//===--- APINotesManager.cpp - Manage API Notes Files ---------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements the APINotesManager class.
//
//===----------------------------------------------------------------------===//

#include "clang/APINotes/APINotesManager.h"
#include "clang/APINotes/APINotesOptions.h"
#include "clang/APINotes/APINotesReader.h"
#include "clang/APINotes/APINotesYAMLCompiler.h"
#include "clang/Basic/DiagnosticIDs.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/SourceMgrAdapter.h"
#include "clang/Basic/Version.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/PrettyStackTrace.h"
#include <sys/stat.h>

using namespace clang;
using namespace api_notes;

#define DEBUG_TYPE "API Notes"
STATISTIC(NumHeaderAPINotes,
          "non-framework API notes files loaded");
STATISTIC(NumPublicFrameworkAPINotes,
          "framework public API notes loaded");
STATISTIC(NumPrivateFrameworkAPINotes,
          "framework private API notes loaded");
STATISTIC(NumFrameworksSearched,
          "frameworks searched");
STATISTIC(NumDirectoriesSearched,
          "header directories searched");
STATISTIC(NumDirectoryCacheHits,
          "directory cache hits");

namespace {
  /// Prints two successive strings, which much be kept alive as long as the
  /// PrettyStackTrace entry.
  class PrettyStackTraceDoubleString : public llvm::PrettyStackTraceEntry {
    StringRef First, Second;
  public:
    PrettyStackTraceDoubleString(StringRef first, StringRef second)
        : First(first), Second(second) {}
    void print(raw_ostream &OS) const override {
      OS << First << Second;
    }
  };
}

APINotesManager::APINotesManager(SourceManager &sourceMgr,
                                 const LangOptions &langOpts)
  : SourceMgr(sourceMgr), ImplicitAPINotes(langOpts.APINotes) { }

APINotesManager::~APINotesManager() {
  // Free the API notes readers.
  for (const auto &entry : Readers) {
    if (auto reader = entry.second.dyn_cast<APINotesReader *>()) {
      delete reader;
    }
  }

  delete CurrentModuleReaders[0];
  delete CurrentModuleReaders[1];
}

std::unique_ptr<APINotesReader>
APINotesManager::loadAPINotes(const FileEntry *apiNotesFile) {
  PrettyStackTraceDoubleString trace("Loading API notes from ",
                                     apiNotesFile->getName());

  // If the API notes file is already in the binary form, load it directly.
  StringRef apiNotesFileName = apiNotesFile->getName();
  StringRef apiNotesFileExt = llvm::sys::path::extension(apiNotesFileName);
  if (!apiNotesFileExt.empty() &&
      apiNotesFileExt.substr(1) == BINARY_APINOTES_EXTENSION) {
    auto compiledFileID = SourceMgr.createFileID(apiNotesFile, SourceLocation(), SrcMgr::C_User);

    // Load the file.
    auto buffer = SourceMgr.getBuffer(compiledFileID, SourceLocation());
    if (!buffer) return nullptr;

    // Load the binary form.
    return APINotesReader::getUnmanaged(buffer, SwiftVersion);
  }

  // Open the source file.
  auto sourceFileID = SourceMgr.createFileID(apiNotesFile, SourceLocation(), SrcMgr::C_User);
  auto sourceBuffer = SourceMgr.getBuffer(sourceFileID, SourceLocation());
  if (!sourceBuffer) return nullptr;

  // Compile the API notes source into a buffer.
  // FIXME: Either propagate OSType through or, better yet, improve the binary
  // APINotes format to maintain complete availability information.
  // FIXME: We don't even really need to go through the binary format at all;
  // we're just going to immediately deserialize it again.
  llvm::SmallVector<char, 1024> apiNotesBuffer;
  std::unique_ptr<llvm::MemoryBuffer> compiledBuffer;
  {
    SourceMgrAdapter srcMgrAdapter(SourceMgr, SourceMgr.getDiagnostics(),
                                   diag::err_apinotes_message,
                                   diag::warn_apinotes_message,
                                   diag::note_apinotes_message,
                                   apiNotesFile);
    llvm::raw_svector_ostream OS(apiNotesBuffer);
    if (api_notes::compileAPINotes(sourceBuffer->getBuffer(),
                                   SourceMgr.getFileEntryForID(sourceFileID),
                                   OS,
                                   api_notes::OSType::Absent,
                                   srcMgrAdapter.getDiagHandler(),
                                   srcMgrAdapter.getDiagContext()))
      return nullptr;

    // Make a copy of the compiled form into the buffer.
    compiledBuffer = llvm::MemoryBuffer::getMemBufferCopy(
               StringRef(apiNotesBuffer.data(), apiNotesBuffer.size()));
  }

  // Load the binary form we just compiled.
  auto reader = APINotesReader::get(std::move(compiledBuffer), SwiftVersion);
  assert(reader && "Could not load the API notes we just generated?");
  return reader;
}

bool APINotesManager::loadAPINotes(const DirectoryEntry *HeaderDir,
                                   const FileEntry *APINotesFile) {
  assert(Readers.find(HeaderDir) == Readers.end());
  if (auto reader = loadAPINotes(APINotesFile)) {
    Readers[HeaderDir] = reader.release();
    return false;
  }

