next: ai part 3

website_next/ask/timing.js

@@ -0,0 +1,68 @@
+/**
+ * @typedef {Object} ResponseStep
+ * @property {string} label
+ * @property {number} [elapsedMs]
+ */
+
+/** @param {number} elapsedMs */
+export function formatDuration(elapsedMs) {
+  if (elapsedMs < 100) return "<0.1s";
+  if (elapsedMs < 60_000) return `${(elapsedMs / 1_000).toFixed(1)}s`;
+
+  const minutes = Math.floor(elapsedMs / 60_000);
+  const seconds = Math.floor((elapsedMs % 60_000) / 1_000);
+  return `${minutes}m ${seconds}s`;
+}
+
+/** @param {string} label */
+function normalizeLabel(label) {
+  return label
+    .replace(/\s*·.*$/, "")
+    .replace(/(?:\.\.\.|…)$/, "")
+    .trim();
+}
+
+/** @param {(steps: ResponseStep[]) => void} onUpdate */
+export function createResponseTimer(onUpdate) {
+  const startedAt = performance.now();
+  /** @type {{ label: string, startedAt: number } | undefined} */
+  let active;
+  /** @type {{ label: string, elapsedMs: number }[]} */
+  const completed = [];
+
+  function publish() {
+    onUpdate(active
+      ? [...completed, { label: active.label }]
+      : [...completed]);
+  }
+
+  function completeActive() {
+    if (!active) return;
+
+    completed.push({
+      label: active.label,
+      elapsedMs: Math.round(performance.now() - active.startedAt),
+    });
+    active = undefined;
+  }
+
+  return {
+    /** @param {string} nextLabel */
+    set(nextLabel) {
+      const label = normalizeLabel(nextLabel);
+      if (label === active?.label) return;
+
+      completeActive();
+      if (label) active = { label, startedAt: performance.now() };
+      publish();
+    },
+    finish() {
+      completeActive();
+      publish();
+      return {
+        elapsedMs: Math.round(performance.now() - startedAt),
+        steps: [...completed],
+      };
+    },
+  };
+}