#pragma once

enum class fsm : u32 // file seek mode
{
	begin,
	cur,
	end,
};

namespace fom // file open mode
{
	enum : u32
	{
		read = 1 << 0,
		write = 1 << 1,
		append = 1 << 2,
		create = 1 << 3,
		trunc = 1 << 4,
		excl = 1 << 5,
	};
};

enum class fse : u32 // filesystem (file or dir) error
{
	ok, // no error
	invalid_arguments,
};

namespace fs
{
	thread_local extern fse g_tls_error;

	struct stat_t
	{
		bool is_directory;
		bool is_writable;
		u64 size;
		s64 atime;
		s64 mtime;
		s64 ctime;
	};

	// Get file information
	bool stat(const std::string& path, stat_t& info);

	// Check whether a file or a directory exists (not recommended, use is_file() or is_dir() instead)
	bool exists(const std::string& path);

	// Check whether the file exists and is NOT a directory
	bool is_file(const std::string& file);

	// Check whether the directory exists and is NOT a file
	bool is_dir(const std::string& dir);

	// Delete empty directory
	bool remove_dir(const std::string& dir);

	// Create directory
	bool create_dir(const std::string& dir);

	// Create directories
	bool create_path(const std::string& path);

	// Rename (move) file or directory
	bool rename(const std::string& from, const std::string& to);

	// Copy file contents
	bool copy_file(const std::string& from, const std::string& to, bool overwrite);

	// Delete file
	bool remove_file(const std::string& file);

	// Change file size (possibly appending zeros)
	bool truncate_file(const std::string& file, u64 length);

	class file final
	{
		using handle_type = std::intptr_t;

		constexpr static handle_type null = -1;

		handle_type m_fd = null;

	public:
		file() = default;

		explicit file(const std::string& filename, u32 mode = fom::read)
		{
			open(filename, mode);
		}

		file(file&& other)
			: m_fd(other.m_fd)
		{
			other.m_fd = null;
		}

		file& operator =(file&& right)
		{
			std::swap(m_fd, right.m_fd);
			return *this;
		}

		~file();

		// Check whether the handle is valid (opened file)
		bool is_opened() const
		{
			return m_fd != null;
		}

		// Check whether the handle is valid (opened file)
		explicit operator bool() const
		{
			return is_opened();
		}

		// Open specified file with specified mode
		bool open(const std::string& filename, u32 mode = fom::read);

		// Change file size (possibly appending zero bytes)
		bool trunc(u64 size) const;

		// Get file information
		bool stat(stat_t& info) const;

		// Close the file explicitly (destructor automatically closes the file)
		bool close();

		// Read the data from the file and return the amount of data written in buffer
		u64 read(void* buffer, u64 count) const;

		// Write the data to the file and return the amount of data actually written
		u64 write(const void* buffer, u64 count) const;

		// Write std::string
		u64 write(const std::string& string) const { return write(string.data(), string.size()); }

		// Move file pointer
		u64 seek(s64 offset, fsm seek_mode = fsm::begin) const;

		// Get file size
		u64 size() const;
	};

	class dir final
	{
		std::unique_ptr<char[]> m_path;
		std::intptr_t m_dd; // handle (aux)

	public:
		dir() = default;

		explicit dir(const std::string& dirname)
		{
			open(dirname);
		}

		dir(dir&& other)
			: m_dd(other.m_dd)
			, m_path(std::move(other.m_path))
		{
		}

		dir& operator =(dir&& right)
		{
			m_dd = right.m_dd;
			m_path = std::move(right.m_path);
			return *this;
		}

		~dir();

		// Check whether the handle is valid (opened directory)
		bool is_opened() const
		{
			return m_path.operator bool();
		}

		// Check whether the handle is valid (opened directory)
		explicit operator bool() const
		{
			return is_opened();
		}

		// Open specified directory
		bool open(const std::string& dirname);
		
		// Close the directory explicitly (destructor automatically closes the directory)
		bool close();

		// Get next directory entry (UTF-8 name and file stat)
		bool read(std::string& name, stat_t& info);
	};
}