"""知识域接口（M3）：草稿、审议、发布、归档，以及"从事项沉淀"。

一条知识的一生：

    工单验收通过（或你手动点"沉淀成知识"）
      -> draft      草稿：系统整理好了，等你核对
      -> in_review  提交审议：让同事看一遍（可选）
      -> published  发布：进团队检索、能被问答引用
      -> archived   归档：不删，退出检索（历史结论不该消失）

为什么要 `draft` 这一步：自动整理的东西一定有"看着像那么回事、其实漏了前提"的情况，
让人扫一眼的成本远低于让整个团队按错的结论办事。发布权收紧到 owner/admin 也是同理——
发布等于团队背书。
"""

from __future__ import annotations

import uuid
from datetime import datetime, timezone
from typing import Annotated, Any

from fastapi import APIRouter, Query
from pydantic import BaseModel, Field
from sqlalchemy import Select, and_, or_, select, update
from sqlalchemy.ext.asyncio import AsyncSession

from ..audit import record as audit_record
from ..deps import MemberDep, SessionDep
from ..domain.knowledge import can_publish_role, sidebar_fields, target_status
from ..errors import AppError, ErrorCode
from ..models_knowledge import DOC_TYPES, KNOWLEDGE_STATUSES, KnowledgeDoc
from ..models_task import Activity, Item
from ..schemas import clamp_limit, decode_cursor, encode_cursor, ok
from ..serializers import item_out, tags_of
from ..services.knowledge import create_draft_from_source, find_doc_by_source
from .attachments import count_for_items, list_for_item

router = APIRouter(prefix="/workspaces/{ws_id}", tags=["知识库"])


# ── 入参 ────────────────────────────────────────────────────────────────
class KnowledgeIn(BaseModel):
    title: str = Field(min_length=1, max_length=200)
    body_md: str = ""
    summary: str = Field(default="", max_length=2000)
    doc_type: str = "note"
    source_item_id: uuid.UUID | None = None
    tag_names: list[str] = Field(default_factory=list)


class KnowledgePatch(BaseModel):
    title: str | None = Field(default=None, min_length=1, max_length=200)
    body_md: str | None = None
    summary: str | None = None
    doc_type: str | None = None
    tag_names: list[str] | None = None
    version: int


class StatusActionIn(BaseModel):
    action: str
    version: int
    note: str = ""


# ── 内部工具 ────────────────────────────────────────────────────────────
async def _load_doc(
    session: AsyncSession, ws_id: uuid.UUID, item_id: uuid.UUID
) -> tuple[Item, KnowledgeDoc]:
    item = await session.get(Item, item_id)
    doc = await session.get(KnowledgeDoc, item_id)
    if item is None or doc is None or item.workspace_id != ws_id or item.kind != "knowledge":
        raise AppError(ErrorCode.KNOWLEDGE_NOT_FOUND, "这份知识不存在")
    return item, doc


async def _log(
    session: AsyncSession, item: Item, actor_id: uuid.UUID, action: str, payload: dict | None = None
) -> None:
    session.add(
        Activity(
            workspace_id=item.workspace_id,
            item_id=item.id,
            actor_id=actor_id,
            action=action,
            payload=payload or {},
        )
    )


async def _source_out(
    session: AsyncSession, ws_id: uuid.UUID, source_item_id: uuid.UUID | None
) -> dict[str, Any] | None:
    if source_item_id is None:
        return None
    source = await session.get(Item, source_item_id)
    if source is None or source.workspace_id != ws_id:
        return None
    return {
        "id": str(source.id),
        "kind": source.kind,
        "title": source.title,
        "status": source.status,
    }


def _doc_out(doc: KnowledgeDoc) -> dict[str, Any]:
    return {
        "doc_type": doc.doc_type,
        "summary": doc.summary,
        "status_hint": doc.status_hint,
        "source_kind": doc.source_kind,
        "source_item_id": str(doc.source_item_id) if doc.source_item_id else None,
        "generated_by": doc.generated_by,
        "published_at": doc.published_at,
        "archived_at": doc.archived_at,
        "chunk_count": doc.chunk_count,
        "author_id": str(doc.author_id),
    }


