#include "Date.hpp"

#include <algorithm>
#include <cassert>
#include <cctype>
#include <charconv>

#include "openvic-simulation/utility/Logger.hpp"
#include "openvic-simulation/utility/StringUtils.hpp"

using namespace OpenVic;

Timespan::Timespan(day_t value) : days { value } {}

bool Timespan::operator<(Timespan other) const { return days < other.days; };
bool Timespan::operator>(Timespan other) const { return days > other.days; };
bool Timespan::operator<=(Timespan other) const { return days <= other.days; };
bool Timespan::operator>=(Timespan other) const { return days >= other.days; };
bool Timespan::operator==(Timespan other) const { return days == other.days; };
bool Timespan::operator!=(Timespan other) const { return days != other.days; };

Timespan Timespan::operator+(Timespan other) const { return days + other.days; }

Timespan Timespan::operator-(Timespan other) const { return days - other.days; }

Timespan Timespan::operator*(day_t factor) const { return days * factor; }

Timespan Timespan::operator/(day_t factor) const { return days / factor; }

Timespan& Timespan::operator+=(Timespan other) {
	days += other.days;
	return *this;
}

Timespan& Timespan::operator-=(Timespan other) {
	days -= other.days;
	return *this;
}

Timespan& Timespan::operator++() {
	days++;
	return *this;
}

Timespan Timespan::operator++(int) {
	Timespan old = *this;
	++(*this);
	return old;
}

Timespan::operator day_t() const {
	return days;
}

Timespan::operator double() const {
	return days;
}

std::string Timespan::to_string() const {
	return std::to_string(days);
}

Timespan::operator std::string() const {
	return to_string();
}

Timespan Timespan::fromYears(day_t num) {
	 return num * Date::DAYS_IN_YEAR;
}

Timespan Timespan::fromMonths(day_t num) {
	 return (num / Date::MONTHS_IN_YEAR) * Date::DAYS_IN_YEAR +
	 	Date::DAYS_UP_TO_MONTH[num % Date::MONTHS_IN_YEAR];
}

Timespan Timespan::fromDays(day_t num) {
	 return num;
}

std::ostream& OpenVic::operator<<(std::ostream& out, Timespan const& timespan) {
	return out << timespan.to_string();
}

Timespan Date::_dateToTimespan(year_t year, month_t month, day_t day) {
	month = std::clamp<month_t>(month, 1, MONTHS_IN_YEAR);
	day = std::clamp<day_t>(day, 1, DAYS_IN_MONTH[month - 1]);
	return year * DAYS_IN_YEAR + DAYS_UP_TO_MONTH[month - 1] + day - 1;
}

Timespan::day_t const* Date::DAYS_UP_TO_MONTH = generate_days_up_to_month();

Timespan::day_t const* Date::generate_days_up_to_month() {
	static Timespan::day_t days_up_to_month[MONTHS_IN_YEAR];
	Timespan::day_t days = 0;
	for (int month = 0; month < MONTHS_IN_YEAR;
		days_up_to_month[month] = days, days += DAYS_IN_MONTH[month++]);
	assert(days == DAYS_IN_YEAR);
	return days_up_to_month;
}

Date::month_t const* Date::MONTH_FROM_DAY_IN_YEAR = generate_month_from_day_in_year();

Date::month_t const* Date::generate_month_from_day_in_year() {
	static month_t month_from_day_in_year[DAYS_IN_YEAR];
	Timespan::day_t days_left = 0;
	for (int day = 0, month = 0; day < DAYS_IN_YEAR;
		days_left = (days_left > 0 ? days_left : DAYS_IN_MONTH[month++]) - 1,
		month_from_day_in_year[day++] = month);
	assert(days_left == 0);
	assert(month_from_day_in_year[DAYS_IN_YEAR - 1] == MONTHS_IN_YEAR);
	return month_from_day_in_year;
}

Date::Date(Timespan total_days) : timespan { total_days } {
	if (timespan < 0) {
		Logger::error("Invalid timespan for date: ", timespan, " (cannot be negative)");
		timespan = 0;
	}
}

Date::Date(year_t year, month_t month, day_t day) : timespan { _dateToTimespan(year, month, day) } {}

Date::year_t Date::getYear() const {
	return static_cast<Timespan::day_t>(timespan) / DAYS_IN_YEAR;
}

Date::month_t Date::getMonth() const {
	return MONTH_FROM_DAY_IN_YEAR[static_cast<Timespan::day_t>(timespan) % DAYS_IN_YEAR];
}

Date::day_t Date::getDay() const {
	return (static_cast<Timespan::day_t>(timespan) % DAYS_IN_YEAR) - DAYS_UP_TO_MONTH[getMonth() - 1] + 1;
}

bool Date::operator<(Date other) const { return timespan < other.timespan; };
bool Date::operator>(Date other) const { return timespan > other.timespan; };
bool Date::operator<=(Date other) const { return timespan <= other.timespan; };
bool Date::operator>=(Date other) const { return timespan >= other.timespan; };
bool Date::operator==(Date other) const { return timespan == other.timespan; };
bool Date::operator!=(Date other) const { return timespan != other.timespan; };

