refactor: extract recorder domain types and modules

src/recorder/segment.ts

@@ -0,0 +1,84 @@
+import fs from "node:fs";
+import path from "node:path";
+import prism from "prism-media";
+import type { SegmentState } from "../types";
+
+export function buildSegmentPaths(
+  userDir: string,
+  startTime: number,
+): { filename: string; jsonFilename: string } {
+  return {
+    filename: path.join(userDir, `${startTime}.ogg`),
+    jsonFilename: path.join(userDir, `${startTime}.json`),
+  };
+}
+
+export function shouldRotateSegment(
+  startTime: number,
+  now: number,
+  recordingSegmentMs: number,
+): boolean {
+  return recordingSegmentMs > 0 && now - startTime >= recordingSegmentMs;
+}
+
+export class SegmentManager {
+  private currentSegment: SegmentState | null = null;
+  private segmentIndex = 0;
+
+  constructor(
+    private readonly userDir: string,
+    private readonly recordingSegmentMs: number,
+  ) {}
+
+  open(oggPacketStream: NodeJS.ReadableStream): SegmentState {
+    const index = this.segmentIndex++;
+    const startTime = Date.now();
+    const { filename, jsonFilename } = buildSegmentPaths(this.userDir, startTime);
+    const oggStream = new prism.opus.OggLogicalBitstream({
+      opusHead: new prism.opus.OpusHead({ channelCount: 2, sampleRate: 48000 }),
+      pageSizeControl: { maxPackets: 10 },
+      crc: true,
+    });
+    const out = fs.createWriteStream(filename);
+    oggPacketStream.pipe(oggStream).pipe(out);
+
+    this.currentSegment = {
+      index,
+      startTime,
+      endTime: null,
+      filename,
+      jsonFilename,
+      oggStream,
+      out,
+    };
+    return this.currentSegment;
+  }
+
+  close(oggPacketStream: NodeJS.ReadableStream): SegmentState | null {
+    if (!this.currentSegment) return null;
+    const segment = this.currentSegment;
+    segment.endTime = Date.now();
+    oggPacketStream.unpipe(segment.oggStream);
+    segment.oggStream.end();
+    this.currentSegment = null;
+    return segment;
+  }
+
+  rotateIfNeeded(oggPacketStream: NodeJS.ReadableStream): SegmentState | null {
+    if (!this.currentSegment) return null;
+    if (
+      !shouldRotateSegment(
+        this.currentSegment.startTime,
+        Date.now(),
+        this.recordingSegmentMs,
+      )
+    )
+      return null;
+    this.close(oggPacketStream);
+    return this.open(oggPacketStream);
+  }
+
+  getCurrent(): SegmentState | null {
+    return this.currentSegment;
+  }
+}