import csv
import os
import uuid
import json
from ics import Calendar, Event
from datetime import datetime
import pytz

UID_STORE_FILE = "event_uids.json"

def load_uids():
    """Load the UID mappings from a JSON file."""
    if os.path.exists(UID_STORE_FILE):
        with open(UID_STORE_FILE, "r") as file:
            return json.load(file)
    return {}

def save_uids(uids):
    """Save the UID mappings to a JSON file."""
    with open(UID_STORE_FILE, "w") as file:
        json.dump(uids, file)

def generate_ical_from_csv(csv_file):
    # Load existing UIDs
    uids = load_uids()

    # Generate the output .ics file name
    ical_file = os.path.splitext(csv_file)[0] + '.ics'

    # Define CET time zone
    cet = pytz.timezone('Europe/Berlin')

    # Create a new calendar
    calendar = Calendar()

    # Read the CSV file
    try:
        with open(csv_file, mode='r', encoding='utf-8-sig', errors='replace') as file:
            reader = csv.DictReader(file, delimiter=';')  # Updated to use ';' as the delimiter
            for row in reader:
                try:
                    # Parse the data from CSV
                    host = row['Host']
                    description = row['Description']
                    date = row['Date'].strip()  # Expected format: DD.MM.YYYY
                    start_time = row['start time'].strip()  # Expected format: HH:MM
                    end_time = row['end time'].strip()  # Expected format: HH:MM
                    location = row['Location']
                    # Combine date and time using the updated date format and apply CET
                    start_datetime = cet.localize(datetime.strptime(f"{date} {start_time}", "%d.%m.%Y %H:%M"))
                    end_datetime = cet.localize(datetime.strptime(f"{date} {end_time}", "%d.%m.%Y %H:%M"))
                    # Create a unique key for the event
                    event_key = f"{description}_{date}_{start_time}_{location}"
                    # Retrieve or generate a UID
                    uid = uids.get(event_key, str(uuid.uuid4()))
                    uids[event_key] = uid
                    # Create a new event
                    event = Event()
                    event.name = f"{description} (Gastgeber: {host})"
                    event.begin = start_datetime
                    event.end = end_datetime
                    event.location = location
                    event.uid = uid  # Set the unique identifier
                    event.last_modified = datetime.now()  # Timestamp for updates
                    # Add the event to the calendar
                    calendar.events.add(event)
                except Exception as e:
                    print(f"Error processing row: {row}. Error: {e}")
        # Write the calendar to an iCal file
        with open(ical_file, mode='w', encoding='utf-8') as file:
            file.writelines(calendar)
        # Save UIDs for future use
        save_uids(uids)

        print(f"iCal file created: {ical_file}")

    except Exception as e:
        print(f"Failed to read CSV file: {csv_file}. Error: {e}")

# Usage Example
if __name__ == "__main__":
    # Ask the user for the CSV file
    csv_file = input("Enter the path to the CSV file: ").strip()

    # Validate the file exists
    if not os.path.isfile(csv_file):
        print("The specified file does not exist. Please try again.")
    else:
        generate_ical_from_csv(csv_file)