clang-tools-extra/clang-doc/HTMLGenerator.cpp

//===-- HTMLGenerator.cpp - HTML Generator ----------------------*- 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
//
//===----------------------------------------------------------------------===//

#include "Generators.h"
#include "Representation.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/JSON.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <string>

using namespace llvm;

namespace clang {
namespace doc {

namespace {

class HTMLTag {
public:
  // Any other tag can be added if required
  enum TagType {
    TAG_A,
    TAG_DIV,
    TAG_H1,
    TAG_H2,
    TAG_H3,
    TAG_LI,
    TAG_LINK,
    TAG_META,
    TAG_P,
    TAG_SCRIPT,
    TAG_SPAN,
    TAG_TITLE,
    TAG_UL,
  };

  HTMLTag() = default;
  constexpr HTMLTag(TagType Value) : Value(Value) {}

  operator TagType() const { return Value; }
  operator bool() = delete;

  bool IsSelfClosing() const;
  llvm::SmallString<16> ToString() const;

private:
  TagType Value;
};

enum NodeType {
  NODE_TEXT,
  NODE_TAG,
};

struct HTMLNode {
  HTMLNode(NodeType Type) : Type(Type) {}
  virtual ~HTMLNode() = default;

  virtual void Render(llvm::raw_ostream &OS, int IndentationLevel) = 0;
  NodeType Type; // Type of node
};

struct TextNode : public HTMLNode {
  TextNode(const Twine &Text)
      : HTMLNode(NodeType::NODE_TEXT), Text(Text.str()) {}

  std::string Text; // Content of node
  void Render(llvm::raw_ostream &OS, int IndentationLevel) override;
};

struct TagNode : public HTMLNode {
  TagNode(HTMLTag Tag) : HTMLNode(NodeType::NODE_TAG), Tag(Tag) {}
  TagNode(HTMLTag Tag, const Twine &Text) : TagNode(Tag) {
    Children.emplace_back(llvm::make_unique<TextNode>(Text.str()));
  }

  HTMLTag Tag; // Name of HTML Tag (p, div, h1)
  std::vector<std::unique_ptr<HTMLNode>> Children; // List of child nodes
  llvm::StringMap<llvm::SmallString<16>>
      Attributes; // List of key-value attributes for tag

  void Render(llvm::raw_ostream &OS, int IndentationLevel) override;
};

constexpr const char *kDoctypeDecl = "<!DOCTYPE html>";

struct HTMLFile {
  std::vector<std::unique_ptr<HTMLNode>> Children; // List of child nodes
  void Render(llvm::raw_ostream &OS) {
    OS << kDoctypeDecl << "\n";
    for (const auto &C : Children) {
      C->Render(OS, 0);
      OS << "\n";
    }
  }
};

} // namespace

bool HTMLTag::IsSelfClosing() const {
  switch (Value) {
  case HTMLTag::TAG_META:
  case HTMLTag::TAG_LINK:
    return true;
  case HTMLTag::TAG_A:
  case HTMLTag::TAG_DIV:
  case HTMLTag::TAG_H1:
  case HTMLTag::TAG_H2:
  case HTMLTag::TAG_H3:
  case HTMLTag::TAG_LI:
  case HTMLTag::TAG_P:
  case HTMLTag::TAG_SCRIPT:
  case HTMLTag::TAG_SPAN:
  case HTMLTag::TAG_TITLE:
  case HTMLTag::TAG_UL:
    return false;
  }
  llvm_unreachable("Unhandled HTMLTag::TagType");
}

