init commit

1 files changed, 117 insertions, 0 deletions

diff --git a/src/jet/dependencies/net.ts b/src/jet/dependencies/net.ts
new file mode 100644
index 0000000..dd7fdb9
--- /dev/null
+++ b/src/jet/dependencies/net.ts
@@ -0,0 +1,117 @@
+import type { Network, FetchRequest, FetchResponse } from '@jet/environment';
+import { fromEntries } from '@amp/web-apps-utils';
+
+import {
+    shouldUseSearchJWT,
+    makeSearchJWTAuthorizationHeader,
+} from '~/config/media-api';
+
+const CORRELATION_KEY_HEADER = 'x-apple-jingle-correlation-key';
+
+type FetchFunction = typeof window.fetch;
+
+// TODO: these URLs are also referenced in `bag` definition; we should have a single
+// source-of-truth for these domains
+const MEDIA_API_ORIGINS = [
+    'https://amp-api.apps.apple.com',
+    'https://amp-api-edge.apps.apple.com',
+    'https://amp-api-search-edge.apps.apple.com',
+];
+
+export interface FeaturesCallbacks {
+    getITFEValues(): string | undefined;
+}
+
+export class Net implements Network {
+    private readonly underlyingFetch: FetchFunction;
+    private readonly getITFEValues: () => string | undefined = () => undefined;
+
+    constructor(
+        underlyingFetch: FetchFunction,
+        featuresCallbacks?: FeaturesCallbacks,
+    ) {
+        this.underlyingFetch = underlyingFetch;
+        this.getITFEValues =
+            featuresCallbacks?.getITFEValues ?? this.getITFEValues;
+    }
+
+    async fetch(request: FetchRequest): Promise<FetchResponse> {
+        const requestStartTime = getTimestampMs();
+        const requestURL = new URL(request.url);
+
+        request.headers = request.headers ?? {};
+
+        if (MEDIA_API_ORIGINS.includes(requestURL.origin)) {
+            // Need to fake this for the server due to Kong origin checks.
+            // Has no effect clientside.
+            request.headers['origin'] = 'https://apps.apple.com';
+
+            const itfe = this.getITFEValues?.();
+
+            if (itfe) {
+                // Add ITFE value as query string when set
+                requestURL.searchParams.set('itfe', itfe);
+            }
+        }
+
+        // The App Store Client will have already injected the JWT from the
+        // `media-token-service` ObjectGraph dependency into the headers. However,
+        // some endpoints need a different JWT. Here we determine if that's the
+        // case and override the existing JWT if necessary.
+        if (shouldUseSearchJWT(requestURL)) {
+            request.headers = {
+                ...request.headers,
+                ...makeSearchJWTAuthorizationHeader(),
+            };
+        }
+
+        // TODO: rdar://78158575: timeout
+        const response = await this.underlyingFetch(requestURL.toString(), {
+            ...request,
+            cache: request.cache ?? undefined,
+            credentials: 'include',
+            headers: request.headers ?? undefined,
+            method: request.method ?? undefined,
+        });
+
+        const responseStartTime = getTimestampMs();
+
+        const { ok, redirected, status, statusText, url } = response;
+
+        const headers = fromEntries(response.headers);
+        const body = await response.text();
+
+        const responseEndTime = getTimestampMs();
+
+        return {
+            ok,
+            headers,
+            redirected,
+            status,
+            statusText,
+            url,
+            body,
+            // TODO: rdar://78158575: redirect: 'manual' to get all metrics?
+            metrics: [
+                {
+                    clientCorrelationKey: response.headers.get(
+                        CORRELATION_KEY_HEADER,
+                    ),
+                    pageURL: response.url,
+                    requestStartTime,
+                    responseStartTime,
+                    responseEndTime,
+                    // TODO: rdar://78158575: responseWasCached?
+                    // TODO: rdar://78158575: parseStartTime/parseEndTime
+                },
+            ],
+        };
+    }
+}
+
+/**
+ * Returns the current UTC timestamp in milliseconds.
+ */
+function getTimestampMs(): number {
+    return Date.now();
+}