  Readers[HeaderDir] = nullptr;
  return true;
}

const FileEntry *APINotesManager::findAPINotesFile(const DirectoryEntry *directory,
                                                   StringRef basename,
                                                   bool wantPublic) {
  FileManager &fileMgr = SourceMgr.getFileManager();

  llvm::SmallString<128> path;
  path += directory->getName();

  unsigned pathLen = path.size();

  StringRef basenameSuffix = "";
  if (!wantPublic) basenameSuffix = "_private";

  // Look for a binary API notes file.
  llvm::sys::path::append(path, 
    llvm::Twine(basename) + basenameSuffix + "." + BINARY_APINOTES_EXTENSION);
  if (const FileEntry *binaryFile = fileMgr.getFile(path))
    return binaryFile;

  // Go back to the original path.
  path.resize(pathLen);

  // Look for the source API notes file.
  llvm::sys::path::append(path, 
    llvm::Twine(basename) + basenameSuffix + "." + SOURCE_APINOTES_EXTENSION);
  return fileMgr.getFile(path);
}

const DirectoryEntry *APINotesManager::loadFrameworkAPINotes(
                        llvm::StringRef FrameworkPath,
                        llvm::StringRef FrameworkName,
                        bool Public) {
  FileManager &FileMgr = SourceMgr.getFileManager();
  
  llvm::SmallString<128> Path;
  Path += FrameworkPath;
  unsigned FrameworkNameLength = Path.size();

  // Form the path to the APINotes file.
  llvm::sys::path::append(Path, "APINotes");
  if (Public)
    llvm::sys::path::append(Path,
                            (llvm::Twine(FrameworkName) + "."
                              + SOURCE_APINOTES_EXTENSION));
  else
    llvm::sys::path::append(Path,
                            (llvm::Twine(FrameworkName) + "_private."
                              + SOURCE_APINOTES_EXTENSION));

  // Try to open the APINotes file.
  const FileEntry *APINotesFile = FileMgr.getFile(Path);
  if (!APINotesFile)
    return nullptr;

  // Form the path to the corresponding header directory.
  Path.resize(FrameworkNameLength);
  if (Public)
    llvm::sys::path::append(Path, "Headers");
  else
    llvm::sys::path::append(Path, "PrivateHeaders");

  // Try to access the header directory.
  const DirectoryEntry *HeaderDir = FileMgr.getDirectory(Path);
  if (!HeaderDir)
    return nullptr;

  // Try to load the API notes.
  if (loadAPINotes(HeaderDir, APINotesFile))
    return nullptr;

  // Success: return the header directory.
  if (Public)
    ++NumPublicFrameworkAPINotes;
  else
    ++NumPrivateFrameworkAPINotes;
  return HeaderDir;
}

bool APINotesManager::loadCurrentModuleAPINotes(
                   const Module *module,
                   bool lookInModule,
                   ArrayRef<std::string> searchPaths) {
  assert(!CurrentModuleReaders[0] &&
         "Already loaded API notes for the current module?");

  FileManager &fileMgr = SourceMgr.getFileManager();
  auto moduleName = module->getTopLevelModuleName();

  // First, look relative to the module itself.
  if (lookInModule) {
    bool foundAny = false;
    unsigned numReaders = 0;

    // Local function to try loading an API notes file in the given directory.
    auto tryAPINotes = [&](const DirectoryEntry *dir, bool wantPublic) {
      if (auto file = findAPINotesFile(dir, moduleName, wantPublic)) {
        foundAny = true;

        // Try to load the API notes file.
        CurrentModuleReaders[numReaders] = loadAPINotes(file).release();
        if (CurrentModuleReaders[numReaders])
          ++numReaders;
      }
    };

    if (module->IsFramework) {
      // For frameworks, we search in the "Headers" or "PrivateHeaders"
      // subdirectory.
      llvm::SmallString<128> path;
      path += module->Directory->getName();
      unsigned pathLen = path.size();

      llvm::sys::path::append(path, "Headers");
      if (auto apinotesDir = fileMgr.getDirectory(path))
        tryAPINotes(apinotesDir, /*wantPublic=*/true);

      path.resize(pathLen);
      llvm::sys::path::append(path, "PrivateHeaders");
      if (auto privateAPINotesDir = fileMgr.getDirectory(path))
        tryAPINotes(privateAPINotesDir, /*wantPublic=*/false);
    } else {
      tryAPINotes(module->Directory, /*wantPublic=*/true);
      tryAPINotes(module->Directory, /*wantPublic=*/false);
    }

    if (foundAny)
      return numReaders > 0;
  }

  // Second, look for API notes for this module in the module API
  // notes search paths.
  for (const auto &searchPath : searchPaths) {
    if (auto searchDir = fileMgr.getDirectory(searchPath)) {
      if (auto file = findAPINotesFile(searchDir, moduleName)) {
        CurrentModuleReaders[0] = loadAPINotes(file).release();
        return !getCurrentModuleReaders().empty();
      }
    }
  }

