package com.imooc;

import java.util.Scanner;

public class PrintCalendar {

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub
    Scanner input =new Scanner(System.in);
    System.out.print("Enter full year: ");
    int year=input.nextInt();
    System.out.print("Enter month: ");
    int month=input.nextInt();
    
    printMonth(year,month);
}
public static void printMonth(int year,int month){
    printMonthTitle(year,month);
    printMonthBody(year,month);
}
private static void printMonthBody(int year, int month) {
    // TODO Auto-generated method stub
    int startDay=getStartDay(year,month);
    int numberOfDaysInMonth=getNumberOfDaysInMonth(year,month);
    
    int i=0;
    for(i=0;i<startDay;i++)
    {
        System.out.print(" ");
    }
    for(i=1;i<=numberOfDaysInMonth;i++){
         System.out.printf("%4d",i);
         if((i+startDay)%7==0)
             System.out.println();
    }
    System.out.println();
}
private static int getStartDay(int year, int month) {
    // TODO Auto-generated method stub
    final int START_DAY_FOR_JAN_1_1800=3;
    int totalNumberOfDays=getTotalNumberOfDays(year,month);
    
    return(totalNumberOfDays+START_DAY_FOR_JAN_1_1800)%7;
}
private static int getTotalNumberOfDays(int year, int month) {
    // TODO Auto-generated method stub
    int total=0;
    for(int i=1800;i<year;i++)
        if(isLeapYear(i))
            total=total+366;
        else
            total=total+365;
    for(int i=1;i<month;i++)
        total=total+getNumberOfDaysInMonth(year,i);
    
    return total;
}
private static int getNumberOfDaysInMonth(int year, int month) {
    // TODO Auto-generated method stub
    if(month==1||month==3||month==7||month==8||month==10||month==12)
        return 31;
    if(month==4||month==6||month==9||month==11)
        return 30;
    if(month==2) return isLeapYear(year)?29:28;
    
    return 0;
}
private static boolean isLeapYear(int year) {
    // TODO Auto-generated method stub
    return year%400==0||(year%4==0&&year%100!=0);
}
private static void printMonthTitle(int year, int month) {
    // TODO Auto-generated method stub
    System.out.println("      "+getMonthName(month)+" "+year);
    System.out.println("-----------------------------");
    System.out.println(" Sun Mon Tue Wed Thu Fri Sat");
}
private static String getMonthName(int month) {
    String monthName="";
    switch(month){
    case 1:monthName="January";break;
    case 2:monthName="February";break;
    case 3:monthName="March";break;
    case 4:monthName="April";break;
    case 5:monthName="May";;break;
    case 6:monthName="June";break;
    case 7:monthName="July";break;
    case 8:monthName="August";break;
    case 9:monthName="September";break;
    case 10:monthName="October";break;
    case 11:monthName="November";break;
    case 12:monthName="December";break;
    }
    return monthName;
}

}