{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE EmptyDataDecls #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-}

module CustomConstraintTest where

import qualified Data.Text as T
import PgInit

share
    [mkPersist sqlSettings, mkMigrate "customConstraintMigrate"]
    [persistLowerCase|
CustomConstraint1
    some_field Text
    deriving Show

CustomConstraint2
    cc_id CustomConstraint1Id constraint=custom_constraint
    deriving Show

CustomConstraint3
    -- | This will lead to a constraint with the name custom_constraint3_cc_id1_fkey
    cc_id1 CustomConstraint1Id
    cc_id2 CustomConstraint1Id
    deriving Show
|]

specs :: Spec
specs = do
    describe "custom constraint used in migration" $ do
        it "custom constraint is actually created" $ runConnAssert $ do
            void $ runMigrationSilent customConstraintMigrate
            void $ runMigrationSilent customConstraintMigrate -- run a second time to ensure the constraint isn't dropped
            let
                query =
                    T.concat
                        [ "SELECT DISTINCT COUNT(*) "
                        , "FROM information_schema.constraint_column_usage ccu, "
                        , "information_schema.key_column_usage kcu, "
                        , "information_schema.table_constraints tc "
                        , "WHERE tc.constraint_type='FOREIGN KEY' "
                        , "AND kcu.constraint_name=tc.constraint_name "
                        , "AND ccu.constraint_name=kcu.constraint_name "
                        , "AND kcu.ordinal_position=1 "
                        , "AND ccu.table_name=? "
                        , "AND ccu.column_name=? "
                        , "AND kcu.table_name=? "
                        , "AND kcu.column_name=? "
                        , "AND tc.constraint_name=?"
                        ]
            [Single exists_] <-
                rawSql
                    query
                    [ PersistText "custom_constraint1"
                    , PersistText "id"
                    , PersistText "custom_constraint2"
                    , PersistText "cc_id"
                    , PersistText "custom_constraint"
                    ]
            liftIO $ 1 @?= (exists_ :: Int)

        it "allows multiple constraints on a single column" $ runConnAssert $ do
            void $ runMigrationSilent customConstraintMigrate
            -- \| Here we add another foreign key on the same column where the default one already exists. In practice, this could be a compound key with another field.
            rawExecute
                "ALTER TABLE \"custom_constraint3\" ADD CONSTRAINT \"extra_constraint\" FOREIGN KEY(\"cc_id1\") REFERENCES \"custom_constraint1\"(\"id\")"
                []
            -- \| This is where the error is thrown in `getColumn`
            void $ getMigration customConstraintMigrate
            pure ()