// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "internal/platform/implementation/windows/file.h"

#include <cstddef>
#include <cstdint>
#include <ios>
#include <memory>
#include <string>

#include "absl/memory/memory.h"
#include "absl/strings/string_view.h"
#include "internal/platform/byte_array.h"
#include "internal/platform/exception.h"
#include "internal/platform/implementation/windows/string_utils.h"
#include "internal/platform/logging.h"

namespace nearby {
namespace windows {

// InputFile
std::unique_ptr<IOFile> IOFile::CreateInputFile(absl::string_view file_path,
                                                size_t size) {
  return absl::WrapUnique(new IOFile(file_path, size));
}

IOFile::IOFile(absl::string_view file_path, size_t size) : path_(file_path) {
  // Always open input file path as wide string on Windows platform.
  std::wstring wide_path = string_utils::StringToWideString(
      std::string(file_path));
  file_.open(wide_path, std::ios::binary | std::ios::in | std::ios::ate);

  total_size_ = file_.tellg();
  if (total_size_ == -1) {
    // Unsure why it consistently returns -1 when the file size exceeds 2GB. If
    // obtaining the file size through tellg fails, use the size provided
    // in the parameters.
    total_size_ = size;
  }

  file_.seekg(0);
}

std::unique_ptr<IOFile> IOFile::CreateOutputFile(absl::string_view path) {
  return std::unique_ptr<IOFile>(new IOFile(path));
}

IOFile::IOFile(absl::string_view file_path)
    : file_(), path_(file_path), total_size_(0) {
  // Always open input file path as wide string on Windows platform.
  std::wstring wide_path =
      string_utils::StringToWideString(path_);
  file_.open(wide_path, std::ios::binary | std::ios::out);
}

ExceptionOr<ByteArray> IOFile::Read(std::int64_t size) {
  try {
    if (!file_.is_open()) {
      return ExceptionOr<ByteArray>{Exception::kIo};
    }

    if (!file_.good()) {
      return ExceptionOr<ByteArray>{Exception::kIo};
    }

    if (file_.eof()) {
      return ExceptionOr<ByteArray>{ByteArray{}};
    }

    if (buffer_.size() < size) {
      buffer_.resize(size);
    }

    file_.read(buffer_.data(), static_cast<ptrdiff_t>(size));
    auto num_bytes_read = file_.gcount();
    if (num_bytes_read == 0) {
      return ExceptionOr<ByteArray>{Exception::kIo};
    }
    return ExceptionOr<ByteArray>(ByteArray(buffer_.data(), num_bytes_read));
  } catch (...) {
    LOG(ERROR) << "Fail to read";
    return ExceptionOr<ByteArray>{Exception::kIo};
  }
}

Exception IOFile::Close() {
  if (file_.is_open()) {
    file_.close();
  }
  return {Exception::kSuccess};
}

Exception IOFile::Write(const ByteArray& data) {
  try {
    if (!file_.is_open()) {
      return {Exception::kIo};
    }

    if (!file_.good()) {
      return {Exception::kIo};
    }

    file_.write(data.data(), data.size());
    return {file_.good() ? Exception::kSuccess : Exception::kIo};
  } catch (...) {
    LOG(ERROR) << "Fail to write";
    return {Exception::kIo};
  }
}

Exception IOFile::Flush() {
  file_.flush();
  return {file_.good() ? Exception::kSuccess : Exception::kIo};
}

}  // namespace windows
}  // namespace nearby