llvm::SmallString<16> HTMLTag::ToString() const {
  switch (Value) {
  case HTMLTag::TAG_A:
    return llvm::SmallString<16>("a");
  case HTMLTag::TAG_DIV:
    return llvm::SmallString<16>("div");
  case HTMLTag::TAG_H1:
    return llvm::SmallString<16>("h1");
  case HTMLTag::TAG_H2:
    return llvm::SmallString<16>("h2");
  case HTMLTag::TAG_H3:
    return llvm::SmallString<16>("h3");
  case HTMLTag::TAG_LI:
    return llvm::SmallString<16>("li");
  case HTMLTag::TAG_LINK:
    return llvm::SmallString<16>("link");
  case HTMLTag::TAG_META:
    return llvm::SmallString<16>("meta");
  case HTMLTag::TAG_P:
    return llvm::SmallString<16>("p");
  case HTMLTag::TAG_SCRIPT:
    return llvm::SmallString<16>("script");
  case HTMLTag::TAG_SPAN:
    return llvm::SmallString<16>("span");
  case HTMLTag::TAG_TITLE:
    return llvm::SmallString<16>("title");
  case HTMLTag::TAG_UL:
    return llvm::SmallString<16>("ul");
  }
  llvm_unreachable("Unhandled HTMLTag::TagType");
}

void TextNode::Render(llvm::raw_ostream &OS, int IndentationLevel) {
  OS.indent(IndentationLevel * 2);
  printHTMLEscaped(Text, OS);
}

void TagNode::Render(llvm::raw_ostream &OS, int IndentationLevel) {
  // Children nodes are rendered in the same line if all of them are text nodes
  bool InlineChildren = true;
  for (const auto &C : Children)
    if (C->Type == NodeType::NODE_TAG) {
      InlineChildren = false;
      break;
    }
  OS.indent(IndentationLevel * 2);
  OS << "<" << Tag.ToString();
  for (const auto &A : Attributes)
    OS << " " << A.getKey() << "=\"" << A.getValue() << "\"";
  if (Tag.IsSelfClosing()) {
    OS << "/>";
    return;
  }
  OS << ">";
  if (!InlineChildren)
    OS << "\n";
  bool NewLineRendered = true;
  for (const auto &C : Children) {
    int ChildrenIndentation =
        InlineChildren || !NewLineRendered ? 0 : IndentationLevel + 1;
    C->Render(OS, ChildrenIndentation);
    if (!InlineChildren && (C == Children.back() ||
                            (C->Type != NodeType::NODE_TEXT ||
                             (&C + 1)->get()->Type != NodeType::NODE_TEXT))) {
      OS << "\n";
      NewLineRendered = true;
    } else
      NewLineRendered = false;
  }
  if (!InlineChildren)
    OS.indent(IndentationLevel * 2);
  OS << "</" << Tag.ToString() << ">";
}

template <typename Derived, typename Base,
          typename = std::enable_if<std::is_base_of<Derived, Base>::value>>
static void AppendVector(std::vector<Derived> &&New,
                         std::vector<Base> &Original) {
  std::move(New.begin(), New.end(), std::back_inserter(Original));
}

// Compute the relative path that names the file path relative to the given
// directory.
static SmallString<128> computeRelativePath(StringRef FilePath,
                                            StringRef Directory) {
  StringRef Path = FilePath;
  while (!Path.empty()) {
    if (Directory == Path)
      return FilePath.substr(Path.size());
    Path = llvm::sys::path::parent_path(Path);
  }

  StringRef Dir = Directory;
  SmallString<128> Result;
  while (!Dir.empty()) {
    if (Dir == FilePath)
      break;
    Dir = llvm::sys::path::parent_path(Dir);
    llvm::sys::path::append(Result, "..");
  }
  llvm::sys::path::append(Result, FilePath.substr(Dir.size()));
  return Result;
}

