/*
 * This file is part of OpenTTD.
 * OpenTTD 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, version 2.
 * OpenTTD 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 OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

/**
 * @file timer_game_economy.cpp
 * This file implements the timer logic for the game-economy-timer.
 */

/**
 * Economy time is used for the regular pace of the game, including:
 * - Industry and house production/consumption
 * - Industry production changes, closure, and spawning
 * - Town growth
 * - Company age and financial statistics
 * - Vehicle financial statistics
 * - Vehicle aging, depreciation, reliability, and renewal
 * - Payment intervals for running and maintenance costs, loan interest, etc.
 * - Cargo payment "time" calculation
 * - Local authority and station ratings change intervals
 */

#include "../stdafx.h"
#include "../openttd.h"
#include "timer.h"
#include "timer_game_economy.h"
#include "timer_game_tick.h"
#include "../vehicle_base.h"
#include "../linkgraph/linkgraph.h"

#include "../safeguards.h"

TimerGameEconomy::Year TimerGameEconomy::year = {};
TimerGameEconomy::Month TimerGameEconomy::month = {};
TimerGameEconomy::Date TimerGameEconomy::date = {};
TimerGameEconomy::DateFract TimerGameEconomy::date_fract = {};
uint TimerGameEconomy::days_since_last_month = {};

/**
 * Converts a Date to a Year, Month & Day.
 * @param date the date to convert from
 * @returns YearMonthDay representation of the Date.
 */
/* static */ TimerGameEconomy::YearMonthDay TimerGameEconomy::ConvertDateToYMD(TimerGameEconomy::Date date)
{
	/* If we're not using wallclock units, we keep the economy date in sync with the calendar. */
	if (!UsingWallclockUnits()) return CalendarConvertDateToYMD(date);

	/* If we're using wallclock units, economy months have 30 days and an economy year has 360 days. */
	TimerGameEconomy::YearMonthDay ymd;
	ymd.year = Year{date.base() / EconomyTime::DAYS_IN_ECONOMY_YEAR};
	ymd.month = (date.base() % EconomyTime::DAYS_IN_ECONOMY_YEAR) / EconomyTime::DAYS_IN_ECONOMY_MONTH;
	ymd.day = (date.base() % EconomyTime::DAYS_IN_ECONOMY_MONTH) + 1;
	return ymd;
}

/**
 * Converts a tuple of Year, Month and Day to a Date.
 * @param year  is a number between 0..MAX_YEAR
 * @param month is a number between 0..11
 * @param day   is a number between 1..31
 * @returns The equivalent date.
 */
/* static */ TimerGameEconomy::Date TimerGameEconomy::ConvertYMDToDate(TimerGameEconomy::Year year, TimerGameEconomy::Month month, TimerGameEconomy::Day day)
{
	/* If we're not using wallclock units, we keep the economy date in sync with the calendar. */
	if (!UsingWallclockUnits()) return CalendarConvertYMDToDate(year, month, day);

	/* If we're using wallclock units, economy months have 30 days and an economy year has 360 days. */
	const int total_months = (year.base() * EconomyTime::MONTHS_IN_YEAR) + month;
	return TimerGameEconomy::Date{(total_months * EconomyTime::DAYS_IN_ECONOMY_MONTH) + day - 1}; // Day is 1-indexed but Date is 0-indexed, hence the - 1.
}

/**
 * Set the date.
 * @param date The new date
 * @param fract The number of ticks that have passed on this date.
 */
/* static */ void TimerGameEconomy::SetDate(TimerGameEconomy::Date date, TimerGameEconomy::DateFract fract)
{
	assert(fract < Ticks::DAY_TICKS);

	TimerGameEconomy::date = date;
	TimerGameEconomy::date_fract = fract;
	TimerGameEconomy::YearMonthDay ymd = TimerGameEconomy::ConvertDateToYMD(date);
	TimerGameEconomy::year = ymd.year;
	TimerGameEconomy::month = ymd.month;
}

