module Hasura.RQL.DDL.Relationship
  ( objRelP2Setup
  , objRelP2
  , arrRelP2Setup
  , arrRelP2
  , delRelFromCatalog
  , validateRelP1
  , runCreateObjRel
  , runCreateArrRel
  , runDropRel
  , runSetRelComment
  , module Hasura.RQL.DDL.Relationship.Types
  )
where

import qualified Database.PG.Query                 as Q

import           Hasura.EncJSON
import           Hasura.Prelude
import           Hasura.RQL.DDL.Deps
import           Hasura.RQL.DDL.Permission         (purgePerm)
import           Hasura.RQL.DDL.Relationship.Types
import           Hasura.RQL.Types
import           Hasura.SQL.Types

import           Data.Aeson.Types
import qualified Data.HashMap.Strict               as HM
import qualified Data.Map.Strict                   as M
import qualified Data.Text                         as T
import           Data.Tuple                        (swap)
import           Instances.TH.Lift                 ()

validateManualConfig
  :: (QErrM m, CacheRM m)
  => FieldInfoMap
  -> RelManualConfig
  -> m ()
validateManualConfig fim rm = do
  let colMapping = M.toList $ rmColumns rm
      remoteQt = rmTable rm
  remoteTabInfo <- askTabInfo remoteQt
  let remoteFim = tiFieldInfoMap remoteTabInfo
  forM_ colMapping $ \(lCol, rCol) -> do
    assertPGCol fim "" lCol
    assertPGCol remoteFim "" rCol
    -- lColType <- askPGType fim lCol ""
    -- rColType <- askPGType remoteFim rCol ""
    -- when (lColType /= rColType) $
    --   throw400 $ mconcat
    --   [ "the types of columns " <> lCol <<> ", " <>> rCol
    --   , " do not match"
    --   ]

persistRel :: QualifiedTable
           -> RelName
           -> RelType
           -> Value
           -> Maybe T.Text
           -> Q.TxE QErr ()
persistRel (QualifiedObject sn tn) rn relType relDef comment =
  Q.unitQE defaultTxErrorHandler [Q.sql|
           INSERT INTO
                  hdb_catalog.hdb_relationship
                  (table_schema, table_name, rel_name, rel_type, rel_def, comment)
           VALUES ($1, $2, $3, $4, $5 :: jsonb, $6)
                |] (sn, tn, rn, relTypeToTxt relType, Q.AltJ relDef, comment) True

checkForColConfilct
  :: (MonadError QErr m)
  => TableInfo
  -> FieldName
  -> m ()
checkForColConfilct tabInfo f =
  case HM.lookup f (tiFieldInfoMap tabInfo) of
    Just _ -> throw400 AlreadyExists $ mconcat
      [ "column/relationship " <>> f
      , " of table " <>> tiName tabInfo
      , " already exists"
      ]
    Nothing -> return ()

objRelP1
  :: (QErrM m, CacheRM m)
  => TableInfo
  -> ObjRelDef
  -> m ()
objRelP1 tabInfo (RelDef rn ru _) = do
  checkForColConfilct tabInfo (fromRel rn)
  let fim = tiFieldInfoMap tabInfo
  case ru of
    RUFKeyOn cn                      -> assertPGCol fim "" cn
    RUManual (ObjRelManualConfig rm) -> validateManualConfig fim rm

createObjRelP1
  :: (UserInfoM m, QErrM m, CacheRM m)
  => CreateObjRel
  -> m ()
createObjRelP1 (WithTable qt rd) = do
  adminOnly
  tabInfo <- askTabInfo qt
  objRelP1 tabInfo rd

