{-|
  Send anonymized metrics to the telemetry server regarding usage of various
  features of Hasura.
-}

module Hasura.Server.Telemetry
  ( runTelemetry
  , mkTelemetryLog
  )
  where

import           Control.Exception     (try)
import           Control.Lens
import           Data.List
import           Data.Text.Conversions (UTF8 (..), decodeText)

import           Hasura.HTTP
import           Hasura.Logging
import           Hasura.Prelude
import           Hasura.RQL.Types
import           Hasura.Server.Init
import           Hasura.Server.Version

import qualified CI
import qualified Control.Concurrent    as C
import qualified Data.Aeson            as A
import qualified Data.Aeson.Casing     as A
import qualified Data.Aeson.TH         as A
import qualified Data.ByteString.Lazy  as BL
import qualified Data.HashMap.Strict   as Map
import qualified Data.Text             as T
import qualified Network.HTTP.Client   as HTTP
import qualified Network.HTTP.Types    as HTTP
import qualified Network.Wreq          as Wreq


data RelationshipMetric
  = RelationshipMetric
  { _rmManual :: !Int
  , _rmAuto   :: !Int
  } deriving (Show, Eq)
$(A.deriveToJSON (A.aesonDrop 3 A.snakeCase) ''RelationshipMetric)

data PermissionMetric
  = PermissionMetric
  { _pmSelect :: !Int
  , _pmInsert :: !Int
  , _pmUpdate :: !Int
  , _pmDelete :: !Int
  , _pmRoles  :: !Int
  } deriving (Show, Eq)
$(A.deriveToJSON (A.aesonDrop 3 A.snakeCase) ''PermissionMetric)

data Metrics
  = Metrics
  { _mtTables        :: !Int
  , _mtViews         :: !Int
  , _mtEnumTables    :: !Int
  , _mtRelationships :: !RelationshipMetric
  , _mtPermissions   :: !PermissionMetric
  , _mtEventTriggers :: !Int
  , _mtRemoteSchemas :: !Int
  , _mtFunctions     :: !Int
  } deriving (Show, Eq)
$(A.deriveToJSON (A.aesonDrop 3 A.snakeCase) ''Metrics)

data HasuraTelemetry
  = HasuraTelemetry
  { _htDbUid       :: !Text
  , _htInstanceUid :: !InstanceId
  , _htVersion     :: !Version
  , _htCi          :: !(Maybe CI.CI)
  , _htMetrics     :: !Metrics
  } deriving (Show)
$(A.deriveToJSON (A.aesonDrop 3 A.snakeCase) ''HasuraTelemetry)

data TelemetryPayload
  = TelemetryPayload
  { _tpTopic :: !Text
  , _tpData  :: !HasuraTelemetry
  } deriving (Show)
$(A.deriveToJSON (A.aesonDrop 3 A.snakeCase) ''TelemetryPayload)

telemetryUrl :: Text
telemetryUrl = "https://telemetry.hasura.io/v1/http"

mkPayload :: Text -> InstanceId -> Version -> Metrics -> IO TelemetryPayload
mkPayload dbId instanceId version metrics = do
  ci <- CI.getCI
  let topic = case version of
        VersionDev _     -> "server_test"
        VersionRelease _ -> "server"
  pure $ TelemetryPayload topic $ HasuraTelemetry dbId instanceId version ci metrics

runTelemetry
  :: (HasVersion)
  => Logger Hasura
  -> HTTP.Manager
  -> IO SchemaCache
  -- ^ an action that always returns the latest schema cache
  -> Text
  -> InstanceId
  -> IO ()
runTelemetry (Logger logger) manager getSchemaCache dbId instanceId = do
  let options = wreqOptions manager []
  forever $ do
    schemaCache <- getSchemaCache
    let metrics = computeMetrics schemaCache
    payload <- A.encode <$> mkPayload dbId instanceId currentVersion metrics
    logger $ debugLBS $ "metrics_info: " <> payload
    resp <- try $ Wreq.postWith options (T.unpack telemetryUrl) payload
    either logHttpEx handleHttpResp resp
    C.threadDelay aDay

  where
    logHttpEx :: HTTP.HttpException -> IO ()
    logHttpEx ex = do
      let httpErr = Just $ mkHttpError telemetryUrl Nothing (Just $ HttpException ex)
      logger $ mkTelemetryLog "http_exception" "http exception occurred" httpErr

