import { buildApiUrl } from '@/constants/Api';
import AsyncStorage from '@react-native-async-storage/async-storage';

type HttpMethod = 'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE';

let inMemoryToken: string | null = null;

export async function setAuthToken(token: string | null): Promise<void> {
  inMemoryToken = token;
}

export function getAuthToken(): string | null {
  return inMemoryToken;
}

export type ApiRequestOptions = {
  method?: HttpMethod;
  headers?: Record<string, string>;
  body?: any;
  signal?: AbortSignal;
};

export type ApiResponse<T> = {
  data: T;
};

async function doFetch<T>(path: string, options: ApiRequestOptions = {}): Promise<T> {
  const url = buildApiUrl(path);
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    ...(options.headers || {}),
  };

  const token = getAuthToken();
  if (token) {
    headers['Authorization'] = `Bearer ${token}`;
  }

  const response = await fetch(url, {
    method: options.method ?? 'GET',
    headers,
    body: options.body != null ? JSON.stringify(options.body) : undefined,
    signal: options.signal,
  });

  const text = await response.text();
  let json: any = null;
  try {
    json = text ? JSON.parse(text) : null;
  } catch {
    // 非 JSON 响应
  }

  if (!response.ok) {
    const errorMessage = (json && (json.message || json.error)) || `HTTP ${response.status}`;
    const error = new Error(errorMessage);
    // @ts-expect-error augment
    error.status = response.status;
    throw error;
  }

  // 支持后端返回 { data: ... } 或直接返回对象
  return (json && (json.data ?? json)) as T;
}

export const api = {
  get: <T>(path: string, options?: ApiRequestOptions) => doFetch<T>(path, { ...options, method: 'GET' }),
  post: <T>(path: string, body?: any, options?: ApiRequestOptions) => doFetch<T>(path, { ...options, method: 'POST', body }),
  put: <T>(path: string, body?: any, options?: ApiRequestOptions) => doFetch<T>(path, { ...options, method: 'PUT', body }),
  patch: <T>(path: string, body?: any, options?: ApiRequestOptions) => doFetch<T>(path, { ...options, method: 'PATCH', body }),
  delete: <T>(path: string, options?: ApiRequestOptions) => doFetch<T>(path, { ...options, method: 'DELETE' }),
};

export const STORAGE_KEYS = {
  authToken: '@auth_token',
  userProfile: '@user_profile',
} as const;

export async function loadPersistedToken(): Promise<string | null> {
  try {
    const t = await AsyncStorage.getItem(STORAGE_KEYS.authToken);
    return t || null;
  } catch {
    return null;
  }
}