#include <cassert>
#include <array>
#include <limits>
#include <sstream>

#include "toolbox.hpp"

namespace asp {
	/**
	 * @brief Convert a given number to string
	 *
	 * @param num Number to convert
	 * @param offset of the string location to append
	 * @param str String to append the number to
	 * @return number of written bytes
	 */
	constexpr size_t ullstr(uint64_t num, const size_t offset, char* const str) noexcept {
		size_t i = 0;

		for (; num > 0; num /= 10)
			str[offset + i++] = char(num % 10) + '0';

		str[offset + i] = '\0';

		for (size_t j = 0; j < i / 2; ++j)
			std::swap(str[offset + j], str[offset + i - j - 1]);
		return i;
	}

	/**
	 * @brief Cast a variable to an unsigned 64 bit integer
	 *
	 * @tparam T Type of the variable to cast
	 * @param vae Variable to cast
	 * @return Casted variable
	 */
	template<typename T>
	static constexpr uint64_t u64(const T var) noexcept {
		return uint64_t(var);
	}

	static constexpr const size_t STR_BUFFER_SIZE = 64;
	static constexpr const int8_t N_TIMES = 11;
	static constexpr const std::array<const char* const, N_TIMES> time_formats = { "ns", "us", "ms", "s", "m", "h", "j", "w", "M", "y", "c" };
	static constexpr const std::array<const uint64_t, N_TIMES> time_numbers = { 1, 1000, 1000000, u64(1e9), u64(6e10), u64(36e11), u64(864e11),
									u64(6048e11), u64(26298e11), u64(315576e11), u64(315576e13) };


	static constexpr size_t N_BYTES = 7;
	static constexpr const std::array<const char[3], N_BYTES> format_prefix = { "B", "KB", "MB", "GB", "TB", "PB", "EB" };

	/**
	 * @brief Convert a given numbers of bytes to a human readable format
	 *
	 * @param n Number of bytes
	 * @return Human readable format of the numbers of bytes
	 */
	std::string format_byte_size(uint64_t n) noexcept {
		char s[STR_BUFFER_SIZE] = { 0 };

		if(n == 0){
			sprintf(s, "0%s", format_prefix[0]);
			return s;
		}

		size_t j = 0;
		for(uint8_t i = uint8_t(format_prefix.size() - 1) * 10; i > 0; i -= 10){
			const uint64_t nsi = n >> i;
			if(nsi > 0){
				const uint8_t idx = i / 10;
				j += ullstr(nsi, j, s);
				for(int k = 0; format_prefix[idx][k] > 0; ++k)
					s[j++] = format_prefix[idx][k];
				s[j++] = ' ';
				n &= u64(-1) >> (64 - i);
			}
		}
		if(n > 0){
			j += ullstr(n, j, s);
			for(int k = 0; format_prefix[0][k] > 0; ++k)
				s[j++] = format_prefix[0][k];
			s[j++] = ' ';
		}

		/* Remove trailing character */
		s[j - 1] = '\0';

		return std::string(s);
	}

	/**
	 * @brief Convert a given number of nanoseconds to a human readable format
	 *
	 * @param time Number of nanoseconds
	 * @return Human readable formatted string
	 */
	std::string format_time_ns(uint64_t time) noexcept {
		char s[STR_BUFFER_SIZE] = {0};
		size_t j = 0;

		if (time == 0){
			sprintf(s, "0%s", time_formats[0]);
			return s;
		}

		uint64_t res;
		for (uint8_t i = time_numbers.size() - 1; i > 0; --i) {
			if (time >= time_numbers[i]) {
				res = time / time_numbers[i];
				time %= time_numbers[i];
				j += ullstr(res, j, s);
				for(int k = 0; time_formats[i][k] > 0; ++k)
					s[j++] = time_formats[i][k];
				s[j++] = ' ';
			}
		}
		if (time >= time_numbers[0]) {
			res = time / time_numbers[0];
			time %= time_numbers[0];
			j += ullstr(res, j, s);
			for(int k = 0; time_formats[0][k] > 0; ++k)
				s[j++] = time_formats[0][k];
			s[j++] = ' ';
		}

		/* Remove trailing character */
		s[j - 1] = '\0';

		std::string ss(s);

		return ss;
	}

	struct separate_thousands : std::numpunct<char> {
		char sep_;
		separate_thousands(const char sep) noexcept : sep_(sep) {}
		char_type do_thousands_sep() const override { return sep_; }  // separate with commas
		string_type do_grouping() const override { return "\3"; } // groups of 3 digit
	};

