import type { WechatLoginPlatform, WechatLoginResult } from '@dukang/shared-types';
import { getRuntimePlatform, isWechatBrowser } from './env';
import type { WeixinSdkConfig } from './types';

/** 非微信内置浏览器时提示（与 C 端 LoginPage 文案一致） */
export const WECHAT_INAPP_REQUIRED_MSG = '请在微信内打开以使用微信一键授权';

const OAUTH_STATE_KEY = 'dukang_wx_oauth_state';

function randomState() {
  return `${Date.now()}_${Math.random().toString(36).slice(2, 10)}`;
}

async function apiRequest<T>(
  config: WeixinSdkConfig,
  path: string,
  options: RequestInit = {},
): Promise<T> {
  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    'X-Client-App': config.clientApp,
    ...(options.headers as Record<string, string>),
  };
  const token = config.getAccessToken?.();
  if (token) headers.Authorization = `Bearer ${token}`;
  const apiBase = config.apiBase ?? '/api/v1';
  const res = await fetch(`${apiBase}${path}`, { ...options, headers });
  const json = await res.json();
  if (json.code !== 0) throw new Error(json.message || '请求失败');
  return json.data as T;
}

/** 获取公众号 OAuth 授权跳转 URL */
export async function getWechatOAuthUrl(
  config: WeixinSdkConfig,
  redirectUri: string,
  scope: 'snsapi_base' | 'snsapi_userinfo' = 'snsapi_userinfo',
): Promise<string> {
  const state = randomState();
  sessionStorage.setItem(OAUTH_STATE_KEY, state);
  const qs = new URLSearchParams({ redirectUri, scope, state });
  const data = await apiRequest<{ url: string }>(config, `/common/wechat/oauth-url?${qs}`);
  return data.url;
}

/** 发起微信 OAuth 登录（H5 公众号内跳转授权） */
export async function startWechatOAuthLogin(config: WeixinSdkConfig, redirectUri?: string): Promise<void> {
  if (!isWechatBrowser()) {
    throw new Error(WECHAT_INAPP_REQUIRED_MSG);
  }
  const uri = redirectUri ?? window.location.href.split('#')[0];
  const url = await getWechatOAuthUrl(config, uri);
  window.location.href = url;
}

/** 小程序 wx.login 获取 code */
export function getMiniProgramLoginCode(): Promise<string> {
  return new Promise((resolve, reject) => {
    if (!window.wx?.login) {
      reject(new Error('wx.login 不可用'));
      return;
    }
    window.wx.login({
      success: (res) => (res.code ? resolve(res.code) : reject(new Error('未获取到 code'))),
      fail: (err) => reject(new Error(err.errMsg || 'wx.login 失败')),
    });
  });
}

/** 用 code 完成微信登录（自动识别 H5 / 小程序） */
export async function loginWithWechatCode(
  config: WeixinSdkConfig,
  code: string,
  platform?: WechatLoginPlatform,
): Promise<WechatLoginResult> {
  const resolvedPlatform = platform ?? (getRuntimePlatform() === 'mini' ? 'mini' : 'h5');
  const loginPath = config.wechatLoginPath ?? '/auth/login/wechat';
  return apiRequest<WechatLoginResult>(config, loginPath, {
    method: 'POST',
    body: JSON.stringify({ code, platform: resolvedPlatform }),
  });
}

/** 处理 OAuth 回调 URL 中的 code 参数并登录 */
export async function handleWechatOAuthCallback(
  config: WeixinSdkConfig,
  searchParams?: URLSearchParams,
): Promise<WechatLoginResult | null> {
  const params = searchParams ?? new URLSearchParams(window.location.search);
  const code = params.get('code');
  if (!code) return null;

  const state = params.get('state');
  const saved = sessionStorage.getItem(OAUTH_STATE_KEY);
  if (saved && state && saved !== state) {
    throw new Error('OAuth state 校验失败');
  }
  sessionStorage.removeItem(OAUTH_STATE_KEY);

  return loginWithWechatCode(config, code, 'h5');
}

/** 微信首登绑定手机号 */
export async function bindWechatPhone(
  config: WeixinSdkConfig,
  payload: { wxSessionKey: string; phone: string; code: string },
): Promise<WechatLoginResult> {
  return apiRequest<WechatLoginResult>(config, '/auth/wechat/bind-phone', {
    method: 'POST',
    body: JSON.stringify(payload),
  });
}

/** 获取微信手机号（小程序 getPhoneNumber 返回的 code，需后端解密） */
export async function getWechatPhoneNumber(config: WeixinSdkConfig): Promise<string> {
  const platform = getRuntimePlatform();
  if (platform !== 'mini') {
    throw new Error('H5 环境请使用短信验证码绑定手机号');
  }
  const phoneCode = await new Promise<string>((resolve, reject) => {
    if (!window.wx?.getPhoneNumber) {
      reject(new Error('getPhoneNumber 不可用'));
      return;
    }
    window.wx.getPhoneNumber({
      success: (res) => (res.code ? resolve(res.code) : reject(new Error('未获取到手机号 code'))),
      fail: (err) => reject(new Error(err.errMsg || '获取手机号失败')),
    });
  });
  const data = await apiRequest<{ phone: string }>(config, '/common/wechat/phone-number', {
    method: 'POST',
    body: JSON.stringify({ code: phoneCode, platform: 'mini' }),
  });
  return data.phone;
}

/** 一键微信登录（自动选择 OAuth 或 wx.login） */
export async function wechatLogin(config: WeixinSdkConfig): Promise<WechatLoginResult | void> {
  const platform = getRuntimePlatform();
  if (platform === 'mini') {
    const code = await getMiniProgramLoginCode();
    return loginWithWechatCode(config, code, 'mini');
  }
  if (platform === 'wechat-h5') {
    await startWechatOAuthLogin(config);
    return;
  }
  throw new Error(WECHAT_INAPP_REQUIRED_MSG);
}