//===- CXExtractAPI.cpp - libclang APIs for manipulating CXAPISet ---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines all libclang APIs related to manipulation CXAPISet
//
//===----------------------------------------------------------------------===//

#include "CXCursor.h"
#include "CXString.h"
#include "CXTranslationUnit.h"
#include "clang-c/CXErrorCode.h"
#include "clang-c/Documentation.h"
#include "clang-c/Index.h"
#include "clang-c/Platform.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/ExtractAPI/API.h"
#include "clang/ExtractAPI/ExtractAPIVisitor.h"
#include "clang/ExtractAPI/Serialization/SymbolGraphSerializer.h"
#include "clang/Frontend/ASTUnit.h"
#include "clang/Frontend/FrontendOptions.h"
#include "clang/Index/USRGeneration.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/CBindingWrapping.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/JSON.h"
#include "llvm/Support/raw_ostream.h"

using namespace clang;
using namespace clang::extractapi;

namespace {
struct LibClangExtractAPIVisitor
    : ExtractAPIVisitor<LibClangExtractAPIVisitor> {
  using Base = ExtractAPIVisitor<LibClangExtractAPIVisitor>;

  LibClangExtractAPIVisitor(ASTContext &Context, APISet &API)
      : ExtractAPIVisitor<LibClangExtractAPIVisitor>(Context, API) {}

  const RawComment *fetchRawCommentForDecl(const Decl *D) const {
    return Context.getRawCommentForAnyRedecl(D);
  }

  // We need to visit implementations as well to ensure that when a user clicks
  // on a method defined only within the implementation that we can still
  // provide a symbol graph for it.
  bool VisitObjCImplementationDecl(const ObjCImplementationDecl *Decl) {
    if (!shouldDeclBeIncluded(Decl))
      return true;

    const ObjCInterfaceDecl *Interface = Decl->getClassInterface();
    StringRef Name = Interface->getName();
    StringRef USR = API.recordUSR(Decl);
    PresumedLoc Loc =
        Context.getSourceManager().getPresumedLoc(Decl->getLocation());
    LinkageInfo Linkage = Decl->getLinkageAndVisibility();
    DocComment Comment;
    if (auto *RawComment = fetchRawCommentForDecl(Interface))
      Comment = RawComment->getFormattedLines(Context.getSourceManager(),
                                              Context.getDiagnostics());

    // Build declaration fragments and sub-heading by generating them for the
    // interface.
    DeclarationFragments Declaration =
        DeclarationFragmentsBuilder::getFragmentsForObjCInterface(Interface);
    DeclarationFragments SubHeading =
        DeclarationFragmentsBuilder::getSubHeading(Decl);

    // Collect super class information.
    SymbolReference SuperClass;
    if (const auto *SuperClassDecl = Decl->getSuperClass()) {
      SuperClass.Name = SuperClassDecl->getObjCRuntimeNameAsString();
      SuperClass.USR = API.recordUSR(SuperClassDecl);
    }

    ObjCInterfaceRecord *ObjCInterfaceRecord = API.addObjCInterface(
        Name, USR, Loc, AvailabilityInfo::createFromDecl(Decl), Linkage,
        Comment, Declaration, SubHeading, SuperClass, isInSystemHeader(Decl));

    // Record all methods (selectors). This doesn't include automatically
    // synthesized property methods.
    recordObjCMethods(ObjCInterfaceRecord, Decl->methods());
    recordObjCProperties(ObjCInterfaceRecord, Decl->properties());
    recordObjCInstanceVariables(ObjCInterfaceRecord, Decl->ivars());

    return true;
  }
};
} // namespace

DEFINE_SIMPLE_CONVERSION_FUNCTIONS(APISet, CXAPISet)

static void WalkupFromMostDerivedType(LibClangExtractAPIVisitor &Visitor,
                                      Decl *D);

template <typename DeclTy>
static bool WalkupParentContext(DeclContext *Parent,
                                LibClangExtractAPIVisitor &Visitor) {
  if (auto *D = dyn_cast<DeclTy>(Parent)) {
    WalkupFromMostDerivedType(Visitor, D);
    return true;
  }
  return false;
}

