// Copyright 2014 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fxcrt/cfx_fileaccess_windows.h"

#include <memory>

#include "core/fxcrt/fx_stream.h"
#include "core/fxcrt/fx_string.h"
#include "core/fxcrt/span_io.h"

// static
std::unique_ptr<FileAccessIface> FileAccessIface::Create() {
  return std::make_unique<CFX_FileAccess_Windows>();
}

CFX_FileAccess_Windows::CFX_FileAccess_Windows() = default;

CFX_FileAccess_Windows::~CFX_FileAccess_Windows() {
  Close();
}

bool CFX_FileAccess_Windows::Open(const ByteString& file_name) {
  if (file_) {
    return false;
  }

  WideString wname = WideString::FromUTF8(ByteStringView(file_name));
  file_ = ::CreateFileW(wname.c_str(), GENERIC_READ,
                        FILE_SHARE_READ | FILE_SHARE_WRITE, nullptr,
                        OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
  if (file_ == INVALID_HANDLE_VALUE) {
    file_ = nullptr;
  }

  return !!file_;
}

void CFX_FileAccess_Windows::Close() {
  if (!file_) {
    return;
  }

  ::CloseHandle(file_);
  file_ = nullptr;
}

FX_FILESIZE CFX_FileAccess_Windows::GetSize() const {
  if (!file_) {
    return 0;
  }

  LARGE_INTEGER size = {};
  if (!::GetFileSizeEx(file_, &size)) {
    return 0;
  }

  return (FX_FILESIZE)size.QuadPart;
}

FX_FILESIZE CFX_FileAccess_Windows::GetPosition() const {
  if (!file_) {
    return (FX_FILESIZE)-1;
  }

  LARGE_INTEGER dist = {};
  LARGE_INTEGER newPos = {};
  if (!::SetFilePointerEx(file_, dist, &newPos, FILE_CURRENT)) {
    return (FX_FILESIZE)-1;
  }

  return (FX_FILESIZE)newPos.QuadPart;
}

FX_FILESIZE CFX_FileAccess_Windows::SetPosition(FX_FILESIZE pos) {
  if (!file_) {
    return (FX_FILESIZE)-1;
  }

  LARGE_INTEGER dist;
  dist.QuadPart = pos;
  LARGE_INTEGER newPos = {};
  if (!::SetFilePointerEx(file_, dist, &newPos, FILE_BEGIN)) {
    return (FX_FILESIZE)-1;
  }

  return (FX_FILESIZE)newPos.QuadPart;
}

size_t CFX_FileAccess_Windows::Read(pdfium::span<uint8_t> buffer) {
  return file_ ? fxcrt::spanread(buffer, file_).size() : 0;
}

bool CFX_FileAccess_Windows::Write(pdfium::span<const uint8_t> buffer) {
  return file_ && fxcrt::spanwrite(buffer, file_) == buffer.size();
}

size_t CFX_FileAccess_Windows::ReadPos(pdfium::span<uint8_t> buffer,
                                       FX_FILESIZE pos) {
  if (!file_) {
    return 0;
  }

  if (pos >= GetSize()) {
    return 0;
  }

  if (SetPosition(pos) == (FX_FILESIZE)-1) {
    return 0;
  }

  return Read(buffer);
}

bool CFX_FileAccess_Windows::Flush() {
  if (!file_) {
    return false;
  }

  return !!::FlushFileBuffers(file_);
}

bool CFX_FileAccess_Windows::Truncate(FX_FILESIZE szFile) {
  if (SetPosition(szFile) == (FX_FILESIZE)-1) {
    return false;
  }

  return !!::SetEndOfFile(file_);
}