from __future__ import annotations

from typing import Any

from yuxi.channels.models import ChannelResponse

_PARAGRAPH_SEP = "\n\n"
_DEFAULT_CHUNK_LIMIT = 16383


def build_post_options(response: ChannelResponse) -> dict[str, Any]:
    return {
        "channel_id": response.identity.channel_chat_id,
        "message": response.content,
        "root_id": response.reply_to_message_id or "",
        "props": response.metadata.get("props", {}),
        "file_ids": response.metadata.get("file_ids", []),
    }


def build_patch_options(chunk_text: str) -> dict[str, Any]:
    return {"message": chunk_text}


def chunk_text_for_outbound(text: str, limit: int = _DEFAULT_CHUNK_LIMIT) -> list[str]:
    """按段落边界将文本拆分为不超过 limit 的分块。

    优先在双换行符（段落）边界拆分；如果单段仍超限，
    则在单换行符（行）边界拆分；如果单行仍超限，则硬截断。
    """
    if len(text) <= limit:
        return [text]

    chunks: list[str] = []
    paragraphs = text.split(_PARAGRAPH_SEP)

    current = ""
    for para in paragraphs:
        if len(para) > limit:
            if current:
                chunks.append(current.rstrip())
                current = ""

            chunks.extend(_split_by_lines(para, limit))
            continue

        candidate = f"{current}{_PARAGRAPH_SEP}{para}" if current else para
        if len(candidate) > limit:
            chunks.append(current.rstrip())
            current = para
        else:
            current = candidate

    if current:
        chunks.append(current.rstrip())

    if not chunks:
        chunks.append(text[:limit])

    return chunks


def _split_by_lines(text: str, limit: int) -> list[str]:
    """在换行符边界拆分超限段落。"""
    chunks: list[str] = []
    lines = text.split("\n")
    current = ""
    for line in lines:
        if len(line) > limit:
            if current:
                chunks.append(current.rstrip())
                current = ""
            chunks.extend(_split_hard(line, limit))
            continue

        candidate = f"{current}\n{line}" if current else line
        if len(candidate) > limit:
            chunks.append(current.rstrip())
            current = line
        else:
            current = candidate

    if current:
        chunks.append(current.rstrip())

    return chunks


def _split_hard(text: str, limit: int) -> list[str]:
    """硬截断超长行。"""
    return [text[i : i + limit] for i in range(0, len(text), limit)]