"""流式闲聊：按句切分文本入队 TTS；飞控 JSON 路径由调用方整块推理后再播。"""

from __future__ import annotations

# 句末：切段送合成
_SENTENCE_END = frozenset("。！？；\n")
# 过长且无句末时，优先在以下标点处断开
_SOFT_BREAK = "，、,"


def take_completed_sentences(buffer: str) -> tuple[list[str], str]:
    """从 buffer 开头取出所有「以句末标点结尾」的完整小段。"""
    segments: list[str] = []
    i = 0
    n = len(buffer)
    while i < n:
        j = i
        while j < n and buffer[j] not in _SENTENCE_END:
            j += 1
        if j >= n:
            break
        raw = buffer[i : j + 1].strip()
        if raw:
            segments.append(raw)
        i = j + 1
    return segments, buffer[i:]


def force_soft_split(remainder: str, max_chars: int) -> tuple[list[str], str]:
    """remainder 长度 >= max_chars 且无句末时，强制切下第一段。"""
    if max_chars <= 0 or len(remainder) < max_chars:
        return [], remainder
    window = remainder[:max_chars]
    cut = -1
    for sep in _SOFT_BREAK:
        p = window.rfind(sep)
        if p > cut:
            cut = p
    if cut <= 0:
        cut = max_chars
    first = remainder[: cut + 1].strip()
    rest = remainder[cut + 1 :]
    out: list[str] = []
    if first:
        out.append(first)
    return out, rest