dsl.scala

/*
 * Copyright 2023 Valdemar Grange
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package gql

import cats._
import cats.implicits._
import gql.ast._
import gql.resolver._
import cats.data._
import scala.reflect.ClassTag
import gql.parser.{Value => V, Const, QueryAst => QA}

object dsl {
  type Fields[F[_], -A] = NonEmptyList[(String, Field[F, A, ?])]

  def tpeNel[F[_], A](
      name: String,
      entries: Fields[F, A]
  ) = Type[F, A](name, entries, Nil)

  def tpe[F[_], A](
      name: String,
      hd: (String, Field[F, A, ?]),
      tl: (String, Field[F, A, ?])*
  ) = Type[F, A](name, NonEmptyList(hd, tl.toList), Nil)

  def fields[F[_], A](
      hd: (String, Field[F, A, ?]),
      tl: (String, Field[F, A, ?])*
  ): Fields[F, A] =
    NonEmptyList[(String, Field[F, A, ?])](hd, tl.toList)

  def input[A](
      name: String,
      fields: Arg[A]
  ): Input[A] = Input(name, fields)

  def arg[A](name: String)(implicit tpe: => In[A]): Arg[A] =
    Arg.make[A](ArgValue(name, Eval.later(tpe), None, None))

  def arg[A](name: String, description: String)(implicit tpe: => In[A]): Arg[A] =
    Arg.make[A](ArgValue(name, Eval.later(tpe), None, Some(description)))

  def arg[A](name: String, default: V[Const, Unit])(implicit tpe: => In[A]): Arg[A] =
    Arg.make[A](ArgValue(name, Eval.later(tpe), Some(default), None))

  def arg[A](name: String, default: V[Const, Unit], description: String)(implicit tpe: => In[A]): Arg[A] =
    Arg.make[A](ArgValue(name, Eval.later(tpe), Some(default), Some(description)))

  def argFull[A] = new PartiallyAppliedArgFull[A]

  def arged[F[_], I, A](a: Arg[A]) = Resolver.argument[F, I, A](a)

  object value {
    def scalar[A](value: A)(implicit tpe: => Scalar[A]) =
      tpe.encoder(value)

    def fromEnum[A](value: A)(implicit tpe: => Enum[A]) =
      tpe.revm.get(value).map(enumValue)

    def enumValue(value: String) = V.EnumValue(value)

    def arr(xs: V[Const, Unit]*) = V.ListValue(xs.toList)

    def obj(xs: (String, V[Const, Unit])*) = V.ObjectValue(xs.toList)

    def nullValue = V.NullValue()
  }

  def eff[I] = new PartiallyAppliedEff[I]

  def lift[F[_], I] = new PartiallyAppliedLift[F, I]

  def build[F[_], I] = new FieldBuilder[F, I]

  final class PartiallyAppliedFieldBuilder[F[_], I](private val dummy: Boolean = false) extends AnyVal {
    def apply[A](f: FieldBuilder[F, I] => A): A = f(build[F, I])
  }

  def builder[F[_], I] = new PartiallyAppliedFieldBuilder[F, I]

  def abst[F[_], T](implicit tpe: => Out[F, T]): AbstractField[F, T] =
    AbstractField[F, T](None, Eval.later(tpe))

  def abstWith[F[_], T, A](arg: Arg[A])(implicit tpe: => Out[F, T]): AbstractField[F, T] =
    AbstractField[F, T](Some(arg), Eval.later(tpe))

  type AbstractFields[F[_]] = NonEmptyList[(String, AbstractField[F, ?])]

  def abstGroup[F[_]](
      hd: (String, AbstractField[F, ?]),
      tl: (String, AbstractField[F, ?])*
  ): AbstractFields[F] =
    NonEmptyList(hd, tl.toList)

  def directive(name: String): Directive[Unit] =
    Directive(name)

  def directive[A](name: String, arg: Arg[A]): Directive[A] =
    Directive(name, DirectiveArg.WithArg(arg))

  protected def addPosition[F[_], A, Pos <: Position[F, A]](pos: Pos): State[SchemaState[F], Pos] =
    State(s => (s.copy(positions = pos :: s.positions), pos))

  def onField[F[_], A](directive: Directive[A], handler: Position.FieldHandler[F, A]): State[SchemaState[F], Position.Field[F, A]] =
    addPosition[F, A, Position.Field[F, A]](Position.Field(directive, handler))