Date Date::operator+(Timespan other) const { return timespan + other; }

Timespan Date::operator-(Date other) const { return timespan - other.timespan; }

Date& Date::operator+=(Timespan other) {
	timespan += other;
	return *this;
}

Date& Date::operator-=(Timespan other) {
	timespan -= other;
	return *this;
}

Date& Date::operator++() {
	timespan++;
	return *this;
}

Date Date::operator++(int) {
	Date old = *this;
	++(*this);
	return old;
}

std::string Date::to_string() const {
	std::stringstream ss;
	ss << *this;
	return ss.str();
}

Date::operator std::string() const {
	return to_string();
}

std::ostream& OpenVic::operator<<(std::ostream& out, Date const& date) {
	return out << static_cast<int>(date.getYear()) << Date::SEPARATOR_CHARACTER << static_cast<int>(date.getMonth()) << Date::SEPARATOR_CHARACTER << static_cast<int>(date.getDay());
}

// Parsed from string of the form YYYY.MM.DD
Date Date::from_string(char const* const str, char const* const end, bool* successful) {
	if (successful != nullptr) *successful = true;

	year_t year = 0;
	month_t month = 1;
	day_t day = 1;

	if (str == nullptr || end <= str) {
		Logger::error("Invalid string start/end pointers: ", static_cast<void const*>(str), " - ", static_cast<void const*>(end));
		if (successful != nullptr) *successful = false;
		return { year, month, day };
	}

	char const* year_end = str;
	while (std::isdigit(*year_end) && ++year_end < end);

	if (year_end <= str) {
		Logger::error("Failed to find year digits in date: ", std::string_view { str, static_cast<size_t>(end - str) });
		if (successful != nullptr) *successful = false;
		return { year, month, day };
	}

	bool sub_successful = false;
	uint64_t val = StringUtils::string_to_uint64(str, year_end, &sub_successful, 10);
	if (!sub_successful || val > std::numeric_limits<year_t>::max()) {
		Logger::error("Failed to read year: ", std::string_view { str, static_cast<size_t>(end - str) });
		if (successful != nullptr) *successful = false;
		return { year, month, day };
	}
	year = val;
	if (year_end < end) {
		if (*year_end == SEPARATOR_CHARACTER) {
			char const* const month_start = year_end + 1;
			char const* month_end = month_start;
			if (month_start < end) {
				while (std::isdigit(*month_end) && ++month_end < end);
			}
			if (month_start >= month_end) {
				Logger::error("Failed to find month digits in date: ", std::string_view { str, static_cast<size_t>(end - str) });
				if (successful != nullptr) *successful = false;
			} else {
				sub_successful = false;
				val = StringUtils::string_to_uint64(month_start, month_end, &sub_successful, 10);
				if (!sub_successful || val < 1 || val > MONTHS_IN_YEAR) {
					Logger::error("Failed to read month: ", std::string_view { str, static_cast<size_t>(end - str) });
					if (successful != nullptr) *successful = false;
				} else {
					month = val;
					if (month_end < end) {
						if (*month_end == SEPARATOR_CHARACTER) {
							char const* const day_start = month_end + 1;
							char const* day_end = day_start;
							if (day_start < end) {
								while (std::isdigit(*day_end) && ++day_end < end);
							}
							if (day_start >= day_end) {
								Logger::error("Failed to find day digits in date: ", std::string_view { str, static_cast<size_t>(end - str) });
								if (successful != nullptr) *successful = false;
							} else {
								sub_successful = false;
								val = StringUtils::string_to_uint64(day_start, day_end, &sub_successful);
								if (!sub_successful || val < 1 || val > DAYS_IN_MONTH[month - 1]) {
									Logger::error("Failed to read day: ", std::string_view { str, static_cast<size_t>(end - str) });
									if (successful != nullptr) *successful = false;
								} else {
									day = val;
									if (day_end < end) {
										Logger::error("Unexpected string \"", std::string_view { day_end, static_cast<size_t>(end - day_end) }, "\" at the end of date ", std::string_view { str, static_cast<size_t>(end - str) });
										if (successful != nullptr) *successful = false;
									}
								}
							}
						} else {
							Logger::error("Unexpected character \"", *month_end, "\" in month of date ", std::string_view { str, static_cast<size_t>(end - str) });
							if (successful != nullptr) *successful = false;
						}
					}
				}
			}
		} else {
			Logger::error("Unexpected character \"", *year_end, "\" in year of date ", std::string_view { str, static_cast<size_t>(end - str) });
			if (successful != nullptr) *successful = false;
		}
	}
	return { year, month, day };
};

Date Date::from_string(char const* str, size_t length, bool* successful) {
	return from_string(str, str + length, successful);
}

Date Date::from_string(std::string_view str, bool* successful) {
	return from_string(str.data(), str.length(), successful);
}