/* =============================================================================
 * spreadsheet_selection.ts  (주인 D)
 * 고름 모델 — 한 칸 · 범위 · 행열 전체 · 전체 · 방향키(Shift 늘림 · Ctrl 끝으로) · 병합으로 늘림 ·
 * 고름 안 Enter/Tab 돌기. DOM 모름(시험이 그대로 부름). 엑셀 동작이 기준.
 * ========================================================================== */

import { colName, parseA1, parseRange, toA1 } from "./spreadsheet_address";
import { MAX_COLS, MAX_ROWS } from "./spreadsheet_types";
import type { CellAddress, CellRange, Sheet } from "./spreadsheet_types";
import type { Selection } from "./spreadsheet_view_types";

export const LAST_R = MAX_ROWS - 1;
export const LAST_C = MAX_COLS - 1;

export function merges(sheet: Sheet): CellRange[] {
  const out: CellRange[] = [];
  for (const t of sheet.병합 ?? []) {
    const m = parseRange(t);
    if (m) out.push(m);
  }
  return out;
}

const overlaps = (a: CellRange, b: CellRange): boolean =>
  a.r0 <= b.r1 && b.r0 <= a.r1 && a.c0 <= b.c1 && b.c0 <= a.c1;

export const inRange = (g: CellRange, r: number, c: number): boolean =>
  r >= g.r0 && r <= g.r1 && c >= g.c0 && c <= g.c1;

/** 병합 일부를 걸친 범위 → 병합 전체를 품게 늘림(늘린 뒤 새로 걸친 것도) */
export function expand(range: CellRange, list: CellRange[]): CellRange {
  const g = { ...range };
  for (let grew = true; grew;) {
    grew = false;
    for (const m of list) {
      if (!overlaps(g, m)) continue;
      if (m.r0 < g.r0 || m.r1 > g.r1 || m.c0 < g.c0 || m.c1 > g.c1) {
        g.r0 = Math.min(g.r0, m.r0);
        g.r1 = Math.max(g.r1, m.r1);
        g.c0 = Math.min(g.c0, m.c0);
        g.c1 = Math.max(g.c1, m.c1);
        grew = true;
      }
    }
  }
  return g;
}

/** 칸이 든 병합(없으면 칸 하나) */
export function mergeAt(sheet: Sheet, r: number, c: number): CellRange {
  return merges(sheet).find((m) => inRange(m, r, c)) ?? { r0: r, c0: c, r1: r, c1: c };
}

/** 숨긴 행 · 필터로 걸러진 행 · 접힌 묶음(방향키 · Enter 가 건너뜀 — 엑셀) */
export function rowHidden(sheet: Sheet, r: number): boolean {
  const row = sheet.행?.[String(r + 1)];
  return !!(row?.숨김 || row?.걸러짐 || row?.묶음?.접힘);
}

export function colHidden(sheet: Sheet, c: number): boolean {
  const cols = sheet.열;
  if (!cols) return false;
  const col = cols[colName(c)];
  return !!(col?.숨김 || col?.묶음?.접힘);
}

export function hasValue(sheet: Sheet, r: number, c: number): boolean {
  const cell = sheet.칸[toA1(r, c)];
  return !!cell && (cell.식 !== undefined || (cell.값 !== undefined && cell.값 !== ""));
}

export function span(a: CellAddress, b: CellAddress): CellRange {
  return {
    r0: Math.min(a.r, b.r),
    c0: Math.min(a.c, b.c),
    r1: Math.max(a.r, b.r),
    c1: Math.max(a.c, b.c),
  };
}

/** 칸 하나 고름 — 병합 안이면 병합 전체 · 활성은 병합 왼위 */
export function selectCell(sheet: Sheet, r: number, c: number): Selection {
  const m = mergeAt(sheet, r, c);
  const at = { r: m.r0, c: m.c0 };
  return { 시트: sheet.id, 범위: [m], 활성: at, 기준: { ...at } };
}

/** 닻(기준)에서 `to` 까지 — 활성은 닻 그대로(엑셀 Shift) */
export function selectSpan(sheet: Sheet, anchor: CellAddress, to: CellAddress): Selection {
  const g = expand(span(anchor, to), merges(sheet));
  return { 시트: sheet.id, 범위: [g], 활성: { ...anchor }, 기준: { ...anchor } };
}

