE" });
  },
  setUserLimits(id: string, limits: UserLimitsInput) {
    return call(`/admin/users/${id}/limits`, {
      method: "POST",
      body: JSON.stringify(limits),
    });
  },
  /** Search Śrīla Prabhupāda's disciples for the link picker. An empty query
   *  returns the first page alphabetically. */
  async disciples(q: string, limit = 25): Promise<AdminDisciple[]> {
    const { data } = await call<AdminDisciple[]>(
      `/admin/disciples${qs({ q, limit })}`,
    );
    return data ?? [];
  },
  /** Mark a user as a direct disciple. Re-linking moves an existing link. */
  linkDisciple(userId: string, discipleId: string) {
    return call(`/admin/users/${userId}/disciple`, {
      method: "POST",
      body: JSON.stringify({ disciple_id: discipleId }),
    });
  },
  unlinkDisciple(userId: string) {
    return call(`/admin/users/${userId}/disciple`, { method: "DELETE" });
  },
  posts(q: string, limit: number, offset: number) {
    return listed<AdminPost>(`/admin/posts${qs({ q, limit, offset })}`);
  },
  hidePost(id: string) {
    return call(`/admin/posts/${id}/hide`, { method: "POST" });
  },
  unhidePost(id: string) {
    return call(`/admin/posts/${id}/hide`, { method: "DELETE" });
  },
  deletePost(id: string) {
    return call(`/admin/posts/${id}`, { method: "DELETE" });
  },
  restorePost(id: string) {
    return call(`/admin/posts/${id}/restore`, { method: "POST" });
  },
  deleteComment(id: string) {
    return call(`/admin/comments/${id}`, { method: "DELETE" });
  },
  restoreComment(id: string) {
    return call(`/admin/comments/${id}/restore`, { method: "POST" });
  },
  collections(q: string, limit: number, offset: number) {
    return listed<AdminCollection>(`/admin/collections${qs({ q, limit, offset })}`);
  },
  shortUrls(q: string, limit: number, offset: number) {
    return listed<AdminShortUrl>(`/admin/short-urls${qs({ q, limit, offset })}`);
  },
  async shortUrlStats(from?: string, to?: string): Promise<ShortUrlStats> {
    const { data } = await call<ShortUrlStats>(
      `/admin/short-urls/stats${qs({ from, to })}`,
    );
    return data;
  },
  feedback(status: string, limit: number, offset: number) {
    return listed<AdminFeedback>(`/admin/feedback${qs({ status, limit, offset })}`);
  },
  replyFeedback(id: string, message: string) {
    return call(`/admin/feedback/${id}/reply`, {
      method: "POST",
      body: JSON.stringify({ message }),
    });
  },
  acknowledgeFeedback(id: string) {
    return call(`/admin/feedback/${id}/acknowledge`, { method: "POST" });
  },
  resolveFeedback(id: string) {
    return call(`/admin/feedback/${id}/resolve`, { method: "POST" });
  },
  reports(type: ReportType, q: string, limit: number, offset: number) {
    return listed<AdminReport>(`/admin/reports${qs({ type, q, limit, offset })}`);
  },
  resolveReport(type: ReportType, id: string, note: string) {
    return call(`/admin/reports/${type}/${id}/resolve`, {
      method: "POST",
      body: JSON.stringify({ note }),
    });
  },
};

// ─── Broadcasts ─────────────────────────────────────────────────────────────

/**
 * Announcements pushed to every user and shown once, in a modal.
 *
 * No history is kept on the user's side: there is no notification row and no
 * tray entry, so a broadcast exists only until each person dismisses it.
 */
export type Broadcast = {
  id: string;
  title: string;
  body: string;
  banner_url?: string | null;
  cta_label?: string | null;
  cta_url?: string | null;
  published_at?: string | null;
  expires_at?: string | null;
  created_at: string;
  /** How many people have dismissed it — the only delivery signal there is. */
  seen_count: number;
};

export type NewBroadcast = {
  title: string;
  body: string;
  banner_key?: string | null;
  cta_label?: string | null;
  cta_url?: string | null;
  expires_at?: string | null;
  publish: boolean;
};

export const broadcasts = {
  list: () => listed<Broadcast>("/admin/broadcasts?limit=50"),

  create: (input: NewBroadcast) =>
    call<Broadcast>("/admin/broadcasts", {
      method: "POST",
      body: JSON.stringify(input),
    }).then((r) => r.data),

  publish: (id: string) =>
    call<Broadcast>(`/admin/broadcasts/${id}/publish`, { method: "POST" }).then(
      (r) => r.data,
    ),

  remove: (id: string) =>
    call<void>(`/admin/broadcasts/${id}`, { method: "DELETE" }),

