/* =============================================================================
 * B06_Section_Section_Drafts.ts
 * 초안 측점 한 벌(272 · 273-2) — 관 · 구조물을 놓거나 옮긴 초안을 공유 상세(횡단 카드 · 유토곡선)에 맞춘다.
 *
 *   · 옛 자리 구조물 측점(서버가 [저장] 때 다시 맞추기 전) = 숨김 — 쥐고 있다가 초안이 다시 그 자리를
 *     심거나 초안이 없어지면 돌려 놓음.
 *   · 새 자리(서버 횡단 없음) = 서버가 미리 떠 준 횡단을 캐시에 얹음(`preview-stations` · 파일 · DB
 *     안 씀) — [저장] 때 서버가 같은 계산으로 정본에 씀. 한 번 뜬 자리는 기억해 다시 안 물음.
 *
 * 심는 자리 규칙 = `plantedChainages`(서버 `resolve_extra_stations` 짝) · 카드 이름 = 서버 측점 이름 규칙
 * (`pipe_station_label` · 종류 이름) · 관 그림 = 짝 산식 `common_util_culvert_sets`.
 * ========================================================================== */

import { fetchDetailPipePoints } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
import {
  fetchStructures,
  fetchStructureTypes,
  readPendingStructures,
  type StructureInstance,
  type StructureType,
} from "../B05_Profile/B05_Profile_Api_Structures";
import { readPendingPipes, type PendingPipes } from "../B05_Profile/B05_Profile_Api_Pipes_Draft";
import {
  attachCulvertSets,
  buildCulvertSets,
  registryDefaults,
} from "@util/common_util_culvert_sets";
import {
  pipeStationMarks,
  plantedChainages,
  SAME_STATION_M,
  structureStationMarks,
} from "../common_util/common_util_structure_station";
import {
  previewStructureSections,
  type CrossSection,
  type SectionDetailResponse,
} from "./B06_Section_Api_Fetch";

type Pipes = PendingPipes;

const near = (a: number, b: number): boolean => Math.abs(a - b) < SAME_STATION_M;
const byChainage = (a: { chainage_m: number }, b: { chainage_m: number }) =>
  a.chainage_m - b.chainage_m;

/** 저장된 관 · 구조물 — 한쪽 초안만 있을 때 심는 자리 셈에 씀 · 저장 뒤(`forgetDraftStations`) 다시 받음. */
const saved = new Map<string, Promise<[Pipes, StructureInstance[]]>>();
/** 미리 뜬 횡단(`프로젝트:노선:누가거리`) — 못 뜬 자리는 null(다시 안 물음) · 저장 뒤 비움. */
const previews = new Map<string, CrossSection | null>();
/** 초안이 빼 둔 옛 자리 측점. */
const parked = new WeakMap<SectionDetailResponse, CrossSection[]>();
/** 상세마다 마지막 맞춤 번호 — 늦게 끝난 옛 맞춤이 새 맞춤을 덮지 않게. */
const turns = new WeakMap<SectionDetailResponse, number>();

/** 저장 · 노선 바뀜 뒤 — 쥔 저장분 · 미리 뜬 횡단을 버림. */
export function forgetDraftStations(projectId: string): void {
  saved.delete(projectId);
  for (const key of [...previews.keys()]) if (key.startsWith(`${projectId}:`)) previews.delete(key);
}

function savedOf(projectId: string): Promise<[Pipes, StructureInstance[]]> {
  let hit = saved.get(projectId);
  if (!hit) {
    hit = Promise.all([
      fetchDetailPipePoints(projectId).then((res) => res.pipe_points as Pipes),
      fetchStructures(projectId).then((res) => res.structures),
    ]);
    hit.catch(() => saved.delete(projectId));
    saved.set(projectId, hit);
  }
  return hit;
}

async function previewOf(
  projectId: string,
  routeId: number,
  chainages: number[],
): Promise<CrossSection[]> {
  const key = (at: number) => `${projectId}:${routeId}:${at.toFixed(3)}`;
  const ask = chainages.filter((at) => !previews.has(key(at)));
  if (ask.length) {
    const got = await previewStructureSections(projectId, ask);
    ask.forEach((at) => previews.set(key(at), got.find((s) => near(s.chainage_m, at)) ?? null));
  }
  return chainages.flatMap((at) => previews.get(key(at)) ?? []);
}