// HTML generation

static std::vector<std::unique_ptr<TagNode>>
genStylesheetsHTML(StringRef InfoPath, const ClangDocContext &CDCtx) {
  std::vector<std::unique_ptr<TagNode>> Out;
  for (const auto &FilePath : CDCtx.UserStylesheets) {
    auto LinkNode = llvm::make_unique<TagNode>(HTMLTag::TAG_LINK);
    LinkNode->Attributes.try_emplace("rel", "stylesheet");
    SmallString<128> StylesheetPath = computeRelativePath("", InfoPath);
    llvm::sys::path::append(StylesheetPath,
                            llvm::sys::path::filename(FilePath));
    // Paths in HTML must be in posix-style
    llvm::sys::path::native(StylesheetPath, llvm::sys::path::Style::posix);
    LinkNode->Attributes.try_emplace("href", StylesheetPath);
    Out.emplace_back(std::move(LinkNode));
  }
  return Out;
}

static std::vector<std::unique_ptr<TagNode>>
genJsScriptsHTML(StringRef InfoPath, const ClangDocContext &CDCtx) {
  std::vector<std::unique_ptr<TagNode>> Out;
  for (const auto &FilePath : CDCtx.JsScripts) {
    auto ScriptNode = llvm::make_unique<TagNode>(HTMLTag::TAG_SCRIPT);
    SmallString<128> ScriptPath = computeRelativePath("", InfoPath);
    llvm::sys::path::append(ScriptPath, llvm::sys::path::filename(FilePath));
    // Paths in HTML must be in posix-style
    llvm::sys::path::native(ScriptPath, llvm::sys::path::Style::posix);
    ScriptNode->Attributes.try_emplace("src", ScriptPath);
    Out.emplace_back(std::move(ScriptNode));
  }
  return Out;
}

static std::unique_ptr<TagNode> genLink(const Twine &Text, const Twine &Link) {
  auto LinkNode = llvm::make_unique<TagNode>(HTMLTag::TAG_A, Text);
  LinkNode->Attributes.try_emplace("href", Link.str());
  return LinkNode;
}

static std::unique_ptr<HTMLNode>
genTypeReference(const Reference &Type, StringRef CurrentDirectory,
                 llvm::Optional<StringRef> JumpToSection = None) {
  if (Type.Path.empty() && !Type.IsInGlobalNamespace) {
    if (!JumpToSection)
      return llvm::make_unique<TextNode>(Type.Name);
    else
      return genLink(Type.Name, "#" + JumpToSection.getValue());
  }
  llvm::SmallString<128> Path =
      computeRelativePath(Type.Path, CurrentDirectory);
  llvm::sys::path::append(Path, Type.Name + ".html");
  // Paths in HTML must be in posix-style
  llvm::sys::path::native(Path, llvm::sys::path::Style::posix);
  if (JumpToSection)
    Path += ("#" + JumpToSection.getValue()).str();
  return genLink(Type.Name, Path);
}

static std::vector<std::unique_ptr<HTMLNode>>
genReferenceList(const llvm::SmallVectorImpl<Reference> &Refs,
                 const StringRef &CurrentDirectory) {
  std::vector<std::unique_ptr<HTMLNode>> Out;
  for (const auto &R : Refs) {
    if (&R != Refs.begin())
      Out.emplace_back(llvm::make_unique<TextNode>(", "));
    Out.emplace_back(genTypeReference(R, CurrentDirectory));
  }
  return Out;
}

static std::vector<std::unique_ptr<TagNode>> genHTML(const EnumInfo &I);
static std::vector<std::unique_ptr<TagNode>> genHTML(const FunctionInfo &I,
                                                     StringRef ParentInfoDir);

static std::vector<std::unique_ptr<TagNode>>
genEnumsBlock(const std::vector<EnumInfo> &Enums) {
  if (Enums.empty())
    return {};

  std::vector<std::unique_ptr<TagNode>> Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H2, "Enums"));
  Out.back()->Attributes.try_emplace("id", "Enums");
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_DIV));
  auto &DivBody = Out.back();
  for (const auto &E : Enums) {
    std::vector<std::unique_ptr<TagNode>> Nodes = genHTML(E);
    AppendVector(std::move(Nodes), DivBody->Children);
  }
  return Out;
}

static std::unique_ptr<TagNode>
genEnumMembersBlock(const llvm::SmallVector<SmallString<16>, 4> &Members) {
  if (Members.empty())
    return nullptr;

