{-# LANGUAGE DeriveLift        #-}
{-# LANGUAGE FlexibleContexts  #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes       #-}
{-# LANGUAGE TemplateHaskell   #-}
{-# LANGUAGE TypeFamilies      #-}

module Hasura.RQL.DDL.Metadata
  ( ReplaceMetadata(..)
  , TableMeta(..)
  , tmObjectRelationships
  , tmArrayRelationships
  , tmInsertPermissions
  , tmSelectPermissions
  , tmUpdatePermissions
  , tmDeletePermissions

  , mkTableMeta
  , applyQP1
  , applyQP2

  , DumpInternalState(..)

  , ExportMetadata(..)
  , fetchMetadata

  , ClearMetadata(..)
  , clearMetadata

  , ReloadMetadata(..)
  ) where

import           Control.Lens
import           Data.Aeson
import           Data.Aeson.Casing
import           Data.Aeson.TH
import           Language.Haskell.TH.Syntax   (Lift)

import qualified Data.HashMap.Strict          as M
import qualified Data.HashSet                 as HS
import qualified Data.List                    as L
import qualified Data.Text                    as T

import           Hasura.Prelude
import           Hasura.RQL.DDL.Utils
import           Hasura.RQL.Types
import           Hasura.SQL.Types

import qualified Database.PG.Query            as Q
import qualified Hasura.RQL.DDL.Permission    as DP
import qualified Hasura.RQL.DDL.QueryTemplate as DQ
import qualified Hasura.RQL.DDL.Relationship  as DR
import qualified Hasura.RQL.DDL.Schema.Table  as DT
import qualified Hasura.RQL.DDL.Subscribe     as DS
import qualified Hasura.RQL.Types.Subscribe   as DTS

data TableMeta
  = TableMeta
  { _tmTable               :: !QualifiedTable
  , _tmObjectRelationships :: ![DR.ObjRelDef]
  , _tmArrayRelationships  :: ![DR.ArrRelDef]
  , _tmInsertPermissions   :: ![DP.InsPermDef]
  , _tmSelectPermissions   :: ![DP.SelPermDef]
  , _tmUpdatePermissions   :: ![DP.UpdPermDef]
  , _tmDeletePermissions   :: ![DP.DelPermDef]
  , _tmEventTriggers       :: ![DTS.EventTriggerDef]
  } deriving (Show, Eq, Lift)

mkTableMeta :: QualifiedTable -> TableMeta
mkTableMeta qt =
  TableMeta qt [] [] [] [] [] [] []

makeLenses ''TableMeta

instance FromJSON TableMeta where
  parseJSON (Object o) = do
    unless (null unexpectedKeys) $
      fail $ "unexpected keys when parsing TableMetadata : "
      <> show (HS.toList unexpectedKeys)

    TableMeta
     <$> o .: tableKey
     <*> o .:? orKey .!= []
     <*> o .:? arKey .!= []
     <*> o .:? ipKey .!= []
     <*> o .:? spKey .!= []
     <*> o .:? upKey .!= []
     <*> o .:? dpKey .!= []
     <*> o .:? etKey .!= []

    where
      tableKey = "table"
      orKey = "object_relationships"
      arKey = "array_relationships"
      ipKey = "insert_permissions"
      spKey = "select_permissions"
      upKey = "update_permissions"
      dpKey = "delete_permissions"
      etKey = "event_triggers"

      unexpectedKeys =
        HS.fromList (M.keys o) `HS.difference` expectedKeySet

      expectedKeySet =
        HS.fromList [ tableKey, orKey, arKey, ipKey
                    , spKey, upKey, dpKey, etKey
                    ]

  parseJSON _ =
    fail "expecting an Object for TableMetadata"

