import times

const zeroTime = fromSeconds(0)

proc format*(ti: TimeInterval, fmt: string): string =
  let info = getGMTime(fromSeconds(0) + ti)
  return info.format(fmt)

proc `-`*(a, b: TimeInfo): TimeInterval =
  return seconds(cast[int](a.toTime - b.toTime))

proc `>`*(a, b: TimeInfo): bool =
  return a.toTime > b.toTime

proc `<`*(a, b: TimeInfo): bool =
  return a.toTime < b.toTime

proc `>=`*(a, b: TimeInfo): bool =
  return a.toTime >= b.toTime

proc `<=`*(a, b: TimeInfo): bool =
  return a.toTime <= b.toTime

proc `>`*(a, b: TimeInterval): bool =
  return (zeroTime + a) > (zeroTime + b)

proc `<`*(a, b: TimeInterval): bool =
  return (zeroTime + a) < (zeroTime + b)

proc `>=`*(a, b: TimeInterval): bool =
  return (zeroTime + a) >= (zeroTime + b)

proc `<=`*(a, b: TimeInterval): bool =
  return (zeroTime + a) <= (zeroTime + b)

proc cmp*(a, b: TimeInfo): int =
  if b == a: return 0
  elif a > b: return 1
  else: return -1

proc startOfDay*(ti: TimeInfo): TimeInfo =
  result = ti
  result.hour = 0
  result.minute = 0
  result.second = 0

proc startOfWeek*(ti: TimeInfo, startDay = dMon): TimeInfo =
  var diff = (ti.weekday.ord - startDay.ord)
  if diff < 0: diff += 7
  return (ti - diff.days).startOfDay

# This is a workaround needed due a bug in Nim's times.parse procedure.
# see: https://github.com/nim-lang/Nim/issues/4922
proc fixedParse*(value, format: string): TimeInfo =
  let firstParsed = parse(value, format)
  let rectified = getLocalTime(toTime(firstParsed))
  if firstParsed.isDST and not rectified.isDST: return rectified + 1.hours
  elif not firstParsed.isDST and rectified.isDST: return rectified - 1.hours
  else: return rectified