{-# language AllowAmbiguousTypes #-}
{-# language DataKinds #-}
{-# language FlexibleContexts #-}
{-# language FlexibleInstances #-}
{-# language MultiParamTypeClasses #-}
{-# language PolyKinds #-}
{-# language RankNTypes #-}
{-# language ScopedTypeVariables #-}
{-# language StandaloneKindSignatures #-}
{-# language TypeApplications #-}
{-# language TypeFamilies #-}
{-# language TypeOperators #-}
{-# language UndecidableInstances #-}

module Rel8.Generic.Table.Record
  ( GTable, GColumns, GContext, gfromColumns, gtoColumns, gtable
  , GToExprs, gfromResult, gtoResult
  )
where

-- base
import Data.Kind ( Constraint, Type )
import Data.Proxy ( Proxy( Proxy ) )
import GHC.Generics
  ( (:*:)( (:*:) ), K1( K1 ), M1( M1 )
  , C, D, S
  , Meta( MetaSel )
  )
import GHC.TypeLits ( KnownSymbol )
import Prelude hiding ( null )

-- rel8
import Rel8.FCF ( Eval, Exp )
import Rel8.Schema.Context ( Col )
import Rel8.Schema.Context.Label ( HLabelable, hlabeler, hunlabeler )
import Rel8.Schema.HTable ( HTable )
import Rel8.Schema.HTable.Label ( HLabel, hlabel, hunlabel )
import Rel8.Schema.HTable.Product ( HProduct(..) )
import qualified Rel8.Schema.Kind as K
import Rel8.Schema.Result ( Result )


type GColumns :: (Type -> Exp K.HTable) -> (Type -> Type) -> K.HTable
type family GColumns _Columns rep where
  GColumns _Columns (M1 D _ rep) = GColumns _Columns rep
  GColumns _Columns (M1 C _ rep) = GColumns _Columns rep
  GColumns _Columns (rep1 :*: rep2) =
    HProduct (GColumns _Columns rep1) (GColumns _Columns rep2)
  GColumns _Columns (M1 S ('MetaSel ('Just label) _ _ _) (K1 _ a)) =
    HLabel label (Eval (_Columns a))


type GContext :: (Type -> Exp K.Context) -> (Type -> Type) -> K.Context
type family GContext _Context rep where
  GContext _Context (M1 _ _ rep) = GContext _Context rep
  GContext _Context (rep1 :*: _rep2) = GContext _Context rep1
  GContext _Context (K1 _ a) = Eval (_Context a)


type GTable
  :: (Type -> Exp Constraint)
  -> (Type -> Exp K.HTable)
  -> K.HContext -> (Type -> Type) -> Constraint
class GTable _Table _Columns context rep
 where
  gfromColumns :: ()
    => (forall a. Eval (_Table a) => Eval (_Columns a) context -> a)
    -> GColumns _Columns rep context
    -> rep x

  gtoColumns :: ()
    => (forall a. Eval (_Table a) => a -> Eval (_Columns a) context)
    -> rep x
    -> GColumns _Columns rep context

  gtable :: ()
    => (forall a proxy. Eval (_Table a) => proxy a -> Eval (_Columns a) context)
    -> GColumns _Columns rep context


instance GTable _Table _Columns context rep =>
  GTable _Table _Columns context (M1 D c rep)
 where
  gfromColumns fromColumns =
    M1 . gfromColumns @_Table @_Columns @context @rep fromColumns
  gtoColumns toColumns (M1 a) =
    gtoColumns @_Table @_Columns @context @rep toColumns a
  gtable = gtable @_Table @_Columns @context @rep


instance GTable _Table _Columns context rep =>
  GTable _Table _Columns context (M1 C c rep)
 where
  gfromColumns fromColumns =
    M1 . gfromColumns @_Table @_Columns @context @rep fromColumns
  gtoColumns toColumns (M1 a) =
    gtoColumns @_Table @_Columns @context @rep toColumns a
  gtable = gtable @_Table @_Columns @context @rep