$(deriveToJSON (aesonDrop 3 snakeCase){omitNothingFields=True} ''TableMeta)

data ClearMetadata
  = ClearMetadata
  deriving (Show, Eq, Lift)
$(deriveToJSON defaultOptions ''ClearMetadata)

instance FromJSON ClearMetadata where
  parseJSON _ = return ClearMetadata

clearMetadata :: Q.TxE QErr ()
clearMetadata = Q.catchE defaultTxErrorHandler $ do
  Q.unitQ "DELETE FROM hdb_catalog.hdb_query_template WHERE is_system_defined <> 'true'" () False
  Q.unitQ "DELETE FROM hdb_catalog.hdb_permission WHERE is_system_defined <> 'true'" () False
  Q.unitQ "DELETE FROM hdb_catalog.hdb_relationship WHERE is_system_defined <> 'true'" () False
  Q.unitQ "DELETE FROM hdb_catalog.hdb_table WHERE is_system_defined <> 'true'" () False
  clearHdbViews

instance HDBQuery ClearMetadata where

  type Phase1Res ClearMetadata = ()
  phaseOne _ = adminOnly

  phaseTwo _ _ = do
    newSc <- liftTx $ clearMetadata >> DT.buildSchemaCache
    writeSchemaCache newSc
    return successMsg

  schemaCachePolicy = SCPReload

data ReplaceMetadata
  = ReplaceMetadata
  { aqTables         :: ![TableMeta]
  , aqQueryTemplates :: ![DQ.CreateQueryTemplate]
  } deriving (Show, Eq, Lift)

$(deriveJSON (aesonDrop 2 snakeCase){omitNothingFields=True} ''ReplaceMetadata)

applyQP1 :: ReplaceMetadata -> P1 ()
applyQP1 (ReplaceMetadata tables templates) = do

  adminOnly

  withPathK "tables" $ do

    checkMultipleDecls "tables" $ map _tmTable tables

    -- process each table
    void $ indexedForM tables $ \table -> withTableName (table ^. tmTable) $ do
      let allRels  = map DR.rdName (table ^. tmObjectRelationships) <>
                     map DR.rdName (table ^. tmArrayRelationships)

          insPerms = map DP.pdRole $ table ^. tmInsertPermissions
          selPerms = map DP.pdRole $ table ^. tmSelectPermissions
          updPerms = map DP.pdRole $ table ^. tmUpdatePermissions
          delPerms = map DP.pdRole $ table ^. tmDeletePermissions
          eventTriggers = map DTS.etdName $ table ^. tmEventTriggers

      checkMultipleDecls "relationships" allRels
      checkMultipleDecls "insert permissions" insPerms
      checkMultipleDecls "select permissions" selPerms
      checkMultipleDecls "update permissions" updPerms
      checkMultipleDecls "delete permissions" delPerms
      checkMultipleDecls "event triggers" eventTriggers

  withPathK "queryTemplates" $
    checkMultipleDecls "query templates" $ map DQ.cqtName templates

  where
    withTableName qt = withPathK (qualTableToTxt qt)

    checkMultipleDecls t l = do
      let dups = getDups l
      unless (null dups) $
        throw400 AlreadyExists $ "multiple declarations exist for the following " <> t <> " : "
        <> T.pack (show dups)

    getDups l =
      l L.\\ HS.toList (HS.fromList l)

applyQP2 :: (UserInfoM m, P2C m) => ReplaceMetadata -> m RespBody
applyQP2 (ReplaceMetadata tables templates) = do

  defaultSchemaCache <- liftTx $ clearMetadata >> DT.buildSchemaCache
  writeSchemaCache defaultSchemaCache

  withPathK "tables" $ do

    -- tables and views
    indexedForM_ (map _tmTable tables) $ \tableName ->
      void $ DT.trackExistingTableOrViewP2 tableName False

    -- Relationships
    indexedForM_ tables $ \table -> do
      withPathK "object_relationships" $
        indexedForM_ (table ^. tmObjectRelationships) $ \objRel ->
        DR.objRelP2 (table ^. tmTable) objRel
      withPathK "array_relationships" $
        indexedForM_ (table ^. tmArrayRelationships) $ \arrRel ->
        DR.arrRelP2 (table ^. tmTable) arrRel

