"""경위도 ↔ 사업지 좌표 묶음 변환(635-5 · 요구 546) — B05 위치 찾기 이동 · 속성 판 경위도.

계산 자리 ③ 서버 단독 · 읽기만. 사업지 좌표계 = 작업 좌표계 창구(`resolve_project_crs` · 설계 노선
`crs_input` 먼저 · WKT 원문 그대로 = 지역 TOWGS84 보존) · pyproj 한 번에 여러 점.
화면은 찾기 · 노드 고름 때만 부름(끌기 중 아님).

  POST /api/projects/{id}/route/coords  {to: "plan" | "lonlat", points: [[a, b], …]}
    → {points: [[a, b], …]}   plan = 경위도 [lon, lat] → [x, y] m · lonlat = 반대
    404 프로젝트 없음 · 422 점 꼴 틀림
"""

from __future__ import annotations

import asyncio
from functools import lru_cache
from pathlib import Path
from typing import Literal
from uuid import UUID

from fastapi import APIRouter, HTTPException
from pydantic import BaseModel, Field
from pyproj import Transformer

from B05_Profile.B05_Profile_Router_Replan import _project_paths

router = APIRouter(prefix="/api/projects", tags=["B05 Route Coords"])

MAX_POINTS = 5000


class CoordsRequest(BaseModel):
    to: Literal["plan", "lonlat"]
    points: list[tuple[float, float]] = Field(max_length=MAX_POINTS)


def project_crs_text(root: Path) -> str:
    """작업 좌표계 pyproj 입력(`EPSG:n` · WKT) — 라이다 `project_epsg` 와 같은 사다리."""
    from common_util.common_util_crs import resolve_project_crs
    from common_util.common_util_route_geometry import load_design_route

    planned = load_design_route(root)
    return resolve_project_crs(root, route_crs_input=planned.crs_input if planned else None)


@lru_cache(maxsize=32)
def _transformer(crs_text: str, to: str) -> Transformer:
    pair = ("EPSG:4326", crs_text) if to == "plan" else (crs_text, "EPSG:4326")
    return Transformer.from_crs(*pair, always_xy=True)


def convert(crs_text: str, to: str, points: list[tuple[float, float]]) -> list[list[float]]:
    """점 묶음 변환 — 경위도 순서 [lon, lat] · 사업지 [x 동, y 북]."""
    if not points:
        return []
    xs, ys = zip(*points)
    a, b = _transformer(crs_text, to).transform(xs, ys)
    return [[float(p), float(q)] for p, q in zip(a, b)]


@router.post("/{project_id}/route/coords", response_model=None)
async def route_coords(project_id: UUID, body: CoordsRequest) -> dict:
    paths = await _project_paths(project_id)
    if paths is None:
        raise HTTPException(status_code=404, detail="프로젝트 저장 경로를 찾을 수 없습니다.")
    crs_text = await asyncio.to_thread(project_crs_text, paths[0])
    points = await asyncio.to_thread(convert, crs_text, body.to, body.points)
    return {"points": points}