instance
  ( GTable _Table _Columns context rep1
  , GTable _Table _Columns context rep2
  )
  => GTable _Table _Columns context (rep1 :*: rep2)
 where
  gfromColumns fromColumns (HProduct a b) =
    gfromColumns @_Table @_Columns @context @rep1 fromColumns a :*:
    gfromColumns @_Table @_Columns @context @rep2 fromColumns b
  gtoColumns toColumns (a :*: b) = HProduct
    (gtoColumns @_Table @_Columns @context @rep1 toColumns a)
    (gtoColumns @_Table @_Columns @context @rep2 toColumns b)
  gtable table = HProduct
    (gtable @_Table @_Columns @context @rep1 table)
    (gtable @_Table @_Columns @context @rep2 table)


instance
  ( HTable (Eval (_Columns a))
  , Eval (_Table a)
  , HLabelable context
  , KnownSymbol label
  , meta ~ 'MetaSel ('Just label) _su _ss _ds
  , k1 ~ K1 i a
  )
  => GTable _Table _Columns context (M1 S meta k1)
 where
  gfromColumns fromColumns = M1 . K1 . fromColumns . hunlabel hunlabeler
  gtoColumns toColumns (M1 (K1 a)) = hlabel hlabeler (toColumns a)
  gtable table = hlabel hlabeler (table (Proxy @a))


type GToExprs
  :: (Type -> Type -> Exp Constraint)
  -> (Type -> Exp K.HTable)
  -> (Type -> Type) -> (Type -> Type) -> Constraint
class GToExprs _ToExprs _Columns exprs rep where
  gfromResult :: ()
    => (forall expr a proxy.
        ( Eval (_ToExprs expr a)
        , HTable (Eval (_Columns expr))
        )
        => proxy expr
        -> Eval (_Columns expr) (Col Result)
        -> a)
    -> GColumns _Columns exprs (Col Result)
    -> rep x
  gtoResult :: ()
    => (forall expr a proxy.
        ( Eval (_ToExprs expr a)
        , HTable (Eval (_Columns expr))
        )
        => proxy expr
        -> a
        -> Eval (_Columns expr) (Col Result))
    -> rep x
    -> GColumns _Columns exprs (Col Result)


instance GToExprs _ToExprs _Columns exprs rep =>
  GToExprs _ToExprs _Columns (M1 D c exprs) (M1 D c rep)
 where
  gfromResult fromResult =
    M1 . gfromResult @_ToExprs @_Columns @exprs fromResult
  gtoResult toResult (M1 a) =
    gtoResult @_ToExprs @_Columns @exprs toResult a


instance GToExprs _ToExprs _Columns exprs rep =>
  GToExprs _ToExprs _Columns (M1 C c exprs) (M1 C c rep)
 where
  gfromResult fromResult =
    M1 . gfromResult @_ToExprs @_Columns @exprs fromResult
  gtoResult toResult (M1 a) =
    gtoResult @_ToExprs @_Columns @exprs toResult a


instance
  ( GToExprs _ToExprs _Columns exprs1 rep1
  , GToExprs _ToExprs _Columns exprs2 rep2
  )
  => GToExprs _ToExprs _Columns (exprs1 :*: exprs2) (rep1 :*: rep2)
 where
  gfromResult fromResult (HProduct a b) =
    gfromResult @_ToExprs @_Columns @exprs1 fromResult a :*:
    gfromResult @_ToExprs @_Columns @exprs2 fromResult b
  gtoResult toResult (a :*: b) =
    HProduct
      (gtoResult @_ToExprs @_Columns @exprs1 toResult a)
      (gtoResult @_ToExprs @_Columns @exprs2 toResult b)


instance
  ( Eval (_ToExprs exprs a)
  , HTable (Eval (_Columns exprs))
  , KnownSymbol label
  , meta ~ 'MetaSel ('Just label) _su _ss _ds
  , k1 ~ K1 i exprs
  , k1' ~ K1 i a
  )
  => GToExprs _ToExprs _Columns (M1 S meta k1) (M1 S meta k1')
 where
  gfromResult fromResult =
    M1 . K1 . fromResult (Proxy @exprs) . hunlabel hunlabeler
  gtoResult toResult (M1 (K1 a)) =
    hlabel hlabeler (toResult (Proxy @exprs) a)