    -- Permissions
    indexedForM_ tables $ \table -> do
      let tableName = table ^. tmTable
      tabInfo <- modifyErrAndSet500 ("apply " <> ) $ askTabInfo tableName
      withPathK "insert_permissions" $ processPerms tabInfo $
        table ^. tmInsertPermissions
      withPathK "select_permissions" $ processPerms tabInfo $
        table ^. tmSelectPermissions
      withPathK "update_permissions" $ processPerms tabInfo $
        table ^. tmUpdatePermissions
      withPathK "delete_permissions" $ processPerms tabInfo $
        table ^. tmDeletePermissions

    indexedForM_ tables $ \table ->
      withPathK "event_triggers" $
        indexedForM_ (table ^. tmEventTriggers) $ \et ->
        DS.subTableP2 (table ^. tmTable) False et

  -- query templates
  withPathK "queryTemplates" $
    indexedForM_ templates $ \template -> do
      qti <- DQ.createQueryTemplateP1 template
      void $ DQ.createQueryTemplateP2 template qti

  return successMsg

  where
    processPerms tabInfo perms =
      indexedForM_ perms $ \permDef -> do
        permInfo <- DP.addPermP1 tabInfo permDef
        DP.addPermP2 (tiName tabInfo) permDef permInfo


instance HDBQuery ReplaceMetadata where

  type Phase1Res ReplaceMetadata = ()
  phaseOne = applyQP1

  phaseTwo q _ = applyQP2 q

  schemaCachePolicy = SCPReload

data ExportMetadata
  = ExportMetadata
  deriving (Show, Eq, Lift)

instance FromJSON ExportMetadata where
  parseJSON _ = return ExportMetadata

$(deriveToJSON defaultOptions ''ExportMetadata)

fetchMetadata :: Q.TxE QErr ReplaceMetadata
fetchMetadata = do
  tables <- Q.catchE defaultTxErrorHandler fetchTables

  let qts          = map (uncurry QualifiedTable) tables
      tableMetaMap = M.fromList $ zip qts $ map mkTableMeta qts

  -- Fetch all the relationships
  relationships <- Q.catchE defaultTxErrorHandler fetchRelationships

  objRelDefs <- mkRelDefs ObjRel relationships
  arrRelDefs <- mkRelDefs ArrRel relationships

  -- Fetch all the permissions
  permissions <- Q.catchE defaultTxErrorHandler fetchPermissions

  -- Parse all the permissions
  insPermDefs <- mkPermDefs PTInsert permissions
  selPermDefs <- mkPermDefs PTSelect permissions
  updPermDefs <- mkPermDefs PTUpdate permissions
  delPermDefs <- mkPermDefs PTDelete permissions

  -- Fetch all the query templates
  qTmpltRows <- Q.catchE defaultTxErrorHandler fetchQTemplates

  qTmpltDefs <- forM qTmpltRows $ \(qtn, Q.AltJ qtDefVal, mComment) -> do
    qtDef <- decodeValue qtDefVal
    return $ DQ.CreateQueryTemplate qtn qtDef mComment

  -- Fetch all event triggers
  eventTriggers <- Q.catchE defaultTxErrorHandler fetchEventTriggers
  triggerMetaDefs <- mkTriggerMetaDefs eventTriggers

  let (_, postRelMap) = flip runState tableMetaMap $ do
        modMetaMap tmObjectRelationships objRelDefs
        modMetaMap tmArrayRelationships arrRelDefs
        modMetaMap tmInsertPermissions insPermDefs
        modMetaMap tmSelectPermissions selPermDefs
        modMetaMap tmUpdatePermissions updPermDefs
        modMetaMap tmDeletePermissions delPermDefs
        modMetaMap tmEventTriggers triggerMetaDefs

