"""B06 종횡단 생성 엔진 오케스트레이터.

확정 경로 GeoJSON과 확정 지표면 모델 sampler로 종단·횡단을 생성하고, 종단은
longitudinal/, 각 횡단은 cross_sections/ 아래 파일로 저장한다. DB 기록용
데이터(경로·요약·측점별 파일)를 준비해 반환한다. 라우터에서 asyncio.to_thread로
호출한다.
"""

import json
from pathlib import Path
from typing import Any

from B06_wf3_ProfileCross.B06_wf3_ProfileCross_Engine_Sampler import build_surface_sampler
from B06_wf3_ProfileCross.B06_wf3_ProfileCross_Engine_Section import (
    SectionGenerationOptions,
    generate_sections,
)
from common_util.common_util_json import atomic_write_json

_STAGE_SUBDIR = Path("B06_wf3_ProfileCross")
_MODELS_SUBDIR = Path("B04_wf1_Surface") / "models"


def _load_route_polyline(project_root: Path, route_data_path: str) -> list[list[float]]:
    """B05가 저장한 경로 GeoJSON에서 3D 폴리라인 좌표열을 로드한다."""
    geojson_path = project_root / Path(route_data_path)
    if not geojson_path.is_file():
        raise FileNotFoundError(f"경로 GeoJSON을 찾을 수 없습니다: {route_data_path}")
    geo = json.loads(geojson_path.read_text(encoding="utf-8"))
    coords = geo.get("geometry", {}).get("coordinates")
    if not coords or len(coords) < 2:
        raise ValueError("경로 GeoJSON에 유효한 LineString 좌표가 없습니다.")
    return [[float(c[0]), float(c[1]), float(c[2]) if len(c) > 2 else 0.0] for c in coords]


def _cross_summary(cross_section: dict[str, Any]) -> dict[str, Any]:
    """횡단면 상세에서 DB data 컬럼에 저장할 요약을 만든다."""
    samples = cross_section.get("samples", [])
    valid_z = [s["elevation_m"] for s in samples if s.get("valid") and s.get("elevation_m") is not None]
    return {
        "chainage_m": cross_section.get("chainage_m"),
        "center_z": cross_section.get("center_z"),
        "azimuth_deg": cross_section.get("azimuth_deg"),
        "sample_count": len(samples),
        "min_elevation_m": min(valid_z) if valid_z else None,
        "max_elevation_m": max(valid_z) if valid_z else None,
    }


def run_section_generation(
    project_root: Path,
    route_data_path: str,
    filter_key: str,
    method: str,
    smooth: bool,
    *,
    options: SectionGenerationOptions | None = None,
    crs: str | None = None,
) -> dict[str, Any]:
    """종횡단을 생성·저장하고 DB 기록용 데이터를 반환한다.

    반환 dict:
      - longitudinal: {file_path, data(요약)}
      - cross_sections: [{chainage_m, sequence_num, data(요약), cross_section_file_path}]
      - result: generate_sections 원본 결과
    """
    polyline = _load_route_polyline(project_root, route_data_path)
    models_dir = project_root / _MODELS_SUBDIR
    sampler = build_surface_sampler(models_dir, filter_key, method, smooth)

    result = generate_sections(
        polyline,
        sampler,
        options,
        source_snapshot={"filter": filter_key, "method": method, "smooth": smooth},
        crs=crs,
    )

    stage_root = project_root / _STAGE_SUBDIR
    long_dir = stage_root / "longitudinal"
    cross_dir = stage_root / "cross_sections"
    long_dir.mkdir(parents=True, exist_ok=True)
    cross_dir.mkdir(parents=True, exist_ok=True)

    # 종단면 저장
    long_file = long_dir / "longitudinal.json"
    atomic_write_json(long_file, result["longitudinal"])
    long_summary = {
        "length_m": result["longitudinal"]["length_m"],
        "station_count": result["summary"]["station_count"],
        "invalid_samples": result["summary"]["invalid_longitudinal_samples"],
    }

    # 측점별 횡단면 저장
    cross_records: list[dict[str, Any]] = []
    for seq, cross_section in enumerate(result["cross_sections"]):
        chainage = float(cross_section["chainage_m"])
        filename = f"cross_{int(round(chainage)):05d}m.json"
        cross_file = cross_dir / filename
        atomic_write_json(cross_file, cross_section)
        cross_records.append(
            {
                "chainage_m": chainage,
                "sequence_num": seq,
                "data": _cross_summary(cross_section),
                "cross_section_file_path": cross_file.relative_to(project_root).as_posix(),
            }
        )

    return {
        "longitudinal": {
            "file_path": long_file.relative_to(project_root).as_posix(),
            "data": long_summary,
        },
        "cross_sections": cross_records,
        "result": result,
    }