/**
 * Check if we are using wallclock units.
 * @param newgame Should we check the settings for a new game (since we are in the main menu)?
 * @return True if the game is using wallclock units, or false if the game is using calendar units.
 */
/* static */ bool TimerGameEconomy::UsingWallclockUnits(bool newgame)
{
	if (newgame) return (_settings_newgame.economy.timekeeping_units == TKU_WALLCLOCK);

	return (_settings_game.economy.timekeeping_units == TKU_WALLCLOCK);
}

template <>
void IntervalTimer<TimerGameEconomy>::Elapsed(TimerGameEconomy::TElapsed trigger)
{
	if (trigger == this->period.trigger) {
		this->callback(1);
	}
}

template <>
void TimeoutTimer<TimerGameEconomy>::Elapsed(TimerGameEconomy::TElapsed trigger)
{
	if (this->fired) return;

	if (trigger == this->period.trigger) {
		this->callback();
		this->fired = true;
	}
}

template <>
bool TimerManager<TimerGameEconomy>::Elapsed([[maybe_unused]] TimerGameEconomy::TElapsed delta)
{
	assert(delta == 1);

	if (_game_mode == GM_MENU) return false;

	TimerGameEconomy::date_fract++;
	if (TimerGameEconomy::date_fract < Ticks::DAY_TICKS) return true;
	TimerGameEconomy::date_fract = 0;

	/* increase day counter */
	TimerGameEconomy::date++;
	++TimerGameEconomy::days_since_last_month;

	TimerGameEconomy::YearMonthDay ymd = TimerGameEconomy::ConvertDateToYMD(TimerGameEconomy::date);

	/* check if we entered a new month? */
	bool new_month = ymd.month != TimerGameEconomy::month;

	/* check if we entered a new year? */
	bool new_year = ymd.year != TimerGameEconomy::year;

	/* update internal variables before calling the daily/monthly/yearly loops */
	TimerGameEconomy::month = ymd.month;
	TimerGameEconomy::year = ymd.year;

	/* Make a temporary copy of the timers, as a timer's callback might add/remove other timers. */
	auto timers = TimerManager<TimerGameEconomy>::GetTimers();

	for (auto timer : timers) {
		timer->Elapsed(TimerGameEconomy::DAY);
	}

	if ((TimerGameEconomy::date.base() % 7) == 3) {
		for (auto timer : timers) {
			timer->Elapsed(TimerGameEconomy::WEEK);
		}
	}

	if (new_month) {
		for (auto timer : timers) {
			timer->Elapsed(TimerGameEconomy::MONTH);
		}

		if ((TimerGameEconomy::month % 3) == 0) {
			for (auto timer : timers) {
				timer->Elapsed(TimerGameEconomy::QUARTER);
			}
		}
	}

	if (new_year) {
		for (auto timer : timers) {
			timer->Elapsed(TimerGameEconomy::YEAR);
		}
	}

	if (new_month) TimerGameEconomy::days_since_last_month = 0;

	/* check if we reached the maximum year, decrement dates by a year */
	if (TimerGameEconomy::year == EconomyTime::MAX_YEAR + 1) {
		TimerGameEconomy::year--;
		int days_this_year = TimerGameEconomy::IsLeapYear(TimerGameEconomy::year) ? EconomyTime::DAYS_IN_LEAP_YEAR : EconomyTime::DAYS_IN_YEAR;
		TimerGameEconomy::date -= TimerGameEconomy::Date{days_this_year};
		for (Vehicle *v : Vehicle::Iterate()) v->ShiftDates(TimerGameEconomy::Date{-days_this_year});
		for (LinkGraph *lg : LinkGraph::Iterate()) lg->ShiftDates(TimerGameEconomy::Date{-days_this_year});
	}

	return true;
}

#ifdef WITH_ASSERT
template <>
void TimerManager<TimerGameEconomy>::Validate(TimerGameEconomy::TPeriod period)
{
	if (period.priority == TimerGameEconomy::Priority::NONE) return;

	/* Validate we didn't make a developer error and scheduled more than one
	 * entry on the same priority/trigger. There can only be one timer on
	 * a specific trigger/priority, to ensure we are deterministic. */
	for (const auto &timer : TimerManager<TimerGameEconomy>::GetTimers()) {
		if (timer->period.trigger != period.trigger) continue;

		assert(timer->period.priority != period.priority);
	}
}
#endif /* WITH_ASSERT */
