#include <algorithm>
#include <array>
#include <fstream>
#include <iomanip>
#include <iostream>

constexpr unsigned line_width = 16;

int hexdump_main(int argc, char** argv) {
	std::ios::sync_with_stdio(false);
	std::ifstream file;
	std::istream& input = [&]() -> std::istream& {
		if (argc <= 1) {
			return std::cin;
		} else {
			file.open(argv[1], std::ios::binary);
			return file;
		}
	}();
	std::array<char, line_width> raw{};
	std::streamsize filepos = 0;
	while (input) {
		input.read(raw.data(), raw.size());
		auto count = input.gcount();
		if (count == 0) {
			break;
		}
		std::cout << std::hex << std::setw(8) << std::setfill('0') << filepos
		          << "  ";
		filepos += count;
		for (std::streamsize i = 0; i != count; ++i) {
			if (i == line_width / 2) {
				std::cout << ' ';
			}
			auto ch = static_cast<unsigned char>(raw[static_cast<std::size_t>(i)]);
			std::cout << std::hex << std::setw(2) << +ch << ' ';
		}
		for (std::streamsize i = count; i != line_width; ++i) {
			if (i == line_width / 2) {
				std::cout << ' ';
			}
			std::cout << "   ";
		}
		std::cout << " |";
		for (std::streamsize i = 0; i != count; ++i) {
			auto ch = raw[static_cast<std::size_t>(i)];
			if (std::isprint(ch) || ch == ' ') {
				std::cout << ch;
			} else {
				std::cout << '.';
			}
		}
		std::cout << "|\n";
	}
	std::cout << std::hex << std::setw(8) << std::setfill('0') << filepos
	          << '\n';
	return 0;
}