//===- ClangExtDefMapGen.cpp -----------------------------------------------===//
//
// 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
//
//===--------------------------------------------------------------------===//
//
// Clang tool which creates a list of defined functions and the files in which
// they are defined.
//
//===--------------------------------------------------------------------===//

#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/Basic/SourceManager.h"
#include "clang/CrossTU/CrossTranslationUnit.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/FrontendActions.h"
#include "clang/Tooling/CommonOptionsParser.h"
#include "clang/Tooling/Tooling.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/Signals.h"
#include <sstream>
#include <string>

using namespace llvm;
using namespace clang;
using namespace clang::cross_tu;
using namespace clang::tooling;

static cl::OptionCategory ClangExtDefMapGenCategory("clang-extdefmapgen options");

class MapExtDefNamesConsumer : public ASTConsumer {
public:
  MapExtDefNamesConsumer(ASTContext &Context)
      : Ctx(Context), SM(Context.getSourceManager()) {}

  ~MapExtDefNamesConsumer() {
    // Flush results to standard output.
    llvm::outs() << createCrossTUIndexString(Index);
  }

  void HandleTranslationUnit(ASTContext &Context) override {
    handleDecl(Context.getTranslationUnitDecl());
  }

private:
  void handleDecl(const Decl *D);
  void addIfInMain(const DeclaratorDecl *DD, SourceLocation defStart);

  ASTContext &Ctx;
  SourceManager &SM;
  llvm::StringMap<std::string> Index;
  std::string CurrentFileName;
};

void MapExtDefNamesConsumer::handleDecl(const Decl *D) {
  if (!D)
    return;

  if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
    if (FD->isThisDeclarationADefinition())
      if (const Stmt *Body = FD->getBody())
        addIfInMain(FD, Body->getBeginLoc());
  } else if (const auto *VD = dyn_cast<VarDecl>(D)) {
    if (cross_tu::containsConst(VD, Ctx) && VD->hasInit())
      if (const Expr *Init = VD->getInit())
        addIfInMain(VD, Init->getBeginLoc());
  }

  if (const auto *DC = dyn_cast<DeclContext>(D))
    for (const Decl *D : DC->decls())
      handleDecl(D);
}

void MapExtDefNamesConsumer::addIfInMain(const DeclaratorDecl *DD,
                                         SourceLocation defStart) {
  llvm::Optional<std::string> LookupName =
      CrossTranslationUnitContext::getLookupName(DD);
  if (!LookupName)
    return;
  assert(!LookupName->empty() && "Lookup name should be non-empty.");

  if (CurrentFileName.empty()) {
    CurrentFileName =
        SM.getFileEntryForID(SM.getMainFileID())->tryGetRealPathName();
    if (CurrentFileName.empty())
      CurrentFileName = "invalid_file";
  }

  switch (DD->getLinkageInternal()) {
  case ExternalLinkage:
  case VisibleNoLinkage:
  case UniqueExternalLinkage:
    if (SM.isInMainFile(defStart))
      Index[*LookupName] = CurrentFileName;
    break;
  default:
    break;
  }
}

class MapExtDefNamesAction : public ASTFrontendAction {
protected:
  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
                                                 llvm::StringRef) {
    return std::make_unique<MapExtDefNamesConsumer>(CI.getASTContext());
  }
};

static cl::extrahelp CommonHelp(CommonOptionsParser::HelpMessage);

int main(int argc, const char **argv) {
  // Print a stack trace if we signal out.
  llvm::InitLLVM X(argc, argv);

  const char *Overview = "\nThis tool collects the USR name and location "
                         "of external definitions in the source files "
                         "(excluding headers).\n";
  CommonOptionsParser OptionsParser(argc, argv, ClangExtDefMapGenCategory,
                                    cl::ZeroOrMore, Overview);

  ClangTool Tool(OptionsParser.getCompilations(),
                 OptionsParser.getSourcePathList());

  return Tool.run(newFrontendActionFactory<MapExtDefNamesAction>().get());
}