    handleHttpResp resp = do
      let statusCode = resp ^. Wreq.responseStatus . Wreq.statusCode
      logger $ debugLBS $ "http_success: " <> resp ^. Wreq.responseBody
      when (statusCode /= 200) $ do
        let httpErr = Just $ mkHttpError telemetryUrl (Just resp) Nothing
        logger $ mkTelemetryLog "http_error" "failed to post telemetry" httpErr

    aDay = 86400 * 1000 * 1000

computeMetrics :: SchemaCache -> Metrics
computeMetrics sc =
  let nTables = countUserTables (isNothing . _tciViewInfo . _tiCoreInfo)
      nViews = countUserTables (isJust . _tciViewInfo . _tiCoreInfo)
      nEnumTables = countUserTables (isJust . _tciEnumValues . _tiCoreInfo)
      allRels = join $ Map.elems $ Map.map (getRels . _tciFieldInfoMap . _tiCoreInfo) userTables
      (manualRels, autoRels) = partition riIsManual allRels
      relMetrics = RelationshipMetric (length manualRels) (length autoRels)
      rolePerms = join $ Map.elems $ Map.map permsOfTbl userTables
      nRoles = length $ nub $ fst <$> rolePerms
      allPerms = snd <$> rolePerms
      insPerms = calcPerms _permIns allPerms
      selPerms = calcPerms _permSel allPerms
      updPerms = calcPerms _permUpd allPerms
      delPerms = calcPerms _permDel allPerms
      permMetrics =
        PermissionMetric selPerms insPerms updPerms delPerms nRoles
      evtTriggers = Map.size $ Map.filter (not . Map.null)
                    $ Map.map _tiEventTriggerInfoMap userTables
      rmSchemas   = Map.size $ scRemoteSchemas sc
      funcs = Map.size $ Map.filter (not . isSystemDefined . fiSystemDefined) $ scFunctions sc

  in Metrics nTables nViews nEnumTables relMetrics permMetrics evtTriggers rmSchemas funcs

  where
    userTables = Map.filter (not . isSystemDefined . _tciSystemDefined . _tiCoreInfo) $ scTables sc
    countUserTables predicate = length . filter predicate $ Map.elems userTables

    calcPerms :: (RolePermInfo -> Maybe a) -> [RolePermInfo] -> Int
    calcPerms fn perms = length $ catMaybes $ map fn perms

    permsOfTbl :: TableInfo -> [(RoleName, RolePermInfo)]
    permsOfTbl = Map.toList . _tiRolePermInfoMap


-- | Logging related

data TelemetryLog
  = TelemetryLog
  { _tlLogLevel  :: !LogLevel
  , _tlType      :: !Text
  , _tlMessage   :: !Text
  , _tlHttpError :: !(Maybe TelemetryHttpError)
  } deriving (Show)

data TelemetryHttpError
  = TelemetryHttpError
  { tlheStatus        :: !(Maybe HTTP.Status)
  , tlheUrl           :: !T.Text
  , tlheHttpException :: !(Maybe HttpException)
  , tlheResponse      :: !(Maybe T.Text)
  } deriving (Show)

instance A.ToJSON TelemetryLog where
  toJSON tl =
    A.object [ "type" A..= _tlType tl
             , "message" A..= _tlMessage tl
             , "http_error" A..= (A.toJSON <$> _tlHttpError tl)
             ]

instance A.ToJSON TelemetryHttpError where
  toJSON tlhe =
    A.object [ "status_code" A..= (HTTP.statusCode <$> tlheStatus tlhe)
             , "url" A..= tlheUrl tlhe
             , "response" A..= tlheResponse tlhe
             , "http_exception" A..= (A.toJSON <$> tlheHttpException tlhe)
             ]


instance ToEngineLog TelemetryLog Hasura where
  toEngineLog tl = (_tlLogLevel tl, ELTInternal ILTTelemetry, A.toJSON tl)

mkHttpError
  :: Text
  -> Maybe (Wreq.Response BL.ByteString)
  -> Maybe HttpException
  -> TelemetryHttpError
mkHttpError url mResp httpEx =
  case mResp of
    Nothing   -> TelemetryHttpError Nothing url httpEx Nothing
    Just resp ->
      let status = resp ^. Wreq.responseStatus
          body = decodeText $ UTF8 (resp ^. Wreq.responseBody)
      in TelemetryHttpError (Just status) url httpEx body

mkTelemetryLog :: Text -> Text -> Maybe TelemetryHttpError -> TelemetryLog
mkTelemetryLog = TelemetryLog LevelInfo