async def _knowledge_out(
    session: AsyncSession, ws_id: uuid.UUID, item: Item, doc: KnowledgeDoc
) -> dict[str, Any]:
    tags = (await tags_of(session, ws_id, [item.id])).get(item.id, [])
    data = item_out(item, tags)
    data["knowledge"] = _doc_out(doc)
    data["source"] = await _source_out(session, ws_id, doc.source_item_id)
    data["attachments"] = await list_for_item(session, ws_id, item.id)
    data["attachment_count"] = len(data["attachments"])
    return data


async def _set_tags_for(
    session: AsyncSession, ws_id: uuid.UUID, item: Item, names: list[str]
) -> None:
    from .items import _set_tags

    await _set_tags(session, ws_id, item, names)


# ── 列表 / 详情 ─────────────────────────────────────────────────────────
@router.get("/knowledge", summary="知识列表")
async def list_knowledge(
    ctx: MemberDep,
    session: SessionDep,
    status: Annotated[list[str] | None, Query()] = None,
    doc_type: Annotated[str | None, Query()] = None,
    source_item_id: Annotated[uuid.UUID | None, Query()] = None,
    q: Annotated[str | None, Query(max_length=100)] = None,
    limit: Annotated[int, Query(ge=1, le=100, description="每页条数")] = 30,
    cursor: Annotated[str | None, Query(description="上一页返回的 next_cursor")] = None,
) -> dict:
    ws_id = ctx.ws_id
    stmt: Select = (
        select(Item, KnowledgeDoc)
        .join(KnowledgeDoc, KnowledgeDoc.item_id == Item.id)
        .where(Item.workspace_id == ws_id, Item.kind == "knowledge", Item.deleted_at.is_(None))
    )
    wanted = [s for s in (status or []) if s in KNOWLEDGE_STATUSES]
    if wanted:
        stmt = stmt.where(KnowledgeDoc.status_hint.in_(wanted))
    if doc_type:
        stmt = stmt.where(KnowledgeDoc.doc_type == doc_type)
    if source_item_id:
        stmt = stmt.where(KnowledgeDoc.source_item_id == source_item_id)
    if q:
        like = f"%{q.strip()}%"
        stmt = stmt.where(
            or_(Item.title.ilike(like), Item.body_md.ilike(like), KnowledgeDoc.summary.ilike(like))
        )
    if cursor:
        cur = decode_cursor(cursor)
        stmt = stmt.where(
            or_(
                Item.updated_at < cur.created_at,
                and_(Item.updated_at == cur.created_at, Item.id < cur.item_id),
            )
        )

    limit = clamp_limit(limit)
    rows = (
        await session.execute(
            stmt.order_by(Item.updated_at.desc(), Item.id.desc()).limit(limit + 1)
        )
    ).all()
    has_more = len(rows) > limit
    rows = rows[:limit]
    tag_map = await tags_of(session, ws_id, [it.id for it, _ in rows])

    items = []
    counts = await count_for_items(session, ws_id, [it.id for it, _ in rows])
    for item, doc in rows:
        data = item_out(item, tag_map.get(item.id, []))
        data["knowledge"] = _doc_out(doc)
        data["source"] = await _source_out(session, ws_id, doc.source_item_id)
        data["attachment_count"] = counts.get(str(item.id), 0)
        items.append(data)

    next_cursor = (
        encode_cursor(rows[-1][0].updated_at, rows[-1][0].id) if has_more and rows else None
    )
    return ok({"items": items, "next_cursor": next_cursor, "has_more": has_more})


@router.get("/knowledge/{item_id}", summary="知识详情")
async def get_knowledge(item_id: uuid.UUID, ctx: MemberDep, session: SessionDep) -> dict:
    item, doc = await _load_doc(session, ctx.ws_id, item_id)
    data = await _knowledge_out(session, ctx.ws_id, item, doc)
    events = (
        await session.execute(
            select(Activity)
            .where(Activity.workspace_id == ctx.ws_id, Activity.item_id == item.id)
            .order_by(Activity.created_at.desc())
            .limit(50)
        )
    ).scalars()
    data["activities"] = [
        {
            "action": e.action,
            "payload": e.payload,
            "actor_id": str(e.actor_id) if e.actor_id else None,
            "created_at": e.created_at,
        }
        for e in events
    ]
    return ok(data)


