//===--- CodeSynthesisDistributedActor.cpp --------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#include "TypeCheckDistributed.h"

#include "TypeChecker.h"
#include "TypeCheckType.h"
#include "swift/AST/ASTPrinter.h"
#include "swift/AST/Availability.h"
#include "swift/AST/Expr.h"
#include "swift/AST/GenericEnvironment.h"
#include "swift/AST/Initializer.h"
#include "swift/AST/ParameterList.h"
#include "swift/AST/TypeCheckRequests.h"
#include "swift/Basic/Defer.h"
#include "swift/ClangImporter/ClangModule.h"
#include "swift/Sema/ConstraintSystem.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "DerivedConformances.h"
using namespace swift;

// Note: This would be nice to implement in DerivedConformanceDistributedActor,
// but we can't since those are lazily triggered and an implementation exists
// for the 'id' property because 'Identifiable.id' has an extension that impls
// it for ObjectIdentifier, and we have to instead emit this stored property.
//
// The "derived" mechanisms are not really geared towards emitting for
// what already has a witness.
static VarDecl *addImplicitDistributedActorIDProperty(
//    DeclContext *parentDC,
    NominalTypeDecl *nominal) {
  if (!nominal || !nominal->isDistributedActor())
    return nullptr;

  // ==== if the 'id' already exists, return it
  auto &C = nominal->getASTContext();
//  if (auto existing = nominal->lookupDirect(C.Id_id))
//    return existing;

  // ==== Synthesize and add 'id' property to the actor decl
  Type propertyType = getDistributedActorIDType(nominal);

  VarDecl *propDecl = new (C)
      VarDecl(/*IsStatic*/false, VarDecl::Introducer::Let,
              SourceLoc(), C.Id_id, nominal);
  propDecl->setImplicit();
  propDecl->setSynthesized();
  propDecl->copyFormalAccessFrom(nominal, /*sourceIsParentContext*/ true);
  propDecl->setInterfaceType(propertyType);

  Pattern *propPat = NamedPattern::createImplicit(C, propDecl);
  propPat->setType(propertyType);

  propPat = TypedPattern::createImplicit(C, propPat, propertyType);
  propPat->setType(propertyType);

  PatternBindingDecl *pbDecl = PatternBindingDecl::createImplicit(
      C, StaticSpellingKind::None, propPat, /*InitExpr*/ nullptr,
      nominal);

  propDecl->setIntroducer(VarDecl::Introducer::Let);

  // mark as nonisolated, allowing access to it from everywhere
  propDecl->getAttrs().add(
      new (C) NonisolatedAttr(/*IsImplicit=*/true));

  nominal->addMember(propDecl);
  nominal->addMember(pbDecl);

  return propDecl;
}

/******************************************************************************/
/************ LOCATING AD-HOC PROTOCOL REQUIREMENT IMPLS **********************/
/******************************************************************************/

AbstractFunctionDecl*
GetDistributedActorSystemRemoteCallFunctionRequest::evaluate(
    Evaluator &evaluator, NominalTypeDecl *decl, bool isVoidReturn) const {
  auto &C = decl->getASTContext();

  // It would be nice to check if this is a DistributedActorSystem
  // "conforming" type, but we can't do this as we invoke this function WHILE
  // deciding if the type conforms or not;

  // Not via `ensureDistributedModuleLoaded` to avoid generating a warning,
  // we won't be emitting the offending decl after all.
  if (!C.getLoadedModule(C.Id_Distributed)) {
    return nullptr;
  }

  auto callId = isVoidReturn ? C.Id_remoteCallVoid : C.Id_remoteCall;

  AbstractFunctionDecl *remoteCallFunc = nullptr;
  for (auto value : decl->lookupDirect(callId)) {
    auto func = dyn_cast<AbstractFunctionDecl>(value);
    if (func && func->isDistributedActorSystemRemoteCall(isVoidReturn)) {
      remoteCallFunc = func;
      break;
    }
  }

  return remoteCallFunc;
}


/******************************************************************************/
/************************ SYNTHESIS ENTRY POINT *******************************/
/******************************************************************************/

VarDecl *GetDistributedActorIDPropertyRequest::evaluate(
    Evaluator &evaluator, NominalTypeDecl *actor) const {
  if (!actor->isDistributedActor())
    return nullptr;

  auto &C = actor->getASTContext();

  // not via `ensureDistributedModuleLoaded` to avoid generating a warning,
  // we won't be emitting the offending decl after all.
  if (!C.getLoadedModule(C.Id_Distributed))
    return nullptr;

  return addImplicitDistributedActorIDProperty(actor);
}

VarDecl *GetDistributedActorSystemPropertyRequest::evaluate(
    Evaluator &evaluator, NominalTypeDecl *actor) const {
  if (!actor->isDistributedActor())
    return nullptr;

  auto &C = actor->getASTContext();

  // not via `ensureDistributedModuleLoaded` to avoid generating a warning,
  // we won't be emitting the offending decl after all.
  if (!C.getLoadedModule(C.Id_Distributed))
    return nullptr;


  if (auto system = actor->lookupDirect(C.Id_actorSystem).begin()) {
    // TODO(distributed): may need to check conformance here?
    return dyn_cast<VarDecl>(*system);
  }

  return nullptr;
}