  return $ ReplaceMetadata (M.elems postRelMap) qTmpltDefs

  where

    modMetaMap l xs = do
      st <- get
      put $ foldr (\(qt, dfn) b -> b & at qt._Just.l %~ (:) dfn) st xs

    mkPermDefs pt = mapM permRowToDef . filter (\pr -> pr ^. _4 == pt)

    permRowToDef (sn, tn, rn, _, Q.AltJ pDef, mComment) = do
      perm <- decodeValue pDef
      return (QualifiedTable sn tn,  DP.PermDef rn perm mComment)

    mkRelDefs rt = mapM relRowToDef . filter (\rr -> rr ^. _4 == rt)

    relRowToDef (sn, tn, rn, _, Q.AltJ rDef, mComment) = do
      using <- decodeValue rDef
      return (QualifiedTable sn tn, DR.RelDef rn using mComment)

    mkTriggerMetaDefs = mapM trigRowToDef

    trigRowToDef (sn, tn, trn, Q.AltJ tDefVal, webhook, nr, rint, Q.AltJ mheaders) = do
      tDef <- decodeValue tDefVal
      return (QualifiedTable sn tn, DTS.EventTriggerDef trn tDef webhook (RetryConf nr rint) mheaders)

    fetchTables =
      Q.listQ [Q.sql|
                SELECT table_schema, table_name from hdb_catalog.hdb_table
                 WHERE is_system_defined = 'false'
                    |] () False

    fetchRelationships =
      Q.listQ [Q.sql|
                SELECT table_schema, table_name, rel_name, rel_type, rel_def::json, comment
                  FROM hdb_catalog.hdb_relationship
                 WHERE is_system_defined = 'false'
                    |] () False

    fetchPermissions =
      Q.listQ [Q.sql|
                SELECT table_schema, table_name, role_name, perm_type, perm_def::json, comment
                  FROM hdb_catalog.hdb_permission
                 WHERE is_system_defined = 'false'
                    |] () False

    fetchQTemplates =
      Q.listQ [Q.sql|
                SELECT template_name, template_defn :: json, comment
                  FROM hdb_catalog.hdb_query_template
                 WHERE is_system_defined = 'false'
                  |] () False
    fetchEventTriggers =
     Q.listQ [Q.sql|
              SELECT e.schema_name, e.table_name, e.name, e.definition::json, e.webhook, e.num_retries, e.retry_interval, e.headers::json
               FROM hdb_catalog.event_triggers e
              |] () False


instance HDBQuery ExportMetadata where

  type Phase1Res ExportMetadata = ()
  phaseOne _ = adminOnly

  phaseTwo _ _ = encode <$> liftTx fetchMetadata

  schemaCachePolicy = SCPNoChange

data ReloadMetadata
  = ReloadMetadata
  deriving (Show, Eq, Lift)

instance FromJSON ReloadMetadata where
  parseJSON _ = return ReloadMetadata

$(deriveToJSON defaultOptions ''ReloadMetadata)

instance HDBQuery ReloadMetadata where

  type Phase1Res ReloadMetadata = ()
  phaseOne _ = adminOnly

  phaseTwo _ _ = do
    sc <- liftTx $ do
      Q.catchE defaultTxErrorHandler clearHdbViews
      DT.buildSchemaCache
    writeSchemaCache sc
    return successMsg

  schemaCachePolicy = SCPReload

data DumpInternalState
  = DumpInternalState
  deriving (Show, Eq, Lift)

instance FromJSON DumpInternalState where
  parseJSON _ = return DumpInternalState

$(deriveToJSON defaultOptions ''DumpInternalState)

instance HDBQuery DumpInternalState where

  type Phase1Res DumpInternalState = ()
  phaseOne _ = adminOnly

  phaseTwo _ _ =
    encode <$> askSchemaCache

  schemaCachePolicy = SCPNoChange