/* =============================================================================
 * D03_PlanAnalysis_UI_Select.ts
 * D03 고름 상태(PLAN 598-1 · 요구 463 9 · 13) — 노드 → 선(토막) → 구역 → 전체 · 연도 구간(왼쪽 해 줄) · 마커.
 *   넓힘 = 같은 것을 다시 누름 — 씨(처음 누른 노드 · 토막)에서 한 단 위 · 전체 다음 = 씨로 돌아옴.
 *   「같은 해」 = 왼쪽 목록 해 줄로만(`year`).
 *   상태 = 화면 기억(저장 안 함) · 꼴이 바뀌면 `sync` 가 사라진 것을 뺌.
 * ========================================================================== */

import { lineLength, sliceLine } from "./logic/D03_PlanAnalysis_Draw";
import type { PlanNetwork, Vertex } from "./logic/D03_PlanAnalysis_Plan";
import {
  lineSegments,
  nodeSegment,
  sameSegment,
  segmentPath,
  segmentPieces,
  type PlanNode,
  type PlanSegment,
} from "./logic/D03_PlanAnalysis_Select";

export type PlanSelectKind = "node" | "segment" | "line" | "all" | "pieces" | "mark";
/** 왼쪽 목록 밝힘 꼴(구간 · 선 · 같은 해). */
export type PlanScope = "piece" | "line" | "year";

export interface PlanSelection {
  kind: PlanSelectKind;
  /** 노드 고름 · 노드 씨. */
  node: PlanNode | null;
  /** 토막 고름(Shift · 끌어 고르기 = 여럿). */
  segments: PlanSegment[];
  /** 구역 고름 · 씨가 든 구역. */
  line: string | null;
  /** 고름에 든 연도 구간 id(구간 · 마커 고름 = 그대로 · 그 밖 = 걸친 구간). */
  pieces: string[];
  /** 고른 마커(그 마커가 여는 구간 id). */
  mark: string | null;
  scope: PlanScope;
  /** 넓힘 씨 — 처음 누른 노드 · 토막. */
  seed: { node: PlanNode } | { segment: PlanSegment } | null;
}

const NEXT: Partial<Record<PlanSelectKind, PlanSelectKind>> = {
  node: "segment",
  segment: "line",
  line: "all",
};

export interface PlanSelect {
  get: () => PlanSelection | null;
  clear: () => void;
  node: (node: PlanNode) => void;
  /** 토막 — `toggle` = 지금 토막 고름에 더함 · 뺌. */
  segments: (segments: PlanSegment[], toggle?: boolean) => void;
  region: (line: string) => void;
  all: () => void;
  /** 연도 구간 — 마커 고름 = 그 마커가 여는 구간. */
  pieces: (ids: string[], mark?: string | null, scope?: PlanScope) => void;
  /** 넓힘 한 단(씨 기준). */
  grow: () => void;
  /** 이 노드 · 토막이 지금 고름 안인가(다시 누름 = 넓힘). */
  holds: (hit: { node?: PlanNode; segment?: PlanSegment }) => boolean;
  /** 밝힐 꺾은선. */
  paths: () => Vertex[][];
  sync: () => void;
}

export function createPlanSelect(network: () => PlanNetwork, onChange: () => void): PlanSelect {
  let selected: PlanSelection | null = null;

  function piecesOf(next: Omit<PlanSelection, "pieces" | "scope">): string[] {
    const net = network();
    if (next.kind === "segment") return segmentPieces(net, next.segments);
    if (next.kind === "line")
      return net.pieces.filter((p) => p.line === next.line).map((p) => p.id);
    if (next.kind === "all") return net.pieces.map((p) => p.id);
    return [];
  }

  function choose(
    next: Omit<PlanSelection, "pieces" | "scope"> & Partial<PlanSelection>,
    quiet = false,
  ): void {
    selected = {
      ...next,
      pieces: next.pieces ?? piecesOf(next),
      scope: next.scope ?? (next.kind === "line" ? "line" : "piece"),
    };
    if (!quiet) onChange();
  }

  const empty = { node: null, segments: [], line: null, mark: null, seed: null };

  function node(at: PlanNode): void {
    choose({ ...empty, kind: "node", node: at, line: at.line, seed: { node: at } });
  }

  function segments(list: PlanSegment[], toggle = false): void {
    let next = list;
    if (toggle && selected?.kind === "segment") {
      const has = (s: PlanSegment): boolean => selected!.segments.some((t) => sameSegment(s, t));
      next = [
        ...selected.segments.filter((s) => !list.some((t) => sameSegment(s, t))),
        ...list.filter((s) => !has(s)),
      ];
    }
    if (!next.length) return clear();
    choose({
      ...empty,
      kind: "segment",
      segments: next,
      line: next[0].line,
      seed: { segment: next[0] },
    });
  }