  auto List = llvm::make_unique<TagNode>(HTMLTag::TAG_UL);
  for (const auto &M : Members)
    List->Children.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_LI, M));
  return List;
}

static std::vector<std::unique_ptr<TagNode>>
genFunctionsBlock(const std::vector<FunctionInfo> &Functions,
                  StringRef ParentInfoDir) {
  if (Functions.empty())
    return {};

  std::vector<std::unique_ptr<TagNode>> Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H2, "Functions"));
  Out.back()->Attributes.try_emplace("id", "Functions");
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_DIV));
  auto &DivBody = Out.back();
  for (const auto &F : Functions) {
    std::vector<std::unique_ptr<TagNode>> Nodes = genHTML(F, ParentInfoDir);
    AppendVector(std::move(Nodes), DivBody->Children);
  }
  return Out;
}

static std::vector<std::unique_ptr<TagNode>>
genRecordMembersBlock(const llvm::SmallVector<MemberTypeInfo, 4> &Members,
                      StringRef ParentInfoDir) {
  if (Members.empty())
    return {};

  std::vector<std::unique_ptr<TagNode>> Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H2, "Members"));
  Out.back()->Attributes.try_emplace("id", "Members");
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_UL));
  auto &ULBody = Out.back();
  for (const auto &M : Members) {
    std::string Access = getAccess(M.Access);
    if (Access != "")
      Access = Access + " ";
    auto LIBody = llvm::make_unique<TagNode>(HTMLTag::TAG_LI);
    LIBody->Children.emplace_back(llvm::make_unique<TextNode>(Access));
    LIBody->Children.emplace_back(genTypeReference(M.Type, ParentInfoDir));
    LIBody->Children.emplace_back(llvm::make_unique<TextNode>(" " + M.Name));
    ULBody->Children.emplace_back(std::move(LIBody));
  }
  return Out;
}

static std::vector<std::unique_ptr<TagNode>>
genReferencesBlock(const std::vector<Reference> &References,
                   llvm::StringRef Title) {
  if (References.empty())
    return {};

  std::vector<std::unique_ptr<TagNode>> Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H2, Title));
  Out.back()->Attributes.try_emplace("id", Title);
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_UL));
  auto &ULBody = Out.back();
  for (const auto &R : References)
    ULBody->Children.emplace_back(
        llvm::make_unique<TagNode>(HTMLTag::TAG_LI, R.Name));
  return Out;
}

static std::unique_ptr<TagNode> writeFileDefinition(const Location &L) {
  return llvm::make_unique<TagNode>(
      HTMLTag::TAG_P,
      "Defined at line " + std::to_string(L.LineNumber) + " of " + L.Filename);
}

static std::vector<std::unique_ptr<TagNode>>
genCommonFileNodes(StringRef Title, StringRef InfoPath,
                   const ClangDocContext &CDCtx) {
  std::vector<std::unique_ptr<TagNode>> Out;
  auto MetaNode = llvm::make_unique<TagNode>(HTMLTag::TAG_META);
  MetaNode->Attributes.try_emplace("charset", "utf-8");
  Out.emplace_back(std::move(MetaNode));
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_TITLE, Title));
  std::vector<std::unique_ptr<TagNode>> StylesheetsNodes =
      genStylesheetsHTML(InfoPath, CDCtx);
  AppendVector(std::move(StylesheetsNodes), Out);
  std::vector<std::unique_ptr<TagNode>> JsNodes =
      genJsScriptsHTML(InfoPath, CDCtx);
  AppendVector(std::move(JsNodes), Out);
  // An empty <div> is generated but the index will be then rendered here
  auto IndexNode = llvm::make_unique<TagNode>(HTMLTag::TAG_DIV);
  IndexNode->Attributes.try_emplace("id", "index");
  IndexNode->Attributes.try_emplace("path", InfoPath);
  Out.emplace_back(std::move(IndexNode));
  return Out;
}

