#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

// If the library is compiled as a DLL, this ensures symbols are exported
#define NUCLEX_PIXELS_SOURCE 1

#include "LinuxFileApi.h"

#if defined(NUCLEX_PIXELS_LINUX)

#include "PosixApi.h" // Linux uses Posix error handling
#include "PosixFileApi.h" // for ThrowExceptionForFileAccessError()

#include <linux/limits.h> // for PATH_MAX
#include <fcntl.h> // ::open() and flags
#include <unistd.h> // ::read(), ::write(), ::close(), etc.

#include <cerrno> // To access ::errno directly
#include <vector> // std::vector

namespace {

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

} // anonymous namespace

namespace Nuclex { namespace Pixels { namespace Platform {

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

  int LinuxFileApi::OpenFileForReading(const std::string &path) {
    int fileDescriptor = ::open(path.c_str(), O_RDONLY | O_LARGEFILE);
    if(unlikely(fileDescriptor < 0)) {
      int errorNumber = errno;

      std::string errorMessage(u8"Could not open file '");
      errorMessage.append(path);
      errorMessage.append(u8"' for reading");

      Platform::PosixFileApi::ThrowExceptionForFileAccessError(errorMessage, errorNumber);
    }

    return fileDescriptor;
  }

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

  int LinuxFileApi::OpenFileForWriting(const std::string &path) {
    int fileDescriptor = ::open(
      path.c_str(),
      O_RDWR | O_CREAT | O_LARGEFILE,
      S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH
    );
    if(unlikely(fileDescriptor < 0)) {
      int errorNumber = errno;

      std::string errorMessage(u8"Could not open file '");
      errorMessage.append(path);
      errorMessage.append(u8"' for writing");

      Platform::PosixFileApi::ThrowExceptionForFileAccessError(errorMessage, errorNumber);
    }

    return fileDescriptor;
  }

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

  std::size_t LinuxFileApi::Seek(int fileDescriptor, ::off_t offset, int anchor) {
    ::off_t absolutePosition = ::lseek(fileDescriptor, offset, anchor);
    if(absolutePosition == -1) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not seek within file", errorNumber
      );
    }

    return static_cast<std::size_t>(absolutePosition);
  }

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

  std::size_t LinuxFileApi::Read(
    int fileDescriptor, std::uint8_t *buffer, std::size_t count
  ) {
    ssize_t result = ::read(fileDescriptor, buffer, count);
    if(unlikely(result == static_cast<ssize_t>(-1))) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not read data from file via positional read", errorNumber
      );
    }

    return static_cast<std::size_t>(result);
  }

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

  std::size_t LinuxFileApi::PositionalRead(
    int fileDescriptor, std::uint8_t *buffer, std::size_t count, std::uint64_t offset
  ) {
    ssize_t result = ::pread(fileDescriptor, buffer, count, offset);
    if(unlikely(result == static_cast<ssize_t>(-1))) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not read data from file", errorNumber
      );
    }

    return static_cast<std::size_t>(result);
  }

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

  std::size_t LinuxFileApi::Write(
    int fileDescriptor, const std::uint8_t *buffer, std::size_t count
  ) {
    ssize_t result = ::write(fileDescriptor, buffer, count);
    if(unlikely(result == static_cast<ssize_t>(-1))) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not write data to file", errorNumber
      );
    }

    return result;
  }

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

  std::size_t LinuxFileApi::PositionalWrite(
    int fileDescriptor, const std::uint8_t *buffer, std::size_t count, std::uint64_t offset
  ) {
    ssize_t result = ::pwrite(fileDescriptor, buffer, count, offset);
    if(unlikely(result == static_cast<ssize_t>(-1))) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not write data to file via positional write", errorNumber
      );
    }

    return result;
  }

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

  std::uint64_t LinuxFileApi::StatFileSize(int fileDescriptor) {
    struct stat fileStatus;

    int failed = ::fstat(fileDescriptor, &fileStatus);
    if(failed) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not query file status", errorNumber
      );
    }

    return static_cast<std::uint64_t>(fileStatus.st_size);
  }

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

  void LinuxFileApi::Close(int fileDescriptor, bool throwOnError /* = true */) {
    int result = ::close(fileDescriptor);
    if(throwOnError && unlikely(result == -1)) {
      int errorNumber = errno;
      Platform::PosixFileApi::ThrowExceptionForFileAccessError(
        u8"Could not close file", errorNumber
      );
    }
  }

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

}}} // namespace Nuclex::Pixels::Platform

#endif // defined(NUCLEX_PIXELS_LINUX)