//===--- NamespaceEndCommentsFixer.cpp --------------------------*- C++ -*-===//

//

// 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

//

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

///

/// \file

/// This file implements NamespaceEndCommentsFixer, a TokenAnalyzer that

/// fixes namespace end comments.

///

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

#include "NamespaceEndCommentsFixer.h"

#include "clang/Basic/TokenKinds.h"

#include "llvm/Support/Debug.h"

#include "llvm/Support/Regex.h"

#define DEBUG_TYPE "namespace-end-comments-fixer"

namespace clang {

namespace format {

namespace {

// Iterates all tokens starting from StartTok to EndTok and apply Fn to all

// tokens between them including StartTok and EndTok. Returns the token after

// EndTok.

const FormatToken *

processTokens(const FormatToken *Tok, tok::TokenKind StartTok,

              tok::TokenKind EndTok,

              llvm::function_ref<void(const FormatToken *)> Fn) {

  if (!Tok || Tok->isNot(StartTok))

    return Tok;

  int NestLevel = 0;

  do {

    if (Tok->is(StartTok))

      ++NestLevel;

    else if (Tok->is(EndTok))

      --NestLevel;

    if (Fn)

      Fn(Tok);

    Tok = Tok->getNextNonComment();

  } while (Tok && NestLevel > 0);

  return Tok;

}

const FormatToken *skipAttribute(const FormatToken *Tok) {

  if (!Tok)

    return nullptr;

  if (Tok->isAttribute()) {

    Tok = Tok->getNextNonComment();

    Tok = processTokens(Tok, tok::l_paren, tok::r_paren, nullptr);

  } else if (Tok->is(tok::l_square)) {

    Tok = processTokens(Tok, tok::l_square, tok::r_square, nullptr);

  }

  return Tok;

}

// Computes the name of a namespace given the namespace token.

// Returns "" for anonymous namespace.

std::string computeName(const FormatToken *NamespaceTok) {

  assert(NamespaceTok &&

         NamespaceTok->isOneOf(tok::kw_namespace, TT_NamespaceMacro) &&

         "expecting a namespace token");

  std::string name;

  const FormatToken *Tok = NamespaceTok->getNextNonComment();

  if (NamespaceTok->is(TT_NamespaceMacro)) {

    // Collects all the non-comment tokens between opening parenthesis

    // and closing parenthesis or comma.

    assert(Tok && Tok->is(tok::l_paren) && "expected an opening parenthesis");

    Tok = Tok->getNextNonComment();

    while (Tok && !Tok->isOneOf(tok::r_paren, tok::comma)) {

      name += Tok->TokenText;

      Tok = Tok->getNextNonComment();

    }

    return name;

  }

  Tok = skipAttribute(Tok);

  std::string FirstNSName;

  // For `namespace [[foo]] A::B::inline C {` or

  // `namespace MACRO1 MACRO2 A::B::inline C {`, returns "A::B::inline C".

  // Peek for the first '::' (or '{' or '(')) and then return all tokens from

  // one token before that up until the '{'. A '(' might be a macro with

  // arguments.

  const FormatToken *FirstNSTok = nullptr;

  while (Tok && !Tok->isOneOf(tok::l_brace, tok::coloncolon, tok::l_paren)) {

    if (FirstNSTok)

      FirstNSName += FirstNSTok->TokenText;

    FirstNSTok = Tok;

    Tok = Tok->getNextNonComment();

  }

  if (FirstNSTok)

    Tok = FirstNSTok;

  Tok = skipAttribute(Tok);

  FirstNSTok = nullptr;

  // Add everything from '(' to ')'.

  auto AddToken = [&name](const FormatToken *Tok) { name += Tok->TokenText; };

  bool IsPrevColoncolon = false;

  bool HasColoncolon = false;

  bool IsPrevInline = false;

  bool NameFinished = false;

  // If we found '::' in name, then it's the name. Otherwise, we can't tell

  // which one is name. For example, `namespace A B {`.