template <typename T,
          typename = std::enable_if<std::is_base_of<T, Info>::value>>
static Index genInfoIndexItem(const std::vector<T> &Infos, StringRef Title) {
  Index Idx(Title, Title);
  for (const auto &C : Infos)
    Idx.Children.emplace_back(C.extractName(),
                              llvm::toHex(llvm::toStringRef(C.USR)));
  return Idx;
}

static std::vector<std::unique_ptr<TagNode>> genHTML(const Index &Index,
                                                     StringRef InfoPath) {
  std::vector<std::unique_ptr<TagNode>> Out;
  if (!Index.Name.empty()) {
    Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_SPAN));
    auto &SpanBody = Out.back();
    if (!Index.JumpToSection)
      SpanBody->Children.emplace_back(genTypeReference(Index, InfoPath));
    else
      SpanBody->Children.emplace_back(genTypeReference(
          Index, InfoPath, StringRef{Index.JumpToSection.getValue()}));
  }
  if (Index.Children.empty())
    return Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_UL));
  const auto &UlBody = Out.back();
  for (const auto &C : Index.Children) {
    auto LiBody = llvm::make_unique<TagNode>(HTMLTag::TAG_LI);
    std::vector<std::unique_ptr<TagNode>> Nodes = genHTML(C, InfoPath);
    AppendVector(std::move(Nodes), LiBody->Children);
    UlBody->Children.emplace_back(std::move(LiBody));
  }
  return Out;
}

static std::unique_ptr<HTMLNode> genHTML(const CommentInfo &I) {
  if (I.Kind == "FullComment") {
    auto FullComment = llvm::make_unique<TagNode>(HTMLTag::TAG_DIV);
    for (const auto &Child : I.Children) {
      std::unique_ptr<HTMLNode> Node = genHTML(*Child);
      if (Node)
        FullComment->Children.emplace_back(std::move(Node));
    }
    return std::move(FullComment);
  } else if (I.Kind == "ParagraphComment") {
    auto ParagraphComment = llvm::make_unique<TagNode>(HTMLTag::TAG_P);
    for (const auto &Child : I.Children) {
      std::unique_ptr<HTMLNode> Node = genHTML(*Child);
      if (Node)
        ParagraphComment->Children.emplace_back(std::move(Node));
    }
    if (ParagraphComment->Children.empty())
      return nullptr;
    return std::move(ParagraphComment);
  } else if (I.Kind == "TextComment") {
    if (I.Text == "")
      return nullptr;
    return llvm::make_unique<TextNode>(I.Text);
  }
  return nullptr;
}

static std::unique_ptr<TagNode> genHTML(const std::vector<CommentInfo> &C) {
  auto CommentBlock = llvm::make_unique<TagNode>(HTMLTag::TAG_DIV);
  for (const auto &Child : C) {
    if (std::unique_ptr<HTMLNode> Node = genHTML(Child))
      CommentBlock->Children.emplace_back(std::move(Node));
  }
  return CommentBlock;
}

static std::vector<std::unique_ptr<TagNode>> genHTML(const EnumInfo &I) {
  std::vector<std::unique_ptr<TagNode>> Out;
  std::string EnumType;
  if (I.Scoped)
    EnumType = "enum class ";
  else
    EnumType = "enum ";

  Out.emplace_back(
      llvm::make_unique<TagNode>(HTMLTag::TAG_H3, EnumType + I.Name));
  Out.back()->Attributes.try_emplace("id",
                                     llvm::toHex(llvm::toStringRef(I.USR)));

  std::unique_ptr<TagNode> Node = genEnumMembersBlock(I.Members);
  if (Node)
    Out.emplace_back(std::move(Node));

  if (I.DefLoc)
    Out.emplace_back(writeFileDefinition(I.DefLoc.getValue()));

  std::string Description;
  if (!I.Description.empty())
    Out.emplace_back(genHTML(I.Description));

  return Out;
}

static std::vector<std::unique_ptr<TagNode>> genHTML(const FunctionInfo &I,
                                                     StringRef ParentInfoDir) {
  std::vector<std::unique_ptr<TagNode>> Out;
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H3, I.Name));
  // USR is used as id for functions instead of name to disambiguate function
  // overloads.
  Out.back()->Attributes.try_emplace("id",
                                     llvm::toHex(llvm::toStringRef(I.USR)));

