{-# LANGUAGE Arrows #-}

module Hasura.RQL.DDL.Schema.Cache.Fields
  ( addNonColumnFields
  , mkRelationshipMetadataObject
  , mkComputedFieldMetadataObject
  ) where
import           Hasura.Prelude

import qualified Data.HashMap.Strict.Extended       as M
import qualified Data.HashSet                       as HS
import qualified Data.Sequence                      as Seq

import           Control.Arrow.Extended
import           Data.Aeson

import qualified Hasura.Incremental                 as Inc

import           Hasura.RQL.DDL.ComputedField
import           Hasura.RQL.DDL.Relationship
import           Hasura.RQL.DDL.Schema.Cache.Common
import           Hasura.RQL.DDL.Schema.Function
import           Hasura.RQL.Types
import           Hasura.RQL.Types.Catalog
import           Hasura.SQL.Types

addNonColumnFields
  :: ( ArrowChoice arr, Inc.ArrowDistribute arr, ArrowWriter (Seq CollectedInfo) arr
     , ArrowKleisli m arr, MonadError QErr m )
  => ( HashMap QualifiedTable TableRawInfo
     , FieldInfoMap PGColumnInfo
     , [CatalogRelation]
     , [CatalogComputedField]
     ) `arr` FieldInfoMap FieldInfo
addNonColumnFields =
  proc (rawTableInfo, columns, relationships, computedFields) -> do
    let foreignKeys = _tciForeignKeys <$> rawTableInfo
    relationshipInfos <-
      (| Inc.keyed (\_ relationshipsByName -> do
           maybeRelationship <- noDuplicates mkRelationshipMetadataObject -< relationshipsByName
           (\info -> join info >- returnA) <-<
             (| traverseA (\relationship -> do
                  info <- buildRelationship -< (foreignKeys, relationship)
                  returnA -< info <&> (, mkRelationshipMetadataObject relationship))
             |) maybeRelationship)
      |) (M.groupOn _crRelName relationships)

    let trackedTableNames = HS.fromList $ M.keys rawTableInfo
    computedFieldInfos <-
      (| Inc.keyed (\_ computedFieldsByName -> do
           maybeComputedField <- noDuplicates mkComputedFieldMetadataObject -< computedFieldsByName
           (\info -> join info >- returnA) <-<
             (| traverseA (\computedField -> do
                  info <- buildComputedField -< (trackedTableNames, computedField)
                  returnA -< info <&> (, mkComputedFieldMetadataObject computedField))
             |) maybeComputedField)
      |) (M.groupOn (_afcName . _cccComputedField) computedFields)

    let mapKey f = M.fromList . map (first f) . M.toList
        relationshipFields = mapKey fromRel $ M.catMaybes relationshipInfos
        computedFieldFields = mapKey fromComputedField $ M.catMaybes computedFieldInfos
    nonColumnFields <-
      (| Inc.keyed (\fieldName fields -> noFieldConflicts -< (fieldName, fields))
      |) (align relationshipFields computedFieldFields)

    (| Inc.keyed (\_ fields -> noColumnConflicts -< fields)
     |) (align columns (M.catMaybes nonColumnFields))
  where
    noFieldConflicts = proc (fieldName, fields) -> case fields of
      This (relationship, metadata) -> returnA -< Just (FIRelationship relationship, metadata)
      That (computedField, metadata) -> returnA -< Just (FIComputedField computedField, metadata)
      These (_, relationshipMetadata) (_, computedFieldMetadata) -> do
        tellA -< Seq.singleton $ CIInconsistency $ ConflictingObjects
          ("conflicting definitions for field " <>> fieldName)
          [relationshipMetadata, computedFieldMetadata]
        returnA -< Nothing

    noColumnConflicts = proc fields -> case fields of
      This columnInfo -> returnA -< FIColumn columnInfo
      That (fieldInfo, _) -> returnA -< fieldInfo
      These columnInfo (_, fieldMetadata) -> do
        recordInconsistency -< (fieldMetadata, "field definition conflicts with postgres column")
        returnA -< FIColumn columnInfo

mkRelationshipMetadataObject :: CatalogRelation -> MetadataObject
mkRelationshipMetadataObject (CatalogRelation qt rn rt rDef cmnt) =
  let objectId = MOTableObj qt $ MTORel rn rt
      definition = toJSON $ WithTable qt $ RelDef rn rDef cmnt
  in MetadataObject objectId definition

buildRelationship
  :: (ArrowChoice arr, ArrowWriter (Seq CollectedInfo) arr)
  => (HashMap QualifiedTable (HashSet ForeignKey), CatalogRelation) `arr` Maybe RelInfo
buildRelationship = proc (foreignKeys, relationship) -> do
  let CatalogRelation tableName rn rt rDef _ = relationship
      metadataObject = mkRelationshipMetadataObject relationship
      schemaObject = SOTableObj tableName $ TORel rn
      addRelationshipContext e = "in relationship " <> rn <<> ": " <> e
  (| withRecordInconsistency (
     (| modifyErrA (do
          (info, dependencies) <- liftEitherA -< case rt of
            ObjRel -> do
              using <- decodeValue rDef
              tableForeignKeys <- getTableInfo tableName foreignKeys
              objRelP2Setup tableName tableForeignKeys (RelDef rn using Nothing)
            ArrRel -> do
              using <- decodeValue rDef
              arrRelP2Setup foreignKeys tableName (RelDef rn using Nothing)
          recordDependencies -< (metadataObject, schemaObject, dependencies)
          returnA -< info)
     |) (addTableContext tableName . addRelationshipContext))
   |) metadataObject

mkComputedFieldMetadataObject :: CatalogComputedField -> MetadataObject
mkComputedFieldMetadataObject (CatalogComputedField column _) =
  let AddComputedField qt name _ _ = column
      objectId = MOTableObj qt $ MTOComputedField name
  in MetadataObject objectId (toJSON column)

buildComputedField
  :: ( ArrowChoice arr, ArrowWriter (Seq CollectedInfo) arr
     , ArrowKleisli m arr, MonadError QErr m )
  => (HashSet QualifiedTable, CatalogComputedField) `arr` Maybe ComputedFieldInfo
buildComputedField = proc (trackedTableNames, computedField) -> do
  let CatalogComputedField column funcDefs = computedField
      AddComputedField qt name def comment = column
      addComputedFieldContext e = "in computed field " <> name <<> ": " <> e
  (| withRecordInconsistency (
     (| modifyErrA (do
          rawfi <- bindErrorA -< handleMultipleFunctions (_cfdFunction def) funcDefs
          bindErrorA -< addComputedFieldP2Setup trackedTableNames qt name def rawfi comment)
     |) (addTableContext qt . addComputedFieldContext))
   |) (mkComputedFieldMetadataObject computedField)