//===-- FileSystem.h --------------------------------------------*- 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
//
//===----------------------------------------------------------------------===//

#ifndef LLDB_HOST_FILESYSTEM_H
#define LLDB_HOST_FILESYSTEM_H

#include "lldb/Host/File.h"
#include "lldb/Utility/DataBuffer.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/LLDBAssert.h"
#include "lldb/Utility/Status.h"
#include "lldb/Utility/TildeExpressionResolver.h"

#include "llvm/Support/Chrono.h"
#include "llvm/Support/VirtualFileSystem.h"

#include "lldb/lldb-types.h"

#include <cstdint>
#include <cstdio>
#include <optional>
#include <sys/stat.h>

namespace lldb_private {
class FileSystem {
public:
  static const char *DEV_NULL;
  static const char *PATH_CONVERSION_ERROR;

  FileSystem()
      : m_fs(llvm::vfs::getRealFileSystem()),
        m_tilde_resolver(std::make_unique<StandardTildeExpressionResolver>()) {}
  FileSystem(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs)
      : m_fs(std::move(fs)),
        m_tilde_resolver(std::make_unique<StandardTildeExpressionResolver>()) {}
  FileSystem(std::unique_ptr<TildeExpressionResolver> tilde_resolver)
      : m_fs(llvm::vfs::getRealFileSystem()),
        m_tilde_resolver(std::move(tilde_resolver)) {}

  FileSystem(const FileSystem &fs) = delete;
  FileSystem &operator=(const FileSystem &fs) = delete;

  static FileSystem &Instance();

  template <class... T> static void Initialize(T &&...t) {
    lldbassert(!InstanceImpl() && "Already initialized.");
    InstanceImpl().emplace(std::forward<T>(t)...);
  }
  static void Terminate();

  Status Symlink(const FileSpec &src, const FileSpec &dst);
  Status Readlink(const FileSpec &src, FileSpec &dst);

  Status ResolveSymbolicLink(const FileSpec &src, FileSpec &dst);

  /// Wraps ::fopen in a platform-independent way.
  FILE *Fopen(const char *path, const char *mode);

  /// Wraps ::open in a platform-independent way.
  int Open(const char *path, int flags, int mode = 0600);

  llvm::Expected<std::unique_ptr<File>>
  Open(const FileSpec &file_spec, File::OpenOptions options,
       uint32_t permissions = lldb::eFilePermissionsFileDefault,
       bool should_close_fd = true);

  /// Get a directory iterator.
  /// \{
  llvm::vfs::directory_iterator DirBegin(const FileSpec &file_spec,
                                         std::error_code &ec);
  llvm::vfs::directory_iterator DirBegin(const llvm::Twine &dir,
                                         std::error_code &ec);
  /// \}

  /// Returns the Status object for the given file.
  /// \{
  llvm::ErrorOr<llvm::vfs::Status> GetStatus(const FileSpec &file_spec) const;
  llvm::ErrorOr<llvm::vfs::Status> GetStatus(const llvm::Twine &path) const;
  /// \}

  /// Returns the modification time of the given file.
  /// \{
  llvm::sys::TimePoint<> GetModificationTime(const FileSpec &file_spec) const;
  llvm::sys::TimePoint<> GetModificationTime(const llvm::Twine &path) const;
  /// \}

  /// Returns the on-disk size of the given file in bytes.
  /// \{
  uint64_t GetByteSize(const FileSpec &file_spec) const;
  uint64_t GetByteSize(const llvm::Twine &path) const;
  /// \}

  /// Return the current permissions of the given file.
  ///
  /// Returns a bitmask for the current permissions of the file (zero or more
  /// of the permission bits defined in File::Permissions).
  /// \{
  uint32_t GetPermissions(const FileSpec &file_spec) const;
  uint32_t GetPermissions(const llvm::Twine &path) const;
  uint32_t GetPermissions(const FileSpec &file_spec, std::error_code &ec) const;
  uint32_t GetPermissions(const llvm::Twine &path, std::error_code &ec) const;
  /// \}

