{-# LANGUAGE BangPatterns      #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes       #-}
{-# LANGUAGE StrictData        #-}
{-# LANGUAGE TemplateHaskell   #-}

{-|
Module      : Headroom.Meta.Version
Description : Type safe representation of Haskell PVP version
Copyright   : (c) 2019-2021 Vaclav Svejcar
License     : BSD-3-Clause
Maintainer  : vaclav.svejcar@gmail.com
Stability   : experimental
Portability : POSIX

This module contains data types and functions for working with
Haskell PVP versions (<https://pvp.haskell.org/faq/>) in type safe way.
-}

module Headroom.Meta.Version
  ( Version(..)
  , parseVersion
  , printVersion
  , printVersionP
  , pvp
  )
where

import           Data.Aeson                          ( FromJSON(..)
                                                     , Value(String)
                                                     )
import           Headroom.Data.Regex                 ( match
                                                     , re
                                                     )
import qualified Headroom.Data.Text                 as T
import           Language.Haskell.TH.Quote           ( QuasiQuoter(..) )
import           RIO
import qualified RIO.Text                           as T


---------------------------------  DATA TYPES  ---------------------------------

-- | Type safe representation of /PVP/ version.
data Version = Version
  { vMajor1 :: Int
  -- ^ first major version
  , vMajor2 :: Int
  -- ^ second major version
  , vMinor  :: Int
  -- ^ minor version
  , vPatch  :: Int
  -- ^ patch level version
  }
  deriving (Eq, Show)


instance Ord Version where
  compare (Version a1 b1 c1 d1) (Version a2 b2 c2 d2) = go pairs
   where
    pairs = [(a1, a2), (b1, b2), (c1, c2), (d1, d2)]
    go [] = EQ
    go ((x, y) : xs) | x /= y    = compare x y
                     | otherwise = go xs


instance FromJSON Version where
  parseJSON (String s) = maybe (error . errorMsg $ s) pure (parseVersion s)
  parseJSON other      = error . errorMsg . tshow $ other


------------------------------  PUBLIC FUNCTIONS  ------------------------------

-- | Parses 'Version' from given text.
--
-- >>> parseVersion "0.3.2.0"
-- Just (Version {vMajor1 = 0, vMajor2 = 3, vMinor = 2, vPatch = 0})
parseVersion :: Text
             -- ^ input text to parse version from
             -> Maybe Version
             -- ^ parsed 'Version'
parseVersion raw = do
  groups <- match [re|^([0-9]+)\.([0-9]+)\.([0-9]+)\.([0-9]+)$|] raw
  check . catMaybes $ T.read <$> groups
 where
  check [ma1, ma2, mi, p] = Just $ Version ma1 ma2 mi p
  check _                 = Nothing


-- | Prints 'Version' in @major1.major2.minor.patch@ format.
--
-- >>> printVersion (Version 0 3 2 0)
-- "0.3.2.0"
printVersion :: Version
             -- ^ 'Version' to print
             -> Text
             -- ^ textual representation
printVersion (Version ma1 ma2 mi p) = T.intercalate "." chunks
  where chunks = tshow <$> [ma1, ma2, mi, p]


-- | Similar to 'printVersion', but adds the @v@ prefix in front of the version
-- number.
--
-- >>> printVersionP (Version 0 3 2 0)
-- "v0.3.2.0"
printVersionP :: Version -> Text
printVersionP = ("v" <>) . printVersion


-- | QuasiQuoter for defining 'Version' values checked at compile time.
--
-- >>> [pvp|1.2.3.4|]
-- Version {vMajor1 = 1, vMajor2 = 2, vMinor = 3, vPatch = 4}
pvp :: QuasiQuoter
pvp = QuasiQuoter { quoteExp  = quoteExpVersion
                  , quotePat  = undefined
                  , quoteType = undefined
                  , quoteDec  = undefined
                  }
 where
  quoteExpVersion txt = [| parseVersionUnsafe . T.pack $ txt |]
    where !_ = parseVersionUnsafe . T.pack $ txt -- check at compile time


------------------------------  PRIVATE FUNCTIONS  -----------------------------

parseVersionUnsafe :: Text -> Version
parseVersionUnsafe raw = case parseVersion raw of
  Nothing  -> error . errorMsg $ raw
  Just res -> res

errorMsg :: Text -> String
errorMsg raw = mconcat
  [ "Value '"
  , T.unpack raw
  , "' is not valid PVP version string. Please define correct version in "
  , "format 'MAJOR1.MAJOR2.MINOR.PATCH' (e.g. '0.4.1.2')."
  ]