import Taro from '@tarojs/taro';
import { secureGet, secureSet, secureRemove } from '@/utils/secure-storage';

const BASE_URL = process.env.TARO_APP_API_URL || 'http://localhost:3000/api/v1';

interface ApiResponse<T> {
  success: boolean;
  data?: T;
  message?: string;
}

async function getHeaders(): Promise<Record<string, string>> {
  const headers: Record<string, string> = { 'Content-Type': 'application/json' };
  const token = secureGet('access_token');
  if (token) headers['Authorization'] = `Bearer ${token}`;
  const patientId = Taro.getStorageSync('current_patient_id');
  if (patientId) headers['X-Patient-Id'] = patientId;
  const tenantId = secureGet('tenant_id');
  if (tenantId) headers['X-Tenant-Id'] = tenantId;
  return headers;
}

// --- Token refresh deduplication ---
let refreshPromise: Promise<boolean> | null = null;

async function tryRefreshToken(): Promise<boolean> {
  if (refreshPromise) return refreshPromise;
  refreshPromise = doRefresh();
  refreshPromise.finally(() => { refreshPromise = null; });
  return refreshPromise;
}

async function doRefresh(): Promise<boolean> {
  const refreshToken = secureGet('refresh_token');
  if (!refreshToken) return false;
  try {
    const res = await Taro.request({
      url: `${BASE_URL}/auth/refresh`,
      method: 'POST',
      data: { refresh_token: refreshToken },
    });
    if (res.statusCode === 200 && res.data?.success) {
      secureSet('access_token', res.data.data.access_token);
      secureSet('refresh_token', res.data.data.refresh_token);
      return true;
    }
  } catch {
    // token 刷新失败
  }
  secureRemove('access_token');
  secureRemove('refresh_token');
  secureRemove('user_data');
  secureRemove('user_roles');
  secureRemove('tenant_id');
  secureRemove('wechat_openid');
  return false;
}

// --- Core request ---
async function request<T>(method: string, path: string, data?: unknown): Promise<T> {
  const headers = await getHeaders();
  const url = `${BASE_URL}${path}`;
  const res = await Taro.request({ url, method: method as any, data, header: headers, timeout: 15000 });

  if (res.statusCode === 401) {
    const refreshed = await tryRefreshToken();
    if (refreshed) return request<T>(method, path, data);
    const pages = Taro.getCurrentPages();
    const currentPath = pages[pages.length - 1]?.path || '';
    if (!currentPath.includes('pages/login')) {
      Taro.reLaunch({ url: '/pages/login/index' });
    }
    throw new Error('登录已过期');
  }

  const body = res.data as ApiResponse<T>;
  if (!body.success) throw new Error(body.message || '请求失败');
  return body.data as T;
}

function buildQuery(params?: Record<string, string | number | undefined>): string {
  if (!params) return '';
  const entries = Object.entries(params).filter(([, v]) => v !== undefined && v !== '');
  return entries.length > 0
    ? '?' +
        entries
          .map(([k, v]) => `${encodeURIComponent(k)}=${encodeURIComponent(String(v))}`)
          .join('&')
    : '';
}

// --- GET request cache + deduplication ---
interface CacheEntry { data: unknown; expiry: number }
const responseCache = new Map<string, CacheEntry>();
const inflightRequests = new Map<string, Promise<unknown>>();
const DEFAULT_CACHE_TTL = 60_000;

function getCacheKey(url: string): string {
  const patientId = Taro.getStorageSync('current_patient_id') || '';
  return `${url}#${patientId}`;
}

export function clearRequestCache(prefix?: string): void {
  if (prefix) {
    for (const key of responseCache.keys()) {
      if (key.includes(prefix)) responseCache.delete(key);
    }
  } else {
    responseCache.clear();
  }
}

export const api = {
  get: <T>(path: string, params?: Record<string, string | number | undefined>, cacheTtl?: number): Promise<T> => {
    const url = `${path}${buildQuery(params)}`;
    const cacheKey = getCacheKey(url);

    const cached = responseCache.get(cacheKey);
    if (cached && Date.now() < cached.expiry) {
      return Promise.resolve(cached.data as T);
    }

    const inflight = inflightRequests.get(cacheKey);
    if (inflight) return inflight as Promise<T>;

    const promise = request<T>('GET', url).then((data) => {
      inflightRequests.delete(cacheKey);
      const ttl = cacheTtl ?? DEFAULT_CACHE_TTL;
      if (ttl > 0) {
        responseCache.set(cacheKey, { data, expiry: Date.now() + ttl });
      }
      return data;
    }).catch((err) => {
      inflightRequests.delete(cacheKey);
      throw err;
    });

    inflightRequests.set(cacheKey, promise);
    return promise;
  },

  post: <T>(path: string, data?: unknown) => request<T>('POST', path, data),
  put: <T>(path: string, data?: unknown) => request<T>('PUT', path, data),
  delete: <T>(path: string, data?: unknown) => request<T>('DELETE', path, data),
};