/** 미리 뜬 횡단에 카드 이름 · 관 그림 — 서버가 [저장] 때 붙이는 것과 같은 규칙. */
function decorate(
  fresh: CrossSection[],
  pipes: Pipes,
  structures: StructureInstance[],
  types: StructureType[],
): void {
  const registry = registryDefaults(types);
  const byId = new Map(types.map((type) => [type.type_id, type]));
  const pipeLabel = (pipe: Pipes[number]): string | null => {
    const facility = pipe.facility ?? "pipe";
    if (facility !== "pipe") return byId.get(facility)?.name ?? facility;
    const values = { ...registry.pipe, ...pipe.options };
    return `${values.pipe_kind} D${Math.trunc(Number(values.pipe_diameter_mm))}`;
  };
  const labels: Array<[number, string]> = [
    ...pipes.flatMap((pipe) => {
      const label = pipeLabel(pipe);
      return label
        ? pipeStationMarks(pipe).map((m): [number, string] => [m.chainage_m, label])
        : [];
    }),
    ...structures.flatMap((structure) => {
      const type = byId.get(structure.type_id);
      const label = type?.name ?? structure.type_id;
      return structureStationMarks(structure, type).map((m): [number, string] => [
        m.chainage_m,
        label,
      ]);
    }),
  ];
  for (const section of fresh) {
    section.preview = true;
    const hit = labels.find(([at]) => near(at, section.chainage_m));
    if (hit) section.structure = hit[1];
  }
  const own = pipes.filter((pipe) =>
    fresh.some((section) => near(section.chainage_m, pipe.chainage_m)),
  );
  attachCulvertSets(
    fresh as unknown as Array<Record<string, unknown>>,
    buildCulvertSets(own, registry),
  );
}

/**
 * 초안에 맞춰 상세의 횡단 목록을 고친다 — 옛 자리 숨김 · 새 자리 미리 뜬 횡단 얹음. 초안이 없으면
 * 서버 목록 그대로(빼 둔 것 돌려 놓음). 미리 뜨기를 못 하면(샘플링 조건 없음 · 끊김) 새 자리는
 * 종전처럼 [저장] 뒤에 섬.
 */
export async function withDraftStations(
  detail: SectionDetailResponse,
  projectId: string,
  routeId: number,
): Promise<void> {
  const turn = (turns.get(detail) ?? 0) + 1;
  turns.set(detail, turn);
  const pipesDraft = readPendingPipes(projectId);
  const structuresDraft = readPendingStructures(projectId);
  const all = [
    ...detail.cross_sections.filter((section) => !section.preview),
    ...(parked.get(detail) ?? []),
  ].sort(byChainage);
  let live = all;
  let stale: CrossSection[] = [];
  let fresh: CrossSection[] = [];
  if (pipesDraft || structuresDraft) {
    const inputs = await Promise.all([
      pipesDraft ?? savedOf(projectId).then(([pipes]) => pipes),
      structuresDraft ?? savedOf(projectId).then(([, structures]) => structures),
      fetchStructureTypes(true),
    ]).catch(() => null);
    if (inputs) {
      const [pipes, structures, types] = inputs;
      const planted = plantedChainages(pipes, structures, types);
      const isStale = (section: CrossSection): boolean =>
        section.kind === "irregular" &&
        !section.grid &&
        planted.every((at) => !near(at, section.chainage_m));
      stale = all.filter(isStale);
      live = all.filter((section) => !isStale(section));
      const missing = planted.filter(
        (at, index) =>
          planted.findIndex((other) => near(other, at)) === index &&
          live.every((section) => !near(section.chainage_m, at)),
      );
      fresh = missing.length ? await previewOf(projectId, routeId, missing).catch(() => []) : [];
      if (fresh.length) decorate(fresh, pipes, structures, types);
    }
  }
  if (turns.get(detail) !== turn) return; // 더 새 맞춤이 돎 — 그쪽이 얹음
  detail.cross_sections.splice(
    0,
    detail.cross_sections.length,
    ...[...live, ...fresh].sort(byChainage),
  );
  parked.set(detail, stale);
}