/** 행 전체(r0~r1) · 열 전체(c0~c1) · 전체 — 활성은 첫 보이는 칸 · 걸친 병합만큼 늘림(엑셀) */
export function selectRows(sheet: Sheet, a: number, b: number, active?: number): Selection {
  const r0 = Math.min(a, b);
  const at = { r: active ?? r0, c: firstVisible(sheet, "c") };
  return {
    시트: sheet.id,
    범위: [expand({ r0, r1: Math.max(a, b), c0: 0, c1: LAST_C }, merges(sheet))],
    활성: at,
    기준: { ...at },
  };
}

export function selectCols(sheet: Sheet, a: number, b: number, active?: number): Selection {
  const c0 = Math.min(a, b);
  const at = { r: firstVisible(sheet, "r"), c: active ?? c0 };
  return {
    시트: sheet.id,
    범위: [expand({ r0: 0, r1: LAST_R, c0, c1: Math.max(a, b) }, merges(sheet))],
    활성: at,
    기준: { ...at },
  };
}

export function selectAll(sheet: Sheet, active?: CellAddress): Selection {
  const at = active ?? { r: firstVisible(sheet, "r"), c: firstVisible(sheet, "c") };
  return {
    시트: sheet.id,
    범위: [{ r0: 0, c0: 0, r1: LAST_R, c1: LAST_C }],
    활성: at,
    기준: { ...at },
  };
}

function firstVisible(sheet: Sheet, axis: "r" | "c"): number {
  let i = 0;
  while (i < 200 && (axis === "r" ? rowHidden(sheet, i) : colHidden(sheet, i))) i++;
  return i;
}

/** 한 칸 옮김 — 숨김 건너뜀 · 끝에서 멈춤 */
function step(sheet: Sheet, at: CellAddress, dr: number, dc: number): CellAddress {
  let { r, c } = at;
  do {
    r += dr;
    c += dc;
  } while (
    r >= 0 &&
    r <= LAST_R &&
    c >= 0 &&
    c <= LAST_C &&
    ((dr && rowHidden(sheet, r)) || (dc && colHidden(sheet, c)))
  );
  if (r < 0 || r > LAST_R || c < 0 || c > LAST_C) return at;
  return { r, c };
}

/** 한 줄(행 또는 열)에서 값 든 자리 — 오름차순 */
function occupied(sheet: Sheet, at: CellAddress, vertical: boolean): number[] {
  const out: number[] = [];
  for (const key of Object.keys(sheet.칸)) {
    const a = parseA1(key);
    if (!a || !hasValue(sheet, a.r, a.c)) continue;
    if (vertical ? a.c === at.c : a.r === at.r) out.push(vertical ? a.r : a.c);
  }
  return out.sort((a, b) => a - b);
}

/** Ctrl+방향 — 값 사이를 뛰어 끝으로(엑셀: 값 칸 뭉치의 끝 · 빈 칸이면 다음 값 · 없으면 시트 끝) */
function jump(sheet: Sheet, at: CellAddress, dr: number, dc: number): CellAddress {
  const vertical = dr !== 0;
  const d = vertical ? dr : dc;
  const pos = vertical ? at.r : at.c;
  const edge = d > 0 ? (vertical ? LAST_R : LAST_C) : 0;
  const set = new Set(occupied(sheet, at, vertical));
  const has = (i: number): boolean => set.has(i);
  const put = (i: number): CellAddress => (vertical ? { r: i, c: at.c } : { r: at.r, c: i });
  if (pos === edge) return at;
  if (has(pos) && has(pos + d)) {
    let i = pos;
    while (i !== edge && has(i + d)) i += d;
    return put(i);
  }
  const sorted = [...set].sort((a, b) => a - b);
  const next = d > 0 ? sorted.find((i) => i > pos) : sorted.reverse().find((i) => i < pos);
  return put(next ?? edge);
}

export interface MoveOptions {
  /** Shift — 닻은 두고 움직이는 끝만 */
  extend?: boolean;
  /** Ctrl — 값 끝으로 */
  jump?: boolean;
}