  def onFragmentSpread[F[_], A](
      directive: Directive[A],
      handler: Position.QueryHandler[QA.FragmentSpread, A]
  ): State[SchemaState[F], Position.FragmentSpread[A]] =
    addPosition[F, A, Position.FragmentSpread[A]](Position.FragmentSpread(directive, handler))

  def onInlineFragmentSpread[F[_], A](
      directive: Directive[A],
      handler: Position.QueryHandler[QA.InlineFragment, A]
  ): State[SchemaState[F], Position.InlineFragmentSpread[A]] =
    addPosition[F, A, Position.InlineFragmentSpread[A]](Position.InlineFragmentSpread(directive, handler))

  def enumVal[A](value: A): EnumValue[A] =
    EnumValue(value)

  def enumType[A](name: String, hd: (String, EnumValue[? <: A]), tl: (String, EnumValue[? <: A])*) =
    Enum[A](name, NonEmptyList(hd, tl.toList))

  def interfaceNel[F[_], A](
      name: String,
      fields: AbstractFields[F]
  ): Interface[F, A] = Interface[F, A](name, fields, Nil)

  def interface[F[_], A](
      name: String,
      hd: (String, AbstractField[F, ?]),
      tl: (String, AbstractField[F, ?])*
  ): Interface[F, A] = interfaceNel[F, A](name, NonEmptyList(hd, tl.toList))

  def interfaceFromNel[F[_], A](
      name: String,
      fields: Fields[F, A]
  ): Interface[F, A] = interfaceNel[F, A](name, fields.map { case (k, v) => k -> v.asAbstract })

  def interfaceFrom[F[_], A](
      name: String,
      hd: (String, Field[F, A, ?]),
      tl: (String, Field[F, A, ?])*
  ): Interface[F, A] = interfaceFromNel[F, A](name, NonEmptyList(hd, tl.toList))

  def union[F[_], A](name: String) = PartiallyAppliedUnion0[F, A](name)

  def optType[F[_], A, B](resolver: Resolver[F, A, B])(implicit tpe: => Out[F, B]): Out[F, Option[A]] =
    OutOpt(tpe, resolver)

  def optType[A](implicit tpe: => In[A]): In[Option[A]] = InOpt(tpe)

  def arrType[F[_], A, C, B](toSeq: C => Seq[A])(resolver: Resolver[F, A, B])(implicit
      tpe: => Out[F, B]
  ): OutArr[F, A, C, B] =
    OutArr(tpe, toSeq, resolver)

  def arrType[F[_], A, G[x] <: Seq[x], B](resolver: Resolver[F, A, B])(implicit
      tpe: => Out[F, B]
  ): OutArr[F, A, G[A], B] =
    OutArr(tpe, identity, resolver)

  def arrType[A](implicit tpe: => In[A]): In[Seq[A]] = InArr[A, Seq[A]](tpe, _.asRight)

  implicit def syntaxForFields[F[_], A](fields: Fields[F, A]): FieldsSyntax[F, A] =
    FieldsSyntax[F, A](fields)

  implicit def syntaxForType[F[_], A](tpe: Type[F, A]): TypeSyntax[F, A] =
    TypeSyntax[F, A](tpe)

  implicit def syntaxForInterface[F[_], A](tpe: Interface[F, A]): InterfaceSyntax[F, A] =
    InterfaceSyntax[F, A](tpe)

  implicit def syntaxForUnion[F[_], A](tpe: Union[F, A]): UnionSyntax[F, A] =
    UnionSyntax[F, A](tpe)

  implicit def syntaxForBatchResolverSignature[F[_], K, V](
      resolver: Resolver[F, Set[K], Map[K, V]]
  ): SyntaxForBatchResolverSignature[F, K, V] =
    SyntaxForBatchResolverSignature[F, K, V](resolver)

  final class FieldBuilder[F[_], I](private val dummy: Boolean = false) extends AnyVal {
    def tpe(
        name: String,
        hd: (String, Field[F, I, ?]),
        tl: (String, Field[F, I, ?])*
    ): Type[F, I] = dsl.tpe[F, I](name, hd, tl: _*)

    def fields(
        hd: (String, Field[F, I, ?]),
        tl: (String, Field[F, I, ?])*
    ): Fields[F, I] = dsl.fields[F, I](hd, tl: _*)

    def from[T](resolver: Resolver[F, I, T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field[F, I, T](resolver, Eval.later(tpe))

    def apply[T](f: Resolver[F, I, I] => Resolver[F, I, T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field[F, I, T](f(Resolver.id[F, I]), Eval.later(tpe))

    def lift = new PartiallyAppliedLift[F, I]

    def eff[T](resolver: I => F[T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field(Resolver.liftF(resolver), Eval.later(tpe))
  }

