"""City areas & responsibility (P3) — list, tree, sync-from-graph, assign."""
from fastapi import APIRouter, HTTPException

from app.auth import CurrentUser
from app.contracts import AreaUpdate
from app.db import list_areas, update_area, upsert_area
from app.api.graph import _get_graph

router = APIRouter()


def _area_level(area_id: str) -> str:
    """Derive admin level from the GB/T 2260 6-digit code."""
    if area_id.isdigit() and len(area_id) == 6:
        if area_id.endswith("0000"):
            return "province"
        if area_id.endswith("00"):
            return "city"
        return "county"
    return "poi"  # semantic graph areas (e.g. jiaxiu_lou)


def _area_parent(area_id: str, level: str) -> str | None:
    if level == "city":
        return area_id[:2] + "0000"
    if level == "county":
        return area_id[:4] + "00"
    return None


@router.get("/areas")
async def _list(_user: CurrentUser = None):
    return await list_areas()


@router.get("/areas/tree")
async def _tree(_user: CurrentUser = None):
    """省 > 市 > 区县 hierarchy, plus a group for 专题/自定义 areas."""
    rows = await list_areas()
    by_id = {r["area_id"]: r for r in rows}

    def node(r):
        return {
            "value": r["area_id"],
            "title": f'{r["name"]}（{r["area_id"]}）',
            "name": r["name"],
            "level": r["level"],
            "children": [],
        }

    nodes = {aid: node(r) for aid, r in by_id.items()}
    roots: list = []
    specials: list = []
    for aid, r in by_id.items():
        lvl = r["level"]
        if lvl == "province":
            roots.append(nodes[aid])
        elif lvl in ("city", "county"):
            parent = r.get("parent_id")
            if parent and parent in nodes:
                nodes[parent]["children"].append(nodes[aid])
            else:
                roots.append(nodes[aid])
        else:
            specials.append(nodes[aid])

    # collapse empty children
    def clean(n):
        n["children"] = [clean(c) for c in n["children"]]
        if not n["children"]:
            n.pop("children")
        return n

    tree = [clean(r) for r in roots]
    if specials:
        tree.append({
            "value": "__special__",
            "title": "专题 / 自定义区域",
            "selectable": False,
            "children": specials,
        })
    return tree


@router.post("/areas/sync-from-graph")
async def _sync(_user: CurrentUser):
    """Pull Area nodes from the knowledge graph, computing admin levels."""
    try:
        g = _get_graph()
        res = g.query("MATCH (a:Area) RETURN a")
    except Exception as e:
        raise HTTPException(400, f"读取图谱失败：{str(e)[:200]}")

    synced = 0
    for row in res.result_set:
        node = row[0]
        props = getattr(node, "properties", {}) or {}
        area_id = str(props.get("area_id") or "").strip()
        if not area_id:
            continue
        name = str(props.get("name") or area_id)
        lvl = _area_level(area_id)
        await upsert_area(area_id, name, lvl, _area_parent(area_id, lvl))
        synced += 1
    return {"synced": synced}


@router.patch("/areas/{area_id}")
async def _update(area_id: str, body: AreaUpdate, _user: CurrentUser):
    row = await update_area(area_id, body.model_dump(exclude_none=True))
    if not row:
        raise HTTPException(404, "区域不存在")
    return row