refactor: 收口前端 SSE 传输层

src/services/visual-novel-runtime/visualNovelRuntimeSse.ts

@@ -2,6 +2,7 @@ import type {
   VisualNovelRunSnapshot,
   VisualNovelRuntimeStreamEvent,
 } from '../../../packages/shared/src/contracts/visualNovel';
+import { readSseJsonStream } from '../sseStream';
 
 type VisualNovelRuntimeSseOptions = {
   fallbackMessage: string;
@@ -9,65 +10,6 @@ type VisualNovelRuntimeSseOptions = {
   onEvent?: (event: VisualNovelRuntimeStreamEvent) => void;
 };
 
-function findSseEventBoundary(buffer: string) {
-  const lfBoundary = buffer.indexOf('\n\n');
-  const crlfBoundary = buffer.indexOf('\r\n\r\n');
-
-  if (lfBoundary === -1 && crlfBoundary === -1) {
-    return null;
-  }
-
-  if (lfBoundary === -1) {
-    return {
-      index: crlfBoundary,
-      length: 4,
-    };
-  }
-
-  if (crlfBoundary === -1 || lfBoundary < crlfBoundary) {
-    return {
-      index: lfBoundary,
-      length: 2,
-    };
-  }
-
-  return {
-    index: crlfBoundary,
-    length: 4,
-  };
-}
-
-function parseSseEventBlock(eventBlock: string) {
-  let eventName = 'message';
-  const dataLines: string[] = [];
-
-  for (const rawLine of eventBlock.split(/\r?\n/u)) {
-    const line = rawLine.trim();
-
-    if (line.startsWith('event:')) {
-      eventName = line.slice(6).trim() || 'message';
-      continue;
-    }
-
-    if (line.startsWith('data:')) {
-      dataLines.push(line.slice(5).trim());
-    }
-  }
-
-  return {
-    eventName,
-    data: dataLines.join('\n'),
-  };
-}
-
-function parseJsonObject(data: string) {
-  try {
-    return JSON.parse(data) as Record<string, unknown>;
-  } catch {
-    return null;
-  }
-}
-
 function normalizeVisualNovelRuntimeEvent(
   eventName: string,
   parsed: Record<string, unknown>,
@@ -115,59 +57,19 @@ export async function readVisualNovelRuntimeRunFromSse(
   response: Response,
   options: VisualNovelRuntimeSseOptions,
 ) {
-  const streamBody = response.body;
-  if (!streamBody) {
-    throw new Error('streaming response body is unavailable');
-  }
-
-  const reader = streamBody.getReader();
-  const decoder = new TextDecoder('utf-8');
-  let buffer = '';
   let finalRun: VisualNovelRunSnapshot | null = null;
 
-  const consumeBuffer = () => {
-    for (;;) {
-      const boundary = findSseEventBoundary(buffer);
-      if (!boundary) {
-        break;
-      }
-
-      const eventBlock = buffer.slice(0, boundary.index);
-      buffer = buffer.slice(boundary.index + boundary.length);
-      const { eventName, data } = parseSseEventBlock(eventBlock);
-      if (!data) {
-        continue;
-      }
-
-      const parsed = parseJsonObject(data);
-      if (!parsed) {
-        continue;
-      }
-
-      const event = normalizeVisualNovelRuntimeEvent(eventName, parsed);
-      if (!event) {
-        continue;
-      }
-
-      const nextRun = handleVisualNovelRuntimeEvent(event, options);
-      if (nextRun) {
-        finalRun = nextRun;
-      }
-    }
-  };
-
-  for (;;) {
-    const { done, value } = await reader.read();
-    if (done) {
-      break;
+  await readSseJsonStream(response, ({ eventName, parsed }) => {
+    const event = normalizeVisualNovelRuntimeEvent(eventName, parsed);
+    if (!event) {
+      return;
     }
 
-    buffer += decoder.decode(value, { stream: true });
-    consumeBuffer();
-  }
-
-  buffer += decoder.decode();
-  consumeBuffer();
+    const nextRun = handleVisualNovelRuntimeEvent(event, options);
+    if (nextRun) {
+      finalRun = nextRun;
+    }
+  });
 
   if (!finalRun) {
     throw new Error(options.incompleteMessage);