#include <psemek/io/file_stream.hpp>
#include <psemek/util/system_error.hpp>

#include <cstring>
#include <codecvt>

namespace psemek::io
{

	static void throw_fopen [[noreturn]] (std::filesystem::path const & path)
	{
		throw util::system_error(std::error_code{errno, std::system_category()}, "Failed to open " + path.string());
	}

	static FILE * safe_fopen(std::filesystem::path const & path, const char * mode)
	{
		std::string path_str = path.string();
		auto f = std::fopen(path_str.c_str(), mode);
		if (!f) throw_fopen(path);
		return f;
	}

	file_istream::file_istream(std::filesystem::path const & path)
		: file_{safe_fopen(path.c_str(), "rb")}
	{}

	void file_istream::reset()
	{
		if (file_)
			std::fclose(file_);
		file_ = nullptr;
	}

	std::size_t file_istream::read(char * p, std::size_t size)
	{
		if (!file_) throw null_istream{};
		return std::fread(p, 1, size, file_);
	}

	static char const * fopen_write_mode(unsigned flags)
	{
		switch (flags)
		{
		case 0: return "wb";
		case file_ostream::append: return "ab";
		default: throw util::exception("Unknown file_ostream open flags");
		}
	}

	file_ostream::file_ostream(std::filesystem::path const & path, unsigned flags)
		: file_{safe_fopen(path.c_str(), fopen_write_mode(flags))}
	{}

	void file_ostream::reset()
	{
		if (file_)
			std::fclose(file_);
		file_ = nullptr;
	}

	std::size_t file_ostream::write(char const * p, std::size_t size)
	{
		if (!file_) throw null_ostream{};
		return std::fwrite(p, 1, size, file_);
	}

	void file_ostream::flush()
	{
		if (!file_) throw null_ostream{};
		std::fflush(file_);
	}

}