{-# LANGUAGE DeriveAnyClass               #-}
{-# LANGUAGE NoGeneralisedNewtypeDeriving #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}

module Hasura.Backends.BigQuery.Source where

import           Hasura.Prelude

import qualified Crypto.PubKey.RSA.Types as Cry
import qualified Data.Aeson              as J
import qualified Data.Aeson.Casing       as J
import qualified Data.Aeson.TH           as J
import qualified Data.ByteString.Lazy    as BL
import qualified Data.HashMap.Strict     as HM
import qualified Data.Text.Encoding      as TE
import qualified Data.X509               as X509
import qualified Data.X509.Memory        as X509

import           Control.Concurrent.MVar

import           Hasura.Incremental      (Cacheable (..))


data PKey = PKey
  { unPKey     :: Cry.PrivateKey
  , originalBS :: Text
  }
  deriving (Show, Eq, Data, Generic, NFData, Hashable)
deriving instance Generic Cry.PrivateKey -- orphan
deriving instance Generic Cry.PublicKey -- orphan
deriving instance J.ToJSON Cry.PrivateKey -- orphan
deriving instance J.ToJSON Cry.PublicKey -- orphan
deriving instance Hashable Cry.PrivateKey -- orphan
deriving instance Hashable Cry.PublicKey -- orphan
instance J.FromJSON PKey where
  parseJSON = J.withText "private_key" $ \k ->
    case X509.readKeyFileFromMemory $ TE.encodeUtf8 k of
      [X509.PrivKeyRSA k'] -> return $ PKey k' k
      _                    -> fail "unable to parse private key"
instance J.ToJSON PKey where
  toJSON PKey{..} = J.toJSON originalBS


newtype GoogleAccessToken
  = GoogleAccessToken Text
  deriving (Show, Eq, J.FromJSON, J.ToJSON, Hashable, Generic, Data, NFData)


data TokenResp
  = TokenResp
  { _trAccessToken :: !GoogleAccessToken
  , _trExpiresAt   :: !Integer -- Number of seconds until expiry from `now`, but we add `now` seconds to this for easy tracking
  } deriving (Eq, Show, Data, NFData, Generic, Hashable)
instance J.FromJSON TokenResp where
  parseJSON = J.withObject "TokenResp" $ \o -> TokenResp
    <$> o J..: "access_token"
    <*> o J..: "expires_in"


dummyTokenResp :: TokenResp
dummyTokenResp = TokenResp (GoogleAccessToken "DUMMY") 0


data ServiceAccount
  = ServiceAccount
  { _saClientEmail :: !Text
  , _saPrivateKey  :: !PKey
  , _saProjectId   :: !Text
  } deriving (Eq, Show, Data, NFData, Generic, Hashable)
$(J.deriveJSON (J.aesonDrop 3 J.snakeCase){J.omitNothingFields=False} ''ServiceAccount)


data ConfigurationJSON a
  = FromEnvJSON Text
  | FromYamlJSON a
  deriving stock (Show, Eq, Generic)
  deriving (NFData, Hashable)
instance J.FromJSON a => J.FromJSON (ConfigurationJSON a) where
  parseJSON = \case
    J.Object o | Just (J.String text) <- HM.lookup "from_env" o -> pure (FromEnvJSON text)
    J.String s -> case J.eitherDecode . BL.fromStrict . TE.encodeUtf8 $ s of
      Left {}  -> fail "error parsing configuration json"
      Right sa -> pure sa
    j -> fmap FromYamlJSON (J.parseJSON j)
instance J.ToJSON a => J.ToJSON (ConfigurationJSON a) where
  toJSON = \case
    FromEnvJSON i  -> J.object ["from_env" J..= i]
    FromYamlJSON j -> J.toJSON j


-- | Configuration inputs when they are a YAML array or an Env var whos value is
-- a comma-separated string
data ConfigurationInputs
  = FromYamls ![Text]
  | FromEnvs !Text
  deriving stock (Show, Eq, Generic)
  deriving (NFData, Hashable)
instance J.ToJSON ConfigurationInputs where
  toJSON = \case
    FromYamls i -> J.toJSON i
    FromEnvs i  -> J.object ["from_env" J..= i]
instance J.FromJSON ConfigurationInputs where
  parseJSON = \case
    J.Object o    -> FromEnvs <$> o J..: "from_env"
    s@(J.Array _) -> FromYamls <$> J.parseJSON s
    _             -> fail "one of array or object must be provided"


-- | Configuration input when the YAML value as well as the Env var have
-- singlular values
data ConfigurationInput
  = FromYaml !Text
  | FromEnv !Text
  deriving stock (Show, Eq, Generic)
  deriving (NFData, Hashable)
instance J.ToJSON ConfigurationInput where
  toJSON = \case
    FromYaml i -> J.toJSON i
    FromEnv i  -> J.object ["from_env" J..= i]
instance J.FromJSON ConfigurationInput where
  parseJSON = \case
    J.Object o     -> FromEnv <$> o J..: "from_env"
    s@(J.String _) -> FromYaml <$> J.parseJSON s
    (J.Number n)   -> FromYaml <$> J.parseJSON (J.String (tshow n))
    _              -> fail "one of string or number or object must be provided"


data BigQueryConnSourceConfig
  = BigQueryConnSourceConfig
  { _cscServiceAccount    :: !(ConfigurationJSON ServiceAccount)
  , _cscDatasets          :: !ConfigurationInputs
  , _cscProjectId         :: !ConfigurationInput -- this is part of service-account.json, but we put it here on purpose
  , _cscGlobalSelectLimit :: !(Maybe ConfigurationInput)
  } deriving (Eq, Generic, NFData)
$(J.deriveJSON (J.aesonDrop 4 J.snakeCase){J.omitNothingFields=True} ''BigQueryConnSourceConfig)
deriving instance Show BigQueryConnSourceConfig
deriving instance Hashable BigQueryConnSourceConfig
instance Cacheable BigQueryConnSourceConfig where
  unchanged _ = (==)


data BigQuerySourceConfig
  = BigQuerySourceConfig
  { _scServiceAccount    :: !ServiceAccount
  , _scDatasets          :: ![Text]
  , _scProjectId         :: !Text -- this is part of service-account.json, but we put it here on purpose
  , _scAccessTokenMVar   :: !(MVar (Maybe TokenResp))
  , _scGlobalSelectLimit :: !Int
  } deriving (Eq)
instance Cacheable BigQuerySourceConfig where
  unchanged _ = (==)
instance J.ToJSON BigQuerySourceConfig where
  toJSON BigQuerySourceConfig{..} =
    J.object
      [ "service_account"     J..= _scServiceAccount
      , "datasets"            J..= _scDatasets
      , "project_id"          J..= _scProjectId
      , "global_select_limit" J..= _scGlobalSelectLimit
      ]