"""把一句话变成任务或知识草稿。

微信只负责把文本送进来，怎么落成事项是这里的事，接口和后台轮询共用同一份逻辑，
免得"网页里发"和"机器人里发"落成两种东西。
"""

from __future__ import annotations

import uuid
from typing import Any

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from ..errors import AppError, ErrorCode
from ..models import Member, Workspace
from ..models_integrations import BotChannel
from ..models_knowledge import KnowledgeDoc
from ..models_task import Item

MAX_TITLE = 180
MAX_BODY = 20000

KNOWLEDGE_PREFIXES = ("知识", "笔记", "note", "knowledge", "kb")
TASK_PREFIXES = ("任务", "待办", "todo", "task")
HELP_PREFIXES = ("?", "？", "帮助", "help", "用法")

HELP_TEXT = (
    "发什么都能用，写法：\n"
    "· 直接说　→ 记成任务\n"
    "· 知识：内容　→ 记成知识草稿（也可以写「笔记：」）\n"
    "· 任务：内容　→ 明确记成任务\n"
    "首行当标题，后面几行当正文；标题里带 #标签 会自动加上。"
)

SEPARATORS = (":", "：", " ", "\u3000")


def split_command(text: str) -> tuple[str, str]:
    """返回 (kind, 去掉前缀后的正文)。"""
    head, _, rest = text.partition("\n")
    probe = head.strip().lower()
    for prefix in HELP_PREFIXES:
        if probe == prefix or probe.startswith(f"{prefix}:") or probe.startswith(f"{prefix}："):
            return "help", rest
    for prefix in KNOWLEDGE_PREFIXES:
        for sep in SEPARATORS:
            if probe.startswith(f"{prefix}{sep}"):
                offset = len(prefix) + len(sep)
                return "knowledge", (head.strip()[offset:] + ("\n" + rest if rest else "")).strip()
    for prefix in TASK_PREFIXES:
        for sep in SEPARATORS:
            if probe.startswith(f"{prefix}{sep}"):
                offset = len(prefix) + len(sep)
                return "task", (head.strip()[offset:] + ("\n" + rest if rest else "")).strip()
    return "task", text


def split_tags(body: str) -> tuple[str, list[str]]:
    """把 `#标签` 摘出来。只认行首和空白后的 #，免得把 "C#" 吃掉。"""
    tags: list[str] = []
    kept: list[str] = []
    for line in body.splitlines():
        rest: list[str] = []
        for word in line.split(" "):
            if word.startswith("#") and len(word) > 1 and not word[1:].isdigit():
                name = word[1:].strip("，,。.;；")
                if name and name.lower() not in {t.lower() for t in tags}:
                    tags.append(name)
                continue
            rest.append(word)
        kept.append(" ".join(rest).rstrip())
    return "\n".join(kept).strip(), tags


def split_title(body: str) -> tuple[str, str]:
    lines = body.splitlines()
    if not lines:
        return "", ""
    return lines[0].strip()[:MAX_TITLE], "\n".join(lines[1:]).strip()[:MAX_BODY]


async def creator_id(session: AsyncSession, channel: BotChannel) -> uuid.UUID:
    """消息记在谁名下：通道创建者；人没了就退回工作区 owner。"""
    if channel.created_by is not None:
        row = await session.execute(
            select(Member.id).where(
                Member.workspace_id == channel.workspace_id,
                Member.user_id == channel.created_by,
                Member.status == "active",
            )
        )
        if row.first() is not None:
            return channel.created_by
    workspace = await session.get(Workspace, channel.workspace_id)
    if workspace is None:  # 理论上不可能：FK 是 CASCADE
        raise AppError(ErrorCode.BOT_TOKEN_INVALID, "接入通道不存在")
    return workspace.owner_id


async def create_task(
    session: AsyncSession,
    *,
    ws_id: uuid.UUID,
    creator: uuid.UUID,
    title: str,
    body: str,
    tags: list[str],
) -> Item:
    item = Item(
        workspace_id=ws_id,
        kind="task",
        title=title,
        body_md=body,
        status="inbox",
        priority=0,
        creator_id=creator,
    )
    session.add(item)
    await session.flush()
    from ..api.items import _log, _set_tags  # 延迟导入：services 不该在模块级依赖 api

    if tags:
        await _set_tags(session, ws_id, item, tags)
    await _log(session, item, creator, "created", {"via": "wechat_clawbot"})
    return item


async def create_knowledge(
    session: AsyncSession,
    *,
    ws_id: uuid.UUID,
    creator: uuid.UUID,
    title: str,
    body: str,
    tags: list[str],
) -> Item:
    item = Item(
        workspace_id=ws_id,
        kind="knowledge",
        title=title,
        body_md=body,
        status="draft",
        creator_id=creator,
    )
    session.add(item)
    await session.flush()
    session.add(
        KnowledgeDoc(
            item_id=item.id,
            workspace_id=ws_id,
            author_id=creator,
            source_item_id=None,
            source_kind="manual",
            doc_type="note",
            status_hint="draft",
            generated_by="human",
        )
    )
    await session.flush()
    from ..api.items import _log, _set_tags  # 延迟导入，理由同上

    if tags:
        await _set_tags(session, ws_id, item, tags)
    await _log(session, item, creator, "knowledge_created", {"via": "wechat_clawbot"})
    return item


def reply_text(kind: str, item: Item) -> str:
    """回话只说"收下了"，不带链接。

    链接是站点地址，可"站点地址"对手机不一定打得开（内网 IP、端口、还没上 HTTPS 的域名），
    发过去反而像坏消息。要看详情回网页里看就行。
    """
    if kind == "knowledge":
        return f"已保存知识草稿：{item.title}"
    return f"已保存任务：{item.title}"


async def handle_text(
    session: AsyncSession,
    channel: BotChannel,
    text: str,
    *,
    base_url: str,
) -> dict[str, Any]:
    """一段文本 → (action, item_id, reply)。调用方负责提交事务与留痕。"""
    kind, body = split_command(text.strip())
    if kind == "help":
        return {"action": "help", "item_id": None, "reply": HELP_TEXT}
    body, tags = split_tags(body)
    title, rest = split_title(body)
    if not title:
        return {"action": "ignored", "item_id": None, "reply": "内容是空的，没记。"}
    creator = await creator_id(session, channel)
    if kind == "knowledge":
        item = await create_knowledge(
            session,
            ws_id=channel.workspace_id,
            creator=creator,
            title=title,
            body=rest,
            tags=tags,
        )
        return {
            "action": "knowledge",
            "item_id": item.id,
            "reply": reply_text("knowledge", item),
        }
    item = await create_task(
        session,
        ws_id=channel.workspace_id,
        creator=creator,
        title=title,
        body=rest,
        tags=tags,
    )
    return {
        "action": "task",
        "item_id": item.id,
        "reply": reply_text("task", item),
    }