objRelP2Setup
  :: (QErrM m, CacheRWM m, MonadTx m)
  => QualifiedTable -> RelDef ObjRelUsing -> m ()
objRelP2Setup qt (RelDef rn ru _) = do
  (relInfo, deps) <- case ru of
    RUManual (ObjRelManualConfig rm) -> do
      let refqt = rmTable rm
          (lCols, rCols) = unzip $ M.toList $ rmColumns rm
          deps  = map (\c -> SchemaDependency (SOTableObj qt $ TOCol c) "lcol") lCols
                  <> map (\c -> SchemaDependency (SOTableObj refqt $ TOCol c) "rcol") rCols
      return (RelInfo rn ObjRel (zip lCols rCols) refqt True, deps)
    RUFKeyOn cn -> do
      res  <- liftTx $ Q.catchE defaultTxErrorHandler $ fetchFKeyDetail cn
      case mapMaybe processRes res of
        [] -> throw400 ConstraintError
                "no foreign constraint exists on the given column"
        [(consName, refsn, reftn, colMapping)] -> do
          let deps = [ SchemaDependency (SOTableObj qt $ TOCons consName) "fkey"
                     , SchemaDependency (SOTableObj qt $ TOCol cn) "using_col"
                     -- this needs to be added explicitly to handle the remote table
                     -- being untracked. In this case, neither the using_col nor
                     -- the constraint name will help.
                     , SchemaDependency (SOTable refqt) "remote_table"
                     ]
              refqt = QualifiedObject refsn reftn
          void $ askTabInfo refqt
          return (RelInfo rn ObjRel colMapping refqt False, deps)
        _  -> throw400 ConstraintError
                "more than one foreign key constraint exists on the given column"
  addRelToCache rn relInfo deps qt
  where
    QualifiedObject sn tn = qt
    fetchFKeyDetail cn =
      Q.listQ [Q.sql|
           SELECT constraint_name, ref_table_table_schema, ref_table, column_mapping
             FROM hdb_catalog.hdb_foreign_key_constraint
            WHERE table_schema = $1
              AND table_name = $2
              AND (column_mapping ->> $3) IS NOT NULL
                |] (sn, tn, cn) False
    processRes (consn, refsn, reftn, mapping) =
      case M.toList (Q.getAltJ mapping) of
      m@[_] -> Just (consn, refsn, reftn, m)
      _     -> Nothing

objRelP2
  :: ( QErrM m
     , CacheRWM m
     , MonadTx m
     )
  => QualifiedTable
  -> ObjRelDef
  -> m ()
objRelP2 qt rd@(RelDef rn ru comment) = do
  objRelP2Setup qt rd
  liftTx $ persistRel qt rn ObjRel (toJSON ru) comment

createObjRelP2
  :: (QErrM m, CacheRWM m, MonadTx m) => CreateObjRel -> m EncJSON
createObjRelP2 (WithTable qt rd) = do
  objRelP2 qt rd
  return successMsg

runCreateObjRel
  :: (QErrM m, CacheRWM m, MonadTx m , UserInfoM m)
  => CreateObjRel -> m EncJSON
runCreateObjRel defn = do
  createObjRelP1 defn
  createObjRelP2 defn

createArrRelP1 :: (UserInfoM m, QErrM m, CacheRM m) => CreateArrRel -> m ()
createArrRelP1 (WithTable qt rd) = do
  adminOnly
  tabInfo    <- askTabInfo qt
  arrRelP1 tabInfo rd

arrRelP1
  :: (QErrM m, CacheRM m)
  => TableInfo -> ArrRelDef -> m ()
arrRelP1 tabInfo (RelDef rn ru _) = do
  checkForColConfilct tabInfo (fromRel rn)
  let fim = tiFieldInfoMap tabInfo
  case ru of
    RUFKeyOn (ArrRelUsingFKeyOn remoteQt rcn) -> do
      remoteTabInfo <- askTabInfo remoteQt
      let rfim = tiFieldInfoMap remoteTabInfo
      -- Check if 'using' column exists
      assertPGCol rfim "" rcn
    RUManual (ArrRelManualConfig rm) ->
      validateManualConfig fim rm

arrRelP2Setup
  :: (QErrM m, CacheRWM m, MonadTx m)
  => QualifiedTable -> ArrRelDef -> m ()
arrRelP2Setup qt (RelDef rn ru _) = do
  (relInfo, deps) <- case ru of
    RUManual (ArrRelManualConfig rm) -> do
      let refqt = rmTable rm
          (lCols, rCols) = unzip $ M.toList $ rmColumns rm
          deps  = map (\c -> SchemaDependency (SOTableObj qt $ TOCol c) "lcol") lCols
                  <> map (\c -> SchemaDependency (SOTableObj refqt $ TOCol c) "rcol") rCols
      return (RelInfo rn ArrRel (zip lCols rCols) refqt True, deps)
    RUFKeyOn (ArrRelUsingFKeyOn refqt refCol) -> do
      let QualifiedObject refSn refTn = refqt
      res <- liftTx $ Q.catchE defaultTxErrorHandler $
        fetchFKeyDetail refSn refTn refCol
      case mapMaybe processRes res of
        [] -> throw400 ConstraintError
                "no foreign constraint exists on the given column"
        [(consName, mapping)] -> do
          let deps = [ SchemaDependency (SOTableObj refqt $ TOCons consName) "remote_fkey"
                     , SchemaDependency (SOTableObj refqt $ TOCol refCol) "using_col"
                     -- we don't need to necessarily track the remote table like we did in
                     -- case of obj relationships as the remote table is indirectly
                     -- tracked by tracking the constraint name and 'using_col'
                     , SchemaDependency (SOTable refqt) "remote_table"
                     ]
          return (RelInfo rn ArrRel (map swap mapping) refqt False, deps)
        _  -> throw400 ConstraintError
                "more than one foreign key constraint exists on the given column"
  addRelToCache rn relInfo deps qt
  where
    QualifiedObject sn tn = qt
    fetchFKeyDetail refsn reftn refcn = Q.listQ [Q.sql|
           SELECT constraint_name, column_mapping
             FROM hdb_catalog.hdb_foreign_key_constraint
            WHERE table_schema = $1
              AND table_name = $2
              AND (column_mapping -> $3) IS NOT NULL
              AND ref_table_table_schema = $4
              AND ref_table = $5
                |] (refsn, reftn, refcn, sn, tn) False
    processRes (consn, mapping) =
      case M.toList (Q.getAltJ mapping) of
      m@[_] -> Just (consn, m)
      _     -> Nothing

