/**
* Opt-in analytics injection for SSR streams.
* Supported environment variables:
* - `GA_MEASUREMENT_ID` — Google Analytics 4 measurement ID
* - `GTM_CONTAINER_ID` — Google Tag Manager web container ID
*
* Netlify configuration-file env vars are build-time only for serverless
* functions, so the Vite/Nitro build paths also bake this public value into
* SSR bundles.
*
* Amplitude and Sentry are initialized client-side via their npm packages
* (see `packages/core/src/client/analytics.ts`). GTM and GA require script
* tag injection because their loaders must be `` +
``
);
}
function getGtmHeadScript(containerId: string): string {
const jsId = JSON.stringify(containerId);
return ``;
}
function getGtmBodyFallback(containerId: string): string {
const src = encodeURIComponent(containerId);
return ``;
}
type AnalyticsInjection = {
head: string;
body: string;
};
function getAnalyticsInjection(): AnalyticsInjection | null {
const containerId = getGtmContainerId();
if (containerId) {
return {
head: getGtmHeadScript(containerId),
body: getGtmBodyFallback(containerId),
};
}
const gaScript = getGaScript();
return gaScript ? { head: gaScript, body: "" } : null;
}
const HEAD_CLOSE_PATTERN = /<\/head>/i;
const BODY_OPEN_PATTERN = /]*>/i;
/**
* Add the configured analytics scripts to a complete HTML document.
*
* The normal app document is streamed through `wrapWithAnalytics`, but
* framework-owned documents such as `/signup` are returned as strings by the
* auth guard and need the same injection path.
*/
export function injectAnalyticsIntoHtml(html: string): string {
const injection = getAnalyticsInjection();
if (!injection) return html;
const headCloseMatch = HEAD_CLOSE_PATTERN.exec(html);
if (!headCloseMatch || headCloseMatch.index === undefined) return html;
let output =
html.slice(0, headCloseMatch.index) +
injection.head +
html.slice(headCloseMatch.index);
if (injection.body) {
const bodyOpenMatch = BODY_OPEN_PATTERN.exec(output);
if (bodyOpenMatch && bodyOpenMatch.index !== undefined) {
const bodyEnd = bodyOpenMatch.index + bodyOpenMatch[0].length;
output =
output.slice(0, bodyEnd) + injection.body + output.slice(bodyEnd);
}
}
return output;
}
export function wrapWithAnalytics(
body: ReadableStream,
): ReadableStream {
const injection = getAnalyticsInjection();
if (!injection) return body;
const decoder = new TextDecoder();
const encoder = new TextEncoder();
let pending = "";
let headInjected = false;
let bodyInjected = !injection.body;
return body.pipeThrough(
new TransformStream({
transform(chunk, controller) {
pending += decoder.decode(chunk, { stream: true });
if (!headInjected) {
const headCloseMatch = HEAD_CLOSE_PATTERN.exec(pending);
if (!headCloseMatch || headCloseMatch.index === undefined) return;
const headEnd = headCloseMatch.index + headCloseMatch[0].length;
controller.enqueue(
encoder.encode(
pending.slice(0, headCloseMatch.index) +
injection.head +
pending.slice(headCloseMatch.index, headEnd),
),
);
pending = pending.slice(headEnd);
headInjected = true;
}
if (!bodyInjected) {
const bodyOpenMatch = BODY_OPEN_PATTERN.exec(pending);
if (!bodyOpenMatch || bodyOpenMatch.index === undefined) return;
const bodyEnd = bodyOpenMatch.index + bodyOpenMatch[0].length;
controller.enqueue(
encoder.encode(pending.slice(0, bodyEnd) + injection.body),
);
pending = pending.slice(bodyEnd);
bodyInjected = true;
}
if (pending) {
controller.enqueue(encoder.encode(pending));
pending = "";
}
},
flush(controller) {
pending += decoder.decode();
if (!headInjected) {
const headCloseMatch = HEAD_CLOSE_PATTERN.exec(pending);
if (headCloseMatch && headCloseMatch.index !== undefined) {
const headEnd = headCloseMatch.index + headCloseMatch[0].length;
controller.enqueue(
encoder.encode(
pending.slice(0, headCloseMatch.index) +
injection.head +
pending.slice(headCloseMatch.index, headEnd),
),
);
pending = pending.slice(headEnd);
headInjected = true;
}
}
if (headInjected && !bodyInjected) {
const bodyOpenMatch = BODY_OPEN_PATTERN.exec(pending);
if (bodyOpenMatch && bodyOpenMatch.index !== undefined) {
const bodyEnd = bodyOpenMatch.index + bodyOpenMatch[0].length;
controller.enqueue(
encoder.encode(pending.slice(0, bodyEnd) + injection.body),
);
pending = pending.slice(bodyEnd);
bodyInjected = true;
}
}
if (pending) controller.enqueue(encoder.encode(pending));
},
}),
);
}