export type SerperAgeFilter = {
  maxAgeDays?: number
  minAgeDays?: number
}

const normalizeDays = (value?: number) => {
  if (typeof value !== 'number') return undefined
  if (!Number.isFinite(value)) return undefined
  if (value <= 0) return undefined
  return Math.floor(value)
}

export function appendSerperAgeModifiers(query: string, filters?: SerperAgeFilter): string {
  if (!filters) return query
  const modifiers: string[] = []
  const normalizedMax = normalizeDays(filters.maxAgeDays)
  const normalizedMin = normalizeDays(filters.minAgeDays)

  if (typeof normalizedMax === 'number') {
    modifiers.push(`newer_than:${normalizedMax}d`)
  }
  if (typeof normalizedMin === 'number') {
    modifiers.push(`older_than:${normalizedMin}d`)
  }

  if (modifiers.length === 0) return query
  return `${query} ${modifiers.join(' ')}`
}