Add WeChat auth entry for H5

hy_qa_asset_backend/frontend/lib/wechatAuth.ts

@@ -0,0 +1,43 @@
+const WECHAT_OAUTH_URL = "https://open.weixin.qq.com/connect/oauth2/authorize";
+
+export type WechatAuthConfig = {
+  appId: string;
+  redirectUri: string;
+  scope: "snsapi_base" | "snsapi_userinfo";
+  state: string;
+};
+
+export function getWechatAuthConfig(): WechatAuthConfig | null {
+  const appId = process.env.NEXT_PUBLIC_WECHAT_APP_ID;
+  const redirectUri =
+    process.env.NEXT_PUBLIC_WECHAT_AUTH_REDIRECT_URI ||
+    (typeof window !== "undefined" ? `${window.location.origin}/h5` : "");
+  const scope = (process.env.NEXT_PUBLIC_WECHAT_AUTH_SCOPE || "snsapi_userinfo") as WechatAuthConfig["scope"];
+
+  if (!appId || !redirectUri) {
+    return null;
+  }
+
+  return {
+    appId,
+    redirectUri,
+    scope,
+    state: "hyqa_h5"
+  };
+}
+
+export function buildWechatOAuthUrl(config: WechatAuthConfig): string {
+  const params = new URLSearchParams({
+    appid: config.appId,
+    redirect_uri: config.redirectUri,
+    response_type: "code",
+    scope: config.scope,
+    state: config.state
+  });
+
+  return `${WECHAT_OAUTH_URL}?${params.toString()}#wechat_redirect`;
+}
+
+export function isWechatBrowser(userAgent: string): boolean {
+  return /MicroMessenger/i.test(userAgent);
+}