import type { WechatJssdkConfig } from '@dukang/shared-types';
import { isWechatBrowser, isWechatDevTools } from './env';
import { DEFAULT_JS_API_LIST } from './types';

const JSSDK_URL = 'https://res.wx.qq.com/open/js/jweixin-1.6.0.js';
const SIGN_URL_CACHE_KEY = 'dukang_wx_sign_url_v2';

let scriptPromise: Promise<void> | null = null;
let configured = false;
let configuredUrl: string | null = null;

/** 清除 JSSDK 配置缓存（路由切换后须重新 wx.config） */
export function resetJssdkConfig(): void {
  configured = false;
  configuredUrl = null;
}

/** 参与 JSSDK 签名的页面 URL：与微信文档一致，取 location.href 去掉 # 后的部分；剔除 OAuth 回调参数 */
export function normalizeJssdkPageUrl(rawUrl: string): string {
  try {
    const url = new URL(rawUrl);
    url.hash = '';
    url.searchParams.delete('code');
    url.searchParams.delete('state');
    const query = url.searchParams.toString();
    return `${url.origin}${url.pathname}${query ? `?${query}` : ''}`;
  } catch {
    const noHash = rawUrl.split('#')[0];
    try {
      const url = new URL(noHash, typeof window !== 'undefined' ? window.location.origin : 'https://localhost');
      url.searchParams.delete('code');
      url.searchParams.delete('state');
      const query = url.searchParams.toString();
      return `${url.origin}${url.pathname}${query ? `?${query}` : ''}`;
    } catch {
      return noHash;
    }
  }
}

function signUrlChanged(prev: string | null, current: string): boolean {
  return prev !== current;
}

/** 记录最近一次签名 URL；SPA 路由或 ?step= 变化时须重新 wx.config */
export function captureIosJssdkEntryUrl(): void {
  if (typeof window === 'undefined') return;
  if (!isWechatBrowser() || isWechatDevTools()) return;
  const current = normalizeJssdkPageUrl(window.location.href);
  const existing = sessionStorage.getItem(SIGN_URL_CACHE_KEY);
  if (!existing) {
    sessionStorage.setItem(SIGN_URL_CACHE_KEY, current);
    return;
  }
  if (signUrlChanged(existing, current)) {
    sessionStorage.setItem(SIGN_URL_CACHE_KEY, current);
    resetJssdkConfig();
  }
}

/** 获取参与 JSSDK 签名的 URL（始终为当前页完整 URL，含 query） */
export function getJssdkSignUrl(rawUrl?: string): string {
  return normalizeJssdkPageUrl(rawUrl ?? (typeof window !== 'undefined' ? window.location.href : ''));
}

function isJssdkDebugEnabled(): boolean {
  if (typeof window === 'undefined') return false;
  try {
    return new URLSearchParams(window.location.search).get('wxdebug') === '1';
  } catch {
    return false;
  }
}

export function stripOAuthParamsFromLocation(): void {
  if (typeof window === 'undefined') return;
  const url = new URL(window.location.href);
  if (!url.searchParams.has('code') && !url.searchParams.has('state')) return;
  url.searchParams.delete('code');
  url.searchParams.delete('state');
  const query = url.searchParams.toString();
  const next = `${url.pathname}${query ? `?${query}` : ''}${url.hash}`;
  window.history.replaceState({}, '', next);
}

function loadScript(): Promise<void> {
  if (typeof document === 'undefined') return Promise.reject(new Error('非浏览器环境'));
  if (window.wx) return Promise.resolve();
  if (scriptPromise) return scriptPromise;

  scriptPromise = new Promise((resolve, reject) => {
    const existing = document.querySelector<HTMLScriptElement>('script[data-dukang-wx-jssdk]');
    if (existing) {
      existing.addEventListener('load', () => resolve());
      existing.addEventListener('error', () => reject(new Error('微信 JSSDK 加载失败')));
      return;
    }
    const script = document.createElement('script');
    script.src = JSSDK_URL;
    script.async = true;
    script.dataset.dukangWxJssdk = '1';
    script.onload = () => resolve();
    script.onerror = () => reject(new Error('微信 JSSDK 加载失败'));
    document.head.appendChild(script);
  });
  return scriptPromise;
}

async function fetchJssdkConfig(apiBase: string, clientApp: string, url: string, token?: string | null) {
  const headers: Record<string, string> = { 'X-Client-App': clientApp };
  if (token) headers.Authorization = `Bearer ${token}`;
  const qs = new URLSearchParams({ url });
  const res = await fetch(`${apiBase}/common/wechat/jssdk-config?${qs}`, { headers });
  const json = await res.json();
  if (json.code !== 0) throw new Error(json.message || '获取 JSSDK 配置失败');
  return json.data as WechatJssdkConfig;
}

/** 初始化微信 JSSDK（H5 公众号内） */
export async function initWechatJssdk(options: {
  apiBase: string;
  clientApp: string;
  url?: string;
  getAccessToken?: () => string | null;
  jsApiList?: string[];
}): Promise<void> {
  captureIosJssdkEntryUrl();
  const { apiBase, clientApp, getAccessToken } = options;
  const pageUrl = options.url ?? getJssdkSignUrl();
  await loadScript();
  if (!window.wx) throw new Error('微信 JSSDK 不可用');

  const config = await fetchJssdkConfig(apiBase, clientApp, pageUrl, getAccessToken?.());
  const jsApiList = options.jsApiList ?? [...DEFAULT_JS_API_LIST];

  configured = false;
  configuredUrl = null;

  await new Promise<void>((resolve, reject) => {
    window.wx!.config({
      ...config,
      jsApiList,
      debug: isJssdkDebugEnabled(),
    });
    window.wx!.ready(() => {
      configured = true;
      configuredUrl = pageUrl;
      resolve();
    });
    window.wx!.error((err) => reject(new Error(err.errMsg || 'wx.config 失败')));
  });
}

export function isJssdkReady(): boolean {
  const signUrl = getJssdkSignUrl();
  return configured && !!window.wx && configuredUrl === signUrl;
}

export async function ensureJssdkReady(options: {
  apiBase: string;
  clientApp: string;
  url?: string;
  getAccessToken?: () => string | null;
  jsApiList?: string[];
}): Promise<void> {
  captureIosJssdkEntryUrl();
  const pageUrl = options.url ?? getJssdkSignUrl();
  if (configuredUrl && signUrlChanged(configuredUrl, pageUrl)) {
    resetJssdkConfig();
  }
  if (!isJssdkReady()) {
    await initWechatJssdk({ ...options, url: pageUrl });
  }
}

if (typeof window !== 'undefined') {
  captureIosJssdkEntryUrl();
}