  while (Tok && Tok->isNot(tok::l_brace)) {

    if (FirstNSTok) {

      if (!IsPrevInline && HasColoncolon && !IsPrevColoncolon) {

        if (FirstNSTok->is(tok::l_paren)) {

          FirstNSTok = Tok =

              processTokens(FirstNSTok, tok::l_paren, tok::r_paren, AddToken);

          continue;

        }

        if (FirstNSTok->isNot(tok::coloncolon)) {

          NameFinished = true;

          break;

        }

      }

      name += FirstNSTok->TokenText;

      IsPrevColoncolon = FirstNSTok->is(tok::coloncolon);

      HasColoncolon = HasColoncolon || IsPrevColoncolon;

      if (FirstNSTok->is(tok::kw_inline)) {

        name += " ";

        IsPrevInline = true;

      }

    }

    FirstNSTok = Tok;

    Tok = Tok->getNextNonComment();

    const FormatToken *TokAfterAttr = skipAttribute(Tok);

    if (TokAfterAttr != Tok)

      FirstNSTok = Tok = TokAfterAttr;

  }

  if (!NameFinished && FirstNSTok && FirstNSTok->isNot(tok::l_brace))

    name += FirstNSTok->TokenText;

  if (FirstNSName.empty() || HasColoncolon)

    return name;

  return name.empty() ? FirstNSName : FirstNSName + " " + name;

}

std::string computeEndCommentText(StringRef NamespaceName, bool AddNewline,

                                  const FormatToken *NamespaceTok,

                                  unsigned SpacesToAdd) {

  std::string text = "//";

  text.append(SpacesToAdd, ' ');

  text += NamespaceTok->TokenText;

  if (NamespaceTok->is(TT_NamespaceMacro))

    text += "(";

  else if (!NamespaceName.empty())

    text += ' ';

  text += NamespaceName;

  if (NamespaceTok->is(TT_NamespaceMacro))

    text += ")";

  if (AddNewline)

    text += '\n';

  return text;

}

bool hasEndComment(const FormatToken *RBraceTok) {

  return RBraceTok->Next && RBraceTok->Next->is(tok::comment);

}

bool validEndComment(const FormatToken *RBraceTok, StringRef NamespaceName,

                     const FormatToken *NamespaceTok) {

  assert(hasEndComment(RBraceTok));

  const FormatToken *Comment = RBraceTok->Next;

  // Matches a valid namespace end comment.

  // Valid namespace end comments don't need to be edited.

  static const llvm::Regex NamespaceCommentPattern =

      llvm::Regex("^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"

                  "namespace( +([a-zA-Z0-9:_ ]+))?\\.? *(\\*/)?$",

                  llvm::Regex::IgnoreCase);

  static const llvm::Regex NamespaceMacroCommentPattern =

      llvm::Regex("^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"

                  "([a-zA-Z0-9_]+)\\(([a-zA-Z0-9:_]*|\".+\")\\)\\.? *(\\*/)?$",

                  llvm::Regex::IgnoreCase);

  SmallVector<StringRef, 8> Groups;

  if (NamespaceTok->is(TT_NamespaceMacro) &&

      NamespaceMacroCommentPattern.match(Comment->TokenText, &Groups)) {

    StringRef NamespaceTokenText = Groups.size() > 4 ? Groups[4] : "";

    // The name of the macro must be used.

    if (NamespaceTokenText != NamespaceTok->TokenText)

      return false;

  } else if (NamespaceTok->isNot(tok::kw_namespace) ||

             !NamespaceCommentPattern.match(Comment->TokenText, &Groups)) {

    // Comment does not match regex.

    return false;

  }

  StringRef NamespaceNameInComment = Groups.size() > 5 ? Groups[5].rtrim() : "";

  // Anonymous namespace comments must not mention a namespace name.

  if (NamespaceName.empty() && !NamespaceNameInComment.empty())

    return false;

  StringRef AnonymousInComment = Groups.size() > 3 ? Groups[3] : "";

  // Named namespace comments must not mention anonymous namespace.

  if (!NamespaceName.empty() && !AnonymousInComment.empty())

    return false;

  if (NamespaceNameInComment == NamespaceName)

    return true;

  // Has namespace comment flowed onto the next line.