  // final class ArgBuilder[A](private val name: String) extends AnyVal {
  //   def full[B](g: ArgValue[A] => ArgValue[A])(f: ArgParam[A] => Either[String, B])(implicit in: => In[A]): Arg[B] =
  //     Arg.makeFrom[A, B](g(ArgValue(name, Eval.later(in), None, None)))(f)

  //   def apply(f: ArgValue[A] => ArgValue[A])(implicit in: => In[A]): Arg[A] =
  //     full(f)(_.value.asRight)(in)
  // }

  // def buildArg[A](name: String): ArgBuilder[A] =
  //   new ArgBuilder[A](name)

  final class PartiallyAppliedLift[F[_], I](private val dummy: Boolean = false) extends AnyVal {
    def apply[T, A](arg: Arg[A])(resolver: (A, I) => Id[T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field(Resolver.lift[F, (A, I)] { case (a, i) => resolver(a, i) }.contraArg(arg), Eval.later(tpe))

    def apply[T](resolver: I => Id[T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field(Resolver.lift[F, I](resolver), Eval.later(tpe))
  }

  final class PartiallyAppliedEff[I](private val dummy: Boolean = false) extends AnyVal {
    def apply[F[_], T, A](arg: Arg[A])(resolver: (A, I) => F[T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field(Resolver.liftF[F, (A, I)] { case (a, i) => resolver(a, i) }.contraArg(arg), Eval.later(tpe))

    def apply[F[_], T](resolver: I => F[T])(implicit tpe: => Out[F, T]): Field[F, I, T] =
      Field(Resolver.liftF(resolver), Eval.later(tpe))
  }

  final case class PartiallyAppliedArgFull[A](private val dummy: Boolean = false) extends AnyVal {
    def apply[B](name: String, default: Option[V[Const, Unit]], description: Option[String])(
        f: ArgParam[A] => Either[String, B]
    )(implicit tpe: => In[A]): Arg[B] =
      Arg.makeFrom[A, B](ArgValue(name, Eval.later(tpe), default, description))(f)
  }

  final case class FieldsSyntax[F[_], A](private val fields: Fields[F, A]) extends AnyVal {
    def addFields(xs: (String, Field[F, A, ?])*) =
      fields concat xs.toList

    def addFieldsNel(xs: NonEmptyList[(String, Field[F, A, ?])]) =
      fields concat xs.toList

    def mapValues[B](f: Field[F, A, ?] => Field[F, B, ?]) =
      fields.map { case (k, v) => k -> f(v) }

    def resolveBy[I2](f: Resolver[F, A, A] => Resolver[F, I2, A]): Fields[F, I2] =
      mapValues(_.compose(f(Resolver.id)))

    def compose[I2](resolver: Resolver[F, I2, A]): Fields[F, I2] =
      resolveBy[I2](_.compose(resolver))
  }

  final case class TypeSyntax[F[_], A](private val tpe: Type[F, A]) extends AnyVal {
    def implements[B](pf: PartialFunction[B, A])(implicit interface: => Interface[F, B]): Type[F, A] =
      tpe.copy(implementations = Implementation(Eval.later(interface))(pf.lift) :: tpe.implementations)

    def subtypeOf[B](implicit ev: A <:< B, tag: ClassTag[A], interface: => Interface[F, B]): Type[F, A] =
      implements[B] { case a: A => a }(interface)

    def addFields(xs: (String, Field[F, A, ?])*) =
      tpe.copy(fields = tpe.fields concat xs.toList)
  }

  final case class InterfaceSyntax[F[_], A](private val tpe: Interface[F, A]) extends AnyVal {
    def implements[B](implicit interface: => Interface[F, B]): Interface[F, A] =
      tpe.copy(implementations = Eval.later(interface) :: tpe.implementations)

    def addAbstractFields(xs: (String, AbstractField[F, ?])*): Interface[F, A] =
      tpe.copy(fields = tpe.fields concat xs.toList)

    def addFields(xs: (String, Field[F, A, ?])*): Interface[F, A] =
      tpe.copy(fields = tpe.fields concat xs.toList.map { case (k, v) => k -> v.asAbstract })
  }

