#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2021 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

#ifndef NUCLEX_STORAGE_FILESYSTEM_FILE_H
#define NUCLEX_STORAGE_FILESYSTEM_FILE_H

#include "Nuclex/Storage/Config.h"
#include "Nuclex/Storage/Blob.h"

#include <string>
#include <ctime>

// Possible additions:
//
// - GetNativePath()
//
//   Possibly useful if paths need to be passed to external tools and third-party
//   libraries, but problematic when .zip and other containers are involved.
//
//   /// <summary>Returns the path the file is stored at in the native format</summary>
//   /// <returns>The file's absolute path in the native OS format</returns>
//   public: virtual const std::string &GetNativePath() const = 0;
//
// - CloseNativeHandle()
//
//   It intuitively sounded like a good idea, but I can't think of a use for this.
//
//   When renaming or deleting files, the FileManager knows to close the handle.
//   Running out of handles should not happen and even that could be dealt with
//   by the FileManager...
//
//   /// <summary>Closes the operating system's file handle if this is a plain file</summary>
//   public: virtual void CloseNativeHandle() const = 0;
//

namespace Nuclex { namespace Storage { namespace FileSystem {

  // ------------------------------------------------------------------------------------------- //

  /// <summary>File storing binary data</summary>
  /// <remarks>
  ///   <para>
  ///     You may be used to the concept of opening files and receiving a handle. In this
  ///     case, a file is simply something you can read from and write to at will.
  ///   <para>
  ///   <para>
  ///     This may seem like a bold design choice, but in many cases (zip archives or memory
  ///     files, for example) a file handle is just an artificial concept. In cases where
  ///     it isn't (accessing files from the underlying operating system, for example), file
  ///     handles can be transparently created and destroyed as needed. Leveraging incremental
  ///     reads is also pretty easy by tracking the location of the file pointer.
  ///   </para>
  ///   <para>
  ///     The interface presented is similar to a memory-mapped file: there is no file pointer
  ///     and you can access the file at any location. Wrappers like the BinaryFileReader
  ///     and BinaryFileWriter will maintain their own file pointers. This makes file reads
  ///     completely insusceptible to threading issues as long as you consider the readers
  ///     as lightweight objects each thread creates as required.
  ///   </para>
  ///   <para>
  ///     If you wish to suppot reading from stdin / writing to stdout with this class,
  ///     simply ensure your reads or writes are strictly sequential. The native filesystem
  ///     implementations are required to not seek unless neccessary.
  ///   </para>
  /// </remarks>
  class File : public Blob {

    /// <summary>Frees all resources owned by the instance</summary>
    public: NUCLEX_STORAGE_API virtual ~File() = default;

    /// <summary>Determines the size of the file</summary>
    /// <returns>The size of the file in bytes</returns>
    public: virtual std::uint64_t GetSize() const override = 0;

    /// <summary>Returns the name of the file</summary>
    /// <returns>The file's name</returns>
    public: virtual const std::string &GetName() const = 0;

    /// <summary>Returns the path the file is stored at in the native format</summary>
    /// <returns>The file's absolute path in the native OS format</returns>
    public: virtual const std::string &GetNativePath() const = 0;

    /// <summary>Changes the name of the file</summary>
    /// <param name="name">New name the file will be known under</param>
    public: virtual void Rename(const std::string &name) = 0;

    /// <summary>Retrieves the time at which the file has been last modified</summary>
    /// <returns>The since since the last modification of the file took place</returns>
    public: virtual std::time_t GetLastModificationTime() const = 0;

    /// <summary>Reads raw data from the file</summary>
    /// <param name="location">Absolute file position data will be read from</param>
    /// <param name="buffer">Buffer into which data will be read</param>
    /// <param name="count">Number of bytes that will be read</param>
    public: virtual void ReadAt(
      std::uint64_t location, void *buffer, std::size_t count
    ) const override = 0;

    /// <summary>Writes raw data into the file</summary>
    /// <param name="location">Absolute file position data will be written to</param>
    /// <param name="buffer">Buffer from which data will be taken</param>
    /// <param name="count">Number of bytes that will be written</param>
    public: virtual void WriteAt(
      std::uint64_t location, const void *buffer, std::size_t count
    ) override = 0;

    /// <summary>Ensures changes to the file have been written to disk</summary>
    public: virtual void Flush() override = 0;

  };

  // ------------------------------------------------------------------------------------------- //

}}} // namespace Nuclex::Storage::FileSystem

#endif // NUCLEX_STORAGE_FILESYSTEM_FILE_H