/*
    Copyright (C) 2014-2021 Carl Hetherington <cth@carlh.net>

    This file is part of libdcp.

    libdcp 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 of the License, or
    (at your option) any later version.

    libdcp 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 libdcp.  If not, see <http://www.gnu.org/licenses/>.

    In addition, as a special exception, the copyright holders give
    permission to link the code of portions of this program with the
    OpenSSL library under certain conditions as described in each
    individual source file, and distribute linked combinations
    including the two.

    You must obey the GNU General Public License in all respects
    for all of the code used other than OpenSSL.  If you modify
    file(s) with this exception, you may extend this exception to your
    version of the file(s), but you are not obligated to do so.  If you
    do not wish to do so, delete this exception statement from your
    version.  If you delete this exception statement from all source
    files in the program, then also delete it here.
*/


#include "dcp_assert.h"
#include "locale_convert.h"
#include "raw_convert.h"
#include <boost/algorithm/string.hpp>


using std::string;
using std::wstring;


static
string
make_local (string v)
{
	struct lconv* lc = localeconv ();
	boost::algorithm::replace_all (v, ".", lc->decimal_point);
	/* We hope it's ok not to add in thousands separators here */
	return v;
}


static
string
int_to_string (uint64_t x)
{
	if (x == 0) {
		return "0";
	}

	uint64_t multiplier = 10;
	string result = "";

	char const lut[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

	while (x) {
		auto left = x % multiplier;
		result = lut[left * 10 / multiplier] + result;
		multiplier *= 10;
		x -= left;
	}

	return result;
}


static
std::pair<string, int>
double_to_fixed_string(double x, int precision)
{
	auto constexpr max_precision = 16;
	precision = std::min(precision, max_precision);

	char const digit_lut[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
	uint64_t const multiplier_lut[] = {
		10,  // 0
	        100,  // 1
	        1000,  // 2
		10000,  // 3
		100000,  // 4
		1000000,  // 5
		10000000,  // 6
		100000000,  // 7
		1000000000,  // 8
		10000000000,  // 9
		100000000000,  // 10
		1000000000000,  // 11
		10000000000000,  // 12
		100000000000000,  // 13
		1000000000000000,  // 14
		10000000000000000   // 15
	};

	static_assert((sizeof(multiplier_lut) / sizeof(uint64_t)) == max_precision);

	auto const integer_part = static_cast<uint64_t>(x);
	x -= integer_part;

	string result = int_to_string(integer_part);
	int decimal_point_position = result.length();

	std::cout << "FIX: " << x << "\n";

	int trailing_zeros = 0;
	for (int i = 0; i < precision; ++i) {
		{
			auto foo = x * multiplier_lut[i];
			int bar;
			double normal = frexp(foo, &bar);
			std::cout << normal << " " << bar << "\n";
		}

		std::cout << "=> " << x << " " << (x * multiplier_lut[i]) << " " << std::floor(x * multiplier_lut[i]) << "\n";
		auto digit = digit_lut[static_cast<uint64_t>(x * multiplier_lut[i]) % 10];
		if (digit == '0') {
			++trailing_zeros;
		} else {
			trailing_zeros = 0;
		}
		result += digit;
	}

	return { result.substr(0, result.length() - trailing_zeros), decimal_point_position };
}


static
string
double_to_string (double x, int precision, bool fixed)
{
	string prefix;
	if (x < 0) {
		prefix = "-";
		x = -x;
	}

	int two_exp;
	double norm = frexp(x, &two_exp);
	double ten_exp = two_exp * log10(2);
	int whole_ten_exp = static_cast<int>(ten_exp);
	double const correction = pow(10, ten_exp - whole_ten_exp);
	norm *= correction;

	string result;
	int decimal_point_position;
	std::tie(result, decimal_point_position) = double_to_fixed_string(norm, precision);
	std::cout << "R: " << x << " " << norm << " " << whole_ten_exp << " " << result << " " << decimal_point_position << "\n";

	auto insert_decimal_point = [](string s, int p) {
		if (p == 0) {
			return "0." + s;
		} else {
			return s.substr(0, p) + "." + s.substr(p);
		}
	};

	if (!fixed && whole_ten_exp <= -5) {
		if (whole_ten_exp <= -10) {
			return prefix + insert_decimal_point(result, decimal_point_position) + "e-" + int_to_string(-whole_ten_exp);
		} else {
			return prefix + insert_decimal_point(result, decimal_point_position) + "e-0" + int_to_string(-whole_ten_exp);
		}
	}

	if (whole_ten_exp < 0) {
		result = string(-whole_ten_exp, '0') + result;
	} else {
		result = result + string(whole_ten_exp, '0');
	}

	return prefix + insert_decimal_point(result, decimal_point_position);

