// monthviewgen.cpp - Xestia Calendar month view generation functions.
//
// (c) 2016-2017 Xestia Software Development.
//
// This file is part of Xestia Calendar.
//
// Xestia Calendar 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 3 of the license.
//
// Xestia Calendar 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 Xestia Calendar. If not, see <http://www.gnu.org/licenses/>

#include "monthviewgen.h"

using namespace std;

int PreviousMonthNumberofDays(int Month, int Year){
	
	// Work out what the previous month is.
	
	// Return 31 if month matches.
	
	if (Month == 1 || Month == 2 || Month == 4 || 
		Month == 6 || Month == 8 || Month == 9 || Month == 11){
	
		return 31;
			
	}
	
	// Return 30 if month matches.
	
	if (Month == 5 || Month == 7 || Month == 10 || Month == 12){
		
		return 30;
		
	}
	
	// Work out if year is a leap year and return 28 or 29
	// for february.
	
	if (Year % 4 == 0){
		
		if (Year % 100 == 0){
			
			if (Year % 400 == 0){
			
				return 29;
				
			} else {
				
				return 28;
				
			}
			
		}
		
		return 29;
		
	} else {
		
		return 28;
		
	}
	
}

XCCalendarMonthViewGrid GenerateMonthGrid(int Month, int Year){
	
	XCCalendarMonthViewGrid MonthViewOutput;
	
	// Work out which day of the week the first day of 
	// the month is.
		
	time_t EmptyTime;
	struct tm * FirstDay;
	int PreviousMonthNumDays = PreviousMonthNumberofDays(Month, Year);
	int PreviousMonthDays = 0;
	int PreviousMonth = 0;
	int PreviousYear = Year;
	int DayWeekCount = 0;
	bool ProcessGrid = true;
	bool FirstWeekProcessing = true;
	
	time(&EmptyTime);
	
	FirstDay = localtime(&EmptyTime);
	FirstDay->tm_year = Year - 1900;
	FirstDay->tm_mon = Month - 1;
	FirstDay->tm_mday = 1;
	
	mktime(FirstDay);
	
	if (FirstDay->tm_wday == 0){
		PreviousMonthDays = 6;
	} else {
		PreviousMonthDays = FirstDay->tm_wday - 1;
	}
	
	if (Month == 1){
		
		PreviousMonth = 12;
		PreviousYear--;
		
	} else {

		PreviousMonth = Month - 1;
		
	}
	
	// Workout the days of the previous month for the
	// first week to be displayed.
	
	XCCalendarMonthViewGridDayWeek FirstWeek;
	
	for (int PreviousMonthDaysProcessing = 0; 
		PreviousMonthDaysProcessing < PreviousMonthDays; 
		PreviousMonthDaysProcessing++){
		
		XCCalendarMonthViewGridDayData DayItem;
			
		DayItem.Day = PreviousMonthNumDays - PreviousMonthDaysProcessing;
		DayItem.Month = PreviousMonth;
		DayItem.Year = PreviousYear;
		DayItem.IsInMonth = false;
			
		FirstWeek.DayList.insert(FirstWeek.DayList.begin(), DayItem);
			
		DayWeekCount++;
			
	}
	
	// Process the actual days of the month.

	XCCalendarMonthViewGridDayWeek MonthWeek;
	int ProcessDay = 1;
	
	while (ProcessGrid == true){
		
		if (DayWeekCount == 7){
			
			// Add to the month view grid.
			
			if (FirstWeekProcessing == true){
				
				FirstWeekProcessing = false;
				MonthViewOutput.WeekList.push_back(FirstWeek);
				
			} else {
			
				MonthViewOutput.WeekList.push_back(MonthWeek);
				MonthWeek.DayList.clear();
				
			}
			
			DayWeekCount = 0;
			continue;
			
		}

		XCCalendarMonthViewGridDayData DayItem;
		
		DayItem.Day = ProcessDay;
		DayItem.Month = Month;
		DayItem.Year = Year;
		DayItem.IsInMonth = true;
		
		if (FirstWeekProcessing == true){
			
			FirstWeek.DayList.push_back(DayItem);
			
		} else {
			
			MonthWeek.DayList.push_back(DayItem);
			
		}

		DayWeekCount++;
		
		if ((Month == 1 || Month == 3 || Month == 5 || 
			Month == 7 || Month == 8 || Month == 10 || Month == 12) && 
			ProcessDay == 31){
	
			break;
			
		}
	
		if ((Month == 4 || Month == 6 || Month == 9 || Month == 11) &&
			ProcessDay == 30){
		
			break;
		
		}
		
		if (Year % 4 == 0){
		
			if (Year % 100 == 0){
			
				if (Year % 400 == 0){
			
					if (Month == 2 && ProcessDay == 29){
					
						break;
						
					}
				
				} else {
				
					if (Month == 2 && ProcessDay == 28){
						
						break;
						
					}
				
				}
			
			}
		
			if (Month == 2 && ProcessDay == 29){

				break;
				
			}
		
		} else if ((Month == 2 && ProcessDay == 28) && Year % 4 != 0){
		
			break;
		
		}
		
		ProcessDay++;
		
		
	}
	
	// At the end of the month add any remaining days
	// (if required).
	
	int NextMonthYear = Year;
	int NextMonth = 0;
	int NextMonthDay = 1;
	
	if (Month == 12){
		
		NextMonth = 1;
		NextMonthYear++;
		
	} else {
		
		NextMonth = Month + 1;
		
	}
	
	for (; DayWeekCount < 7; DayWeekCount++){
	
		XCCalendarMonthViewGridDayData DayItem;
		
		DayItem.Day = NextMonthDay;
		DayItem.Month = NextMonth;
		DayItem.Year = NextMonthYear;
		DayItem.IsInMonth = false;

		MonthWeek.DayList.push_back(DayItem);
		NextMonthDay++;
		
	}
	
	if (DayWeekCount == 7){

		MonthViewOutput.WeekList.push_back(MonthWeek);
		
	}
	
	return MonthViewOutput;
	
}