  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_P));
  auto &FunctionHeader = Out.back();

  std::string Access = getAccess(I.Access);
  if (Access != "")
    FunctionHeader->Children.emplace_back(
        llvm::make_unique<TextNode>(Access + " "));
  if (I.ReturnType.Type.Name != "") {
    FunctionHeader->Children.emplace_back(
        genTypeReference(I.ReturnType.Type, ParentInfoDir));
    FunctionHeader->Children.emplace_back(llvm::make_unique<TextNode>(" "));
  }
  FunctionHeader->Children.emplace_back(
      llvm::make_unique<TextNode>(I.Name + "("));

  for (const auto &P : I.Params) {
    if (&P != I.Params.begin())
      FunctionHeader->Children.emplace_back(llvm::make_unique<TextNode>(", "));
    FunctionHeader->Children.emplace_back(
        genTypeReference(P.Type, ParentInfoDir));
    FunctionHeader->Children.emplace_back(
        llvm::make_unique<TextNode>(" " + P.Name));
  }
  FunctionHeader->Children.emplace_back(llvm::make_unique<TextNode>(")"));

  if (I.DefLoc)
    Out.emplace_back(writeFileDefinition(I.DefLoc.getValue()));

  std::string Description;
  if (!I.Description.empty())
    Out.emplace_back(genHTML(I.Description));

  return Out;
}

static std::vector<std::unique_ptr<TagNode>>
genHTML(const NamespaceInfo &I, Index &InfoIndex, std::string &InfoTitle) {
  std::vector<std::unique_ptr<TagNode>> Out;
  if (I.Name.str() == "")
    InfoTitle = "Global Namespace";
  else
    InfoTitle = ("namespace " + I.Name).str();

  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H1, InfoTitle));

  std::string Description;
  if (!I.Description.empty())
    Out.emplace_back(genHTML(I.Description));

  std::vector<std::unique_ptr<TagNode>> ChildNamespaces =
      genReferencesBlock(I.ChildNamespaces, "Namespaces");
  AppendVector(std::move(ChildNamespaces), Out);
  std::vector<std::unique_ptr<TagNode>> ChildRecords =
      genReferencesBlock(I.ChildRecords, "Records");
  AppendVector(std::move(ChildRecords), Out);

  std::vector<std::unique_ptr<TagNode>> ChildFunctions =
      genFunctionsBlock(I.ChildFunctions, I.Path);
  AppendVector(std::move(ChildFunctions), Out);
  std::vector<std::unique_ptr<TagNode>> ChildEnums =
      genEnumsBlock(I.ChildEnums);
  AppendVector(std::move(ChildEnums), Out);

  if (!I.ChildNamespaces.empty())
    InfoIndex.Children.emplace_back("Namespaces", "Namespaces");
  if (!I.ChildRecords.empty())
    InfoIndex.Children.emplace_back("Records", "Records");
  if (!I.ChildFunctions.empty())
    InfoIndex.Children.emplace_back(
        genInfoIndexItem(I.ChildFunctions, "Functions"));
  if (!I.ChildEnums.empty())
    InfoIndex.Children.emplace_back(genInfoIndexItem(I.ChildEnums, "Enums"));

  return Out;
}

static std::vector<std::unique_ptr<TagNode>>
genHTML(const RecordInfo &I, Index &InfoIndex, std::string &InfoTitle) {
  std::vector<std::unique_ptr<TagNode>> Out;
  InfoTitle = (getTagType(I.TagType) + " " + I.Name).str();
  Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_H1, InfoTitle));

  if (I.DefLoc)
    Out.emplace_back(writeFileDefinition(I.DefLoc.getValue()));

  std::string Description;
  if (!I.Description.empty())
    Out.emplace_back(genHTML(I.Description));

