const STORE_KEY = 'aigen-default-video-duration'
export const VIDEO_DURATION_MIN = 0.5
export const VIDEO_DURATION_MAX = 120
export const VIDEO_DURATION_DEFAULT = 5

export function clampVideoDuration(raw: unknown, fallback = VIDEO_DURATION_DEFAULT) {
  const value = Number(raw)
  if (!Number.isFinite(value)) return fallback
  return Math.min(VIDEO_DURATION_MAX, Math.max(VIDEO_DURATION_MIN, Math.round(value * 10) / 10))
}

export function defaultVideoDurationPref() {
  if (!import.meta.client) return VIDEO_DURATION_DEFAULT
  try {
    return clampVideoDuration(localStorage.getItem(STORE_KEY), VIDEO_DURATION_DEFAULT)
  } catch {
    return VIDEO_DURATION_DEFAULT
  }
}

export function setDefaultVideoDurationPref(raw: unknown) {
  const next = clampVideoDuration(raw, VIDEO_DURATION_DEFAULT)
  if (import.meta.client) {
    try {
      localStorage.setItem(STORE_KEY, String(next))
    } catch { /* ignore */ }
  }
  return next
}

/** Length of one generated part (extension delta), not the stitched family total. */
export function clipPartDuration(
  clip: { duration?: number; parentClipId?: string | null },
  parent?: { duration?: number } | null
) {
  const own = Number(clip.duration)
  const prior = Number(parent?.duration)
  if (clip.parentClipId && Number.isFinite(own) && Number.isFinite(prior) && own > prior + 0.4) {
    return clampVideoDuration(own - prior)
  }
  return clampVideoDuration(own)
}