static void WalkupFromMostDerivedType(LibClangExtractAPIVisitor &Visitor,
                                      Decl *D) {
  switch (D->getKind()) {
#define ABSTRACT_DECL(DECL)
#define DECL(CLASS, BASE)                                                      \
  case Decl::CLASS:                                                            \
    Visitor.WalkUpFrom##CLASS##Decl(static_cast<CLASS##Decl *>(D));            \
    break;
#include "clang/AST/DeclNodes.inc"
  }

  for (auto *Parent = D->getDeclContext(); Parent != nullptr;
       Parent = Parent->getParent()) {
    if (WalkupParentContext<ObjCContainerDecl>(Parent, Visitor))
      return;
    if (WalkupParentContext<TagDecl>(Parent, Visitor))
      return;
  }
}

static CXString GenerateCXStringFromSymbolGraphData(llvm::json::Object Obj) {
  llvm::SmallString<0> BackingString;
  llvm::raw_svector_ostream OS(BackingString);
  OS << Value(std::move(Obj));
  return cxstring::createDup(BackingString.str());
}

enum CXErrorCode clang_createAPISet(CXTranslationUnit tu, CXAPISet *out_api) {
  if (cxtu::isNotUsableTU(tu) || !out_api)
    return CXError_InvalidArguments;

  ASTUnit *Unit = cxtu::getASTUnit(tu);

  auto &Ctx = Unit->getASTContext();
  auto Lang = Unit->getInputKind().getLanguage();
  APISet *API = new APISet(Ctx.getTargetInfo().getTriple(), Lang,
                           Unit->getMainFileName().str());
  LibClangExtractAPIVisitor Visitor(Ctx, *API);

  for (auto It = Unit->top_level_begin(); It != Unit->top_level_end(); ++It) {
    Visitor.TraverseDecl(*It);
  }

  *out_api = wrap(API);
  return CXError_Success;
}

void clang_disposeAPISet(CXAPISet api) { delete unwrap(api); }

CXString clang_getSymbolGraphForUSR(const char *usr, CXAPISet api) {
  auto *API = unwrap(api);

  if (auto SGF = SymbolGraphSerializer::serializeSingleSymbolSGF(usr, *API))
    return GenerateCXStringFromSymbolGraphData(std::move(*SGF));

  return cxstring::createNull();
}

CXString clang_getSymbolGraphForCursor(CXCursor cursor) {
  cursor = clang_getCursorReferenced(cursor);
  CXCursorKind Kind = clang_getCursorKind(cursor);
  if (!clang_isDeclaration(Kind))
    return cxstring::createNull();

  const Decl *D = cxcursor::getCursorDecl(cursor);

  if (!D)
    return cxstring::createNull();

  CXTranslationUnit TU = cxcursor::getCursorTU(cursor);
  if (!TU)
    return cxstring::createNull();

  ASTUnit *Unit = cxtu::getASTUnit(TU);

  auto &Ctx = Unit->getASTContext();

  auto Lang = Unit->getInputKind().getLanguage();
  APISet API(Ctx.getTargetInfo().getTriple(), Lang,
             Unit->getMainFileName().str());
  LibClangExtractAPIVisitor Visitor(Ctx, API);

  const Decl *CanonicalDecl = D->getCanonicalDecl();
  CanonicalDecl = CanonicalDecl ? CanonicalDecl : D;

  SmallString<128> USR;
  if (index::generateUSRForDecl(CanonicalDecl, USR))
    return cxstring::createNull();

  WalkupFromMostDerivedType(Visitor, const_cast<Decl *>(CanonicalDecl));
  auto *Record = API.findRecordForUSR(USR);

  if (!Record)
    return cxstring::createNull();

  for (const auto &Fragment : Record->Declaration.getFragments()) {
    if (Fragment.Declaration)
      WalkupFromMostDerivedType(Visitor,
                                const_cast<Decl *>(Fragment.Declaration));
  }

  if (auto SGF = SymbolGraphSerializer::serializeSingleSymbolSGF(USR, API))
    return GenerateCXStringFromSymbolGraphData(std::move(*SGF));

  return cxstring::createNull();
}