/**
 * Convert a TradingView interval string to seconds.
 * Plain numbers are minutes (TradingView convention), suffixed forms use the suffix.
 * Examples: "15" → 900, "1D" → 86400, "1W" → 604800
 */
export function intervalToSeconds(interval: string): number {
  const numericInterval = parseInt(interval)
  if (!isNaN(numericInterval) && interval === numericInterval.toString()) {
    return numericInterval * 60 // plain number = minutes
  }
  const match = interval.match(/^(\d+)([SMHDW])$/)
  if (match) {
    const value = parseInt(match[1])
    switch (match[2]) {
      case 'S': return value
      case 'M': return value * 60
      case 'H': return value * 3600
      case 'D': return value * 86400
      case 'W': return value * 604800
    }
  }
  return 60 // fallback: 1 minute
}