//===-- Reproducer.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
//
//===----------------------------------------------------------------------===//

#include "lldb/Utility/Reproducer.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/Utility/ReproducerProvider.h"
#include "lldb/Utility/Timer.h"

#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/raw_ostream.h"

using namespace lldb_private;
using namespace lldb_private::repro;
using namespace llvm;
using namespace llvm::yaml;

static llvm::Optional<bool> GetEnv(const char *var) {
  std::string val = llvm::StringRef(getenv(var)).lower();
  if (val == "0" || val == "off")
    return false;
  if (val == "1" || val == "on")
    return true;
  return {};
}

Reproducer &Reproducer::Instance() { return *InstanceImpl(); }

llvm::Error Reproducer::Initialize(ReproducerMode mode,
                                   llvm::Optional<FileSpec> root) {
  lldbassert(!InstanceImpl() && "Already initialized.");
  InstanceImpl().emplace();

  // The environment can override the capture mode.
  if (mode != ReproducerMode::Replay) {
    if (llvm::Optional<bool> override = GetEnv("LLDB_CAPTURE_REPRODUCER")) {
      if (*override)
        mode = ReproducerMode::Capture;
      else
        mode = ReproducerMode::Off;
    }
  }

  switch (mode) {
  case ReproducerMode::Capture: {
    if (!root) {
      SmallString<128> repro_dir;
      auto ec = sys::fs::createUniqueDirectory("reproducer", repro_dir);
      if (ec)
        return make_error<StringError>(
            "unable to create unique reproducer directory", ec);
      root.emplace(repro_dir);
    } else {
      auto ec = sys::fs::create_directory(root->GetPath());
      if (ec)
        return make_error<StringError>("unable to create reproducer directory",
                                       ec);
    }
    return Instance().SetCapture(root);
  } break;
  case ReproducerMode::Replay:
    return Instance().SetReplay(root, /*passive*/ false);
  case ReproducerMode::PassiveReplay:
    return Instance().SetReplay(root, /*passive*/ true);
  case ReproducerMode::Off:
    break;
  };

  return Error::success();
}

void Reproducer::Initialize() {
  llvm::cantFail(Initialize(repro::ReproducerMode::Off, llvm::None));
}

bool Reproducer::Initialized() { return InstanceImpl().operator bool(); }

void Reproducer::Terminate() {
  lldbassert(InstanceImpl() && "Already terminated.");
  InstanceImpl().reset();
}

Optional<Reproducer> &Reproducer::InstanceImpl() {
  static Optional<Reproducer> g_reproducer;
  return g_reproducer;
}

const Generator *Reproducer::GetGenerator() const {
  std::lock_guard<std::mutex> guard(m_mutex);
  if (m_generator)
    return &(*m_generator);
  return nullptr;
}

const Loader *Reproducer::GetLoader() const {
  std::lock_guard<std::mutex> guard(m_mutex);
  if (m_loader)
    return &(*m_loader);
  return nullptr;
}

Generator *Reproducer::GetGenerator() {
  std::lock_guard<std::mutex> guard(m_mutex);
  if (m_generator)
    return &(*m_generator);
  return nullptr;
}

Loader *Reproducer::GetLoader() {
  std::lock_guard<std::mutex> guard(m_mutex);
  if (m_loader)
    return &(*m_loader);
  return nullptr;
}

llvm::Error Reproducer::SetCapture(llvm::Optional<FileSpec> root) {
  std::lock_guard<std::mutex> guard(m_mutex);

  if (root && m_loader)
    return make_error<StringError>(
        "cannot generate a reproducer when replay one",
        inconvertibleErrorCode());

  if (!root) {
    m_generator.reset();
    return Error::success();
  }

  m_generator.emplace(*root);
  return Error::success();
}

llvm::Error Reproducer::SetReplay(llvm::Optional<FileSpec> root, bool passive) {
  std::lock_guard<std::mutex> guard(m_mutex);

  if (root && m_generator)
    return make_error<StringError>(
        "cannot replay a reproducer when generating one",
        inconvertibleErrorCode());

  if (!root) {
    m_loader.reset();
    return Error::success();
  }

  m_loader.emplace(*root, passive);
  if (auto e = m_loader->LoadIndex())
    return e;

  return Error::success();
}

FileSpec Reproducer::GetReproducerPath() const {
  if (auto g = GetGenerator())
    return g->GetRoot();
  if (auto l = GetLoader())
    return l->GetRoot();
  return {};
}

static FileSpec MakeAbsolute(const FileSpec &file_spec) {
  SmallString<128> path;
  file_spec.GetPath(path, false);
  llvm::sys::fs::make_absolute(path);
  return FileSpec(path, file_spec.GetPathStyle());
}

