{-# LANGUAGE CPP #-}
{-# LANGUAGE BangPatterns #-}
{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnboxedTuples #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  OpenTelemetry.Trace.Id
-- Copyright   :  (c) Ian Duncan, 2021
-- License     :  BSD-3
-- Description :  Trace and Span ID generation, validation, serialization, and deserialization
-- Maintainer  :  Ian Duncan
-- Stability   :  experimental
-- Portability :  non-portable (GHC extensions)
--
-- Trace and Span Id generation
--
-- No Aeson instances are provided since they've got the potential to be
-- transport-specific in format. Use newtypes for serialisation instead.
--
-----------------------------------------------------------------------------

module OpenTelemetry.Trace.Id
  ( -- * Working with 'TraceId's
    TraceId
    -- ** Creating 'TraceId's
  , newTraceId
    -- ** Checking 'TraceId's for validity
  , isEmptyTraceId
    -- ** Encoding / decoding 'TraceId' from bytes
  , traceIdBytes
  , bytesToTraceId
    -- ** Encoding / decoding 'TraceId' from a given 'Base' encoding
  , baseEncodedToTraceId
  , traceIdBaseEncodedBuilder
  , traceIdBaseEncodedByteString
  , traceIdBaseEncodedText
    -- * Working with 'SpanId's
  , SpanId
    -- ** Creating 'SpanId's
  , newSpanId
    -- ** Checking 'SpanId's for validity
  , isEmptySpanId
    -- ** Encoding / decoding 'SpanId' from bytes
  , spanIdBytes
  , bytesToSpanId
    -- ** Encoding / decoding 'SpanId' from a given 'Base' encoding
  , Base(..)
  , baseEncodedToSpanId
  , spanIdBaseEncodedBuilder
  , spanIdBaseEncodedByteString
  , spanIdBaseEncodedText
  ) where

import OpenTelemetry.Trace.Id.Generator
import Control.Monad.IO.Class
import Data.ByteArray.Encoding
import Data.ByteString (ByteString)
import qualified Data.ByteString as BS
import Data.ByteString.Builder (Builder)
import qualified Data.ByteString.Builder as B
import Data.Hashable (Hashable)
import Data.Text (Text)
import Data.Text.Encoding (decodeUtf8)

import Data.ByteString.Short.Internal
import GHC.Exts
import GHC.ST
import Prelude hiding (length)

-- TODO faster encoding decoding via something like
-- https://github.com/lemire/Code-used-on-Daniel-Lemire-s-blog/blob/03fc2e82fdef2c6fd25721203e1654428fee123d/2019/04/17/hexparse.cpp#L390

-- | A valid trace identifier is a 16-byte array with at least one non-zero byte.
newtype TraceId = TraceId ShortByteString
  deriving stock (Ord, Eq)
  deriving newtype (Hashable)

-- | A valid span identifier is an 8-byte array with at least one non-zero byte.
newtype SpanId = SpanId ShortByteString
  deriving stock (Ord, Eq)
  deriving newtype (Hashable)

instance Show TraceId where
  show = show . traceIdBaseEncodedText Base16

instance IsString TraceId where
  fromString str = case baseEncodedToTraceId Base16 (fromString str) of
    Left err -> error err
    Right ok -> ok

instance Show SpanId where
  show = show . spanIdBaseEncodedText Base16

instance IsString SpanId where
  fromString str = case baseEncodedToSpanId Base16 (fromString str) of
    Left err -> error err
    Right ok -> ok

-- | Generate a 'TraceId' using the provided 'IdGenerator'
--
-- This function is generally called by the @hs-opentelemetry-sdk@,
-- but may be useful in some testing situations.
--
-- @since 0.1.0.0
newTraceId :: MonadIO m => IdGenerator -> m TraceId
newTraceId gen = liftIO (TraceId . toShort <$> generateTraceIdBytes gen)

-- | Check whether all bytes in the 'TraceId' are zero.
--
-- @since 0.1.0.0
isEmptyTraceId :: TraceId -> Bool
isEmptyTraceId (TraceId (SBS arr)) =
  isTrue#
    (eqWord#
      (or#
#if MIN_VERSION_base(4,17,0)
        (word64ToWord# (indexWord64Array# arr 0#))
        (word64ToWord# (indexWord64Array# arr 1#)))
#else
        (indexWord64Array# arr 0#)
        (indexWord64Array# arr 1#))
#endif
      (int2Word# 0#))

