/***
 * Copyright (C) Microsoft. All rights reserved.
 * Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
 *
 * =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 *
 * fileio.h
 *
 * Asynchronous I/O: stream buffer implementation details
 *
 * We're going to some lengths to avoid exporting C++ class member functions and implementation details across
 * module boundaries, and the factoring requires that we keep the implementation details away from the main header
 * files. The supporting functions, which are in this file, use C-like signatures to avoid as many issues as
 * possible.
 *
 * For the latest on this and related APIs, please see: https://github.com/Microsoft/cpprestsdk
 *
 * =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 ****/
#pragma once

#ifdef _WIN32
#include <cstdint>
#endif

#include "cpprest/details/basic_types.h"
#include "pplx/pplxtasks.h"

namespace Concurrency
{
namespace streams
{
namespace details
{
/// <summary>
/// A record containing the essential private data members of a file stream,
/// in particular the parts that need to be shared between the public header
/// file and the implementation in the implementation file.
/// </summary>
struct _file_info
{
    _ASYNCRTIMP _file_info(std::ios_base::openmode mode, size_t buffer_size)
        : m_rdpos(0)
        , m_wrpos(0)
        , m_atend(false)
        , m_buffer_size(buffer_size)
        , m_buffer(nullptr)
        , m_bufoff(0)
        , m_bufsize(0)
        , m_buffill(0)
        , m_mode(mode)
    {
    }

    // Positional data

    size_t m_rdpos;
    size_t m_wrpos;
    bool m_atend;

    // Input buffer

    size_t m_buffer_size; // The intended size of the buffer to read into.
    char* m_buffer;

    size_t m_bufoff;                          // File position that the start of the buffer represents.
    msl::safeint3::SafeInt<size_t> m_bufsize; // Buffer allocated size, as actually allocated.
    size_t m_buffill;                         // Amount of file data actually in the buffer

    std::ios_base::openmode m_mode;

    pplx::extensibility::recursive_lock_t m_lock;
};

/// <summary>
/// This interface provides the necessary callbacks for completion events.
/// </summary>
class _filestream_callback
{
public:
    virtual void on_opened(_In_ details::_file_info*) {}
    virtual void on_closed() {}
    virtual void on_error(const std::exception_ptr&) {}
    virtual void on_completed(size_t) {}

protected:
    virtual ~_filestream_callback() {}
};

} // namespace details
} // namespace streams
} // namespace Concurrency

extern "C"
{
/// <summary>
/// Open a file and create a streambuf instance to represent it.
/// </summary>
/// <param name="callback">A pointer to the callback interface to invoke when the file has been opened.</param>
/// <param name="filename">The name of the file to open</param>
/// <param name="mode">A creation mode for the stream buffer</param>
/// <param name="prot">A file protection mode to use for the file stream (not supported on Linux)</param>
/// <returns><c>true</c> if the opening operation could be initiated, <c>false</c> otherwise.</returns>
/// <remarks>
/// True does not signal that the file will eventually be successfully opened, just that the process was started.
/// </remarks>
#if !defined(__cplusplus_winrt)
    _ASYNCRTIMP bool __cdecl _open_fsb_str(_In_ concurrency::streams::details::_filestream_callback* callback,
                                           const utility::char_t* filename,
                                           std::ios_base::openmode mode,
                                           int prot);
#endif

/// <summary>
/// Create a streambuf instance to represent a WinRT file.
/// </summary>
/// <param name="callback">A pointer to the callback interface to invoke when the file has been opened.</param>
/// <param name="file">The file object</param>
/// <param name="mode">A creation mode for the stream buffer</param>
/// <returns><c>true</c> if the opening operation could be initiated, <c>false</c> otherwise.</returns>
/// <remarks>
/// True does not signal that the file will eventually be successfully opened, just that the process was started.
/// This is only available for WinRT.
/// </remarks>
#if defined(__cplusplus_winrt)
    _ASYNCRTIMP bool __cdecl _open_fsb_stf_str(_In_ concurrency::streams::details::_filestream_callback* callback,
                                               ::Windows::Storage::StorageFile ^ file,
                                               std::ios_base::openmode mode,
                                               int prot);
#endif

