/**
 * Format a number as a price string with 2 decimal places and thousands separators.
 * e.g. 1234.5 → "1,234.50"
 */
export function formatPrice(n: number): string {
  return n.toLocaleString('en-US', {
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  });
}

/**
 * Format a number as a percentage string with 2 decimal places.
 * e.g. 12.345 → "12.35%"
 */
export function formatPercent(n: number): string {
  return `${n.toLocaleString('en-US', {
    minimumFractionDigits: 2,
    maximumFractionDigits: 2,
  })}%`;
}

/**
 * Format a large number with K/M/B suffix.
 * Values >= 1_000_000_000 → "1.23B"
 * Values >= 1_000_000     → "456.7M"
 * Values >= 1_000         → "12.3K"
 * Values < 1_000          → plain number, no suffix
 */
export function formatLargeNumber(n: number): string {
  const abs = Math.abs(n);
  const sign = n < 0 ? '-' : '';

  if (abs >= 1_000_000_000) {
    return `${sign}${(abs / 1_000_000_000).toFixed(2).replace(/\.?0+$/, '')}B`;
  }
  if (abs >= 1_000_000) {
    return `${sign}${(abs / 1_000_000).toFixed(1).replace(/\.?0+$/, '')}M`;
  }
  if (abs >= 1_000) {
    return `${sign}${(abs / 1_000).toFixed(1).replace(/\.?0+$/, '')}K`;
  }
  return n.toString();
}

/**
 * Format an ISO date string as a short date.
 * e.g. "2025-01-15T14:30:00Z" → "Jan 15, 2025"
 */
export function formatDate(d: string): string {
  const date = new Date(d);
  return date.toLocaleDateString('en-US', {
    month: 'short',
    day: 'numeric',
    year: 'numeric',
  });
}

/**
 * Format an ISO date string as a date with time.
 * e.g. "2025-01-15T14:30:00Z" → "Jan 15, 2025 2:30 PM"
 */
export function formatDateTime(d: string): string {
  const date = new Date(d);
  return `${date.toLocaleDateString('en-US', {
    month: 'short',
    day: 'numeric',
    year: 'numeric',
  })} ${date.toLocaleTimeString('en-US', {
    hour: 'numeric',
    minute: '2-digit',
    hour12: true,
  })}`;
}

// ── Metric display helpers ─────────────────────────────────────────────────
// Shared by the Signals backtest/paper-trade panels. Dashboard and
// OpenTradesPanel deliberately still carry their own copies — migrating them is
// a separate change, not drive-by scope.

/** R-multiple with an explicit sign. e.g. 1.2 → "+1.20R", null → "—" */
export function fmtR(v: number | null | undefined): string {
  if (v === null || v === undefined) return '—';
  return `${v > 0 ? '+' : ''}${v.toFixed(2)}R`;
}

/** e.g. 12.34 → "12.3%" */
export function fmtPct(v: number | null | undefined): string {
  return v === null || v === undefined ? '—' : `${v.toFixed(1)}%`;
}

/** e.g. 12.34 → "+12.3%" */
export function fmtSignedPct(v: number | null | undefined): string {
  if (v === null || v === undefined) return '—';
  return `${v > 0 ? '+' : ''}${v.toFixed(1)}%`;
}

/** Always rendered negative, whatever sign the source uses. 17.3 → "-17.3%" */
export function fmtDrawdown(v: number | null | undefined): string {
  return v === null || v === undefined ? '—' : `-${Math.abs(v).toFixed(1)}%`;
}

/** e.g. 15.3 → "15.3d" */
export function fmtDays(v: number | null | undefined): string {
  return v === null || v === undefined ? '—' : `${v.toFixed(1)}d`;
}

/** Unitless ratios — Sharpe, Sortino, Calmar, Gain/Pain, profit factor. */
export function fmtRatio(v: number | null | undefined): string {
  return v === null || v === undefined ? '—' : v.toFixed(2);
}

/**
 * Signed currency, using U+2212 for negatives. e.g. -12.3 → "−$12.30"
 * Use wherever a value can go negative and the unit is money.
 * (For a bare unsigned amount there is already `formatPrice` above.)
 */
export function fmtSignedMoney(v: number | null | undefined): string {
  if (v === null || v === undefined) return '—';
  return `${v >= 0 ? '+' : '−'}$${Math.abs(v).toFixed(2)}`;
}

/** Green above zero, red below, neutral at zero or null. */
export function rColor(v: number | null | undefined): string {
  if (v === null || v === undefined) return 'text-gray-400';
  if (v > 0) return 'text-emerald-400';
  if (v < 0) return 'text-red-400';
  return 'text-gray-300';
}