/* =============================================================================
 * B05_Profile_UI_Page_Helpers.ts
 * B05 화면의 순수 도우미 — 설계폭 조회, 모델 경계 변환, 저장분 → 마커 복원,
 * 비정규 측점의 3D 좌표 선형보간.
 *
 * 화면 본체(B05_Profile_UI_Page)가 700줄 한계에 닿아 분리했다.
 * 전부 상태를 갖지 않는 변환 함수라 화면 흐름과 독립적이다.
 * ========================================================================== */

import type { RoutePanelValues } from "./B05_Profile_UI_Panel";
import type {
  ModelBounds,
  PlacedRoutePoint,
  RouteDesignPoints,
  RoutePointKind,
} from "./B05_Profile_UI_Markers";
import type { CirclePoint, RouteLatestResponse, RoutePoint } from "./B05_Profile_Api_Fetch";
import type { PipeFacility } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
import type { SectionStation } from "../B06_Section/B06_Section_Api_Fetch";
import {
  irregularLabel,
  irregularStationId,
  type IrregularStation,
} from "./B05_Profile_UI_IrregularStations";

type GradeClass = RoutePanelValues["gradeClass"];
export type RoadWidths = Record<GradeClass, number>;

export const DEFAULT_ROAD_WIDTHS: RoadWidths = { trunk: 3, branch: 3, work: 2.5 };

export async function fetchRoadWidths(projectId: string): Promise<RoadWidths> {
  const response = await fetch(`/api/projects/${projectId}/sections/road-widths`);
  if (!response.ok) return DEFAULT_ROAD_WIDTHS;
  const payload = (await response.json()) as { forest_road_min_width_m?: Partial<RoadWidths> };
  return { ...DEFAULT_ROAD_WIDTHS, ...payload.forest_road_min_width_m };
}

export function toBounds(bounds: {
  x_min: number;
  x_max: number;
  y_min: number;
  y_max: number;
  z_min: number;
  z_max: number;
}): ModelBounds {
  return {
    x: [bounds.x_min, bounds.x_max],
    y: [bounds.y_min, bounds.y_max],
    z: [bounds.z_min, bounds.z_max],
  };
}

export function placed(
  type: RoutePointKind,
  point: RoutePoint | CirclePoint,
  index = 0,
): PlacedRoutePoint {
  return {
    id: `${type}-restored-${index}`,
    type,
    x: point.x,
    y: point.y,
    // 표고를 모르면 모르는 채로 넘긴다 — 0으로 눕히면 마커가 지형 한참 아래 평면에 깔린다.
    z: point.z ?? null,
    ...(type === "ap" || type === "fp" ? { radius_m: (point as CirclePoint).radius_m ?? 25 } : {}),
  };
}

export function restorePoints(latest: RouteLatestResponse): RouteDesignPoints {
  const points = latest.route_params?.points;
  return {
    bp: points?.bp ? placed("bp", points.bp) : null,
    ep: points?.ep ? placed("ep", points.ep) : null,
    cp: (points?.cp ?? []).map((point, index) => placed("cp", point, index)),
    ap: (points?.ap ?? []).map((point, index) => placed("ap", point, index)),
    fp: (points?.fp ?? []).map((point, index) => placed("fp", point, index)),
  };
}

export function routePoint(point: PlacedRoutePoint): RoutePoint {
  // 서버 스키마는 표고를 빼면 "모름"으로 받는다 — null은 undefined로 바꿔 보낸다.
  return { x: point.x, y: point.y, z: point.z ?? undefined };
}

export function circlePoint(point: PlacedRoutePoint): CirclePoint {
  return { ...routePoint(point), radius_m: point.radius_m ?? 25 };
}

/**
 * 비정규 측점을 규칙 측점 좌표 사이 chainage로 선형보간해 `SectionStation`(월드 좌표·프레임 포함)으로
 * 만든다. 백엔드가 아직 이 측점의 횡단을 생성하지 않으므로, 3D 표시에 필요한 위치만 근사한다.
 * 노선 범위를 벗어난 chainage는 제외한다.
 */
export function interpolateIrregularStations(
  base: SectionStation[],
  list: IrregularStation[],
  maxChainage: number,
): SectionStation[] {
  const sorted = [...base].sort((a, b) => a.chainage_m - b.chainage_m);
  if (!sorted.length) return [];
  const anchorAt = (chainage: number): SectionStation => {
    if (chainage <= sorted[0].chainage_m) return sorted[0];
    const last = sorted[sorted.length - 1];
    if (chainage >= last.chainage_m) return last;
    let lo = sorted[0];
    let hi = last;
    for (let index = 1; index < sorted.length; index += 1) {
      if (sorted[index].chainage_m >= chainage) {
        lo = sorted[index - 1];
        hi = sorted[index];
        break;
      }
    }
    const span = hi.chainage_m - lo.chainage_m;
    const t = span > 1e-9 ? (chainage - lo.chainage_m) / span : 0;
    const lerp = (a: number, b: number): number => a + (b - a) * t;
    const centerZ =
      lo.center_z !== null && hi.center_z !== null
        ? lerp(lo.center_z, hi.center_z)
        : (lo.center_z ?? hi.center_z);
    return {
      ...lo,
      center_x: lerp(lo.center_x, hi.center_x),
      center_y: lerp(lo.center_y, hi.center_y),
      center_z: centerZ,
      frame: {
        left_xy: [
          lerp(lo.frame.left_xy[0], hi.frame.left_xy[0]),
          lerp(lo.frame.left_xy[1], hi.frame.left_xy[1]),
        ],
      },
    };
  };
  return list
    .filter((entry) => entry.chainage_m >= 0 && entry.chainage_m <= maxChainage + 1e-6)
    .map((entry) => ({
      ...anchorAt(entry.chainage_m),
      station_id: irregularStationId(entry.id),
      chainage_m: entry.chainage_m,
      label: irregularLabel(entry),
      kind: "irregular" as const,
      // 3D 측점 라벨이 `측점번호 구조물명`으로 표기할 수 있게 구조물 이름을 실어 보낸다.
      structure: entry.structure,
    }));
}

/** 시설 종류별 표시 이름 — 그래프·3D 라벨용(배관은 관종·관경까지 따로 붙인다). */
export const FACILITY_NAMES: Record<PipeFacility, string> = {
  pipe: "배수관",
  box_culvert: "BOX암거",
  ford_pavement: "물넘이포장",
  ford_bridge: "세월교",
};