{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
module EasyLogger.LogStr
    ( LogStr (..)
    , ToLogStr (..)
    , logStrLen
    , fromLogStr
    , mkMinLogStrLen
    ) where

import qualified Data.ByteString         as BS
import           Data.ByteString.Builder (Builder)
import qualified Data.ByteString.Builder as B
import qualified Data.ByteString.Char8   as S8
import qualified Data.ByteString.Lazy    as BL
import           Data.String             (IsString (..))
import qualified Data.Text               as T
import qualified Data.Text.Encoding      as T
import qualified Data.Text.Lazy          as TL
import qualified Data.Text.Lazy.Encoding as TL

import           Data.Int
import           Data.Word

toBuilder :: BS.ByteString -> Builder
toBuilder = B.byteString

fromBuilder :: Builder -> BS.ByteString
fromBuilder = BL.toStrict . B.toLazyByteString


-- | Log message builder. Use ('<>') to append two LogStr in O(1).
data LogStr = LogStr !Int Builder

instance Semigroup LogStr where
    {-# INLINE (<>) #-}
    LogStr s1 b1 <> LogStr s2 b2 = LogStr (s1 + s2) (b1 <> b2)

instance Monoid LogStr where
    mempty = LogStr 0 (toBuilder BS.empty)

instance IsString LogStr where
    {-# INLINE fromString #-}
    fromString = toLogStr . TL.pack

-- | Converting 'LogStr' to 'ByteString'.
fromLogStr :: LogStr -> BS.ByteString
fromLogStr (LogStr _ builder) = fromBuilder builder

logStrLen :: LogStr -> Int
logStrLen (LogStr l _) = l

mkMinLogStrLen :: Int -> LogStr -> LogStr
mkMinLogStrLen minLen logStr@(LogStr l _)
  | len > 0 = logStr <> LogStr len (toBuilder $ BS.replicate (minLen - l) space)
  | otherwise = logStr
  where
    len = minLen - l
    space = 32


-- | Types that can be converted to a 'LogStr'. Instances for
-- types from the @text@ library use a UTF-8 encoding. Instances
-- for numerical types use a decimal encoding.
class ToLogStr msg where
    toLogStr :: msg -> LogStr

instance ToLogStr LogStr where
    {-# INLINE toLogStr #-}
    toLogStr = id
instance ToLogStr S8.ByteString where
    {-# INLINE toLogStr #-}
    toLogStr bs = LogStr (BS.length bs) (toBuilder bs)
instance ToLogStr BL.ByteString where
    {-# INLINE toLogStr #-}
    toLogStr b = LogStr (fromIntegral (BL.length b)) (B.lazyByteString b)
instance ToLogStr Builder where
    {-# INLINE toLogStr #-}
    toLogStr x = let b = B.toLazyByteString x in LogStr (fromIntegral (BL.length b)) (B.lazyByteString b)
instance ToLogStr String where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . TL.pack
instance ToLogStr T.Text where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . T.encodeUtf8
instance ToLogStr TL.Text where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . TL.encodeUtf8

-- | @since 2.4.14
instance ToLogStr Int where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.intDec
-- | @since 2.4.14
instance ToLogStr Int8 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.int8Dec
-- | @since 2.4.14
instance ToLogStr Int16 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.int16Dec
-- | @since 2.4.14
instance ToLogStr Int32 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.int32Dec
-- | @since 2.4.14
instance ToLogStr Int64 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.int64Dec

-- | @since 2.4.14
instance ToLogStr Word where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.wordDec
-- | @since 2.4.14
instance ToLogStr Word8 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.word8Dec
-- | @since 2.4.14
instance ToLogStr Word16 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.word16Dec
-- | @since 2.4.14
instance ToLogStr Word32 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.word32Dec
-- | @since 2.4.14
instance ToLogStr Word64 where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.word64Dec

-- | @since 2.4.14
instance ToLogStr Integer where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.integerDec
-- | @since 2.4.14
instance ToLogStr Float where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.floatDec
-- | @since 2.4.14
instance ToLogStr Double where
    {-# INLINE toLogStr #-}
    toLogStr = toLogStr . B.doubleDec

instance Show LogStr where
  show = show . T.decodeUtf8 . fromLogStr

instance Eq LogStr where
  a == b = fromLogStr a == fromLogStr b