  function clear(): void {
    selected = null;
    onChange();
  }

  /** 씨 기준 한 단 — 노드 → 토막 → 구역 → 전체 → 씨. */
  function grow(): void {
    if (!selected?.seed) return;
    const seed = selected.seed;
    const next = NEXT[selected.kind];
    const line = "node" in seed ? seed.node.line : seed.segment.line;
    if (next === "segment") {
      const seg = "node" in seed ? nodeSegment(network(), seed.node) : seed.segment;
      if (seg) choose({ ...empty, kind: "segment", segments: [seg], line, seed });
    } else if (next === "line") choose({ ...empty, kind: "line", line, seed });
    else if (next === "all") choose({ ...empty, kind: "all", line, seed });
    else if ("node" in seed) node(seed.node);
    else choose({ ...empty, kind: "segment", segments: [seed.segment], line, seed });
  }

  function holds(hit: { node?: PlanNode; segment?: PlanSegment }): boolean {
    const s = selected;
    if (!s || s.kind === "pieces" || s.kind === "mark") return false;
    if (s.kind === "all") return true;
    const line = hit.node?.line ?? hit.segment?.line;
    if (s.kind === "line") return line === s.line;
    if (s.kind === "node")
      return !!hit.node && hit.node.line === s.node!.line && hit.node.vertex === s.node!.vertex;
    if (hit.segment) return s.segments.some((t) => sameSegment(t, hit.segment!));
    return s.segments.some(
      (t) =>
        t.line === hit.node!.line &&
        (t.index === hit.node!.vertex || t.index + 1 === hit.node!.vertex),
    );
  }

  function paths(): Vertex[][] {
    const s = selected;
    const net = network();
    if (!s || s.kind === "node") return [];
    if (s.kind === "segment")
      return s.segments
        .map((seg) => segmentPath(net, seg))
        .filter((p): p is [Vertex, Vertex] => !!p);
    if (s.kind === "line") return net.lines.filter((l) => l.id === s.line).map((l) => l.vertices);
    if (s.kind === "all") return net.lines.map((l) => l.vertices);
    return s.pieces.flatMap((id) => {
      const piece = net.pieces.find((p) => p.id === id);
      const v = net.lines.find((l) => l.id === piece?.line)?.vertices;
      return piece && v ? [sliceLine(v, piece.from_m, piece.to_m)] : [];
    });
  }

  /** 사라진 것 뺌 — 부르는 쪽(페이지 `refresh`)이 다시 그림(여기서 onChange 를 부르면 돌고 돎). */
  function sync(): void {
    const s = selected;
    if (!s) return;
    const net = network();
    const vertexCount = (line: string | null): number =>
      net.lines.find((l) => l.id === line)?.vertices.length ?? 0;
    const okNode = (n: PlanNode): boolean => n.vertex < vertexCount(n.line);
    const okSeg = (g: PlanSegment): boolean => g.index + 1 < vertexCount(g.line);
    if (s.kind === "pieces" || s.kind === "mark") {
      const ids = new Set(net.pieces.map((p) => p.id));
      const pieces = s.pieces.filter((id) => ids.has(id));
      selected = pieces.length
        ? { ...s, pieces, mark: s.mark && ids.has(s.mark) ? s.mark : null }
        : null;
      if (selected?.kind === "mark" && !selected.mark) selected = { ...selected, kind: "pieces" };
      return;
    }
    const seed =
      s.seed && ("node" in s.seed ? okNode(s.seed.node) : okSeg(s.seed.segment)) ? s.seed : null;
    const segments = s.segments.filter(okSeg);
    const alive = {
      all: net.lines.length > 0,
      line: vertexCount(s.line) > 0,
      node: !!s.node && okNode(s.node),
      segment: segments.length > 0,
    }[s.kind];
    if (alive) choose({ ...s, segments, seed, pieces: undefined }, true);
    else selected = null;
  }

  return {
    get: () => selected,
    clear,
    node,
    segments,
    region: (line) => choose({ ...empty, kind: "line", line, seed: lineSeed(line) }),
    all: () => choose({ ...empty, kind: "all", seed: null }),
    pieces(ids, mark = null, scope = "piece") {
      const list = [...new Set(ids)];
      if (!list.length) return clear();
      const net = network();
      choose({
        ...empty,
        kind: mark ? "mark" : "pieces",
        line: net.pieces.find((p) => p.id === list[0])?.line ?? null,
        pieces: list,
        mark,
        scope,
      });
    },
    grow,
    holds,
    paths,
    sync,
  };

  /** 구역 씨 = 첫 토막(구역에서 넓힘 = 전체 → 첫 토막). */
  function lineSeed(line: string): { segment: PlanSegment } | null {
    const first = lineSegments(network(), line)[0];
    return first ? { segment: first } : null;
  }
}

/** 고름 길이(m) — 토막 · 구역 · 전체 · 구간. */
export function selectionLength(paths: Vertex[][]): number {
  return paths.reduce((sum, path) => sum + lineLength(path), 0);
}