  // } // namespace

  //   // verylongnamespacenamethatdidnotfitonthepreviouscommentline

  if (!(Comment->Next && Comment->Next->is(TT_LineComment)))

    return false;

  static const llvm::Regex CommentPattern = llvm::Regex(

      "^/[/*] *( +([a-zA-Z0-9:_]+))?\\.? *(\\*/)?$", llvm::Regex::IgnoreCase);

  // Pull out just the comment text.

  if (!CommentPattern.match(Comment->Next->TokenText, &Groups))

    return false;

  NamespaceNameInComment = Groups.size() > 2 ? Groups[2] : "";

  return NamespaceNameInComment == NamespaceName;

}

void addEndComment(const FormatToken *RBraceTok, StringRef EndCommentText,

                   const SourceManager &SourceMgr,

                   tooling::Replacements *Fixes) {

  auto EndLoc = RBraceTok->Tok.getEndLoc();

  auto Range = CharSourceRange::getCharRange(EndLoc, EndLoc);

  auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, EndCommentText));

  if (Err) {

    llvm::errs() << "Error while adding namespace end comment: "

                 << llvm::toString(std::move(Err)) << "\n";

  }

}

void updateEndComment(const FormatToken *RBraceTok, StringRef EndCommentText,

                      const SourceManager &SourceMgr,

                      tooling::Replacements *Fixes) {

  assert(hasEndComment(RBraceTok));

  const FormatToken *Comment = RBraceTok->Next;

  auto Range = CharSourceRange::getCharRange(Comment->getStartOfNonWhitespace(),

                                             Comment->Tok.getEndLoc());

  auto Err = Fixes->add(tooling::Replacement(SourceMgr, Range, EndCommentText));

  if (Err) {

    llvm::errs() << "Error while updating namespace end comment: "

                 << llvm::toString(std::move(Err)) << "\n";

  }

}

} // namespace

const FormatToken *

getNamespaceToken(const AnnotatedLine *Line,

                  const SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {

  if (!Line->Affected || Line->InPPDirective || !Line->startsWith(tok::r_brace))

    return nullptr;

  size_t StartLineIndex = Line->MatchingOpeningBlockLineIndex;

  if (StartLineIndex == UnwrappedLine::kInvalidIndex)

    return nullptr;

  assert(StartLineIndex < AnnotatedLines.size());

  const FormatToken *NamespaceTok = AnnotatedLines[StartLineIndex]->First;

  if (NamespaceTok->is(tok::l_brace)) {

    // "namespace" keyword can be on the line preceding '{', e.g. in styles

    // where BraceWrapping.AfterNamespace is true.

    if (StartLineIndex > 0) {

      NamespaceTok = AnnotatedLines[StartLineIndex - 1]->First;

      if (AnnotatedLines[StartLineIndex - 1]->endsWith(tok::semi))

        return nullptr;

    }

  }

  return NamespaceTok->getNamespaceToken();

}

StringRef

getNamespaceTokenText(const AnnotatedLine *Line,

                      const SmallVectorImpl<AnnotatedLine *> &AnnotatedLines) {

  const FormatToken *NamespaceTok = getNamespaceToken(Line, AnnotatedLines);

  return NamespaceTok ? NamespaceTok->TokenText : StringRef();

}

NamespaceEndCommentsFixer::NamespaceEndCommentsFixer(const Environment &Env,

                                                     const FormatStyle &Style)

    : TokenAnalyzer(Env, Style) {}

std::pair<tooling::Replacements, unsigned> NamespaceEndCommentsFixer::analyze(

    TokenAnnotator &Annotator, SmallVectorImpl<AnnotatedLine *> &AnnotatedLines,

    FormatTokenLexer &Tokens) {

  const SourceManager &SourceMgr = Env.getSourceManager();

  AffectedRangeMgr.computeAffectedLines(AnnotatedLines);

  tooling::Replacements Fixes;

  // Spin through the lines and ensure we have balanced braces.

  int Braces = 0;

  for (AnnotatedLine *Line : AnnotatedLines) {

    FormatToken *Tok = Line->First;

    while (Tok) {

      Braces += Tok->is(tok::l_brace) ? 1 : Tok->is(tok::r_brace) ? -1 : 0;