  // Didn't find any API notes.
  return false;
}

llvm::SmallVector<APINotesReader *, 2> APINotesManager::findAPINotes(SourceLocation Loc) {
  llvm::SmallVector<APINotesReader *, 2> Results;

  // If there are readers for the current module, return them.
  if (!getCurrentModuleReaders().empty()) {
    Results.append(getCurrentModuleReaders().begin(), getCurrentModuleReaders().end());
    return Results;
  }

  // If we're not allowed to implicitly load API notes files, we're done.
  if (!ImplicitAPINotes) return Results;

  // If we don't have source location information, we're done.
  if (Loc.isInvalid()) return Results;

  // API notes are associated with the expansion location. Retrieve the
  // file for this location.
  SourceLocation ExpansionLoc = SourceMgr.getExpansionLoc(Loc);
  FileID ID = SourceMgr.getFileID(ExpansionLoc);
  if (ID.isInvalid()) return Results;
  const FileEntry *File = SourceMgr.getFileEntryForID(ID);
  if (!File) return Results;

  // Look for API notes in the directory corresponding to this file, or one of
  // its its parent directories.
  const DirectoryEntry *Dir = File->getDir();
  FileManager &FileMgr = SourceMgr.getFileManager();
  llvm::SetVector<const DirectoryEntry *,
                  SmallVector<const DirectoryEntry *, 4>,
                  llvm::SmallPtrSet<const DirectoryEntry *, 4>> DirsVisited;
  do {
    // Look for an API notes reader for this header search directory.
    auto Known = Readers.find(Dir);

    // If we already know the answer, chase it.
    if (Known != Readers.end()) {
      ++NumDirectoryCacheHits;

      // We've been redirected to another directory for answers. Follow it.
      if (auto OtherDir = Known->second.dyn_cast<const DirectoryEntry *>()) {
        DirsVisited.insert(Dir);
        Dir = OtherDir;
        continue;
      }

      // We have the answer.
      if (auto Reader = Known->second.dyn_cast<APINotesReader *>())
        Results.push_back(Reader);
      break;
    }

    // Look for API notes corresponding to this directory.
    StringRef Path = Dir->getName();
    if (llvm::sys::path::extension(Path) == ".framework") {
      // If this is a framework directory, check whether there are API notes
      // in the APINotes subdirectory.
      auto FrameworkName = llvm::sys::path::stem(Path);
      ++NumFrameworksSearched;

      // Look for API notes for both the public and private headers.
      const DirectoryEntry *PublicDir
        = loadFrameworkAPINotes(Path, FrameworkName, /*Public=*/true);
      const DirectoryEntry *PrivateDir
        = loadFrameworkAPINotes(Path, FrameworkName, /*Public=*/false);

      if (PublicDir || PrivateDir) {
        // We found API notes: don't ever look past the framework directory.
        Readers[Dir] = nullptr;

        // Pretend we found the result in the public or private directory,
        // as appropriate. All headers should be in one of those two places,
        // but be defensive here.
        if (!DirsVisited.empty()) {
          if (DirsVisited.back() == PublicDir) {
            DirsVisited.pop_back();
            Dir = PublicDir;
          } else if (DirsVisited.back() == PrivateDir) {
            DirsVisited.pop_back();
            Dir = PrivateDir;
          }
        }

        // Grab the result.
        if (auto Reader = Readers[Dir].dyn_cast<APINotesReader *>())
          Results.push_back(Reader);
        break;
      }
    } else {
      // Look for an APINotes file in this directory.
      llvm::SmallString<128> APINotesPath;
      APINotesPath += Dir->getName();
      llvm::sys::path::append(APINotesPath,
                              (llvm::Twine("APINotes.")
                                 + SOURCE_APINOTES_EXTENSION));

      // If there is an API notes file here, try to load it.
      ++NumDirectoriesSearched;
      if (const FileEntry *APINotesFile = FileMgr.getFile(APINotesPath)) {
        if (!loadAPINotes(Dir, APINotesFile)) {
          ++NumHeaderAPINotes;
          if (auto Reader = Readers[Dir].dyn_cast<APINotesReader *>())
            Results.push_back(Reader);
          break;
        }
      }
    }

    // We didn't find anything. Look at the parent directory.
    if (!DirsVisited.insert(Dir)) {
      Dir = 0;
      break;
    }

    StringRef ParentPath = llvm::sys::path::parent_path(Path);
    while (llvm::sys::path::stem(ParentPath) == "..") {
      ParentPath = llvm::sys::path::parent_path(ParentPath);
    }
    if (ParentPath.empty()) {
      Dir = nullptr;
    } else {
      Dir = FileMgr.getDirectory(ParentPath);
    }
  } while (Dir);

  // Path compression for all of the directories we visited, redirecting
  // them to the directory we ended on. If no API notes were found, the
  // resulting directory will be NULL, indicating no API notes.
  for (const auto Visited : DirsVisited) {
    Readers[Visited] = Dir;
  }

  return Results;
}