"""구조물 자리 기울기 — 물넘이포장 · 맹암거 측점의 노면(287-4 · 288-1).

그 자리 횡단 설계 = 측구 없음 · 노면 = 한 경사로 지대 낮은 쪽(`compute_cross_design(tilted=…,
tilt_pct=…)`). 경사 = 물넘이 경사각도(%) · 맹암거 암거 경사(%) · 비면 표준 횡단경사.
  · 물넘이포장 = 관 지점 정본(pipe_points) 범위(기준 ± 월류 폭/2).
  · 맹암거 = 구조물 정본(structures.json) A군 점형 · 기준 측점 한 곳 — 횡단 dict 에
    `underdrain`(높이 · 경사)을 얹어 횡단도가 돌 무늬 형상을 그림(TS 짝
    `common_util_structure_underdrain.ts`).
판정 폭 = 포장 범위와 같은 0.02 m(`paved_at`).
"""

from __future__ import annotations

import logging
from pathlib import Path
from typing import Any

from B05_Profile.B05_Profile_Structures_Repository import load_structures
from B06_Section.B06_Section_Engine_Culvert import load_culvert_sets

logger = logging.getLogger(__name__)

UNDERDRAIN_TYPE_ID = "cross_underdrain"
_EDGE_TOLERANCE_M = 0.02

TiltRange = tuple[float, float, float | None]


def _number(value: Any) -> float | None:
    try:
        parsed = float(value)
    except (TypeError, ValueError):
        return None
    return parsed if parsed == parsed else None


def load_underdrains(project_root: Path) -> list[dict[str, Any]]:
    """구조물 정본의 맹암거 — `{structure_id, chainage_m, height_m, slope_pct}` ·
    실패하면 빈 목록."""
    try:
        structures = load_structures(str(project_root))[1]
    except Exception:  # noqa: BLE001 — 정본을 못 읽어도 설계 계산은 이어 간다
        logger.exception("B06 맹암거를 읽지 못했습니다 (없음으로 본다)")
        return []
    found: list[dict[str, Any]] = []
    for structure in structures:
        if structure.type_id != UNDERDRAIN_TYPE_ID:
            continue
        options = structure.options or {}
        height = _number(options.get("culvert_height_m"))
        slope = _number(options.get("culvert_slope_pct"))
        found.append(
            {
                "structure_id": structure.structure_id,
                "chainage_m": float(structure.anchor_m()),
                "height_m": height if height and height > 0 else None,
                "slope_pct": slope if slope and slope > 0 else None,
            }
        )
    return found


def tilt_ranges(project_root: Path | None) -> list[TiltRange]:
    """측구 없이 노면을 지대 낮은 쪽 한 경사로 기울이는 자리 — (시작, 끝, 경사 %)."""
    if project_root is None:
        return []
    out: list[TiltRange] = []
    for at, spec in load_culvert_sets(project_root).items():
        if spec.get("type") == "ford_pavement":
            half = float(spec.get("span_m") or 0.0) / 2.0
            out.append((at - half, at + half, spec.get("slope_pct")))
    for drain in load_underdrains(project_root):
        out.append((drain["chainage_m"], drain["chainage_m"], drain["slope_pct"]))
    return out


def tilt_args(chainage_m: float, ranges: list[TiltRange]) -> dict[str, Any]:
    """그 측점의 구조물 자리 기울기 — `compute_cross_design(**...)` 로 넘김 ·
    저장분 짝 `stored_tilt`."""
    tol = _EDGE_TOLERANCE_M
    hit = next((r for r in ranges if r[0] - tol <= chainage_m <= r[1] + tol), None)
    pct = hit[2] if hit else None
    return {"tilted": hit is not None, "tilt_pct": float(pct) if pct is not None else None}


def attach_underdrains(project_root: Path, cross_sections: list[dict[str, Any]]) -> int:
    """맹암거 기준 측점의 횡단 dict 에 `underdrain` 을 얹는다. 얹은 개수를 돌려준다."""
    drains = load_underdrains(project_root)
    attached = 0
    for section in cross_sections:
        chainage = _number(section.get("chainage_m"))
        if chainage is None:
            continue
        hit = next(
            (d for d in drains if abs(d["chainage_m"] - chainage) <= _EDGE_TOLERANCE_M), None
        )
        if hit:
            section["underdrain"] = dict(hit)
            attached += 1
    return attached