#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_STORAGE_SOURCE 1

#include "PosixFileApi.h"

#if !defined(NUCLEX_STORAGE_WIN32)

#include "../../Helpers/PosixApi.h"

#include <cstdio> // for fopen() and fclose()
#include <cerrno> // To access ::errno directly
#include <cassert> // for assert()
#include <limits> // for std::numeric_limits

namespace Nuclex { namespace Storage { namespace FileSystem {

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

  FILE *PosixFileApi::OpenFileForReading(const std::string &path) {
    static const char *fileMode = "rb";

    FILE *file = ::fopen(path.c_str(), fileMode);
    if(file == nullptr) {
      int errorNumber = errno;

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

      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }

    return file;
  }

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

  FILE *PosixFileApi::OpenFileForWriting(const std::string &path) {
    static const char *fileMode = "w+b";

    FILE *file = ::fopen(path.c_str(), fileMode);
    if(file == nullptr) {
      int errorNumber = errno;

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

      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }

    return file;
  }

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

  void PosixFileApi::Close(FILE *file, bool throwOnError /* = true */) {
    int result = ::fclose(file);
    if(throwOnError && (result != 0)) {
      int errorNumber = errno;
      std::string errorMessage(u8"Could not close file");
      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }
  }

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

  std::size_t PosixFileApi::Read(FILE *file, std::uint8_t *buffer, std::size_t count) {
    size_t readByteCount = ::fread(buffer, 1, count, file);
    if(readByteCount == 0) {
      int errorNumber = errno;

      int result = ::feof(file);
      if(result != 0) {
        return 0; // Read was successful, but end of file has been reached
      }

      std::string errorMessage(u8"Could not read data from file");
      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }

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

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

  std::size_t PosixFileApi::Write(FILE *file, const std::uint8_t *buffer, std::size_t count) {
    size_t writtenByteCount = ::fwrite(buffer, 1, count, file);
    if(writtenByteCount == 0) {
      int errorNumber = errno;

      int result = ::ferror(file);
      if(result == 0) {
        return 0; // Write was successful but no bytes could be written ?_?
      }

      std::string errorMessage(u8"Could not write data to file");
      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }

    return writtenByteCount;
  }
                      
  // ------------------------------------------------------------------------------------------- //

  void PosixFileApi::Seek(FILE *file, std::uint64_t location) {
    //assert((location < std::numeric_limits<long>::max())) && u8"Location fits in long");
    int result = ::fseek(file, static_cast<long>(location), SEEK_SET);
    if(result == -1) {
      int errorNumber = errno;
      std::string errorMessage(u8"Could not move file cursor");
      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }
  }

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

  std::uint64_t PosixFileApi::Tell(FILE *file) {
    long position = ::ftell(file);
    if(position == -1) {
      int errorNumber = errno;
      std::string errorMessage(u8"Could not retrieve file cursor position");
      Helpers::PosixApi::ThrowExceptionForSystemError(errorMessage, errorNumber);
    }

    return static_cast<std::uint64_t>(position);
  }

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

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

#endif // !defined(NUCLEX_STORAGE_WIN32)