//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "LambdaFunctionNameCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/MacroInfo.h"
#include "clang/Lex/Preprocessor.h"

using namespace clang::ast_matchers;

namespace clang::tidy::bugprone {

namespace {

static constexpr bool DefaultIgnoreMacros = false;

// Keep track of macro expansions that contain both __FILE__ and __LINE__. If
// such a macro also uses __func__ or __FUNCTION__, we don't want to issue a
// warning because __FILE__ and __LINE__ may be useful even if __func__ or
// __FUNCTION__ is not, especially if the macro could be used in the context of
// either a function body or a lambda body.
class MacroExpansionsWithFileAndLine : public PPCallbacks {
public:
  explicit MacroExpansionsWithFileAndLine(llvm::DenseSet<SourceRange> *SME)
      : SuppressMacroExpansions(SME) {}

  void MacroExpands(const Token &MacroNameTok, const MacroDefinition &MD,
                    SourceRange Range, const MacroArgs *Args) override {
    bool HasFile = false;
    bool HasLine = false;
    for (const Token &T : MD.getMacroInfo()->tokens()) {
      if (T.is(tok::identifier)) {
        const StringRef IdentName = T.getIdentifierInfo()->getName();
        if (IdentName == "__FILE__")
          HasFile = true;
        else if (IdentName == "__LINE__")
          HasLine = true;
      }
    }
    if (HasFile && HasLine)
      SuppressMacroExpansions->insert(Range);
  }

private:
  llvm::DenseSet<SourceRange> *SuppressMacroExpansions;
};

AST_MATCHER(CXXMethodDecl, isInLambda) { return Node.getParent()->isLambda(); }

} // namespace

LambdaFunctionNameCheck::LambdaFunctionNameCheck(StringRef Name,
                                                 ClangTidyContext *Context)
    : ClangTidyCheck(Name, Context),
      IgnoreMacros(Options.get("IgnoreMacros", DefaultIgnoreMacros)) {}

void LambdaFunctionNameCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  Options.store(Opts, "IgnoreMacros", IgnoreMacros);
}

void LambdaFunctionNameCheck::registerMatchers(MatchFinder *Finder) {
  Finder->addMatcher(
      cxxMethodDecl(isInLambda(),
                    hasBody(forEachDescendant(
                        predefinedExpr(hasAncestor(cxxMethodDecl().bind("fn")))
                            .bind("E"))),
                    equalsBoundNode("fn")),
      this);
}

void LambdaFunctionNameCheck::registerPPCallbacks(
    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
  PP->addPPCallbacks(std::make_unique<MacroExpansionsWithFileAndLine>(
      &SuppressMacroExpansions));
}

void LambdaFunctionNameCheck::check(const MatchFinder::MatchResult &Result) {
  const auto *E = Result.Nodes.getNodeAs<PredefinedExpr>("E");
  if (E->getIdentKind() != PredefinedIdentKind::Func &&
      E->getIdentKind() != PredefinedIdentKind::Function) {
    // We don't care about other PredefinedExprs.
    return;
  }
  if (E->getLocation().isMacroID()) {
    if (IgnoreMacros)
      return;

    auto ER =
        Result.SourceManager->getImmediateExpansionRange(E->getLocation());
    if (SuppressMacroExpansions.contains(ER.getAsRange())) {
      // This is a macro expansion for which we should not warn.
      return;
    }
  }

  diag(E->getLocation(),
       "inside a lambda, '%0' expands to the name of the function call "
       "operator; consider capturing the name of the enclosing function "
       "explicitly")
      << PredefinedExpr::getIdentKindName(E->getIdentKind());
}

} // namespace clang::tidy::bugprone