	/**
	 * @brief Format a given integer with a given seperator for each thousands.
	 *
	 * @param k Integer
	 * @param sep Thousand seperator
	 * @return Formatted integer
	 */
	std::string thousand_sep(const int64_t k, const char sep) noexcept {
		std::ostringstream out;
		out.imbue(std::locale(out.getloc(), new separate_thousands(sep)));
		out << k;
		return out.str();
	}

	/**
	 * @brief Format a given integer with ',' for each thousands.
	 *
	 * @param k Integer
	 * @return Formatted integer
	 */
	std::string thousand_sep(const int64_t k) noexcept {
		return thousand_sep(k, ',');
	}

	/**
	 * @brief Run some unitary tests on format functions
	 *
	 */
	void toolbox_unit_test(void) noexcept {
		assert(std::string("0B")                                            == format_byte_size(0));
		assert(std::string("1B")                                            == format_byte_size(1));
		assert(std::string("1KB")                                           == format_byte_size(1 << 10));
		assert(std::string("1MB")                                           == format_byte_size(1 << 20));
		assert(std::string("1GB")                                           == format_byte_size(1 << 30));
		assert(std::string("1TB")                                           == format_byte_size(u64(1) << 40));
		assert(std::string("1PB")                                           == format_byte_size(u64(1) << 50));
		assert(std::string("1EB")                                           == format_byte_size(u64(1) << 60));
		assert(std::string("15EB 1023PB 1023TB 1023GB 1023MB 1023KB 1023B") == format_byte_size(std::numeric_limits<uint64_t>::max()));
		assert(std::string("15EB 1023PB 1023TB 1023GB 1023MB 1023KB 1023B") == format_byte_size(18446744073709551615ull));
		assert(std::string("10EB 1000PB 1000TB 1000GB 1000MB 1000KB 1000B") == format_byte_size(12656215539330294760ull));

		assert(std::string("0ns")                                            == format_time_ns(0));
		assert(std::string("1ns")                                            == format_time_ns(1));
		assert(std::string("10ns")                                           == format_time_ns(10));
		assert(std::string("1us")                                            == format_time_ns(1e3));
		assert(std::string("1ms")                                            == format_time_ns(1e6));
		assert(std::string("10ms")                                           == format_time_ns(1e7));
		assert(std::string("100ms")                                          == format_time_ns(1e8));
		assert(std::string("1s")                                             == format_time_ns(1e9));
		assert(std::string("10s")                                            == format_time_ns(1e10));
		assert(std::string("1m")                                             == format_time_ns(6e10));
		assert(std::string("1m 26s 400ms")                                   == format_time_ns(864e8));
		assert(std::string("1m 40s")                                         == format_time_ns(1e11));
		assert(std::string("16m 40s")                                        == format_time_ns(1e12));
		assert(std::string("1h")                                             == format_time_ns(36e11));
		assert(std::string("1j")                                             == format_time_ns(864e11));
		assert(std::string("1w")                                             == format_time_ns(6048e11));
		assert(std::string("1w 4j 13h 46m 40s")                              == format_time_ns(1e15));
		assert(std::string("2w")                                             == format_time_ns(12096e11));
		assert(std::string("3w 6j 5h 5m 35s 800ms")                          == format_time_ns(23511358e8));
		assert(std::string("3w 6j 7h 43m 4s 700ms")                          == format_time_ns(23605847e8));
		assert(std::string("3w 6j 7h 43m 11s 600ms")                         == format_time_ns(23605916e8));
		assert(std::string("3w 6j 13h 18m 33s 200ms")                        == format_time_ns(23807132e8));
		assert(std::string("4w 1j 12h 44m 2s 900ms")                         == format_time_ns(25514429e8));
		assert(std::string("1M")                                             == format_time_ns(26298e11));
		assert(std::string("1M 1w 2j 13h 30m")                               == format_time_ns(3456e12));
		assert(std::string("4M 4j 6h")                                       == format_time_ns(108864e11));
		assert(std::string("11M 2w 5j 13h 22m 48s")                          == format_time_ns(30617568e9));
		assert(std::string("11M 4w 2j 4h 30m")                               == format_time_ns(31536e12));
		assert(std::string("1y")                                             == format_time_ns(315576e11));
		assert(std::string("11M 4w 2j 10h 18m 45s")                          == format_time_ns(31556925e9));
		assert(std::string("11M 4w 2j 10h 19m 12s")                          == format_time_ns(31556952e9));
		assert(std::string("1y 9m 9s")                                       == format_time_ns(31558149e9));
		assert(std::string("1y 18h")                                         == format_time_ns(316224e11));
		assert(std::string("4y")                                             == format_time_ns(1262304e11));
		assert(std::string("5y")                                             == format_time_ns(157788e12));
		assert(std::string("10y")                                            == format_time_ns(315576e12));
		assert(std::string("15y")                                            == format_time_ns(473364e12));
		assert(std::string("20y")                                            == format_time_ns(631152e12));
		assert(std::string("31y 8M 1w 19h 46m 40s")                          == format_time_ns(1e18));
		assert(std::string("50y")                                            == format_time_ns(157788e13));
		assert(std::string("1c")                                             == format_time_ns(315576e13));
		assert(std::string("5c 84y 6M 2w 1j 8h 34m 33s 709ms 551us 615ns")   == format_time_ns(std::numeric_limits<uint64_t>::max()));
		assert(std::string("5c 84y 6M 2w 1j 8h 34m 33s 709ms 551us 615ns")   == format_time_ns(18446744073709551615ull));
		assert(std::string("1c 10y 10M 3w 6j 10h 10m 10s 100ms 100us 100ns") == format_time_ns(3500003410100100100));

