/** 보조지표 차트 hline 역할 — DSL에 숫자(K_70) 대신 저장해 DB 설정 변경 시 자동 반영 */
export const THRESHOLD_HL_OVER = 'HL_OVER';
export const THRESHOLD_HL_MID = 'HL_MID';
export const THRESHOLD_HL_UNDER = 'HL_UNDER';

export type ThresholdHlineRole = typeof THRESHOLD_HL_OVER | typeof THRESHOLD_HL_MID | typeof THRESHOLD_HL_UNDER;

export function isThresholdSymbol(field?: string): boolean {
  return field === THRESHOLD_HL_OVER || field === THRESHOLD_HL_MID || field === THRESHOLD_HL_UNDER;
}

export function isThresholdFieldOrSymbol(field?: string): boolean {
  return !!field && (field.startsWith('K_') || isThresholdSymbol(field));
}

type HlThresh = { over?: number; mid?: number; under?: number };

export function resolveThresholdFromDef(
  field: string | undefined,
  indicatorType: string,
  hlThresh: Record<string, HlThresh>,
): number | null {
  if (!field) return null;
  const th = hlThresh[indicatorType] ?? {};
  if (field === THRESHOLD_HL_OVER) return th.over ?? null;
  if (field === THRESHOLD_HL_MID) return th.mid ?? null;
  if (field === THRESHOLD_HL_UNDER) return th.under ?? null;
  if (field.startsWith('K_')) {
    const n = parseFloat(field.slice(2));
    return Number.isFinite(n) ? n : null;
  }
  return null;
}

/** 레거시 K_ 값 → hline 역할 심볼 (정확 일치 우선, 없으면 가장 가까운 역할) */
export function inferThresholdSymbolFromLegacy(
  field: string | undefined,
  indicatorType: string,
  hlThresh: Record<string, HlThresh>,
): string | undefined {
  if (!field?.startsWith('K_')) return field;
  const val = parseFloat(field.slice(2));
  if (!Number.isFinite(val)) return field;
  const th = hlThresh[indicatorType] ?? {};
  const eps = 0.0001;
  if (th.over != null && Math.abs(th.over - val) < eps) return THRESHOLD_HL_OVER;
  if (th.mid != null && Math.abs(th.mid - val) < eps) return THRESHOLD_HL_MID;
  if (th.under != null && Math.abs(th.under - val) < eps) return THRESHOLD_HL_UNDER;

  const candidates: { role: ThresholdHlineRole; v: number }[] = [];
  if (th.over != null) candidates.push({ role: THRESHOLD_HL_OVER, v: th.over });
  if (th.mid != null) candidates.push({ role: THRESHOLD_HL_MID, v: th.mid });
  if (th.under != null) candidates.push({ role: THRESHOLD_HL_UNDER, v: th.under });
  if (candidates.length === 0) return defaultInheritedThresholdField(indicatorType);

  let best = candidates[0];
  let bestDiff = Math.abs(best.v - val);
  for (const c of candidates.slice(1)) {
    const d = Math.abs(c.v - val);
    if (d < bestDiff) {
      best = c;
      bestDiff = d;
    }
  }
  return best.role;
}

/** 상속 모드(thresholdOverride=false) — K_ 스냅샷을 hline 역할 심볼로 정규화 */
export function resolveInheritedThresholdField(
  field: string | undefined,
  indicatorType: string,
  hlThresh: Record<string, HlThresh>,
): string | undefined {
  if (!field) return field;
  if (isThresholdSymbol(field)) return field;
  if (field.startsWith('K_')) {
    return inferThresholdSymbolFromLegacy(field, indicatorType, hlThresh)
      ?? defaultInheritedThresholdField(indicatorType);
  }
  return field;
}

/** 상속 모드 기본 rightField — 과열선 역할 */
export function defaultInheritedThresholdField(indicatorType: string): string {
  switch (indicatorType) {
    case 'DISPARITY':
    case 'VOLUME_OSC':
    case 'TRIX':
      return THRESHOLD_HL_MID;
    default:
      return THRESHOLD_HL_OVER;
  }
}