from __future__ import annotations

from datetime import datetime
from typing import List, Optional

from fastapi import APIRouter, HTTPException
from fastapi.responses import Response
from pydantic import BaseModel

from app.db import get_pool
from app.routers.models import _bump_all_domain_versions

router = APIRouter(tags=["model_groups"])


class GroupIn(BaseModel):
    name: str
    note: Optional[str] = None


class GroupUpdate(BaseModel):
    name: Optional[str] = None
    note: Optional[str] = None


class GroupOut(BaseModel):
    id: int
    name: str
    note: Optional[str]
    model_count: int = 0
    created_at: datetime
    updated_at: datetime


class BatchAssignGroupIn(BaseModel):
    group_id: Optional[int] = None   # None 表示清除分组
    model_ids: List[int]


@router.get("/model-groups", response_model=List[GroupOut])
async def list_groups() -> List[GroupOut]:
    pool = get_pool()
    rows = await pool.fetch(
        """
        SELECT g.id, g.name, g.note, g.created_at, g.updated_at,
               COUNT(m.id) AS model_count
        FROM model_groups g
        LEFT JOIN models m ON m.group_id = g.id
        GROUP BY g.id
        ORDER BY g.created_at ASC
        """
    )
    return [GroupOut(**dict(r)) for r in rows]


@router.post("/model-groups", response_model=GroupOut, status_code=201)
async def create_group(body: GroupIn) -> GroupOut:
    pool = get_pool()
    row = await pool.fetchrow(
        """
        INSERT INTO model_groups (name, note)
        VALUES ($1, $2)
        RETURNING id, name, note, created_at, updated_at
        """,
        body.name, body.note,
    )
    return GroupOut(**dict(row), model_count=0)


@router.put("/model-groups/{group_id}", response_model=GroupOut)
async def update_group(group_id: int, body: GroupUpdate) -> GroupOut:
    pool = get_pool()
    existing = await pool.fetchrow(
        "SELECT id, name, note, created_at, updated_at FROM model_groups WHERE id = $1",
        group_id,
    )
    if existing is None:
        raise HTTPException(status_code=404, detail="分组不存在")
    new_name = body.name if body.name is not None else existing["name"]
    new_note = body.note if body.note is not None else existing["note"]
    row = await pool.fetchrow(
        """
        UPDATE model_groups SET name = $1, note = $2, updated_at = NOW()
        WHERE id = $3
        RETURNING id, name, note, created_at, updated_at
        """,
        new_name, new_note, group_id,
    )
    count = await pool.fetchval("SELECT COUNT(*) FROM models WHERE group_id = $1", group_id)
    return GroupOut(**dict(row), model_count=count or 0)


@router.delete("/model-groups/{group_id}", status_code=204, response_model=None)
async def delete_group(group_id: int) -> Response:
    pool = get_pool()
    # 删除分组时，将该分组下的模型 group_id 置为 NULL
    async with pool.acquire() as conn:
        async with conn.transaction():
            await conn.execute("UPDATE models SET group_id = NULL WHERE group_id = $1", group_id)
            result = await conn.execute("DELETE FROM model_groups WHERE id = $1", group_id)
    if result == "DELETE 0":
        raise HTTPException(status_code=404, detail="分组不存在")
    return Response(status_code=204)


@router.post("/model-groups/batch-assign", status_code=200)
async def batch_assign_group(body: BatchAssignGroupIn) -> dict:
    """批量将模型归入某个分组（group_id=None 则清除分组）"""
    if not body.model_ids:
        return {"updated": 0}
    pool = get_pool()
    if body.group_id is not None:
        exists = await pool.fetchval("SELECT id FROM model_groups WHERE id = $1", body.group_id)
        if not exists:
            raise HTTPException(status_code=404, detail="分组不存在")
    async with pool.acquire() as conn:
        async with conn.transaction():
            result = await conn.execute(
                "UPDATE models SET group_id = $1 WHERE id = ANY($2::bigint[])",
                body.group_id, body.model_ids,
            )
            updated = int(result.split()[-1]) if result else 0
            if updated > 0:
                await _bump_all_domain_versions(conn)
    return {"updated": updated}