		assert(std::string("0")                          == thousand_sep(0));
		assert(std::string("1")                          == thousand_sep(1));
		assert(std::string("10")                         == thousand_sep(10));
		assert(std::string("100")                        == thousand_sep(100));
		assert(std::string("1,000")                      == thousand_sep(1e3));
		assert(std::string("10,000")                     == thousand_sep(1e4));
		assert(std::string("100,000")                    == thousand_sep(1e5));
		assert(std::string("1,000,000")                  == thousand_sep(1e6));
		assert(std::string("10,000,000")                 == thousand_sep(1e7));
		assert(std::string("100,000,000")                == thousand_sep(1e8));
		assert(std::string("1,000,000,000")              == thousand_sep(1e9));
		assert(std::string("10,000,000,000")             == thousand_sep(1e10));
		assert(std::string("100,000,000,000")            == thousand_sep(1e11));
		assert(std::string("1,000,000,000,000")          == thousand_sep(1e12));
		assert(std::string("10,000,000,000,000")         == thousand_sep(1e13));
		assert(std::string("100,000,000,000,000")        == thousand_sep(1e14));
		assert(std::string("1,000,000,000,000,000")      == thousand_sep(1e15));
		assert(std::string("10,000,000,000,000,000")     == thousand_sep(1e16));
		assert(std::string("100,000,000,000,000,000")    == thousand_sep(1e17));
		assert(std::string("1,000,000,000,000,000,000")  == thousand_sep(1e18));
		assert(std::string("1,234,567,890")              == thousand_sep(1234567890));
		assert(std::string("9,876,543,210")              == thousand_sep(9876543210));
		assert(std::string("9,223,372,036,854,775,807")  == thousand_sep(std::numeric_limits<int64_t>::max()));

		assert(std::string("-1")                         == thousand_sep(-1));
		assert(std::string("-10")                        == thousand_sep(-10));
		assert(std::string("-100")                       == thousand_sep(-100));
		assert(std::string("-1,000")                     == thousand_sep(-1e3));
		assert(std::string("-10,000")                    == thousand_sep(-1e4));
		assert(std::string("-100,000")                   == thousand_sep(-1e5));
		assert(std::string("-1,000,000")                 == thousand_sep(-1e6));
		assert(std::string("-10,000,000")                == thousand_sep(-1e7));
		assert(std::string("-100,000,000")               == thousand_sep(-1e8));
		assert(std::string("-1,000,000,000")             == thousand_sep(-1e9));
		assert(std::string("-10,000,000,000")            == thousand_sep(-1e10));
		assert(std::string("-100,000,000,000")           == thousand_sep(-1e11));
		assert(std::string("-1,000,000,000,000")         == thousand_sep(-1e12));
		assert(std::string("-10,000,000,000,000")        == thousand_sep(-1e13));
		assert(std::string("-100,000,000,000,000")       == thousand_sep(-1e14));
		assert(std::string("-1,000,000,000,000,000")     == thousand_sep(-1e15));
		assert(std::string("-10,000,000,000,000,000")    == thousand_sep(-1e16));
		assert(std::string("-100,000,000,000,000,000")   == thousand_sep(-1e17));
		assert(std::string("-1,000,000,000,000,000,000") == thousand_sep(-1e18));
		assert(std::string("-1,234,567,890")             == thousand_sep(-1234567890));
		assert(std::string("-9,876,543,210")             == thousand_sep(-9876543210));
		assert(std::string("-9,223,372,036,854,775,808") == thousand_sep(std::numeric_limits<int64_t>::min()));
	}
}