/* =============================================================================
 * logic/B01_Dashboard_Home_Layout.ts
 * 홈 꼴 고르기 · 묶어 세기(PLAN 547-2) — 순수 함수 · 시험 `test_547_2_home_layout.py`
 *   진행 중 1 = one · 2~3 = few · 4~8 = list · 9 넘음 = many · 0 = empty
 *   고정 small = list(9 넘음 = many) · large = one(1) / few(2 넘음)
 * ========================================================================== */

export type HomeLayout = "empty" | "one" | "few" | "list" | "many";
export type HomeFixed = "auto" | "small" | "large";

export const STALE_DAYS = 14;
export const MANY_FROM = 9;

export function homeLayout(count: number, fixed: HomeFixed = "auto"): HomeLayout {
  if (count <= 0) return "empty";
  if (fixed === "large") return count === 1 ? "one" : "few";
  if (fixed === "small") return count >= MANY_FROM ? "many" : "list";
  if (count === 1) return "one";
  if (count <= 3) return "few";
  return count < MANY_FROM ? "list" : "many";
}

interface StageLike {
  stage_index: number;
  stage_total: number;
  stale_days?: number | null;
}

export const isStale = (card: StageLike): boolean => (card.stale_days ?? 0) >= STALE_DAYS;

/** 단계 분포 — 시작 전(첫 단계) · 설계 중 · 확정 대기(마지막 단계) */
export function stageBuckets(cards: StageLike[]): { start: number; working: number; last: number } {
  const out = { start: 0, working: 0, last: 0 };
  for (const c of cards) {
    if (c.stage_index <= 0) out.start += 1;
    else if (c.stage_index >= c.stage_total - 1) out.last += 1;
    else out.working += 1;
  }
  return out;
}

/** 묶어 세기 — 많은 차례 · 같으면 이름 차례 */
export function countBy<T>(
  items: T[],
  key: (item: T) => string,
): { label: string; count: number }[] {
  const counts = new Map<string, number>();
  for (const item of items) counts.set(key(item), (counts.get(key(item)) ?? 0) + 1);
  return [...counts]
    .map(([label, count]) => ({ label, count }))
    .sort((a, b) => b.count - a.count || a.label.localeCompare(b.label));
}

/** 앞 limit 개 + 나머지 하나로 묶음(「그 밖 N 곳」) */
export function topWithRest(
  rows: { label: string; count: number }[],
  limit: number,
): { label: string; count: number; rest?: number }[] {
  if (rows.length <= limit) return rows;
  const rest = rows.slice(limit - 1);
  return [
    ...rows.slice(0, limit - 1),
    { label: "", count: rest.reduce((sum, r) => sum + r.count, 0), rest: rest.length },
  ];
}

/** 원 그래프 조각 — 둘레 100 기준 stroke-dasharray · stroke-dashoffset(12 시 시작 · 시계 방향) */
export function donutArcs(values: number[]): { dash: string; offset: number }[] {
  const total = values.reduce((sum, v) => sum + v, 0);
  if (total <= 0) return [];
  let start = 0;
  return values.map((v) => {
    const len = (v / total) * 100;
    const arc = { dash: `${round2(len)} ${round2(100 - len)}`, offset: round2(25 - start) };
    start += len;
    return arc;
  });
}

const round2 = (v: number): number => Math.round(v * 100) / 100;