import json
import datetime

class Calendar:
    def __init__(self, filename="calendar_data.json"):
        self.filename = filename
        self.reminders = self.load_calendar()
        self.current_date = datetime.date.today()

    
    def load_calendar(self):
        """Load reminders from a file."""
        try:
            with open(self.filename, "r") as file:
                return json.load(file)
        except (FileNotFoundError, json.JSONDecodeError):
            return {}

    
    def save_calendar(self):
        """Save reminders to a file."""
        with open(self.filename, "w") as file:
            json.dump(self.reminders, file, indent=4)

    
    def add_reminder(self, date, reminder):
        """Add a reminder for a specific date."""
        if date not in self.reminders:
            self.reminders[date] = []
        self.reminders[date].append(reminder)
        self.save_calendar()
        print(f"Reminder added for {date}: {reminder}")

    def add_daterange(self, date_start, date_end, reminder):
        """Add a reminder for a date range."""
        date_yyyymm = date_start[:-2]
        date_start_day = int(date_start[-2:])
        date_end_day = int(date_end[-2:])
        for day_int in range(date_start_day, date_end_day+1):
            day_str = f"{day_int:02d}"
            date = str(date_yyyymm)+day_str
            if str(date) not in self.reminders:
                self.reminders[date] = []
            self.reminders[date].append(reminder)

            # debug
            # print(f"day_int: {day_int}")
            # print(f"day_str: {day_str}")
            # print(f"date: {date}")
            # print(f"reminder: {reminder}")
            
        self.save_calendar()
        print(f"Reminder added from {date_start} to {date_end} (inclusive of start and end dates): {reminder}")
        

    
    def show_all_reminders(self):
        """Show all past and future reminders in our calendar app"""
        if (self.reminders is None) or len(self.reminders)<1:
            print("No reminders in calendar app. Please create an event reminder to start using the app.")
        else:
            print("#  Date    Event Description")
            for i,(dt,event_description) in enumerate(self.reminders.items()):
                print(f"{i+1}. {dt} {event_description}")

    
    def show_future_reminders(self):
        """Show all future reminders in our calendar app"""
        if (self.reminders is None) or len(self.reminders)<1:
            print("No future reminders in calendar app. Please create a future event reminder.")
        else:
            current_datetime = datetime.datetime.now()
            
            print("#  Date    Event Description")
            print_counter=1
            for i,(dt,event_description) in enumerate(self.reminders.items()):
                dt = datetime.datetime.strptime(dt, '%Y-%m-%d')
                
                if current_datetime.date() <= dt.date():
                    print(f"{print_counter}. {dt.date()} {event_description}")
                    print_counter+=1

    
    def show_reminders(self, date):
        """Show reminders for a specific date."""
        if date in self.reminders:
            print(f"Reminders for {date}:")
            for i, reminder in enumerate(self.reminders[date], 1):
                print(f"{i}. {reminder}")
        else:
            print(f"No reminders for {date}.")

    
    def show_month(self, user_mth):
        """Show reminders for a specific month."""
        if (self.reminders is None) or len(self.reminders)<1:
            print(f"No reminders for month: {user_mth}.")
        else:
            # user_mth = int(user_mth)
            print(f"Event reminders for month: {user_mth}")
            print("#  Date    Event Description")
            print_counter=1
            for i,(dt,event_description) in enumerate(self.reminders.items()):
                # dt = datetime.datetime.strptime(dt, '%Y-%m-%d')
                # dt_month = dt.month
                dt_month = dt.split("-")[1]

                # print(f"user_mth: {user_mth}")
                # print(f"dt: {dt}")
                # print(f"dt_month: {dt_month}")
                
                if user_mth == dt_month:
                    print(f"{print_counter}. {dt} {event_description}")
                    print_counter+=1




if __name__ == "__main__":
    calendar = Calendar()
    
    while True:
        print("\nCalendar Menu:")
        print("1. Add Reminder for 1 day")
        print("2. Add Reminder for date range (in the same month, including weekends)")
        print("3. Show All Past and Future Reminders")
        print("4. Show All Future Reminders")
        print("5. Show Reminders for Specific Day")
        print("6. Show Reminders for Specific Month")
        print("7. Exit")
        choice = input("Choose an option number: ")

        # user create event reminder
        if choice == "1":
            date = input("Enter date (YYYY-MM-DD): ")
            reminder = input("Enter description for event reminder: ")
            calendar.add_reminder(date, reminder)
        elif choice == "2":
            date_start = input("Enter start date (YYYY-MM-DD): ")
            date_end = input("Enter end date (YYYY-MM-DD): ")
            reminder = input("Enter description for event reminder: ")
            calendar.add_daterange(date_start, date_end, reminder)

        # list ALL or future reminders
        elif choice == "3":
            calendar.show_all_reminders()
        elif choice == "4":
            calendar.show_future_reminders()

        # list reminders for specific date or month
        elif choice == "5":
            date = input("Enter date (YYYY-MM-DD): ")
            calendar.show_reminders(date)
        elif choice == "6":
            user_mth = input("Enter month number (MM): ")
            calendar.show_month(user_mth)

            
        elif choice == "7":
            calendar.save_calendar()
            break
        else:
            print("Invalid option. Please try again.")