Generator::Generator(FileSpec root) : m_root(MakeAbsolute(std::move(root))) {
  GetOrCreate<repro::WorkingDirectoryProvider>();
  GetOrCreate<repro::HomeDirectoryProvider>();
}

Generator::~Generator() {
  if (!m_done) {
    if (m_auto_generate) {
      Keep();
      llvm::cantFail(Finalize(GetRoot()));
    } else {
      Discard();
    }
  }
}

ProviderBase *Generator::Register(std::unique_ptr<ProviderBase> provider) {
  std::lock_guard<std::mutex> lock(m_providers_mutex);
  std::pair<const void *, std::unique_ptr<ProviderBase>> key_value(
      provider->DynamicClassID(), std::move(provider));
  auto e = m_providers.insert(std::move(key_value));
  return e.first->getSecond().get();
}

void Generator::Keep() {
  LLDB_SCOPED_TIMER();
  assert(!m_done);
  m_done = true;

  for (auto &provider : m_providers)
    provider.second->Keep();

  AddProvidersToIndex();
}

void Generator::Discard() {
  LLDB_SCOPED_TIMER();
  assert(!m_done);
  m_done = true;

  for (auto &provider : m_providers)
    provider.second->Discard();

  llvm::sys::fs::remove_directories(m_root.GetPath());
}

void Generator::SetAutoGenerate(bool b) { m_auto_generate = b; }

bool Generator::IsAutoGenerate() const { return m_auto_generate; }

const FileSpec &Generator::GetRoot() const { return m_root; }

void Generator::AddProvidersToIndex() {
  FileSpec index = m_root;
  index.AppendPathComponent("index.yaml");

  std::error_code EC;
  auto strm = std::make_unique<raw_fd_ostream>(index.GetPath(), EC,
                                               sys::fs::OpenFlags::OF_None);
  yaml::Output yout(*strm);

  std::vector<std::string> files;
  files.reserve(m_providers.size());
  for (auto &provider : m_providers) {
    files.emplace_back(provider.second->GetFile());
  }

  yout << files;
}

Loader::Loader(FileSpec root, bool passive)
    : m_root(MakeAbsolute(std::move(root))), m_loaded(false),
      m_passive_replay(passive) {}

llvm::Error Loader::LoadIndex() {
  if (m_loaded)
    return llvm::Error::success();

  FileSpec index = m_root.CopyByAppendingPathComponent("index.yaml");

  auto error_or_file = MemoryBuffer::getFile(index.GetPath());
  if (auto err = error_or_file.getError())
    return make_error<StringError>("unable to load reproducer index", err);

  yaml::Input yin((*error_or_file)->getBuffer());
  yin >> m_files;
  if (auto err = yin.error())
    return make_error<StringError>("unable to read reproducer index", err);

  // Sort files to speed up search.
  llvm::sort(m_files);

  // Remember that we've loaded the index.
  m_loaded = true;

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

bool Loader::HasFile(StringRef file) {
  assert(m_loaded);
  auto it = std::lower_bound(m_files.begin(), m_files.end(), file.str());
  return (it != m_files.end()) && (*it == file);
}

void Verifier::Verify(
    llvm::function_ref<void(llvm::StringRef)> error_callback,
    llvm::function_ref<void(llvm::StringRef)> warning_callback,
    llvm::function_ref<void(llvm::StringRef)> note_callack) const {
  if (!m_loader) {
    error_callback("invalid loader");
    return;
  }

  FileSpec vfs_mapping = m_loader->GetFile<FileProvider::Info>();
  ErrorOr<std::unique_ptr<MemoryBuffer>> buffer =
      vfs::getRealFileSystem()->getBufferForFile(vfs_mapping.GetPath());
  if (!buffer) {
    error_callback("unable to read files: " + buffer.getError().message());
    return;
  }

  IntrusiveRefCntPtr<vfs::FileSystem> vfs = vfs::getVFSFromYAML(
      std::move(buffer.get()), nullptr, vfs_mapping.GetPath());
  if (!vfs) {
    error_callback("unable to initialize the virtual file system");
    return;
  }

  auto &redirecting_vfs = static_cast<vfs::RedirectingFileSystem &>(*vfs);
  redirecting_vfs.setFallthrough(false);

