{-# LANGUAGE OverloadedStrings #-}

-- |Contains functions to log WAI request in JSON format
module Chakra.RequestLogging
  (jsonRequestLogger)
where

import           Data.Aeson                           as X (KeyValue ((.=)),
                                                            ToJSON (toJSON),
                                                            Value (String),
                                                            encode, object)
import qualified Data.ByteString.Builder              as BB (toLazyByteString)

import           Data.Default                         (Default (def))
import           Data.IP                              (fromHostAddress,
                                                       fromIPv4)
import           Network.HTTP.Types                   as H (HttpVersion (HttpVersion),
                                                            QueryItem,
                                                            Status (statusCode))
import           Network.Socket                       (PortNumber,
                                                       SockAddr (..))
import           Network.Wai
import           Network.Wai.Middleware.RequestLogger (OutputFormat (..),
                                                       OutputFormatterWithDetails,
                                                       mkRequestLogger,
                                                       outputFormat)
import           RIO                                  (Text, Word32,
                                                       decodeUtf8With,
                                                       lenientDecode,
                                                       maybeToList)
import qualified RIO.ByteString                       as B (ByteString, concat)
import qualified RIO.ByteString.Lazy                  as BL
import qualified RIO.Text                             as T
import           RIO.Time                             (NominalDiffTime)
import           System.Log.FastLogger                (toLogStr)
import           Text.Printf                          (printf)

-- | JSON formatted request log middleware for WAI applications
-- | it logs the given appName and appVer values
jsonRequestLogger :: Text -> Text -> IO Middleware
jsonRequestLogger envName appVer =
  mkRequestLogger $
  def {outputFormat = CustomOutputFormatWithDetails (formatAsJSONCustom envName appVer)}

formatAsJSONCustom :: Text -> Text -> OutputFormatterWithDetails
formatAsJSONCustom envName appVer date req status responseSize duration reqBody response =
  toLogStr
    (encode $
     object
       [ "env" .= envName
       , "appVersion" .= appVer
       , "request" .= requestToJSON req reqBody (Just duration)
       , "response" .=
         object
           [ "status" .= statusCode status
           , "size" .= responseSize
           , "body" .=
             if statusCode status >= 400
               then Just .
                    decodeUtf8With lenientDecode .
                    BL.toStrict . BB.toLazyByteString $ response
               else Nothing
           ]
       , "time" .= decodeUtf8With lenientDecode date
       ]) <>
  "\n"

requestToJSON :: Request -> [B.ByteString] -> Maybe NominalDiffTime -> Value
requestToJSON req reqBody duration =
  object $
  [ "method" .= decodeUtf8With lenientDecode (requestMethod req)
  , "path" .= decodeUtf8With lenientDecode (rawPathInfo req)
  , "queryString" .= map queryItemToJSON (queryString req)
  , "size" .= requestBodyLengthToJSON (requestBodyLength req)
  , "body" .= decodeUtf8With lenientDecode (B.concat reqBody)
  , "remoteHost" .= sockToJSON (remoteHost req)
  , "httpVersion" .= httpVersionToJSON (httpVersion req)
      -- , "headers" .= requestHeadersToJSON (requestHeaders req)
  ] <>
  maybeToList
    (("durationMs" .=) .
     readAsDouble . printf "%.2f" . rationalToDouble . (* 1000) . toRational <$>
     duration)
  where
    rationalToDouble :: Rational -> Double
    rationalToDouble = fromRational

readAsDouble :: String -> Double
readAsDouble = read

queryItemToJSON :: QueryItem -> Value
queryItemToJSON (name, mValue) =
  toJSON
    ( decodeUtf8With lenientDecode name
    , fmap (decodeUtf8With lenientDecode) mValue)

word32ToHostAddress :: Word32 -> Text
word32ToHostAddress = T.intercalate "." . map (T.pack . show) . fromIPv4 . fromHostAddress

sockToJSON :: SockAddr -> Value
sockToJSON (SockAddrInet pn ha) =
  object ["port" .= portToJSON pn, "hostAddress" .= word32ToHostAddress ha]
sockToJSON (SockAddrInet6 pn _ ha _) =
  object ["port" .= portToJSON pn, "hostAddress" .= ha]
sockToJSON (SockAddrUnix sock) =
  object ["unix" .= sock]

portToJSON :: PortNumber -> Value
portToJSON = toJSON . toInteger

httpVersionToJSON :: HttpVersion -> Value
httpVersionToJSON (HttpVersion major minor) = String $ T.pack (show major) <> "." <> T.pack (show minor)

requestBodyLengthToJSON :: RequestBodyLength -> Value
requestBodyLengthToJSON ChunkedBody     = String "Unknown"
requestBodyLengthToJSON (KnownLength l) = toJSON l