  /** Presign a banner upload; returns the PUT URL and the key to submit. */
  presignBanner: (contentType: string) =>
    call<{ upload_url: string; key: string }>(
      "/admin/broadcasts/banner-presign",
      { method: "POST", body: JSON.stringify({ content_type: contentType }) },
    ).then((r) => r.data),
};

// ─── Reward gifts ───────────────────────────────────────────────────────────

/** A sticker from the sādhana catalog, sendable as an occasional gift. */
export type GiftableReward = {
  id: string;
  key: string;
  name: string;
  meaning: string;
  image_url: string;
};

export const rewardGifts = {
  catalog: () => call<GiftableReward[]>("/admin/reward-gifts/catalog").then((r) => r.data),

  /** Presign artwork for a custom gift. Returns the final public URL too,
   *  since sadhna_rewards.image_url stores an absolute address. */
  presignImage: (contentType: string) =>
    call<{ upload_url: string; image_url: string }>(
      "/admin/reward-gifts/image-presign",
      { method: "POST", body: JSON.stringify({ content_type: contentType }) },
    ).then((r) => r.data),

  /** Delete a custom sticker. Cascades out of every gallery and vault. */
  remove: (key: string) =>
    call<void>(`/admin/reward-gifts/${encodeURIComponent(key)}`, {
      method: "DELETE",
    }),

  /** Add a sticker to the catalog. It reaches nobody until it is sent. */
  create: (input: { name: string; meaning: string; image_url: string }) =>
    call<GiftableReward>("/admin/reward-gifts/catalog", {
      method: "POST",
      body: JSON.stringify(input),
    }).then((r) => r.data),

  /** Hand a reward to every account, unopened. Idempotent — a repeat only
   *  reaches people who don't already have it. */
  send: (rewardKey: string) =>
    call<{ granted: number }>("/admin/reward-gifts", {
      method: "POST",
      body: JSON.stringify({ reward_key: rewardKey }),
    }).then((r) => r.data),
};

// ─── Vāṇī of the Day ────────────────────────────────────────────────────────

/** One decided day. `payload` is the blob the home-page CTA renders. */
export type VaniPick = {
  day: string;
  kind: "verse" | "prose" | "transcript";
  ref_id: string;
  payload: {
    kind: string;
    label: string;
    title: string;
    subtitle: string;
    href: string;
    book_title?: string;
    date?: string;
  };
};

/** A search hit, narrowed to what pinning needs. */
export type VaniCandidate = {
  collection: string;
  doc_id: string;
  title: string;
  snippet: string;
  url: string;
};

/** Typesense collection → the kind the vani picker uses. */
const VANI_KINDS: Record<string, VaniPick["kind"]> = {
  verses: "verse",
  prose: "prose",
  transcriptions: "transcript",
};

export function vaniKindFor(collection: string): VaniPick["kind"] | null {
  return VANI_KINDS[collection] ?? null;
}

export const vani = {
  /** Decided days from today onward. */
  schedule: () => call<VaniPick[]>("/admin/vani?limit=30").then((r) => r.data),

  /** Pin one item to a day. Only the reference travels — the BFF rebuilds the
   *  display blob, so a pinned pick renders exactly like an automatic one. */
  set: (input: { day: string; kind: VaniPick["kind"]; ref_id: string }) =>
    call<VaniPick>("/admin/vani", {
      method: "POST",
      body: JSON.stringify(input),
    }).then((r) => r.data),

  /** Hand the day back to the random picker. */
  clear: (day: string) =>
    call<void>(`/admin/vani/${encodeURIComponent(day)}`, { method: "DELETE" }),

