async function adminFetch<T>(path: string, init?: RequestInit): Promise<T> {
  const response = await fetch(path, {
    ...init,
    credentials: 'include',
    headers: {
      Accept: 'application/json',
      ...(init?.body ? { 'Content-Type': 'application/json' } : {}),
      ...(init?.headers ?? {}),
    },
  });
  const payload = (await response.json().catch(() => ({}))) as {
    data?: T;
    message?: string;
    error?: { code: string; message: string };
  };
  if (!response.ok) {
    throw new Error(payload?.error?.message ?? payload?.message ?? `请求失败 (${response.status})`);
  }
  return (payload.data !== undefined ? payload.data : payload) as T;
}

export type AdminUser = {
  id: string;
  username: string;
  slug: string;
  email: string;
  displayName: string;
  role: string;
  status: string;
  balanceCents: number;
  createdAt: string;
};

export type AdminSummary = {
  totalUsers: number;
  activeUsers: number;
  totalBalanceCents: number;
  llm?: {
    keyCount: number;
    selectedKeyName: string | null;
    globalModel: string | null;
  };
};

export type LlmKey = {
  id: string;
  name: string;
  provider: string;
  model?: string;
  models?: string[];
  isSelected: boolean;
  createdAt?: string;
};

export type LedgerEntry = {
  id: string;
  userId: string;
  username?: string;
  type: string;
  amountCents: number;
  note: string;
  createdAt: string;
};

export type UsageRecord = {
  id: string;
  userId: string;
  username?: string;
  provider: string;
  model: string;
  inputTokens: number;
  outputTokens: number;
  costCents: number;
  createdAt: string;
};

// ─── Summary ──────────────────────────────────────────────────────────────────

export async function fetchAdminSummary() {
  return adminFetch<{ summary: AdminSummary }>('/admin-api/summary');
}

// ─── Users ────────────────────────────────────────────────────────────────────

export async function fetchAdminUsers(params: {
  page?: number;
  pageSize?: number;
  search?: string;
  role?: string;
  status?: string;
}) {
  const q = new URLSearchParams();
  if (params.page) q.set('page', String(params.page));
  if (params.pageSize) q.set('pageSize', String(params.pageSize));
  if (params.search) q.set('search', params.search);
  if (params.role) q.set('role', params.role);
  if (params.status) q.set('status', params.status);
  return adminFetch<{ users: AdminUser[]; total: number; page: number; pageSize: number; totalPages: number }>(
    `/admin-api/users?${q}`,
  );
}

export async function createAdminUser(body: {
  username: string;
  password: string;
  displayName?: string;
  role?: string;
}) {
  return adminFetch<{ user: AdminUser }>('/admin-api/users', {
    method: 'POST',
    body: JSON.stringify(body),
  });
}

export async function patchAdminUser(
  userId: string,
  patch: { role?: string; status?: string; displayName?: string; password?: string },
) {
  return adminFetch<{ user: AdminUser }>(`/admin-api/users/${userId}`, {
    method: 'PATCH',
    body: JSON.stringify(patch),
  });
}

export async function rechargeUser(userId: string, amountCents: number, note = '') {
  return adminFetch<{ user: AdminUser }>(`/admin-api/users/${userId}/recharge`, {
    method: 'POST',
    body: JSON.stringify({ amountCents, note }),
  });
}

// ─── Billing ──────────────────────────────────────────────────────────────────

export async function fetchAdminLedger(params: { page?: number; pageSize?: number } = {}) {
  const q = new URLSearchParams();
  if (params.page) q.set('page', String(params.page));
  if (params.pageSize) q.set('pageSize', String(params.pageSize));
  return adminFetch<{ entries: LedgerEntry[]; total: number; page: number; totalPages: number }>(
    `/admin-api/ledger?${q}`,
  );
}

export async function fetchAdminUsage(params: { page?: number; pageSize?: number } = {}) {
  const q = new URLSearchParams();
  if (params.page) q.set('page', String(params.page));
  if (params.pageSize) q.set('pageSize', String(params.pageSize));
  return adminFetch<{ records: UsageRecord[]; total: number; page: number; totalPages: number }>(
    `/admin-api/usage?${q}`,
  );
}

// ─── LLM Providers ───────────────────────────────────────────────────────────

export async function fetchLlmKeys() {
  return adminFetch<{ keys: LlmKey[] }>('/admin-api/llm-providers/keys');
}

export async function createLlmKey(body: {
  name: string;
  provider: string;
  apiKey: string;
  model?: string;
  models?: string;
  baseUrl?: string;
}) {
  return adminFetch<{ key: LlmKey }>('/admin-api/llm-providers/keys', {
    method: 'POST',
    body: JSON.stringify(body),
  });
}

export async function patchLlmKey(keyId: string, patch: { name?: string; apiKey?: string; model?: string }) {
  return adminFetch<{ key: LlmKey }>(`/admin-api/llm-providers/keys/${keyId}`, {
    method: 'PATCH',
    body: JSON.stringify(patch),
  });
}

export async function selectLlmKey(keyId: string) {
  return adminFetch(`/admin-api/llm-providers/keys/${keyId}/select`, { method: 'POST' });
}

export async function deleteLlmKey(keyId: string) {
  return adminFetch(`/admin-api/llm-providers/keys/${keyId}`, { method: 'DELETE' });
}

export async function testLlmKey(keyId: string) {
  return adminFetch<{ ok: boolean; model?: string; error?: string }>(
    `/admin-api/llm-providers/keys/${keyId}/test`,
    { method: 'POST' },
  );
}

export async function fetchLlmGlobal() {
  return adminFetch<{ settings: { model: string | null } }>('/admin-api/llm-providers/global');
}

export async function putLlmGlobal(model: string) {
  return adminFetch('/admin-api/llm-providers/global', {
    method: 'PUT',
    body: JSON.stringify({ model }),
  });
}

export async function syncLlmProviders() {
  return adminFetch<{ synced: number }>('/admin-api/llm-providers/sync', { method: 'POST' });
}