/**
 * 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,
  });
  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 AdminUser = {
  id: string;
  email: string | null;
  handle: string;
  name: string;
  avatar_url: string | null;
  role: string;
  plan: string;
  email_verified_at: string | null;
  banned_at: string | null;
  created_at: string;
};

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;
  message: string;
  contact_email: string | null;
  created_at: string;
  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;
  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)
  async login(email: string, password: string): Promise<LoginResult> {
    const { data } = await call<LoginResult>("/auth/login", {
      method: "POST",
      body: JSON.stringify({ email, password }),
    });
    return data;
  },
  async verifyLoginOtp(
    email: string,
    password: string,
    otp: string,
  ): Promise<Me> {
    const { data } = await call<{ user: Me }>("/auth/verify-login-otp", {
      method: "POST",
      body: JSON.stringify({ email, password, otp }),
    });
    return data.user;
  },
  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
  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" });
  },
  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 })}`);
  },
  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 }),
    });
  },
  reports(type: ReportType, q: string, limit: number, offset: number) {
    return listed<AdminReport>(`/admin/reports${qs({ type, q, limit, offset })}`);
  },
  resolveReport(type: ReportType, id: string) {
    return call(`/admin/reports/${type}/${id}/resolve`, { method: "POST" });
  },
};