  {
    llvm::Expected<std::string> working_dir =
        GetDirectoryFrom<WorkingDirectoryProvider>(m_loader);
    if (working_dir) {
      if (!vfs->exists(*working_dir))
        warning_callback("working directory '" + *working_dir + "' not in VFS");
      vfs->setCurrentWorkingDirectory(*working_dir);
    } else {
      warning_callback("no working directory in reproducer: " +
                       toString(working_dir.takeError()));
    }
  }

  {
    llvm::Expected<std::string> home_dir =
        GetDirectoryFrom<HomeDirectoryProvider>(m_loader);
    if (home_dir) {
      if (!vfs->exists(*home_dir))
        warning_callback("home directory '" + *home_dir + "' not in VFS");
    } else {
      warning_callback("no home directory in reproducer: " +
                       toString(home_dir.takeError()));
    }
  }

  {
    Expected<std::string> symbol_files =
        m_loader->LoadBuffer<SymbolFileProvider>();
    if (symbol_files) {
      std::vector<SymbolFileProvider::Entry> entries;
      llvm::yaml::Input yin(*symbol_files);
      yin >> entries;
      for (const auto &entry : entries) {
        if (!entry.module_path.empty() && !vfs->exists(entry.module_path)) {
          warning_callback("'" + entry.module_path + "': module path for " +
                           entry.uuid + " not in VFS");
        }
        if (!entry.symbol_path.empty() && !vfs->exists(entry.symbol_path)) {
          warning_callback("'" + entry.symbol_path + "': symbol path for " +
                           entry.uuid + " not in VFS");
        }
      }
    } else {
      llvm::consumeError(symbol_files.takeError());
    }
  }

  // Missing files in the VFS are notes rather than warnings. Because the VFS
  // is a snapshot, temporary files could have been removed between when they
  // were recorded and when the reproducer was generated.
  std::vector<llvm::StringRef> roots = redirecting_vfs.getRoots();
  for (llvm::StringRef root : roots) {
    std::error_code ec;
    vfs::recursive_directory_iterator iter(*vfs, root, ec);
    vfs::recursive_directory_iterator end;
    for (; iter != end && !ec; iter.increment(ec)) {
      ErrorOr<vfs::Status> status = vfs->status(iter->path());
      if (!status)
        note_callack("'" + iter->path().str() +
                     "': " + status.getError().message());
    }
  }
}

static llvm::Error addPaths(StringRef path,
                            function_ref<void(StringRef)> callback) {
  auto buffer = llvm::MemoryBuffer::getFile(path);
  if (!buffer)
    return errorCodeToError(buffer.getError());

  SmallVector<StringRef, 0> paths;
  (*buffer)->getBuffer().split(paths, '\0');
  for (StringRef p : paths) {
    if (!p.empty() && llvm::sys::fs::exists(p))
      callback(p);
  }

  return errorCodeToError(llvm::sys::fs::remove(path));
}

llvm::Error repro::Finalize(Loader *loader) {
  if (!loader)
    return make_error<StringError>("invalid loader",
                                   llvm::inconvertibleErrorCode());

  FileSpec reproducer_root = loader->GetRoot();
  std::string files_path =
      reproducer_root.CopyByAppendingPathComponent("files.txt").GetPath();
  std::string dirs_path =
      reproducer_root.CopyByAppendingPathComponent("dirs.txt").GetPath();

  FileCollector collector(
      reproducer_root.CopyByAppendingPathComponent("root").GetPath(),
      reproducer_root.GetPath());

  if (Error e =
          addPaths(files_path, [&](StringRef p) { collector.addFile(p); }))
    return e;

  if (Error e =
          addPaths(dirs_path, [&](StringRef p) { collector.addDirectory(p); }))
    return e;

  FileSpec mapping =
      reproducer_root.CopyByAppendingPathComponent(FileProvider::Info::file);
  if (auto ec = collector.copyFiles(/*stop_on_error=*/false))
    return errorCodeToError(ec);
  collector.writeMapping(mapping.GetPath());

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

llvm::Error repro::Finalize(const FileSpec &root) {
  Loader loader(root);
  if (Error e = loader.LoadIndex())
    return e;
  return Finalize(&loader);
}