feat: fetch-event-source util

packages/bridge-controller/package.json

@@ -60,7 +60,6 @@
     "@metamask/multichain-network-controller": "^1.0.1",
     "@metamask/polling-controller": "^14.0.1",
     "@metamask/utils": "^11.8.1",
-    "@microsoft/fetch-event-source": "^2.0.1",
     "bignumber.js": "^9.1.2",
     "reselect": "^5.1.1",
     "uuid": "^8.3.2"

packages/bridge-controller/src/utils/fetch-server-events.ts

@@ -0,0 +1,65 @@
+export type SSEMessage = {
+  event?: string;
+  data: string;
+};
+
+export type SSEOptions = RequestInit & {
+  onMessage: (data: unknown, event?: string) => void;
+  onError?: (err: Error) => void;
+};
+
+/**
+ * Streams server-sent events from the given URL
+ *
+ * @param url - The URL to stream events from
+ * @param options - The options for the SSE stream
+ */
+export const fetchServerEvents = async (url: string, options: SSEOptions) => {
+  const controller = new AbortController();
+  const signal = options.signal ?? controller.signal;
+
+  try {
+    const response = await fetch(url, { signal });
+    if (!response.ok || !response.body) {
+      throw new Error(`${response.status}`);
+    }
+
+    const reader = response.body.getReader();
+    const decoder = new TextDecoder('utf-8');
+    let buffer = '';
+
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) {
+        break;
+      }
+
+      buffer += decoder.decode(value, { stream: true });
+
+      // parse SSE messages on double newline
+      const parts = buffer.split('\n\n');
+      buffer = parts.pop() || '';
+
+      for (const chunk of parts) {
+        const lines = chunk.split('\n');
+        let eventName: string | undefined;
+        const dataLines: string[] = [];
+
+        for (const line of lines) {
+          if (line.startsWith('event:')) {
+            eventName = line.slice(6).trim();
+          } else if (line.startsWith('data:')) {
+            dataLines.push(line.slice(5).trim());
+          }
+        }
+
+        if (dataLines.length > 0) {
+          const rawData = dataLines.join('\n');
+          options.onMessage(JSON.parse(rawData), eventName);
+        }
+      }
+    }
+  } catch (error) {
+    options.onError?.(error);
+  }
+};

packages/bridge-controller/src/utils/fetch.ts

@@ -1,13 +1,13 @@
 import { StructError } from '@metamask/superstruct';
 import type { CaipAssetType, CaipChainId, Hex } from '@metamask/utils';
 import type { EventSourceMessage } from '@microsoft/fetch-event-source';
-import { fetchEventSource } from '@microsoft/fetch-event-source';
 
 import { isBitcoinChainId } from './bridge';
 import {
   formatAddressToCaipReference,
   formatChainIdToDec,
 } from './caip-formatters';
+import { fetchServerEvents } from './fetch-server-events';
 import type { FeatureId } from './validators';
 import {
   validateQuoteResponse,
@@ -337,14 +337,14 @@ export async function fetchBridgeQuoteStream(
   };
 
   const urlStream = `${bridgeApiBaseUrl}/getQuoteStream?${queryParams}`;
-  await fetchEventSource(urlStream, {
-    headers: {
-      ...getClientHeaders(clientId, clientVersion),
-      'Content-Type': 'text/event-stream',
-    },
+  await fetchServerEvents(urlStream, {
+    // headers: {
+    //   ...getClientHeaders(clientId, clientVersion),
+    //   'Content-Type': 'text/event-stream',
+    // },
     signal,
-    onmessage: onMessage,
-    onerror: (e) => {
+    onMessage,
+    onError: (e) => {
       // Rethrow error to prevent silent fetch failures
       throw new Error(e.toString());
     },