# ── 创建 / 修改 ─────────────────────────────────────────────────────────
@router.post("/knowledge", summary="新建知识（手记或引用来源）")
async def create_knowledge(body: KnowledgeIn, ctx: MemberDep, session: SessionDep) -> dict:
    ws_id = ctx.ws_id
    if body.doc_type not in DOC_TYPES:
        raise AppError(ErrorCode.VALIDATION_ERROR, f"未知的知识类型：{body.doc_type}")

    source: Item | None = None
    if body.source_item_id is not None:
        source = await session.get(Item, body.source_item_id)
        if source is None or source.workspace_id != ws_id or source.kind not in ("task", "ticket"):
            raise AppError(
                ErrorCode.KNOWLEDGE_SOURCE_REQUIRED,
                "来源必须是与本知识同一工作区的任务或工单",
            )

    item = Item(
        workspace_id=ws_id,
        kind="knowledge",
        title=body.title.strip(),
        body_md=body.body_md,
        status="draft",
        creator_id=ctx.user.id,
    )
    session.add(item)
    await session.flush()

    doc = KnowledgeDoc(
        item_id=item.id,
        workspace_id=ws_id,
        author_id=ctx.user.id,
        source_item_id=source.id if source else None,
        source_kind="manual" if source is None else source.kind,
        doc_type=body.doc_type,
        status_hint="draft",
        summary=body.summary,
        generated_by="human",
    )
    session.add(doc)
    await session.flush()
    await _log(session, item, ctx.user.id, "knowledge_created", {"generated_by": "human"})
    await _set_tags_for(session, ws_id, item, body.tag_names)
    await audit_record(
        session,
        workspace_id=ws_id,
        actor_user_id=ctx.user.id,
        action="knowledge.create",
        target_type="item",
        target_id=str(item.id),
    )
    return ok(await _knowledge_out(session, ws_id, item, doc))


@router.patch("/knowledge/{item_id}", summary="修改知识内容")
async def patch_knowledge(
    item_id: uuid.UUID, body: KnowledgePatch, ctx: MemberDep, session: SessionDep
) -> dict:
    ws_id = ctx.ws_id
    item, doc = await _load_doc(session, ws_id, item_id)
    if item.status == "published":
        raise AppError(
            ErrorCode.KNOWLEDGE_STATUS_INVALID,
            "已发布的知识不能直接改内容，先撤回成草稿",
            details={"from": item.status, "allowed_actions": ["archive"]},
        )
    if body.doc_type is not None and body.doc_type not in DOC_TYPES:
        raise AppError(ErrorCode.VALIDATION_ERROR, f"未知的知识类型：{body.doc_type}")

    values: dict[str, Any] = {}
    if body.title is not None:
        values["title"] = body.title.strip()
    if body.body_md is not None:
        values["body_md"] = body.body_md
    if body.summary is not None:
        values["summary"] = body.summary
    if body.doc_type is not None:
        values["doc_type"] = body.doc_type

    if values:
        values["updated_at"] = datetime.now(timezone.utc)
        result = await session.execute(
            update(Item)
            .where(
                Item.id == item.id,
                Item.workspace_id == ws_id,
                Item.version == body.version,
                Item.deleted_at.is_(None),
            )
            .values(version=Item.version + 1, **values)
        )
        if result.rowcount == 0:
            await session.refresh(item)
            raise AppError(
                ErrorCode.VERSION_CONFLICT,
                "这条内容刚被别人改过",
                details={"current_version": item.version},
            )
        await session.refresh(item)
    if body.doc_type is not None:
        doc.doc_type = body.doc_type
    if body.summary is not None:
        doc.summary = body.summary
    if body.tag_names is not None:
        await _set_tags_for(session, ws_id, item, body.tag_names)
    await session.flush()
    return ok(await _knowledge_out(session, ws_id, item, doc))


