/* =============================================================================
 * B06_Section_Station_Swap.ts
 * 측점 수가 바뀔 때 횡단 목록 갈아끼움(PLAN 346-2 4파) — 계산 묶음 측점(`PipelineStation[]`) → 새 상세 객체.
 *
 *   · 같은 측점(열쇠 · 없으면 같은 자리 같은 종류)은 앞 횡단을 이어 받음 — 설계 · 구조물 제원 · 이름 그대로 ·
 *     자리(누가거리 · 좌표 · 방위 · 확폭)와 지반 표본(채워 왔으면)만 새것.
 *   · 새 측점 = 지반 표본 + 기본 설계(계획고 0 → 낡음 → 브라우저 다시 셈이 곧 채움).
 *   · 빠진 측점 = 목록에서 뺌(세션 고침은 열쇠로 남음 · 노선이 바뀐 때만 「노선 밖 고침」 · 부르는 쪽).
 *   · 옛 상세는 그대로 둠 — 새 객체를 돌려줌(쥔 쪽이 갈아끼움).
 *
 * ⚠ 파이썬·TS 짝 — `B05_Profile_Engine_Sections_Core.py` `format_station` ↔ `formatStation`.
 *   거울 시험 `resources/tester/test_346_2_station_swap.py`.
 * 순수 계산(DOM · fetch · 세션 없음).
 * ========================================================================== */

import type { PipelineStation } from "../../A00_Common/design/logic/design_pipeline_types";
import type { CrossSection, SectionDetailResponse, SectionStation } from "../B06_Section_Api_Fetch";

interface Sample {
  offset_m: number;
  elevation_m: number | null;
  valid: boolean;
}

/** 지반 표본(중심 → 바깥 · 좌 +) → 엔진 표본(오프셋 오름차순 · 우 −). */
export function groundSamples(station: PipelineStation): Sample[] {
  const ground = station.ground;
  if (!ground) return [];
  const point = (offset: number, z: number | null): Sample => ({
    offset_m: offset,
    elevation_m: z,
    valid: z !== null && Number.isFinite(z),
  });
  const right = ground.right.map((s) => point(-s.offsetM, s.z));
  const left = ground.left.map((s) => point(s.offsetM, s.z));
  const out = [...right, ...left];
  if (ground.centerZ !== null && !out.some((s) => Math.abs(s.offset_m) < 1e-9))
    out.push(point(0, ground.centerZ));
  return out.sort((a, b) => a.offset_m - b.offset_m);
}

/** 짝: `format_station` — `STA.k+mmm.mmm`. */
export function formatStation(chainageM: number): string {
  const at = Math.max(chainageM, 0);
  const km = Math.floor(at / 1000);
  const rest = (at - km * 1000).toFixed(3).padStart(7, "0");
  return `STA.${km}+${rest}`;
}

/** 서버 측점 id 꼴(`station_000000484210` = 누가거리 mm 12자리). */
export const stationIdOf = (chainageM: number): string =>
  `station_${String(Math.round(chainageM * 1000)).padStart(12, "0")}`;

/** 새 측점의 기본 설계 — 계획고 0 이라 늘 낡음 → 다시 셈이 세션 선택 · 기본값으로 채움. */
const freshDesign = () =>
  ({
    design_elevation_m: 0,
    ground_type: "ripping_rock",
    section_mode: "left_cut",
    ditch_type: "standard",
  }) as unknown as NonNullable<CrossSection["design"]>;

function kindOf(station: PipelineStation): SectionStation["kind"] {
  if (station.kind === "end") return station.key.endsWith("EP") ? "ep" : "bp";
  return station.kind === "grid" ? "regular" : "irregular";
}

/** 같은 목록인가 — 열쇠 · 누가거리가 차례대로 같음(제자리 갱신이면 갈아끼우지 않음). */
export function sameStationList(
  sections: ReadonlyArray<{ chainage_m: number }>,
  oldKeys: ReadonlyArray<string>,
  stations: ReadonlyArray<PipelineStation>,
): boolean {
  return (
    sections.length === stations.length &&
    stations.every(
      (station, index) =>
        Math.abs(station.chainageM - sections[index].chainage_m) < 1e-6 &&
        (oldKeys[index] === station.key || kindOf(station) === "regular"),
    )
  );
}

