module SemVer(
  makeVersion,
  incrementMajor,
  incrementMinor,
  incrementPatch,
  IncludingNegativeVersion,
) where

import Text.Printf
import Data.Typeable
import Control.Exception
import Data.List

newtype VersionNumber = VersionNumber Integer deriving Eq
instance Show VersionNumber where
  show (VersionNumber a) = show a

increment (VersionNumber a) = VersionNumber $ a + 1
zero = VersionNumber 0

data Version = Version {
  major :: VersionNumber,
  minor :: VersionNumber,
  patch :: VersionNumber
} deriving(Eq)

instance Show Version where
  show (Version ma mi p) = intercalate "." $ show <$> [ma, mi, p]

data IncludingNegativeVersion = IncludingNegativeVersion deriving Typeable
instance Show IncludingNegativeVersion where
    show IncludingNegativeVersion = "バージョン番号に負の数が含まれています。"
instance Exception IncludingNegativeVersion

makeVersion :: Integer -> Integer -> Integer -> Version
makeVersion major minor patch = if allNonNegative then result else throw IncludingNegativeVersion
  where
    allNonNegative = major >= 0 && minor >= 0 && patch >= 0
    result = Version {
      major = VersionNumber major,
      minor  = VersionNumber minor,
      patch = VersionNumber patch
    }

incrementPatch :: Version -> Version
incrementPatch v = Version {
  major = major v,
  minor  = minor v,
  patch = increment $ patch v
}

incrementMinor :: Version -> Version
incrementMinor v = Version {
  major = major v,
  minor  = increment $ minor v,
  patch = zero
}

incrementMajor :: Version -> Version
incrementMajor v = Version {
  major = increment $ major v,
  minor  = zero,
  patch = zero
}