  /// Returns whether the given file exists.
  /// \{
  bool Exists(const FileSpec &file_spec) const;
  bool Exists(const llvm::Twine &path) const;
  /// \}

  /// Returns whether the given file is readable.
  /// \{
  bool Readable(const FileSpec &file_spec) const;
  bool Readable(const llvm::Twine &path) const;
  /// \}

  /// Returns whether the given path is a directory.
  /// \{
  bool IsDirectory(const FileSpec &file_spec) const;
  bool IsDirectory(const llvm::Twine &path) const;
  /// \}

  /// Returns whether the given path is local to the file system.
  /// \{
  bool IsLocal(const FileSpec &file_spec) const;
  bool IsLocal(const llvm::Twine &path) const;
  /// \}

  /// Make the given file path absolute.
  /// \{
  std::error_code MakeAbsolute(llvm::SmallVectorImpl<char> &path) const;
  std::error_code MakeAbsolute(FileSpec &file_spec) const;
  /// \}

  /// Resolve path to make it canonical.
  /// \{
  void Resolve(llvm::SmallVectorImpl<char> &path);
  void Resolve(FileSpec &file_spec);
  /// \}

  /// Remove a single file.
  ///
  /// The path must specify a file and not a directory.
  /// \{
  Status RemoveFile(const FileSpec &file_spec);
  Status RemoveFile(const llvm::Twine &path);
  /// \}

  //// Create memory buffer from path.
  /// \{
  std::shared_ptr<DataBuffer> CreateDataBuffer(const llvm::Twine &path,
                                               uint64_t size = 0,
                                               uint64_t offset = 0);
  std::shared_ptr<DataBuffer> CreateDataBuffer(const FileSpec &file_spec,
                                               uint64_t size = 0,
                                               uint64_t offset = 0);
  std::shared_ptr<WritableDataBuffer>
  CreateWritableDataBuffer(const llvm::Twine &path, uint64_t size = 0,
                           uint64_t offset = 0);
  std::shared_ptr<WritableDataBuffer>
  CreateWritableDataBuffer(const FileSpec &file_spec, uint64_t size = 0,
                           uint64_t offset = 0);
  /// \}

  /// Call into the Host to see if it can help find the file.
  bool ResolveExecutableLocation(FileSpec &file_spec);

  /// Get the user home directory.
  bool GetHomeDirectory(llvm::SmallVectorImpl<char> &path) const;
  bool GetHomeDirectory(FileSpec &file_spec) const;

  enum EnumerateDirectoryResult {
    /// Enumerate next entry in the current directory.
    eEnumerateDirectoryResultNext,
    /// Recurse into the current entry if it is a directory or symlink, or next
    /// if not.
    eEnumerateDirectoryResultEnter,
    /// Stop directory enumerations at any level.
    eEnumerateDirectoryResultQuit
  };

  typedef EnumerateDirectoryResult (*EnumerateDirectoryCallbackType)(
      void *baton, llvm::sys::fs::file_type file_type, llvm::StringRef);

  typedef std::function<EnumerateDirectoryResult(
      llvm::sys::fs::file_type file_type, llvm::StringRef)>
      DirectoryCallback;

  void EnumerateDirectory(llvm::Twine path, bool find_directories,
                          bool find_files, bool find_other,
                          EnumerateDirectoryCallbackType callback,
                          void *callback_baton);

  std::error_code GetRealPath(const llvm::Twine &path,
                              llvm::SmallVectorImpl<char> &output) const;

  llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> GetVirtualFileSystem() {
    return m_fs;
  }

  void SetHomeDirectory(std::string home_directory);

private:
  static std::optional<FileSystem> &InstanceImpl();
  llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> m_fs;
  std::unique_ptr<TildeExpressionResolver> m_tilde_resolver;
  std::string m_home_directory;
};
} // namespace lldb_private

#endif