  /** Pin whatever an app link points at. The only reliable way to choose a
   *  specific item: slugs are not indexed, so searching one matches on its
   *  words instead ("720720sb-london" → anything mentioning London). */
  setByURL: (input: { day: string; url: string }) =>
    call<VaniPick>("/admin/vani/by-url", {
      method: "POST",
      body: JSON.stringify(input),
    }).then((r) => r.data),

  /**
   * Search the vāṇī-eligible collections.
   *
   * SCOPED server-side via `type`, not filtered here: `type=all` blends every
   * collection and ranks by relevance, so the top hits are dominated by
   * letters and glossary entries and a client-side filter throws the whole
   * page away — which is exactly what made this look broken.
   */
  search: async (q: string): Promise<VaniCandidate[]> => {
    const { data } = await call<{ results: VaniCandidate[] }>(
      `/search?type=verses,prose,transcriptions&limit=20&q=${encodeURIComponent(q)}`,
    );
    return (data?.results ?? []).filter(
      (r) => r.doc_id && vaniKindFor(r.collection),
    );
  },
};

// ─── Staff, roles and permissions ───────────────────────────────────────────

/** The signed-in staff member's role and effective permissions. */
export type StaffMe = {
  role_key: string;
  role_name: string;
  permissions: string[];
};

/** Held only by superadmins: managing other staff and roles. */
export const MANAGE_STAFF = "admins:manage";

export type Permission = { key: string; group: string; label: string };

export type AdminRole = {
  id: string;
  key: string;
  name: string;
  description: string;
  is_system: boolean;
  permissions: string[];
  member_count: number;
};

export type StaffMember = {
  user_id: string;
  handle: string;
  name: string;
  email?: string | null;
  avatar_url?: string | null;
  role_id: string;
  role_key: string;
  role_name: string;
  blocked_at?: string | null;
};

export const staff = {
  /** Resolves only for staff; a non-staff or blocked account gets a 403. */
  me: () => call<StaffMe>("/admin/me").then((r) => r.data),
  catalog: () => call<Permission[]>("/admin/permissions").then((r) => r.data),
  list: () => call<StaffMember[]>("/admin/staff").then((r) => r.data),
  grant: (handle: string, roleId: string) =>
    call<StaffMember>("/admin/staff", {
      method: "POST",
      body: JSON.stringify({ handle, role_id: roleId }),
    }).then((r) => r.data),
  changeRole: (userId: string, roleId: string) =>
    call<StaffMember>(`/admin/staff/${userId}`, {
      method: "PATCH",
      body: JSON.stringify({ role_id: roleId }),
    }).then((r) => r.data),
  revoke: (userId: string) =>
    call<void>(`/admin/staff/${userId}`, { method: "DELETE" }),
  setBlocked: (userId: string, blocked: boolean) =>
    call<StaffMember>(`/admin/staff/${userId}/block`, {
      method: blocked ? "POST" : "DELETE",
    }).then((r) => r.data),

  roles: () => call<AdminRole[]>("/admin/roles").then((r) => r.data),
  createRole: (input: { name: string; description: string; permissions: string[] }) =>
    call<AdminRole>("/admin/roles", { method: "POST", body: JSON.stringify(input) }).then(
      (r) => r.data,
    ),
  updateRole: (
    id: string,
    input: { name: string; description: string; permissions: string[] },
  ) =>
    call<AdminRole>(`/admin/roles/${id}`, {
      method: "PATCH",
      body: JSON.stringify(input),
    }).then((r) => r.data),
  deleteRole: (id: string) => call<void>(`/admin/roles/${id}`, { method: "DELETE" }),
};

