#include<stdio.h>
#include<stdlib.h>
#include<math.h>

// print函数用于显示菜单时，打印星号和空格。 
void print(char c, int n)
{
    int i;
    for (i = 1; i <= n; i++)
    {
        putchar(c);
    }
}

// 查询某年某月某日的日期是周几。
int getWeekday(int year, int month, int day) {
    // 计算1582年10月4日后是星期几的函数
    if (year <= 1582) {
        if (month < 3) {
            year--;
            month += 12;
        }
        int h = (day + 2 * month + 3 * (month + 1) / 5 + year + year / 4 - year / 100 + year / 400) % 7;
        return h + 1;
    }
    // 计算1582年10月4日及以前给定日期是星期几的函数
    else if (year > 1582) {
        if (month < 3) {
            year--;
            month += 12;
        }
        int c = year / 100;
        int y = year % 100;
        int m = month;
        int d = day;
        int w = c / 4 - 2 * c + y + y / 4 + (13 * (m + 1) / 5) + d - 1;
        w = w % 7;
        if (w < 0) {
            w += 7;
        }
        return w;
    }
    return -1; 
}

// 检查日期合法性的函数
int isDateValid(int year, int month, int day) {
    if (month < 1 || month > 12) {
        return 0;
    }
    if (day < 1) {
        return 0;
    }
    if (month == 2) {
        if (((year % 4 == 0 && year % 100!= 0) || year % 400 == 0) && day > 29) {
            return 0;
        }
        else if (day > 28) {
            return 0;
        }
    }
    return 1;
}

// 判断是否为闰年
int isLeapYear(int year) {
    return ((year % 4 == 0 && year % 100!= 0) || year % 400 == 0);
}

// 获取指定月份的天数
int getDaysInMonth(int month, int year) {
    int days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
    if (month == 2 && isLeapYear(year)) {
        return 29;
    }
    return days[month - 1];
}

// 输出日历头部（月份和星期）
void printCalendarHeader(int month, int year) {
    const char* months[] = { "一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月" };
    if (year == 1582 && month == 10) {
        printf("\n十月 1582 (Special Month)\n");
    }
    else {
        printf("\n%s %d\n", months[month - 1], year);
    }
    printf("星期一 星期二 星期三 星期四 星期五 星期六 星期日\n");
}

// 输出日历主体（日期部分）
void printCalendarBody(int month, int year, int format,int day) { 
    int daysInMonth = getDaysInMonth(month, year);
     if (month < 3) {
        year--;
        month += 12;
    }
    int k = year % 100;
    int j = year / 100;
    int firstDay =(day + 13 * (month + 1) / 5 + k + k / 4 + j / 4 + 5 * j) % 7-1;
    if (format == 1) {  // 单列格式输出逻辑
        if (year == 1582 && month == 10) {  
            for (int day = 1; day <=4; day++) {
                printf("  %.2d   ", day);
				if ((firstDay + day) % 7 == 0) {
                    printf("\n");
                }
				}
            for (int day = 15; day <= daysInMonth; day++) {
                printf("  %.2d   ", day);
                if ((firstDay + day) % 7 == 0) {
                    printf("\n");
                }
            }
			}else {
        	for (int i = 0; i < firstDay; i++) {
                printf("        ");
            }
			for (int day = 1; day <= daysInMonth; day++) {
            printf("  %.2d   ",day);
            if((firstDay + day) % 7 == 0){
			printf("\n");
			}
			}
		}
		}else {  //双列格式输出逻辑
        if (year == 1582 && month == 10) {
            for (int day = 1; day <=4; day++) {
                printf("  %.2d   ", day);
            }
            for (int day = 15; day <= daysInMonth; day++) {
                printf("  %.2d   ", day);
                if ((firstDay + day) % 7 == 0) {
                    printf("\n");
                }
            }
            if ((firstDay + daysInMonth) % 7!= 0) {
                printf("\n");
            }
        }
        else {
            for (int i = 1; i < firstDay; i++) {
                printf("    ");
            }

            for (int day = 1; day <= daysInMonth; day++) {
                printf("  %.2d   ", day);
                if ((firstDay + day) % 7 == 6) {
                    printf("\n");
                }
            }
            if ((firstDay + daysInMonth) % 7!= 6) {
                printf("\n");
            }
        }
    }
}
void showMenu()
{
    putchar('\n');
    print(' ', 10);
    print('*', 60);
    putchar('\n');
    print(' ', 20);
    printf("1--查询某年某月某日的日期是周几\n");
    print(' ', 20);
    printf("2--该年是否为闰年\n");
    print(' ', 20);
    printf("3--输入年份，输出这一年的日历\n"); 
    print(' ', 10);
    print('*', 60);
    putchar('\n');
}

int main()
{
    int choice;
    char ifcontinue;
    int year, month, day; 

    showMenu();
    // 选择菜单。
    while (1) {
        printf("\n请选择一个菜单(1-3): ");
        scanf("%d", &choice);
        switch (choice) {
        case 1:
            printf("请输入年份：");
            scanf("%d", &year);
            printf("请输入月份：");
            scanf("%d", &month);
            printf("请输入日期：");
            scanf("%d", &day);
            if (isDateValid(year, month, day)) {
                int weekday = getWeekday(year, month, day);
                switch (weekday) {
                case 0:
                    printf("%d年%d月%d日是星期日\n", year, month, day);
                    break;
                case 1:
                    printf("%d年%d月%d日是星期一\n", year, month, day);
                    break;
                case 2:
                    printf("%d年%d月%d日是星期二\n", year, month, day);
                    break;
                case 3:
                    printf("%d年%d月%d日是星期三\n", year, month, day);
                    break;
                case 4:
                    printf("%d年%d月%d日是星期四\n", year, month, day);
                    break;
                case 5:
                    printf("%d年%d月%d日是星期五\n", year, month, day);
                    break;
                case 6:
                    printf("%d年%d月%d日是星期六\n", year, month, day);
                    break;
                default:
                    printf("计算出现错误\n");
                }
            }
            else {
                printf("输入的日期不合法，请重新输入正确的日期\n");
            }
            break;
        case 2:
            printf("请输入一个年份: ");
            scanf("%d", &year);
            if (isLeapYear(year)) {
                printf("%d年是闰年\n", year);
            }
            else {
                printf("%d年不是闰年\n", year);
            }
            break;
        case 3:
            printf("请输入年份: ");
            scanf("%d", &year);
            int format;
            printf("请选择日历输出格式（1表示单列，2表示双列）: "); 
            scanf("%d", &format);
            for (int m = 1; m <= 12; m++) {
                printCalendarHeader(m, year);
                printCalendarBody(m, year, format,day);
            }
            break;
        default:
            printf("\n无效\n");
        }
        printf("\n返回请输入6:");
        getchar();  // 处理scanf输入后的换行符
        ifcontinue = getchar();
        if (ifcontinue!= '6') {
            break;
        }
    }

    return 0;
}