      Tok = Tok->Next;

    }

  }

  // Don't attempt to comment unbalanced braces or this can

  // lead to comments being placed on the closing brace which isn't

  // the matching brace of the namespace. (occurs during incomplete editing).

  if (Braces != 0)

    return {Fixes, 0};

  std::string AllNamespaceNames;

  size_t StartLineIndex = SIZE_MAX;

  StringRef NamespaceTokenText;

  unsigned int CompactedNamespacesCount = 0;

  for (size_t I = 0, E = AnnotatedLines.size(); I != E; ++I) {

    const AnnotatedLine *EndLine = AnnotatedLines[I];

    const FormatToken *NamespaceTok =

        getNamespaceToken(EndLine, AnnotatedLines);

    if (!NamespaceTok)

      continue;

    FormatToken *RBraceTok = EndLine->First;

    if (RBraceTok->Finalized)

      continue;

    RBraceTok->Finalized = true;

    const FormatToken *EndCommentPrevTok = RBraceTok;

    // Namespaces often end with '};'. In that case, attach namespace end

    // comments to the semicolon tokens.

    if (RBraceTok->Next && RBraceTok->Next->is(tok::semi))

      EndCommentPrevTok = RBraceTok->Next;

    if (StartLineIndex == SIZE_MAX)

      StartLineIndex = EndLine->MatchingOpeningBlockLineIndex;

    std::string NamespaceName = computeName(NamespaceTok);

    if (Style.CompactNamespaces) {

      if (CompactedNamespacesCount == 0)

        NamespaceTokenText = NamespaceTok->TokenText;

      if ((I + 1 < E) &&

          NamespaceTokenText ==

              getNamespaceTokenText(AnnotatedLines[I + 1], AnnotatedLines) &&

          StartLineIndex - CompactedNamespacesCount - 1 ==

              AnnotatedLines[I + 1]->MatchingOpeningBlockLineIndex &&

          !AnnotatedLines[I + 1]->First->Finalized) {

        if (hasEndComment(EndCommentPrevTok)) {

          // remove end comment, it will be merged in next one

          updateEndComment(EndCommentPrevTok, std::string(), SourceMgr, &Fixes);

        }

        ++CompactedNamespacesCount;

        if (!NamespaceName.empty())

          AllNamespaceNames = "::" + NamespaceName + AllNamespaceNames;

        continue;

      }

      NamespaceName += AllNamespaceNames;

      CompactedNamespacesCount = 0;

      AllNamespaceNames = std::string();

    }

    // The next token in the token stream after the place where the end comment

    // token must be. This is either the next token on the current line or the

    // first token on the next line.

    const FormatToken *EndCommentNextTok = EndCommentPrevTok->Next;

    if (EndCommentNextTok && EndCommentNextTok->is(tok::comment))

      EndCommentNextTok = EndCommentNextTok->Next;

    if (!EndCommentNextTok && I + 1 < E)

      EndCommentNextTok = AnnotatedLines[I + 1]->First;

    bool AddNewline = EndCommentNextTok &&

                      EndCommentNextTok->NewlinesBefore == 0 &&

                      EndCommentNextTok->isNot(tok::eof);

    const std::string EndCommentText =

        computeEndCommentText(NamespaceName, AddNewline, NamespaceTok,

                              Style.SpacesInLineCommentPrefix.Minimum);

    if (!hasEndComment(EndCommentPrevTok)) {

      unsigned LineCount = 0;

      for (auto J = StartLineIndex + 1; J < I; ++J)

        LineCount += AnnotatedLines[J]->size();

      if (LineCount > Style.ShortNamespaceLines) {

        addEndComment(EndCommentPrevTok,

                      std::string(Style.SpacesBeforeTrailingComments, ' ') +

                          EndCommentText,

                      SourceMgr, &Fixes);

      }

    } else if (!validEndComment(EndCommentPrevTok, NamespaceName,

                                NamespaceTok)) {

      updateEndComment(EndCommentPrevTok, EndCommentText, SourceMgr, &Fixes);

    }

    StartLineIndex = SIZE_MAX;

  }

  return {Fixes, 0};

}

} // namespace format

} // namespace clang