from __future__ import annotations


def chunk_text(text: str, limit: int, mode: str = "paragraph") -> list[str]:
    if len(text) <= limit:
        return [text]

    if mode == "length":
        return _chunk_by_length(text, limit)
    if mode == "newline":
        return _chunk_by_newline(text, limit)
    return _chunk_by_paragraph(text, limit)


def _chunk_by_paragraph(text: str, limit: int) -> list[str]:
    chunks = []
    paragraphs = text.split("\n\n")

    for para in paragraphs:
        if len(para) <= limit:
            chunks.append(para)
            continue

        sentences = para.replace("\n", " ").split(". ")
        current = ""

        for sentence in sentences:
            sep = ". " if current else ""
            candidate = f"{current}{sep}{sentence}"

            if current and len(candidate) + 1 > limit:
                chunks.append(current + ".")
                current = sentence
            else:
                current = candidate

        if current:
            if not current.endswith("."):
                current += "."
            chunks.append(current)

    merged = []
    for chunk in chunks:
        if merged and len(merged[-1]) + len(chunk) + 2 <= limit:
            merged[-1] = f"{merged[-1]}\n\n{chunk}"
        else:
            merged.append(chunk)

    return merged


def _chunk_by_length(text: str, limit: int) -> list[str]:
    chunks = []
    for i in range(0, len(text), limit):
        chunks.append(text[i : i + limit])
    return chunks


def _chunk_by_newline(text: str, limit: int) -> list[str]:
    lines = text.split("\n")
    chunks = []
    current = ""
    for line in lines:
        candidate = f"{current}\n{line}" if current else line
        if len(candidate) > limit and current:
            chunks.append(current)
            current = line
        else:
            current = candidate
    if current:
        chunks.append(current)
    return chunks