/*
 * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
 * Copyright (C) 2016 Furrtek
 *
 * This file is part of PortaPack.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program 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
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#include "file.hpp"

#include <algorithm>
#include <locale>
#include <codecvt>

Optional<File::Error> File::open_fatfs(const std::filesystem::path& filename, BYTE mode) {
	auto result = f_open(&f, reinterpret_cast<const TCHAR*>(filename.c_str()), mode);
	if( result == FR_OK ) {
		if( mode & FA_OPEN_ALWAYS ) {
			const auto result = f_lseek(&f, f_size(&f));
			if( result != FR_OK ) {
				f_close(&f);
			}
		}
	}

	if( result == FR_OK ) {
		return { };
	} else {
		return { result };
	}
}

Optional<File::Error> File::open(const std::filesystem::path& filename) {
	return open_fatfs(filename, FA_READ);
}

Optional<File::Error> File::append(const std::filesystem::path& filename) {
	return open_fatfs(filename, FA_WRITE | FA_OPEN_ALWAYS);
}

Optional<File::Error> File::create(const std::filesystem::path& filename) {
	return open_fatfs(filename, FA_WRITE | FA_CREATE_ALWAYS);
}

File::~File() {
	f_close(&f);
}

File::Result<File::Size> File::read(void* const data, const Size bytes_to_read) {
	UINT bytes_read = 0;
	const auto result = f_read(&f, data, bytes_to_read, &bytes_read);
	if( result == FR_OK ) {
		return { static_cast<size_t>(bytes_read) };
	} else {
		return { static_cast<Error>(result) };
	}
}

File::Result<File::Size> File::write(const void* const data, const Size bytes_to_write) {
	UINT bytes_written = 0;
	const auto result = f_write(&f, data, bytes_to_write, &bytes_written);
	if( result == FR_OK ) {
		if( bytes_to_write == bytes_written ) {
			return { static_cast<File::Size>(bytes_written) };
		} else {
			return Error { FR_DISK_FULL };
		}
	} else {
		return { static_cast<Error>(result) };
	}
}

File::Result<File::Offset> File::seek(const Offset new_position) {
	/* NOTE: Returns *old* position, not new position */
	const auto old_position = f_tell(&f);
	const auto result = f_lseek(&f, new_position);
	if( result != FR_OK ) {
		return { static_cast<Error>(result) };
	}
	if( f_tell(&f) != new_position ) {
		return { static_cast<Error>(FR_BAD_SEEK) };
	}
	return { static_cast<File::Offset>(old_position) };
}

File::Size File::size() {
	return { static_cast<File::Size>(f_size(&f)) };
}

Optional<File::Error> File::write_line(const std::string& s) {
	const auto result_s = write(s.c_str(), s.size());
	if( result_s.is_error() ) {
		return { result_s.error() };
	}

	const auto result_crlf = write("\r\n", 2);
	if( result_crlf.is_error() ) {
		return { result_crlf.error() };
	}

	return { };
}

Optional<File::Error> File::sync() {
	const auto result = f_sync(&f);
	if( result == FR_OK ) {
		return { };
	} else {
		return { result };
	}
}

/* Range used for filename matching.
 * Start and end are inclusive positions of "???" */
struct pattern_range {
	size_t start;
	size_t end;
};

/* Finds the last file matching the specified pattern that
 * can be automatically incremented (digits in pattern).
 * NB: assumes a patten with contiguous '?' like "FOO_???.txt". */
static std::filesystem::path find_last_ordinal_match(
	const std::filesystem::path& folder,
	const std::filesystem::path& pattern,
	pattern_range range
) {
	auto last_match = std::filesystem::path();
	auto can_increment = [range](const auto& path) {
		for (auto i = range.start; i <= range.end; ++i)
			if (!isdigit(path.native()[i]))
				return false;

		return true;
	};

	for (const auto& entry : std::filesystem::directory_iterator(folder, pattern)) {
		if (std::filesystem::is_regular_file(entry.status()) && can_increment(entry.path())) {
			const auto& match = entry.path();
			if( match > last_match ) {
				last_match = match;
			}
		}
	}

	return last_match;
}

/* Given a file path like "FOO_0001.txt" increment it to "FOO_0002.txt". */
static std::filesystem::path increment_filename_ordinal(
	const std::filesystem::path& path, pattern_range range
) {
	auto name = path.filename().native();

	for (auto i = range.end; i >= range.start; --i) {
		auto& c = name[i];