  final case class UnionSyntax[F[_], A](private val tpe: Union[F, A]) extends AnyVal {
    def variant[B](pf: PartialFunction[A, B])(implicit innerTpe: => Type[F, B]): Union[F, A] =
      tpe.copy(types = Variant[F, A, B](Eval.later(innerTpe))(pf.lift) :: tpe.types)

    def subtype[B: ClassTag](implicit ev: B <:< A, innerTpe: => Type[F, B]): Union[F, A] =
      variant[B] { case a: B => a }(innerTpe)
  }

  final case class PartiallyAppliedUnion1[F[_], A](private val name: String, private val hd: Variant[F, A, ?]) {
    def variant[B](pf: PartialFunction[A, B])(implicit innerTpe: => Type[F, B]): Union[F, A] =
      Union[F, A](name, NonEmptyList.of(hd, Variant[F, A, B](Eval.later(innerTpe))(pf.lift)), None)

    def subtype[B: ClassTag](implicit ev: B <:< A, innerTpe: => Type[F, B]): Union[F, A] =
      variant[B] { case a: B => a }(innerTpe)
  }

  final case class PartiallyAppliedUnion0[F[_], A](name: String) extends AnyVal {
    def variant[B](pf: PartialFunction[A, B])(implicit innerTpe: => Type[F, B]): PartiallyAppliedUnion1[F, A] =
      PartiallyAppliedUnion1[F, A](name, Variant[F, A, B](Eval.later(innerTpe))(pf.lift))

    def subtype[B: ClassTag](implicit ev: B <:< A, innerTpe: => Type[F, B]): PartiallyAppliedUnion1[F, A] =
      variant[B] { case a: B => a }(innerTpe)
  }

  final case class SyntaxForBatchResolverSignature[F[_], K, V](private val r: Resolver[F, Set[K], Map[K, V]]) extends AnyVal {
    def optionals[G[_]: Foldable: Functor]: Resolver[F, G[K], G[Option[V]]] =
      r.contramap[G[K]](_.toList.toSet).tupleIn.map { case (m, g) => g.map(m.get) }

    def values[G[_]: Foldable: FunctorFilter: Functor]: Resolver[F, G[K], G[V]] =
      optionals[G].map(_.collect { case Some(v) => v })

    def force[G[_]: Foldable: FunctorFilter: Functor](implicit
        S: ShowMissingKeys[K]
    ): Resolver[F, G[K], G[V]] =
      r.contramap[G[K]](_.toList.toSet).tupleIn.map { case (m, g) => g.map(k => (k, m.get(k))) }.fallibleMap { gov =>
        val errs = gov.collect { case (k, None) => k }
        errs.toList.toNel match {
          case None     => gov.collect { case (_, Some(v)) => v }.rightIor[String]
          case Some(xs) => S.showMissingKeys(xs).leftIor[G[V]]
        }
      }

    def optional: Resolver[F, K, Option[V]] =
      optionals[Id]

    def forceOne(implicit S: ShowMissingKeys[K]): Resolver[F, K, V] =
      optional.tupleIn.fallibleMap {
        case (Some(v), _) => v.rightIor[String]
        case (None, k)    => S.showMissingKeys(NonEmptyList.one(k)).leftIor[V]
      }

    def forceNE[G[_]: NonEmptyTraverse](implicit S: ShowMissingKeys[K]): Resolver[F, G[K], G[V]] =
      force[List]
        .contramap[G[K]](_.toList)
        .tupleIn
        .fallibleMap { case (v, ks) =>
          val varr = v.toVector
          ks.mapWithIndex { case (_, i) => varr(i) }.rightIor
        }
  }

  trait ShowMissingKeys[A] {
    def showMissingKeys(xs: NonEmptyList[A]): String
  }

  object ShowMissingKeys {
    def apply[A](implicit ev: ShowMissingKeys[A]): ShowMissingKeys[A] = ev

    def showFull[A](show: NonEmptyList[A] => String): ShowMissingKeys[A] =
      new ShowMissingKeys[A] {
        def showMissingKeys(xs: NonEmptyList[A]): String = show(xs)
      }

    def showForKey[A: Show](prefix: String): ShowMissingKeys[A] =
      showFull(xs => s"$prefix: ${xs.map(_.show).mkString_(", ")}")

    def show[A](showKey: A => String, prefix: String): ShowMissingKeys[A] =
      showForKey[A](prefix)(Show.show(showKey))
  }
}