/** 방향키 · Home 류 공통 — 새 고름 */
export function move(
  sheet: Sheet,
  sel: Selection,
  dr: number,
  dc: number,
  opts: MoveOptions = {},
): Selection {
  const list = merges(sheet);
  if (!opts.extend) {
    const from = sel.활성;
    const m = mergeAt(sheet, from.r, from.c);
    // 병합에서 나갈 때는 병합 끝에서 한 칸
    const edge = { r: dr > 0 ? m.r1 : m.r0, c: dc > 0 ? m.c1 : m.c0 };
    const to = opts.jump ? jump(sheet, edge, dr, dc) : step(sheet, edge, dr, dc);
    if (to.r === edge.r && to.c === edge.c) return selectCell(sheet, from.r, from.c);
    return selectCell(sheet, to.r, to.c);
  }
  const g = sel.범위[sel.범위.length - 1] ?? span(sel.활성, sel.활성); // 여러 범위면 마지막(활성) 범위
  const anchor = sel.기준;
  // 움직이는 끝 = 닻에서 먼 쪽
  const far = {
    r: Math.abs(g.r1 - anchor.r) >= Math.abs(anchor.r - g.r0) ? g.r1 : g.r0,
    c: Math.abs(g.c1 - anchor.c) >= Math.abs(anchor.c - g.c0) ? g.c1 : g.c0,
  };
  let to = opts.jump ? jump(sheet, far, dr, dc) : step(sheet, far, dr, dc);
  // 줄이는 쪽이면 병합 너머까지 한 번에
  for (let guard = 0; guard < 50; guard++) {
    const next = expand(span(anchor, to), list);
    if (!sameRange(next, g) || to === far) break;
    to = step(sheet, to, dr, dc);
  }
  return {
    시트: sheet.id,
    범위: [...sel.범위.slice(0, -1), expand(span(anchor, to), list)],
    활성: { ...sel.활성 },
    기준: { ...anchor },
  };
}

export const sameRange = (a: CellRange, b: CellRange): boolean =>
  a.r0 === b.r0 && a.c0 === b.c0 && a.r1 === b.r1 && a.c1 === b.c1;

/** 쓰인 칸 끝(Ctrl+End) */
export function usedEnd(sheet: Sheet): CellAddress {
  let r = 0;
  let c = 0;
  for (const key of Object.keys(sheet.칸)) {
    const a = parseA1(key);
    if (!a) continue;
    r = Math.max(r, a.r);
    c = Math.max(c, a.c);
  }
  return { r, c };
}

/** 고름 안 Enter/Tab 돌기 — 범위가 한 칸(또는 병합 하나)이면 null(밖으로 옮김) */
export function cycle(sheet: Sheet, sel: Selection, dr: number, dc: number): Selection | null {
  const g = sel.범위[0];
  if (!g) return null;
  const list = merges(sheet);
  if (list.some((m) => sameRange(m, g)) || (g.r0 === g.r1 && g.c0 === g.c1)) return null;
  // 행 전체 · 열 전체는 쓰인 칸 끝까지만 돎
  const end = usedEnd(sheet);
  const box = {
    ...g,
    r1: g.r1 === LAST_R ? Math.max(end.r, g.r0) : g.r1,
    c1: g.c1 === LAST_C ? Math.max(end.c, g.c0) : g.c1,
  };
  let { r, c } = sel.활성;
  const cur = mergeAt(sheet, r, c);
  const rows = box.r1 - box.r0 + 1;
  const cols = box.c1 - box.c0 + 1;
  for (let n = 0; n < rows * cols; n++) {
    if (dr) {
      r += dr;
      if (r > box.r1) ((r = box.r0), (c = c + 1 > box.c1 ? box.c0 : c + 1));
      if (r < box.r0) ((r = box.r1), (c = c - 1 < box.c0 ? box.c1 : c - 1));
    } else {
      c += dc;
      if (c > box.c1) ((c = box.c0), (r = r + 1 > box.r1 ? box.r0 : r + 1));
      if (c < box.c0) ((c = box.c1), (r = r - 1 < box.r0 ? box.r1 : r - 1));
    }
    if (rowHidden(sheet, r) || colHidden(sheet, c)) continue;
    const m = mergeAt(sheet, r, c);
    if (m.r0 !== r || m.c0 !== c || sameRange(m, cur)) continue;
    return { ...sel, 범위: sel.범위.map((x) => ({ ...x })), 활성: { r, c } };
  }
  return null;
}

/** 고름 안 칸 전부(행열 전체는 쓰인 끝까지) — Ctrl+Enter · 지우기 대상 */
export function cellsOf(sheet: Sheet, sel: Selection): CellAddress[] {
  const end = usedEnd(sheet);
  const out: CellAddress[] = [];
  for (const g of sel.범위) {
    const r1 = g.r1 === LAST_R ? Math.max(end.r, g.r0) : g.r1;
    const c1 = g.c1 === LAST_C ? Math.max(end.c, g.c0) : g.c1;
    for (let r = g.r0; r <= r1; r++) for (let c = g.c0; c <= c1; c++) out.push({ r, c });
  }
  return out;
}