-- | Access the byte-level representation of the provided 'TraceId'
--
-- @since 0.1.0.0
traceIdBytes :: TraceId -> ByteString
traceIdBytes (TraceId bytes) = fromShort bytes

-- | Convert a 'ByteString' to a 'TraceId'. Will fail if the 'ByteString'
-- is not exactly 16 bytes long.
--
-- @since 0.1.0.0
bytesToTraceId :: ByteString -> Either String TraceId
bytesToTraceId bs = if BS.length bs == 16
  then Right $ TraceId $ toShort bs
  else Left "bytesToTraceId: TraceId must be 8 bytes long"

-- | Convert a 'ByteString' of a specified base-encoding into a 'TraceId'.
-- Will fail if the decoded value is not exactly 16 bytes long.
--
-- @since 0.1.0.0
baseEncodedToTraceId :: Base -> ByteString -> Either String TraceId
baseEncodedToTraceId b bs = do
  r <- convertFromBase b bs
  bytesToTraceId r

-- | Output a 'TraceId' into a base-encoded bytestring 'Builder'.
--
-- @since 0.1.0.0
traceIdBaseEncodedBuilder :: Base -> TraceId -> Builder
traceIdBaseEncodedBuilder b = B.byteString . convertToBase b . traceIdBytes

-- | Output a 'TraceId' into a base-encoded 'ByteString'.
--
-- @since 0.1.0.0
traceIdBaseEncodedByteString :: Base -> TraceId -> ByteString
traceIdBaseEncodedByteString b = convertToBase b . traceIdBytes

-- | Output a 'TraceId' into a base-encoded 'Text'.
--
-- @since 0.1.0.0
traceIdBaseEncodedText :: Base -> TraceId -> Text
traceIdBaseEncodedText b = decodeUtf8 . traceIdBaseEncodedByteString b

-- | Generate a 'SpanId' using the provided 'IdGenerator'
--
-- This function is generally called by the @hs-opentelemetry-sdk@,
-- but may be useful in some testing situations.
--
-- @since 0.1.0.0
newSpanId :: MonadIO m => IdGenerator -> m SpanId
newSpanId gen = liftIO (SpanId . toShort <$> generateSpanIdBytes gen)

-- | Check whether all bytes in the 'SpanId' are zero.
--
-- @since 0.1.0.0
isEmptySpanId :: SpanId -> Bool
isEmptySpanId (SpanId (SBS arr)) = isTrue#
  (eqWord#
#if MIN_VERSION_base(4,17,0)
    (word64ToWord# (indexWord64Array# arr 0#))
#else
    (indexWord64Array# arr 0#)
#endif
    (int2Word# 0#))

-- | Access the byte-level representation of the provided 'SpanId'
--
-- @since 0.1.0.0
spanIdBytes :: SpanId -> ByteString
spanIdBytes (SpanId bytes) = fromShort bytes

-- | Convert a 'ByteString' of a specified base-encoding into a 'SpanId'.
-- Will fail if the decoded value is not exactly 8 bytes long.
--
-- @since 0.1.0.0
bytesToSpanId :: ByteString -> Either String SpanId
bytesToSpanId bs = if BS.length bs == 8
  then Right $ SpanId $ toShort bs
  else Left "bytesToSpanId: SpanId must be 8 bytes long"

-- | Convert a 'ByteString' of a specified base-encoding into a 'SpanId'.
-- Will fail if the decoded value is not exactly 8 bytes long.
--
-- @since 0.1.0.0
baseEncodedToSpanId :: Base -> ByteString -> Either String SpanId
baseEncodedToSpanId b bs = do
  r <- convertFromBase b bs
  bytesToSpanId r

-- | Output a 'SpanId' into a base-encoded bytestring 'Builder'.
--
-- @since 0.1.0.0
spanIdBaseEncodedBuilder :: Base -> SpanId -> Builder
spanIdBaseEncodedBuilder b = B.byteString . convertToBase b . spanIdBytes

-- | Output a 'SpanId' into a base-encoded 'ByteString'.
--
-- @since 0.1.0.0
spanIdBaseEncodedByteString :: Base -> SpanId -> ByteString
spanIdBaseEncodedByteString b = convertToBase b . spanIdBytes

-- | Output a 'SpanId' into a base-encoded 'Text'.
--
-- @since 0.1.0.0
spanIdBaseEncodedText :: Base -> SpanId -> Text
spanIdBaseEncodedText b = decodeUtf8 . spanIdBaseEncodedByteString b