arrRelP2
  :: (QErrM m, CacheRWM m, MonadTx m)
  => QualifiedTable -> ArrRelDef -> m ()
arrRelP2 qt rd@(RelDef rn u comment) = do
  arrRelP2Setup qt rd
  liftTx $ persistRel qt rn ArrRel (toJSON u) comment

createArrRelP2
  :: (QErrM m, CacheRWM m, MonadTx m) => CreateArrRel -> m EncJSON
createArrRelP2 (WithTable qt rd) = do
  arrRelP2 qt rd
  return successMsg

runCreateArrRel
  :: (QErrM m, CacheRWM m, MonadTx m , UserInfoM m)
  => CreateArrRel -> m EncJSON
runCreateArrRel defn = do
  createArrRelP1 defn
  createArrRelP2 defn

dropRelP1 :: (UserInfoM m, QErrM m, CacheRM m) => DropRel -> m [SchemaObjId]
dropRelP1 (DropRel qt rn cascade) = do
  adminOnly
  tabInfo <- askTabInfo qt
  _       <- askRelType (tiFieldInfoMap tabInfo) rn ""
  sc      <- askSchemaCache
  let depObjs = getDependentObjs sc relObjId
  when (depObjs /= [] && not (or cascade)) $ reportDeps depObjs
  return depObjs
  where
    relObjId = SOTableObj qt $ TORel rn

purgeRelDep
  :: (CacheRWM m, MonadTx m) => SchemaObjId -> m ()
purgeRelDep (SOTableObj tn (TOPerm rn pt)) =
  purgePerm tn rn pt
purgeRelDep d = throw500 $ "unexpected dependency of relationship : "
                <> reportSchemaObj d

dropRelP2
  :: (QErrM m, CacheRWM m, MonadTx m)
  => DropRel -> [SchemaObjId] -> m EncJSON
dropRelP2 (DropRel qt rn _) depObjs = do
  mapM_ purgeRelDep depObjs
  delRelFromCache rn qt
  liftTx $ delRelFromCatalog qt rn
  return successMsg

runDropRel
  :: (QErrM m, CacheRWM m, MonadTx m , UserInfoM m)
  => DropRel -> m EncJSON
runDropRel defn = do
  depObjs <- dropRelP1 defn
  dropRelP2 defn depObjs

delRelFromCatalog
  :: QualifiedTable
  -> RelName
  -> Q.TxE QErr ()
delRelFromCatalog (QualifiedObject sn tn) rn =
  Q.unitQE defaultTxErrorHandler [Q.sql|
           DELETE FROM
                  hdb_catalog.hdb_relationship
           WHERE table_schema =  $1
             AND table_name = $2
             AND rel_name = $3
                |] (sn, tn, rn) True

validateRelP1
  :: (UserInfoM m, QErrM m, CacheRM m)
  => QualifiedTable -> RelName -> m RelInfo
validateRelP1 qt rn = do
  adminOnly
  tabInfo <- askTabInfo qt
  askRelType (tiFieldInfoMap tabInfo) rn ""

setRelCommentP2
  :: (QErrM m, MonadTx m)
  => SetRelComment -> m EncJSON
setRelCommentP2 arc = do
  liftTx $ setRelComment arc
  return successMsg

runSetRelComment
  :: (QErrM m, CacheRWM m, MonadTx m , UserInfoM m)
  => SetRelComment -> m EncJSON
runSetRelComment defn = do
  void $ validateRelP1 qt rn
  setRelCommentP2 defn
  where
    SetRelComment qt rn _ = defn

setRelComment :: SetRelComment
              -> Q.TxE QErr ()
setRelComment (SetRelComment (QualifiedObject sn tn) rn comment) =
  Q.unitQE defaultTxErrorHandler [Q.sql|
           UPDATE hdb_catalog.hdb_relationship
           SET comment = $1
           WHERE table_schema =  $2
             AND table_name = $3
             AND rel_name = $4
                |] (comment, sn, tn, rn) True