		// Not a digit or would overflow the counter.
		if (c < u'0' || c > u'9' || (c == u'9' && i == range.start))
			return { };

		if (c == u'9')
			c = '0';
		else {
			c++;
			break;
		}
	}

	return { name };
}

std::filesystem::path next_filename_matching_pattern(const std::filesystem::path& filename_pattern) {
	auto path = filename_pattern.parent_path();
	auto pattern = filename_pattern.filename();
	auto range = pattern_range {
		pattern.native().find_first_of(u'?'),
		pattern.native().find_last_of(u'?')
	};

	const auto match = find_last_ordinal_match(path, pattern, range);

	if (match.empty()) {
		auto pattern_str = pattern.native();
		for (auto i = range.start; i <= range.end; ++i)
			pattern_str[i] = u'0';
		return path / pattern_str;
	}

	auto next_name = increment_filename_ordinal(match, range);
	return next_name.empty() ? next_name : path / next_name;
}

std::vector<std::filesystem::path> scan_root_files(const std::filesystem::path& directory,
	const std::filesystem::path& extension) {
	
	std::vector<std::filesystem::path> file_list { };
	
	for(const auto& entry : std::filesystem::directory_iterator(directory, extension)) {
		if( std::filesystem::is_regular_file(entry.status()) ) {
			file_list.push_back(entry.path());
		}
	}
	
	return file_list;
}

std::vector<std::filesystem::path> scan_root_directories(const std::filesystem::path& directory) {
	
	std::vector<std::filesystem::path> directory_list { };
	
	for(const auto& entry : std::filesystem::directory_iterator(directory, "*")) {
		if( std::filesystem::is_directory(entry.status()) ) {
			directory_list.push_back(entry.path());
		}
	}
	
	return directory_list;
}

std::filesystem::filesystem_error delete_file(const std::filesystem::path& file_path) {
	return { f_unlink(reinterpret_cast<const TCHAR*>(file_path.c_str())) };
}

std::filesystem::filesystem_error rename_file(
	const std::filesystem::path& file_path,
	const std::filesystem::path& new_name
) {
	return { f_rename(reinterpret_cast<const TCHAR*>(file_path.c_str()), reinterpret_cast<const TCHAR*>(new_name.c_str())) };
}

std::filesystem::filesystem_error copy_file(
	const std::filesystem::path& file_path,
	const std::filesystem::path& dest_path
) {
	File src;
	File dst;
	constexpr size_t buffer_size = 128;
	uint8_t buffer[buffer_size];

	auto error = src.open(file_path);
	if (error.is_valid()) return error.value();

	error = dst.create(dest_path);
	if (error.is_valid()) return error.value();

	while (true) {
		auto result = src.read(buffer, buffer_size);
		if (result.is_error()) return result.error();

		result = dst.write(buffer, result.value());
		if (result.is_error()) return result.error();

		if (result.value() < buffer_size)
			break;
	}

	return { };
}

FATTimestamp file_created_date(const std::filesystem::path& file_path) {
	FILINFO filinfo;
	
	f_stat(reinterpret_cast<const TCHAR*>(file_path.c_str()), &filinfo);
	
	return { filinfo.fdate, filinfo.ftime };
}

std::filesystem::filesystem_error make_new_file(
	const std::filesystem::path& file_path
) {
	File f;
	auto result = f.create(file_path);
	return result.is_valid()
		? result.value()
		: std::filesystem::filesystem_error{ };
}

std::filesystem::filesystem_error make_new_directory(
	const std::filesystem::path& dir_path
) {
	return { f_mkdir(reinterpret_cast<const TCHAR*>(dir_path.c_str())) };
}

std::filesystem::filesystem_error ensure_directory(
	const std::filesystem::path& dir_path
) {
	if (dir_path.empty() || std::filesystem::file_exists(dir_path))
		return { };

	auto result = ensure_directory(dir_path.parent_path());
	if (result.code())
		return result;

	return make_new_directory(dir_path);
}

namespace std {
namespace filesystem {

std::string filesystem_error::what() const {
	switch(err) {
	case FR_OK: 					return "ok";
	case FR_DISK_ERR:				return "disk error";
	case FR_INT_ERR:				return "insanity detected";
	case FR_NOT_READY:				return "SD card not ready";
	case FR_NO_FILE:				return "no file";
	case FR_NO_PATH:				return "no path";
	case FR_INVALID_NAME:			return "invalid name";
	case FR_DENIED:					return "denied";
	case FR_EXIST:					return "exists";
	case FR_INVALID_OBJECT:			return "invalid object";
	case FR_WRITE_PROTECTED:		return "write protected";
	case FR_INVALID_DRIVE:			return "invalid drive";
	case FR_NOT_ENABLED:			return "not enabled";
	case FR_NO_FILESYSTEM:			return "no filesystem";
	case FR_MKFS_ABORTED:			return "mkfs aborted";
	case FR_TIMEOUT:				return "timeout";
	case FR_LOCKED:					return "locked";
	case FR_NOT_ENOUGH_CORE:		return "not enough core";
	case FR_TOO_MANY_OPEN_FILES:	return "too many open files";
	case FR_INVALID_PARAMETER:		return "invalid parameter";
	case FR_EOF:					return "end of file";
	case FR_DISK_FULL:				return "disk full";
	case FR_BAD_SEEK:				return "bad seek";
	case FR_UNEXPECTED:				return "unexpected";
	default:						return "unknown";
	}
}