/** 조작값 맵 열쇠(`85.05` · `85.05:outlet` · `b85.05`)의 누가거리를 새 자리로 — 안 옮기는 열쇠는 그대로. */
export function renameChainageKeys<V>(
  values: ReadonlyMap<string, V>,
  moves: ReadonlyMap<string, string>,
): Map<string, V> {
  const out = new Map<string, V>();
  for (const [key, value] of values) {
    const match = /^(b?)(-?\d+\.\d{2})(:.*)?$/.exec(key);
    const to = match && moves.get(match[2]);
    out.set(to ? `${match[1]}${to}${match[3] ?? ""}` : key, value);
  }
  return out;
}

export interface StationSwap {
  detail: SectionDetailResponse;
  added: string[];
  removed: string[];
  /** 이어 받은 측점 중 누가거리가 바뀐 것 — 옛 0.01 m 글 → 새 글(조작값 맵 옮김). */
  moves: Map<string, string>;
  /** 이어 받은 측점 중 좌표가 0.01 m 넘게 움직인 것이 있나 — 노선이 바뀐 차례(「노선 밖 고침」 셈). */
  moved: boolean;
}

/**
 * 새 측점 목록으로 상세를 새로 짬. `oldKeys` = 지금 상세 측점마다 열쇠(같은 차례 · `stationKeysOf`) ·
 * 열쇠가 안 맞으면 같은 자리(0.01 m) · 같은 종류의 앞 횡단을 씀.
 */
export function swapCrossSections(
  detail: SectionDetailResponse,
  stations: ReadonlyArray<PipelineStation>,
  oldKeys: ReadonlyArray<string>,
  intervalM: number | null,
): StationSwap {
  const byKey = new Map(detail.cross_sections.map((section, i) => [oldKeys[i], section]));
  const used = new Set<CrossSection>();
  let moved = false;
  const added: string[] = [];
  const moves = new Map<string, string>();
  const text = (chainageM: number) => chainageM.toFixed(2);
  const priorOf = (station: PipelineStation): CrossSection | undefined => {
    const hit = byKey.get(station.key);
    if (hit && !used.has(hit)) return hit;
    return detail.cross_sections.find(
      (section) =>
        !used.has(section) &&
        section.kind === kindOf(station) &&
        Math.abs(section.chainage_m - station.chainageM) < 0.01,
    );
  };
  const longStations: SectionStation[] = [];
  const cross_sections = stations.map((station): CrossSection => {
    const prior = priorOf(station);
    if (prior) used.add(prior);
    else added.push(station.key);
    if (prior && Math.hypot(prior.center_x - station.x, prior.center_y - station.y) > 0.01)
      moved = true;
    if (prior && text(prior.chainage_m) !== text(station.chainageM))
      moves.set(text(prior.chainage_m), text(station.chainageM));
    const kind = kindOf(station);
    const onGrid =
      kind === "irregular" &&
      !!intervalM &&
      Math.abs(station.chainageM / intervalM - Math.round(station.chainageM / intervalM)) < 1e-6;
    const place = {
      station_id: prior?.station_id ?? stationIdOf(station.chainageM),
      chainage_m: station.chainageM,
      label: formatStation(station.chainageM),
      kind,
      ...(onGrid ? { grid: true } : {}),
      center_z: station.ground?.centerZ ?? prior?.center_z ?? null,
      azimuth_deg: station.azimuthDeg,
      plan_radius_m: station.planRadiusM,
      curve_outer_side: station.curveOuterSide,
      curve_widening_m: station.curveWideningM,
      center_x: station.x,
      center_y: station.y,
      frame: { left_xy: [station.left[0], station.left[1]] as [number, number] },
    };
    longStations.push({ ...place, ...(prior?.structure ? { structure: prior.structure } : {}) });
    const samples = station.ground ? groundSamples(station) : (prior?.samples ?? []);
    return prior ? { ...prior, ...place, samples } : { ...place, samples, design: freshDesign() };
  });
  const removed = detail.cross_sections
    .map((section, i) => (used.has(section) ? null : oldKeys[i]))
    .filter((key): key is string => key !== null);
  const last = stations[stations.length - 1]?.chainageM ?? detail.longitudinal.length_m;
  return {
    detail: {
      ...detail,
      longitudinal: { ...detail.longitudinal, stations: longStations, length_m: last },
      cross_sections,
    },
    added,
    removed,
    moved,
    moves,
  };
}