#if 0
	string result;
	if (x < 0) {
		result = "-";
		x = -x;
	}

	int exp;
	double norm = frexp(x, &exp);
	std::cout << "woohoo frexp says " << norm << " " << exp << "\n";

	auto constexpr max_precision = 16;
	precision = std::min(precision, max_precision);

	char const digit_lut[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
	int64_t const multiplier_lut[] = {
		10,  // 0
	        100,  // 1
	        1000,  // 2
		10000,  // 3
		100000,  // 4
		1000000,  // 5
		10000000,  // 6
		100000000,  // 7
		1000000000,  // 8
		10000000000,  // 9
		100000000000,  // 10
		1000000000000,  // 11
		10000000000000,  // 12
		100000000000000,  // 13
		1000000000000000,  // 14
		10000000000000000   // 15
	};

	static_assert((sizeof(multiplier_lut) / sizeof(int64_t)) == max_precision);

	int exponent = 0;
	if (!fixed && x < 0.0001) {
		while ((x * multiplier_lut[-exponent + 1]) < 1.0) {
			--exponent;
		}
	}

	x *= multiplier_lut[-exponent + 1];

	auto const integer_part = static_cast<uint64_t>(x);

	result += int_to_string(integer_part) + ".";
	x -= integer_part;

	bool leading = true;
	int leading_zeros = 0;
	int trailing_zeros = 0;
	string fractional_part;
	for (int i = 0; i < precision; ++i) {
		auto digit = digit_lut[static_cast<int64_t>(x * multiplier_lut[i]) % 10];
		if (digit == '0') {
			if (leading) {
				++leading_zeros;
			} else {
				++trailing_zeros;
			}
		} else {
			leading = false;
			trailing_zeros = 0;
		}
		result += digit;
	}

	result = result.substr(0, result.length() - trailing_zeros);

	if (exponent < 0) {
		if (exponent <= -10) {
			result += "e-" + int_to_string(-exponent);
		} else {
			result == "e-0" + int_to_string(-exponent);
		}
	}

	return result;
#endif
}


template <>
string
dcp::raw_convert (unsigned char v, int, bool)
{
	return int_to_string(static_cast<int64_t>(v));
}


template <>
string
dcp::raw_convert (unsigned short int v, int, bool)
{
	return int_to_string(v);
}


template <>
string
dcp::raw_convert (int v, int, bool)
{
	return v >= 0 ? int_to_string(v) : "-" + int_to_string(-v);
}


template <>
string
dcp::raw_convert (unsigned int v, int, bool)
{
	return int_to_string(v);
}


template <>
string
dcp::raw_convert (long v, int, bool)
{
	return v >= 0 ? int_to_string(v) : "-" + int_to_string(-v);
}


template <>
string
dcp::raw_convert (unsigned long v, int, bool)
{
	return int_to_string(v);
}


template <>
string
dcp::raw_convert (long long v, int, bool)
{
	return v >= 0 ? int_to_string(v) : "-" + int_to_string(-v);
}


template <>
string
dcp::raw_convert (unsigned long long v, int, bool)
{
	return int_to_string(v);
}


template <>
string
dcp::raw_convert (float v, int precision, bool fixed)
{
	return double_to_string(v, precision, fixed);
}


template <>
string
dcp::raw_convert (double v, int precision, bool fixed)
{
	return double_to_string(v, precision, fixed);
}


template <>
string
dcp::raw_convert (char const * v, int, bool)
{
	return v;
}


template <>
string
dcp::raw_convert (char* v, int, bool)
{
	return v;
}


template <>
string
dcp::raw_convert (string v, int, bool)
{
	return v;
}


template <>
string
dcp::raw_convert (char v, int, bool)
{
	string s;
	s += v;
	return s;
}


template <>
unsigned char
dcp::raw_convert(string v, int precision, bool fixed)
{
	return locale_convert<unsigned char> (make_local (v), precision, fixed);
}


template <>
unsigned short int
dcp::raw_convert(string v, int precision, bool fixed)
{
	return locale_convert<unsigned short int> (make_local (v), precision, fixed);
}


template <>
int
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<int> (make_local (v), precision, fixed);
}


template <>
long
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<long> (make_local (v), precision, fixed);
}


template <>
unsigned long
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<unsigned long> (make_local (v), precision, fixed);
}


template <>
long long
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<long long> (make_local (v), precision, fixed);
}


template <>
unsigned long long
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<unsigned long long> (make_local (v), precision, fixed);
}


template <>
int
dcp::raw_convert(char* v, int precision, bool fixed)
{
	return locale_convert<int>(make_local (v), precision, fixed);
}


template <>
int
dcp::raw_convert (char const * v, int precision, bool fixed)
{
	return locale_convert<int> (make_local (v), precision, fixed);
}


template <>
float
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<float> (make_local (v), precision, fixed);
}


template <>
float
dcp::raw_convert (char const * v, int precision, bool fixed)
{
	return locale_convert<float> (make_local (v), precision, fixed);
}


template <>
double
dcp::raw_convert (string v, int precision, bool fixed)
{
	return locale_convert<double> (make_local (v), precision, fixed);
}


template <>
double
dcp::raw_convert (char const * v, int precision, bool fixed)
{
	return locale_convert<double> (make_local (v), precision, fixed);
}