chore: merge with web UI project

web/src/core/sse/StreamEvent.ts

@@ -0,0 +1,4 @@
+export interface StreamEvent {
+  type: string;
+  data: object;
+}

web/src/core/sse/fetch-stream.ts

@@ -0,0 +1,70 @@
+import { type StreamEvent } from "./StreamEvent";
+
+export async function* fetchStream<T extends StreamEvent>(
+  url: string,
+  init: RequestInit,
+): AsyncIterable<T> {
+  const response = await fetch(url, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+      "Cache-Control": "no-cache",
+    },
+    ...init,
+  });
+  if (response.status !== 200) {
+    throw new Error(`Failed to fetch from ${url}: ${response.status}`);
+  }
+  // Read from response body, event by event. An event always ends with a '\n\n'.
+  const reader = response.body
+    ?.pipeThrough(new TextDecoderStream())
+    .getReader();
+  if (!reader) {
+    throw new Error("Response body is not readable");
+  }
+  let buffer = "";
+  while (true) {
+    const { done, value } = await reader.read();
+    if (done) {
+      break;
+    }
+    buffer += value;
+    while (true) {
+      const index = buffer.indexOf("\n\n");
+      if (index === -1) {
+        break;
+      }
+      const chunk = buffer.slice(0, index);
+      buffer = buffer.slice(index + 2);
+      const event = parseEvent<T>(chunk);
+      if (event) {
+        yield event;
+      }
+    }
+  }
+}
+
+function parseEvent<T extends StreamEvent>(chunk: string) {
+  let resultType = "message";
+  let resultData: object | null = null;
+  for (const line of chunk.split("\n")) {
+    const pos = line.indexOf(": ");
+    if (pos === -1) {
+      continue;
+    }
+    const key = line.slice(0, pos);
+    const value = line.slice(pos + 2);
+    if (key === "event") {
+      resultType = value;
+    } else if (key === "data") {
+      resultData = JSON.parse(value);
+    }
+  }
+  if (resultType === "message" && resultData === null) {
+    return undefined;
+  }
+  return {
+    type: resultType,
+    data: resultData,
+  } as T;
+}

web/src/core/sse/index.ts

@@ -0,0 +1,2 @@
+export * from "./fetch-stream";
+export * from "./StreamEvent";