module Hasura.RQL.DDL.ScheduledTrigger
  ( runCreateCronTrigger
  , runDeleteCronTrigger
  , addCronTriggerToCatalog
  , deleteCronTriggerFromCatalog
  , resolveCronTrigger
  , runCreateScheduledEvent
  ) where

import           Hasura.Db
import           Hasura.EncJSON
import           Hasura.Prelude
import           Hasura.RQL.DDL.EventTrigger (getHeaderInfosFromConf)
import           Hasura.RQL.Types
import           Hasura.RQL.Types.Catalog    (CatalogCronTrigger(..))
import           Hasura.Eventing.ScheduledTrigger

import qualified Database.PG.Query     as Q
import qualified Data.Time.Clock       as C
import qualified Data.HashMap.Strict   as Map

-- | runCreateCronTrigger will update a existing cron trigger when the 'replace'
--   value is set to @true@ and when replace is @false@ a new cron trigger will
--   be created
runCreateCronTrigger :: (CacheRWM m, MonadTx m) => CreateCronTrigger ->  m EncJSON
runCreateCronTrigger CreateCronTrigger {..} = do
  let q = (CronTriggerMetadata cctName
                               cctWebhook
                               cctCronSchedule
                               cctPayload
                               cctRetryConf
                               cctHeaders
                               cctIncludeInMetadata
                               cctComment)
  case cctReplace of
    True -> updateCronTrigger q
    False -> do
        cronTriggersMap <- scCronTriggers <$> askSchemaCache
        case Map.lookup (ctName q) cronTriggersMap of
          Nothing -> pure ()
          Just _ -> throw400 AlreadyExists $
                    "cron trigger with name: "
                    <> (triggerNameToTxt $ ctName q)
                    <> " already exists"

        addCronTriggerToCatalog q
        buildSchemaCacheFor $ MOCronTrigger $ ctName q
        return successMsg

addCronTriggerToCatalog :: (MonadTx m) => CronTriggerMetadata ->  m ()
addCronTriggerToCatalog CronTriggerMetadata {..} = liftTx $ do
  Q.unitQE defaultTxErrorHandler
    [Q.sql|
      INSERT into hdb_catalog.hdb_cron_triggers
        (name, webhook_conf, cron_schedule, payload, retry_conf, header_conf, include_in_metadata, comment)
      VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
    |] (ctName, Q.AltJ ctWebhook, ctSchedule, Q.AltJ <$> ctPayload, Q.AltJ ctRetryConf
       ,Q.AltJ ctHeaders, ctIncludeInMetadata, ctComment) False
  currentTime <- liftIO C.getCurrentTime
  let scheduleTimes = generateScheduleTimes currentTime 100 ctSchedule -- generate next 100 events
  insertCronEvents $ map (CronEventSeed ctName) scheduleTimes

resolveCronTrigger
  :: (QErrM m, MonadIO m)
  => CatalogCronTrigger -> m CronTriggerInfo
resolveCronTrigger CatalogCronTrigger {..} = do
  webhookInfo <- resolveWebhook _cctWebhookConf
  headerInfo <- getHeaderInfosFromConf headers
  pure $
    CronTriggerInfo _cctName
                    _cctCronSchedule
                    _cctPayload
                    retryConf
                    webhookInfo
                    headerInfo
                    _cctComment
  where
    retryConf = fromMaybe defaultSTRetryConf _cctRetryConf

    headers = fromMaybe [] _cctHeaderConf

updateCronTrigger :: (CacheRWM m, MonadTx m) => CronTriggerMetadata -> m EncJSON
updateCronTrigger cronTriggerMetadata = do
  checkExists $ ctName cronTriggerMetadata
  updateCronTriggerInCatalog cronTriggerMetadata
  buildSchemaCacheFor $ MOCronTrigger $ ctName cronTriggerMetadata
  return successMsg

updateCronTriggerInCatalog :: (MonadTx m) => CronTriggerMetadata -> m ()
updateCronTriggerInCatalog CronTriggerMetadata {..} = liftTx $ do
  Q.unitQE defaultTxErrorHandler
   [Q.sql|
    UPDATE hdb_catalog.hdb_cron_triggers
    SET webhook_conf = $2,
        cron_schedule = $3,
        payload = $4,
        retry_conf = $5,
        include_in_metadata = $6,
        comment = $7
    WHERE name = $1
   |] (ctName, Q.AltJ ctWebhook, ctSchedule, Q.AltJ <$> ctPayload, Q.AltJ ctRetryConf
      , ctIncludeInMetadata, ctComment) False
  -- since the cron trigger is updated, clear all its future events which are not retries
  Q.unitQE defaultTxErrorHandler
   [Q.sql|
    DELETE FROM hdb_catalog.hdb_cron_events
    WHERE trigger_name = $1 AND scheduled_time > now() AND tries = 0
   |] (Identity ctName) False

runDeleteCronTrigger :: (CacheRWM m, MonadTx m) => ScheduledTriggerName -> m EncJSON
runDeleteCronTrigger (ScheduledTriggerName stName) = do
  checkExists stName
  deleteCronTriggerFromCatalog stName
  withNewInconsistentObjsCheck buildSchemaCache
  return successMsg

deleteCronTriggerFromCatalog :: (MonadTx m) => TriggerName -> m ()
deleteCronTriggerFromCatalog triggerName = liftTx $ do
  Q.unitQE defaultTxErrorHandler
   [Q.sql|
    DELETE FROM hdb_catalog.hdb_cron_triggers
    WHERE name = $1
   |] (Identity triggerName) False

runCreateScheduledEvent :: (MonadTx m) => CreateScheduledEvent -> m EncJSON
runCreateScheduledEvent CreateScheduledEvent {..} = do
  liftTx $ Q.unitQE defaultTxErrorHandler
     [Q.sql|
      INSERT INTO hdb_catalog.hdb_scheduled_events
      (webhook_conf,scheduled_time,payload,retry_conf,header_conf,comment)
      VALUES
      ($1, $2, $3, $4, $5, $6)
     |] ( Q.AltJ cseWebhook
        , cseScheduleAt
        , Q.AltJ csePayload
        , Q.AltJ cseRetryConf
        , Q.AltJ cseHeaders
        , cseComment)
        False
  pure successMsg

checkExists :: (CacheRM m, MonadError QErr m) => TriggerName -> m ()
checkExists name = do
  cronTriggersMap <- scCronTriggers <$> askSchemaCache
  void $ onNothing (Map.lookup name cronTriggersMap) $
    throw400 NotExists $
      "cron trigger with name: " <> (triggerNameToTxt name) <> " does not exist"