// ─── Quizzes ────────────────────────────────────────────────────────────────

export type QuizTargetKind = "chapter" | "lecture" | "conversation" | "standalone";

export type QuizOption = { id?: string; ord?: number; body: string; is_correct: boolean };

export type QuizQuestion = {
  id?: string;
  ord?: number;
  prompt: string;
  explanation: string;
  /** "Select all that apply": one or more options correct. */
  multi: boolean;
  options: QuizOption[];
};

export type Quiz = {
  id: string;
  title: string;
  description: string;
  target_kind: QuizTargetKind;
  target_path?: string | null;
  target_title: string;
  published_at?: string | null;
  created_at: string;
  updated_at: string;
  question_count: number;
  attempt_count?: number;
  completed_count?: number;
  questions?: QuizQuestion[];
};

export type QuizDraft = {
  title: string;
  description: string;
  /** Pasted app link; empty for a stand-alone quiz. */
  target_url: string;
  /** Optional override for the resolved content title. */
  target_title: string;
  /** Omitted once a quiz has attempts — its questions are frozen. */
  questions?: QuizQuestion[];
};

export type QuizParticipant = {
  user_id: string;
  handle: string;
  name: string;
  avatar_url?: string | null;
  started_at: string;
  completed_at?: string | null;
  answered: number;
  score: number;
  total: number;
  total_ms: number;
};

export type QuizQuestionStat = {
  id: string;
  ord: number;
  prompt: string;
  multi: boolean;
  answered: number;
  correct: number;
  avg_ms: number;
  median_ms: number;
  options: (QuizOption & { id: string; picks: number })[];
};

export type QuizResultItem = QuizQuestion & {
  chosen_option_ids: string[];
  is_correct: boolean;
  response_ms?: number | null;
};

export type QuizResult = {
  quiz: Quiz;
  score: number;
  total: number;
  started_at: string;
  completed_at?: string | null;
  total_ms: number;
  items: QuizResultItem[];
};

export const quizzes = {
  list: () => call<Quiz[]>("/admin/quizzes").then((r) => r.data),
  get: (id: string) => call<Quiz>(`/admin/quizzes/${id}`).then((r) => r.data),
  create: (draft: QuizDraft) =>
    call<Quiz>("/admin/quizzes", { method: "POST", body: JSON.stringify(draft) }).then(
      (r) => r.data,
    ),
  update: (id: string, draft: QuizDraft) =>
    call<Quiz>(`/admin/quizzes/${id}`, { method: "PUT", body: JSON.stringify(draft) }).then(
      (r) => r.data,
    ),
  setPublished: (id: string, on: boolean) =>
    call<Quiz>(`/admin/quizzes/${id}/publish`, { method: on ? "POST" : "DELETE" }).then(
      (r) => r.data,
    ),
  remove: (id: string) => call<void>(`/admin/quizzes/${id}`, { method: "DELETE" }),
  participants: (id: string) =>
    call<QuizParticipant[]>(`/admin/quizzes/${id}/participants`).then((r) => r.data),
  participant: (id: string, userId: string) =>
    call<QuizResult>(`/admin/quizzes/${id}/participants/${userId}`).then((r) => r.data),
  responses: (id: string) =>
    call<QuizQuestionStat[]>(`/admin/quizzes/${id}/responses`).then((r) => r.data),
  /** Deletes one person's attempt; the quiz is pending for them again. */
  resetParticipant: (id: string, userId: string) =>
    call<void>(`/admin/quizzes/${id}/participants/${userId}`, { method: "DELETE" }),
};

// ─── Feedback categories ────────────────────────────────────────────────────

/** One option on the app's /feedback form. `key` is fixed once created. */
export type FeedbackCategory = {
  key: string;
  label: string;
  description: string;
  sort_order: number;
  archived_at?: string | null;
  /** How much feedback is filed under it. */
  usage_count?: number;
};

export const feedbackCategories = {
  list: () =>
    call<FeedbackCategory[]>("/admin/feedback/categories").then((r) => r.data),
  create: (label: string, description: string) =>
    call<FeedbackCategory>("/admin/feedback/categories", {
      method: "POST",
      body: JSON.stringify({ label, description }),
    }).then((r) => r.data),
  update: (key: string, v: { label: string; description: string; archived: boolean }) =>
    call<void>(`/admin/feedback/categories/${encodeURIComponent(key)}`, {
      method: "PUT",
      body: JSON.stringify(v),
    }),
  remove: (key: string) =>
    call<void>(`/admin/feedback/categories/${encodeURIComponent(key)}`, {
      method: "DELETE",
    }),
  reorder: (keys: string[]) =>
    call<void>("/admin/feedback/categories/order", {
      method: "PUT",
      body: JSON.stringify({ keys }),
    }),
};