refactor(channels): share draft stream loop across slack and telegram

src/channels/draft-stream-loop.ts

@@ -0,0 +1,92 @@
+export type DraftStreamLoop = {
+  update: (text: string) => void;
+  flush: () => Promise<void>;
+  stop: () => void;
+  resetPending: () => void;
+  waitForInFlight: () => Promise<void>;
+};
+
+export function createDraftStreamLoop(params: {
+  throttleMs: number;
+  isStopped: () => boolean;
+  sendOrEditStreamMessage: (text: string) => Promise<void>;
+}): DraftStreamLoop {
+  let lastSentAt = 0;
+  let pendingText = "";
+  let inFlightPromise: Promise<void> | undefined;
+  let timer: ReturnType<typeof setTimeout> | undefined;
+
+  const flush = async () => {
+    if (timer) {
+      clearTimeout(timer);
+      timer = undefined;
+    }
+    while (!params.isStopped()) {
+      if (inFlightPromise) {
+        await inFlightPromise;
+        continue;
+      }
+      const text = pendingText;
+      if (!text.trim()) {
+        pendingText = "";
+        return;
+      }
+      pendingText = "";
+      lastSentAt = Date.now();
+      const current = params.sendOrEditStreamMessage(text).finally(() => {
+        if (inFlightPromise === current) {
+          inFlightPromise = undefined;
+        }
+      });
+      inFlightPromise = current;
+      await current;
+      if (!pendingText) {
+        return;
+      }
+    }
+  };
+
+  const schedule = () => {
+    if (timer) {
+      return;
+    }
+    const delay = Math.max(0, params.throttleMs - (Date.now() - lastSentAt));
+    timer = setTimeout(() => {
+      void flush();
+    }, delay);
+  };
+
+  return {
+    update: (text: string) => {
+      if (params.isStopped()) {
+        return;
+      }
+      pendingText = text;
+      if (inFlightPromise) {
+        schedule();
+        return;
+      }
+      if (!timer && Date.now() - lastSentAt >= params.throttleMs) {
+        void flush();
+        return;
+      }
+      schedule();
+    },
+    flush,
+    stop: () => {
+      pendingText = "";
+      if (timer) {
+        clearTimeout(timer);
+        timer = undefined;
+      }
+    },
+    resetPending: () => {
+      pendingText = "";
+    },
+    waitForInFlight: async () => {
+      if (inFlightPromise) {
+        await inFlightPromise;
+      }
+    },
+  };
+}