/* =============================================================================
 * design_calc_profile.ts
 * 계산 자리 「서버」 종단 길(PLAN 511-B B-3) — 판(`design_calc_sites.ts`)이 profile 묶음을 server 로 둔 때
 * 묶음 planline 의 새 지반 첫 계획선 꼭짓점(P1 · `profile.base`)과 profile 단계 계획선 짓기(P2 ~ P4 · P8 ·
 * `profile.alignment`)를 서버 Node 가 같은 TS 로 셈(창구 `POST /projects/{id}/calc`). both 면 브라우저 그대로.
 * 서버 실패(끊김 밖) = 경고 한 줄 · 브라우저 값.
 * ========================================================================== */

import { calcOnServerNow } from "./design_calc_sites";
import { serverCalc } from "./design_calc_server";
import type { StageFn } from "./logic/design_pipeline_types";
import {
  groundFollowingBasePvi,
  groundProfile,
  type GroundFollowingInput,
} from "../../B05_Profile/logic/B05_Profile_Grade_Ground";
import { profileStage } from "../../B05_Profile/logic/B05_Profile_Pipeline_Grade";
import {
  emptyEdits,
  type AlignmentNode,
  type ProfileAlignment,
} from "../../B05_Profile/logic/B05_Profile_UI_Profile_Alignment";

const KEY = "profile";
const r6 = (value: number): number => Number(value.toFixed(6));

/** 서버 값 — 끊김은 그대로 던짐(묶음이 버림) · 그 밖 실패는 브라우저 값. */
async function orLocal<T>(signal: AbortSignal, remote: () => Promise<T>, local: () => T) {
  try {
    return await remote();
  } catch (error) {
    if (signal.aborted) throw error;
    console.warn("[calc-server] profile 실패 — 브라우저 값", error);
    return local();
  }
}

/** planline `groundPvi` — 서버면 첫 계획선 꼭짓점 약속(0.000001 m · `groundFollowingBasePvi` 꼴) · 아니면 null
 *  (브라우저 셈 · 단계 동기). 판은 앞 ground 단계가 이미 받음(`calcOnServerNow`). */
export function groundPviAt(
  input: GroundFollowingInput,
  signal: AbortSignal,
): Promise<AlignmentNode[] | null> | null {
  if (!calcOnServerNow(KEY)) return null;
  const local = () => groundFollowingBasePvi(input);
  const profile = groundProfile(input.samples);
  if (!profile) return null;
  return orLocal(
    signal,
    async () => {
      const follow = {
        stations: input.stations,
        start_offset_m: input.startOffsetM ?? 0,
        end_offset_m: input.endOffsetM ?? 0,
      };
      const inputs = { profile: { ...profile, policy: input.policy, ground_following: follow } };
      const results = await serverCalc(KEY, ["profile.base"], inputs, signal);
      const nodes = results["profile.base"] as AlignmentNode[] | null;
      return (
        nodes?.map((node) => ({
          chainage_m: r6(node.chainage_m),
          elevation_m: r6(node.elevation_m),
        })) ?? null
      );
    },
    local,
  );
}

/** profile 단계 — 첫 계획선 + 계획고 편집 → 종단(서버면 `profile.alignment` · 아니면 동기 그대로). */
export const profileAt: StageFn<"profile"> = (ctx) => {
  const base = ctx.out.planline;
  if (!base || !calcOnServerNow(KEY)) return profileStage(ctx);
  return orLocal(
    ctx.signal,
    async () => {
      const profile = {
        chainage: base.chainage,
        ground: base.ground,
        policy: base.policy,
        stations: base.stations,
        base_pvi: base.basePvi,
        edits: ctx.inputs.alignment ?? emptyEdits(),
        only_explicit_curves: base.onlyExplicitCurves,
      };
      const results = await serverCalc(KEY, ["profile.alignment"], { profile }, ctx.signal);
      return results["profile.alignment"] as ProfileAlignment;
    },
    () => profileStage(ctx) as ProfileAlignment,
  );
};