path path::parent_path() const {
	const auto index = _s.find_last_of(preferred_separator);
	if( index == _s.npos ) {
		return { }; // NB: Deviation from STL.
	} else {
		return _s.substr(0, index);
	}
}

path path::extension() const {
	const auto t = filename().native();
	const auto index = t.find_last_of(u'.');
	if( index == t.npos ) {
		return { };
	} else {
		return t.substr(index);
	}
}

path path::filename() const {
	const auto index = _s.find_last_of(preferred_separator);
	if( index == _s.npos ) {
		return _s;
	} else {
		return _s.substr(index + 1);
	}
}

path path::stem() const {
	const auto t = filename().native();
	const auto index = t.find_last_of(u'.');
	if( index == t.npos ) {
		return t;
	} else {
		return t.substr(0, index);
	}
}

std::string path::string() const {
	std::wstring_convert<std::codecvt_utf8_utf16<path::value_type>, path::value_type> conv;
	return conv.to_bytes(native());
}

path& path::replace_extension(const path& replacement) {
	const auto t = extension().native();
	_s.erase(_s.size() - t.size());
	if( !replacement._s.empty() ) {
		if( replacement._s.front() != u'.' ) {
			_s += u'.';
		}
		_s += replacement._s;
	}
	return *this;
}

bool operator==(const path& lhs, const path& rhs) {
	return lhs.native() == rhs.native();
}

bool operator!=(const path& lhs, const path& rhs) {
	return !(lhs == rhs);
}

bool operator<(const path& lhs, const path& rhs) {
	return lhs.native() < rhs.native();
}

bool operator>(const path& lhs, const path& rhs) {
	return lhs.native() > rhs.native();
}

path operator+(const path& lhs, const path& rhs) {
	path result = lhs;
	result += rhs;
	return result;
}

path operator/(const path& lhs, const path& rhs) {
	path result = lhs;
	result /= rhs;
	return result;
}

directory_iterator::directory_iterator(
	std::filesystem::path path,
	std::filesystem::path wild
) : pattern { wild }
{
	impl = std::make_shared<Impl>();
	const auto result = f_findfirst(&impl->dir, &impl->filinfo,
		reinterpret_cast<const TCHAR*>(path.c_str()),
		reinterpret_cast<const TCHAR*>(pattern.c_str()));
	if (result != FR_OK || impl->filinfo.fname[0] == (TCHAR)'\0') {
		impl.reset();
		// TODO: Throw exception if/when I enable exceptions...
	}
}

directory_iterator& directory_iterator::operator++() {
	const auto result = f_findnext(&impl->dir, &impl->filinfo);
	if( (result != FR_OK) || (impl->filinfo.fname[0] == 0) ) {
		impl.reset();
	}
	return *this;
}

bool is_directory(const file_status s) {
	return (s & AM_DIR);
}

bool is_regular_file(const file_status s) {
	return !(s & AM_DIR);
}

bool file_exists(const path& file_path) {
	FILINFO filinfo;
	auto fr = f_stat(reinterpret_cast<const TCHAR*>(file_path.c_str()), &filinfo);
	
	return fr == FR_OK;
}

bool is_directory(const path& file_path) {
	FILINFO filinfo;
	auto fr = f_stat(reinterpret_cast<const TCHAR*>(file_path.c_str()), &filinfo);
	
	return fr == FR_OK && is_directory(static_cast<file_status>(filinfo.fattrib));
}

space_info space(const path& p) {
	DWORD free_clusters { 0 };
	FATFS* fs;
	if( f_getfree(reinterpret_cast<const TCHAR*>(p.c_str()), &free_clusters, &fs) == FR_OK ) {
#if _MAX_SS != _MIN_SS
		static_assert(false, "FatFs not configured for fixed sector size");
#else
		const std::uintmax_t cluster_bytes = fs->csize * _MIN_SS;
		return {
			(fs->n_fatent - 2) * cluster_bytes,
			free_clusters * cluster_bytes,
			free_clusters * cluster_bytes,
		};
#endif
	} else {
		return { 0, 0, 0 };
	}
}

} /* namespace filesystem */
} /* namespace std */