  std::vector<std::unique_ptr<HTMLNode>> Parents =
      genReferenceList(I.Parents, I.Path);
  std::vector<std::unique_ptr<HTMLNode>> VParents =
      genReferenceList(I.VirtualParents, I.Path);
  if (!Parents.empty() || !VParents.empty()) {
    Out.emplace_back(llvm::make_unique<TagNode>(HTMLTag::TAG_P));
    auto &PBody = Out.back();
    PBody->Children.emplace_back(llvm::make_unique<TextNode>("Inherits from "));
    if (Parents.empty())
      AppendVector(std::move(VParents), PBody->Children);
    else if (VParents.empty())
      AppendVector(std::move(Parents), PBody->Children);
    else {
      AppendVector(std::move(Parents), PBody->Children);
      PBody->Children.emplace_back(llvm::make_unique<TextNode>(", "));
      AppendVector(std::move(VParents), PBody->Children);
    }
  }

  std::vector<std::unique_ptr<TagNode>> Members =
      genRecordMembersBlock(I.Members, I.Path);
  AppendVector(std::move(Members), Out);
  std::vector<std::unique_ptr<TagNode>> ChildRecords =
      genReferencesBlock(I.ChildRecords, "Records");
  AppendVector(std::move(ChildRecords), Out);

  std::vector<std::unique_ptr<TagNode>> ChildFunctions =
      genFunctionsBlock(I.ChildFunctions, I.Path);
  AppendVector(std::move(ChildFunctions), Out);
  std::vector<std::unique_ptr<TagNode>> ChildEnums =
      genEnumsBlock(I.ChildEnums);
  AppendVector(std::move(ChildEnums), Out);

  if (!I.Members.empty())
    InfoIndex.Children.emplace_back("Members", "Members");
  if (!I.ChildRecords.empty())
    InfoIndex.Children.emplace_back("Records", "Records");
  if (!I.ChildFunctions.empty())
    InfoIndex.Children.emplace_back(
        genInfoIndexItem(I.ChildFunctions, "Functions"));
  if (!I.ChildEnums.empty())
    InfoIndex.Children.emplace_back(genInfoIndexItem(I.ChildEnums, "Enums"));

  return Out;
}

/// Generator for HTML documentation.
class HTMLGenerator : public Generator {
public:
  static const char *Format;

  llvm::Error generateDocForInfo(Info *I, llvm::raw_ostream &OS,
                                 const ClangDocContext &CDCtx) override;
  bool createResources(ClangDocContext &CDCtx) override;
};

const char *HTMLGenerator::Format = "html";

llvm::Error HTMLGenerator::generateDocForInfo(Info *I, llvm::raw_ostream &OS,
                                              const ClangDocContext &CDCtx) {
  HTMLFile F;
  std::string InfoTitle;
  auto MainContentNode = llvm::make_unique<TagNode>(HTMLTag::TAG_DIV);
  Index InfoIndex;
  switch (I->IT) {
  case InfoType::IT_namespace: {
    std::vector<std::unique_ptr<TagNode>> Nodes = genHTML(
        *static_cast<clang::doc::NamespaceInfo *>(I), InfoIndex, InfoTitle);
    AppendVector(std::move(Nodes), MainContentNode->Children);
    break;
  }
  case InfoType::IT_record: {
    std::vector<std::unique_ptr<TagNode>> Nodes = genHTML(
        *static_cast<clang::doc::RecordInfo *>(I), InfoIndex, InfoTitle);
    AppendVector(std::move(Nodes), MainContentNode->Children);
    break;
  }
  case InfoType::IT_enum: {
    std::vector<std::unique_ptr<TagNode>> Nodes =
        genHTML(*static_cast<clang::doc::EnumInfo *>(I));
    AppendVector(std::move(Nodes), MainContentNode->Children);
    break;
  }
  case InfoType::IT_function: {
    std::vector<std::unique_ptr<TagNode>> Nodes =
        genHTML(*static_cast<clang::doc::FunctionInfo *>(I), "");
    AppendVector(std::move(Nodes), MainContentNode->Children);
    break;
  }
  case InfoType::IT_default:
    return llvm::make_error<llvm::StringError>("Unexpected info type.\n",
                                               llvm::inconvertibleErrorCode());
  }