# ── 状态动作 ────────────────────────────────────────────────────────────
@router.post("/knowledge/{item_id}/status", summary="提交审议 / 发布 / 归档 / 恢复")
async def change_status(
    item_id: uuid.UUID, body: StatusActionIn, ctx: MemberDep, session: SessionDep
) -> dict:
    ws_id = ctx.ws_id
    item, doc = await _load_doc(session, ws_id, item_id)
    to_status = target_status(body.action, item.status)

    # 发布等于团队背书；归档/恢复作者自己就能做
    if body.action == "publish" and not can_publish_role(ctx.role):
        raise AppError(
            ErrorCode.KNOWLEDGE_FORBIDDEN,
            "只有管理员可以发布知识",
            details={"role": ctx.role},
        )

    now = datetime.now(timezone.utc)
    result = await session.execute(
        update(Item)
        .where(
            Item.id == item.id,
            Item.workspace_id == ws_id,
            Item.version == body.version,
            Item.deleted_at.is_(None),
        )
        .values(version=Item.version + 1, status=to_status, updated_at=now)
    )
    if result.rowcount == 0:
        await session.refresh(item)
        raise AppError(
            ErrorCode.VERSION_CONFLICT,
            "这条内容刚被别人改过",
            details={"current_version": item.version},
        )
    await session.refresh(item)
    # 发布时间/归档时间记在 knowledge_doc 上（item 只有 status）
    doc.status_hint = to_status
    stamps = sidebar_fields(to_status, now)
    if "published_at" in stamps:
        doc.published_at = stamps["published_at"]
        doc.archived_at = None
    if "archived_at" in stamps:
        doc.archived_at = stamps["archived_at"]
    await _log(
        session,
        item,
        ctx.user.id,
        "knowledge_status_changed",
        {"action": body.action, "to": to_status, "note": body.note},
    )
    await audit_record(
        session,
        workspace_id=ws_id,
        actor_user_id=ctx.user.id,
        action=f"knowledge.{body.action}",
        target_type="item",
        target_id=str(item.id),
        payload={"to": to_status},
    )
    await session.flush()
    return ok(await _knowledge_out(session, ws_id, item, doc))


# ── 从任务/工单沉淀 ─────────────────────────────────────────────────────
@router.post("/items/{item_id}/knowledge", summary="把这件事沉淀成知识草稿")
async def promote_to_knowledge(
    item_id: uuid.UUID,
    ctx: MemberDep,
    session: SessionDep,
    doc_type: Annotated[str, Query()] = "postmortem",
) -> dict:
    ws_id = ctx.ws_id
    source = await session.get(Item, item_id)
    if source is None or source.workspace_id != ws_id or source.kind not in ("task", "ticket"):
        raise AppError(ErrorCode.ITEM_NOT_FOUND, "任务不存在")
    if doc_type not in DOC_TYPES:
        raise AppError(ErrorCode.VALIDATION_ERROR, f"未知的知识类型：{doc_type}")

    existing = await find_doc_by_source(session, ws_id, source.id)
    if existing is not None:
        raise AppError(
            ErrorCode.KNOWLEDGE_ALREADY_EXISTS,
            "这件事已经沉淀过了",
            details={"knowledge_id": str(existing.item_id)},
        )

    resolution = ""
    if source.kind == "ticket":
        from ..models_ticket import TicketExt

        ext = await session.get(TicketExt, source.id)
        if ext is not None and ext.resolution_md:
            resolution = ext.resolution_md

    doc_item, doc = await create_draft_from_source(
        session,
        ws_id=ws_id,
        source=source,
        author_id=ctx.user.id,
        generated_by="rule" if source.kind == "ticket" else "human",
        resolution_md=resolution,
        doc_type=doc_type,
    )
    await _log(
        session, doc_item, ctx.user.id, "knowledge_created", {"source_item_id": str(source.id)}
    )
    await audit_record(
        session,
        workspace_id=ws_id,
        actor_user_id=ctx.user.id,
        action="knowledge.promote",
        target_type="item",
        target_id=str(doc_item.id),
        payload={"source_item_id": str(source.id)},
    )
    # 与"新建知识"返回同一种形状：知识本体 + source，前端不用记两套
    return ok(await _knowledge_out(session, ws_id, doc_item, doc))