feat(chat): add Edge TTS playback

src/components/chat/speechStartOptions.ts

@@ -0,0 +1,98 @@
+const compactWhitespace = (value: string) => value.replace(/\s+/g, " ").trim();
+const MAX_SPEECH_CHUNK_LENGTH = 520;
+const MIN_SPEECH_CHUNK_LENGTH = 180;
+const SPEECH_SENTENCE_PATTERN = /[^。！？!?；;\n]+(?:[。！？!?；;]+|(?=\n|$))/g;
+
+const normalizeWithOffsetMap = (value: string) => {
+  let normalized = "";
+  const offsetMap: number[] = [];
+  let isPreviousWhitespace = false;
+
+  Array.from(value).forEach((char, index) => {
+    if (/\s/u.test(char)) {
+      if (!isPreviousWhitespace && normalized.length > 0) {
+        normalized += " ";
+        offsetMap.push(index);
+      }
+      isPreviousWhitespace = true;
+      return;
+    }
+
+    normalized += char;
+    offsetMap.push(index);
+    isPreviousWhitespace = false;
+  });
+
+  return {
+    normalized: normalized.trimEnd(),
+    offsetMap,
+  };
+};
+
+export function findSpeechSelectionStartOffset(
+  text: string,
+  selectedText: string,
+): number | null {
+  const needle = selectedText.trim();
+  if (!needle) return null;
+
+  const exactIndex = text.indexOf(needle);
+  if (exactIndex >= 0) return exactIndex;
+
+  const normalizedNeedle = compactWhitespace(needle);
+  if (!normalizedNeedle) return null;
+
+  const haystack = normalizeWithOffsetMap(text);
+  const normalizedIndex = haystack.normalized.indexOf(normalizedNeedle);
+  if (normalizedIndex < 0) return null;
+
+  return haystack.offsetMap[normalizedIndex] ?? null;
+}
+
+export function splitSpeechTextIntoChunks(text: string): string[] {
+  const normalizedText = text.trim();
+  if (!normalizedText) return [];
+
+  const segments = Array.from(normalizedText.matchAll(SPEECH_SENTENCE_PATTERN), (match) =>
+    compactWhitespace(match[0]),
+  ).filter(Boolean);
+  const sourceSegments = segments.length > 0 ? segments : [normalizedText];
+  const chunks: string[] = [];
+  let currentChunk = "";
+
+  const flush = () => {
+    if (!currentChunk) return;
+    chunks.push(currentChunk);
+    currentChunk = "";
+  };
+
+  const pushLongSegment = (segment: string) => {
+    for (let offset = 0; offset < segment.length; offset += MAX_SPEECH_CHUNK_LENGTH) {
+      chunks.push(segment.slice(offset, offset + MAX_SPEECH_CHUNK_LENGTH));
+    }
+  };
+
+  sourceSegments.forEach((segment) => {
+    if (segment.length > MAX_SPEECH_CHUNK_LENGTH) {
+      flush();
+      pushLongSegment(segment);
+      return;
+    }
+
+    const candidate = currentChunk ? `${currentChunk}${segment}` : segment;
+    if (
+      currentChunk &&
+      candidate.length > MAX_SPEECH_CHUNK_LENGTH &&
+      currentChunk.length >= MIN_SPEECH_CHUNK_LENGTH
+    ) {
+      flush();
+      currentChunk = segment;
+      return;
+    }
+
+    currentChunk = candidate;
+  });
+
+  flush();
+  return chunks;
+}