    /// <summary>
    /// Close a file stream buffer.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="callback">A pointer to the callback interface to invoke when the file has been opened.</param>
    /// <returns><c>true</c> if the closing operation could be initiated, <c>false</c> otherwise.</returns>
    /// <remarks>
    /// True does not signal that the file will eventually be successfully closed, just that the process was started.
    /// </remarks>
    _ASYNCRTIMP bool __cdecl _close_fsb_nolock(_In_ concurrency::streams::details::_file_info** info,
                                               _In_ concurrency::streams::details::_filestream_callback* callback);
    _ASYNCRTIMP bool __cdecl _close_fsb(_In_ concurrency::streams::details::_file_info** info,
                                        _In_ concurrency::streams::details::_filestream_callback* callback);

    /// <summary>
    /// Write data from a buffer into the file stream.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="callback">A pointer to the callback interface to invoke when the write request is
    /// completed.</param> <param name="ptr">A pointer to a buffer where the data should be placed</param> <param
    /// name="count">The size (in characters) of the buffer</param> <returns>0 if the read request is still outstanding,
    /// -1 if the request failed, otherwise the size of the data read into the buffer</returns>
    _ASYNCRTIMP size_t __cdecl _putn_fsb(_In_ concurrency::streams::details::_file_info* info,
                                         _In_ concurrency::streams::details::_filestream_callback* callback,
                                         const void* ptr,
                                         size_t count,
                                         size_t char_size);

    /// <summary>
    /// Read data from a file stream into a buffer
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="callback">A pointer to the callback interface to invoke when the write request is
    /// completed.</param> <param name="ptr">A pointer to a buffer where the data should be placed</param> <param
    /// name="count">The size (in characters) of the buffer</param> <returns>0 if the read request is still outstanding,
    /// -1 if the request failed, otherwise the size of the data read into the buffer</returns>
    _ASYNCRTIMP size_t __cdecl _getn_fsb(_In_ concurrency::streams::details::_file_info* info,
                                         _In_ concurrency::streams::details::_filestream_callback* callback,
                                         _Out_writes_(count) void* ptr,
                                         _In_ size_t count,
                                         size_t char_size);

    /// <summary>
    /// Flush all buffered data to the underlying file.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="callback">A pointer to the callback interface to invoke when the write request is
    /// completed.</param> <returns><c>true</c> if the request was initiated</returns>
    _ASYNCRTIMP bool __cdecl _sync_fsb(_In_ concurrency::streams::details::_file_info* info,
                                       _In_ concurrency::streams::details::_filestream_callback* callback);

    /// <summary>
    /// Get the size of the underlying file.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <returns>The file size</returns>
    _ASYNCRTIMP utility::size64_t __cdecl _get_size(_In_ concurrency::streams::details::_file_info* info,
                                                    size_t char_size);

    /// <summary>
    /// Adjust the internal buffers and pointers when the application seeks to a new read location in the stream.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="pos">The new position (offset from the start) in the file stream</param>
    /// <returns><c>true</c> if the request was initiated</returns>
    _ASYNCRTIMP size_t __cdecl _seekrdpos_fsb(_In_ concurrency::streams::details::_file_info* info,
                                              size_t pos,
                                              size_t char_size);

    /// <summary>
    /// Adjust the internal buffers and pointers when the application seeks to a new read location in the stream.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="pos">The new position (offset from the start) in the file stream</param>
    /// <returns><c>true</c> if the request was initiated</returns>
    _ASYNCRTIMP size_t __cdecl _seekrdtoend_fsb(_In_ concurrency::streams::details::_file_info* info,
                                                int64_t offset,
                                                size_t char_size);

    /// <summary>
    /// Adjust the internal buffers and pointers when the application seeks to a new write location in the stream.
    /// </summary>
    /// <param name="info">The file info record of the file</param>
    /// <param name="pos">The new position (offset from the start) in the file stream</param>
    /// <returns><c>true</c> if the request was initiated</returns>
    _ASYNCRTIMP size_t __cdecl _seekwrpos_fsb(_In_ concurrency::streams::details::_file_info* info,
                                              size_t pos,
                                              size_t char_size);
}