  std::vector<std::unique_ptr<TagNode>> BasicNodes =
      genCommonFileNodes(InfoTitle, I->Path, CDCtx);
  AppendVector(std::move(BasicNodes), F.Children);
  std::vector<std::unique_ptr<TagNode>> InfoIndexHTML =
      genHTML(InfoIndex, I->Path);
  AppendVector(std::move(InfoIndexHTML), F.Children);
  F.Children.emplace_back(std::move(MainContentNode));
  F.Render(OS);

  return llvm::Error::success();
}

static std::string getRefType(InfoType IT) {
  switch (IT) {
  case InfoType::IT_default:
    return "default";
  case InfoType::IT_namespace:
    return "namespace";
  case InfoType::IT_record:
    return "record";
  case InfoType::IT_function:
    return "function";
  case InfoType::IT_enum:
    return "enum";
  }
  llvm_unreachable("Unknown InfoType");
}

static bool SerializeIndex(ClangDocContext &CDCtx) {
  std::error_code OK;
  std::error_code FileErr;
  llvm::SmallString<128> FilePath;
  llvm::sys::path::native(CDCtx.OutDirectory, FilePath);
  llvm::sys::path::append(FilePath, "index_json.js");
  llvm::raw_fd_ostream OS(FilePath, FileErr, llvm::sys::fs::F_None);
  if (FileErr != OK) {
    llvm::errs() << "Error creating index file: " << FileErr.message() << "\n";
    return false;
  }
  CDCtx.Idx.sort();
  llvm::json::OStream J(OS, 2);
  std::function<void(Index)> IndexToJSON = [&](Index I) {
    J.object([&] {
      J.attribute("USR", toHex(llvm::toStringRef(I.USR)));
      J.attribute("Name", I.Name);
      J.attribute("RefType", getRefType(I.RefType));
      J.attribute("Path", I.Path);
      J.attributeArray("Children", [&] {
        for (const Index &C : I.Children)
          IndexToJSON(C);
      });
    });
  };
  OS << "var JsonIndex = `\n";
  IndexToJSON(CDCtx.Idx);
  OS << "`;\n";
  return true;
}

static bool CopyFile(StringRef FilePath, StringRef OutDirectory) {
  llvm::SmallString<128> PathWrite;
  llvm::sys::path::native(OutDirectory, PathWrite);
  llvm::sys::path::append(PathWrite, llvm::sys::path::filename(FilePath));
  llvm::SmallString<128> PathRead;
  llvm::sys::path::native(FilePath, PathRead);
  std::error_code OK;
  std::error_code FileErr = llvm::sys::fs::copy_file(PathRead, PathWrite);
  if (FileErr != OK) {
    llvm::errs() << "Error creating file "
                 << llvm::sys::path::filename(FilePath) << ": "
                 << FileErr.message() << "\n";
    return false;
  }
  return true;
}

bool HTMLGenerator::createResources(ClangDocContext &CDCtx) {
  if (!SerializeIndex(CDCtx))
    return false;
  for (const auto &FilePath : CDCtx.UserStylesheets)
    if (!CopyFile(FilePath, CDCtx.OutDirectory))
      return false;
  for (const auto &FilePath : CDCtx.FilesToCopy)
    if (!CopyFile(FilePath, CDCtx.OutDirectory))
      return false;
  return true;
}

static GeneratorRegistry::Add<HTMLGenerator> HTML(HTMLGenerator::Format,
                                                  "Generator for HTML output.");

// This anchor is used to force the linker to link in the generated object
// file and thus register the generator.
volatile int HTMLGeneratorAnchorSource = 0;

} // namespace doc
} // namespace clang