import os
import msal
import requests
import json
from datetime import datetime
from dateutil import parser

# Read Azure app credentials from environment variables
client_id = os.getenv('AZURE_CLIENT_ID')
tenant_id = os.getenv('AZURE_TENANT_ID')

if not client_id or not tenant_id:
    raise ValueError("Please set the AZURE_CLIENT_ID and AZURE_TENANT_ID environment variables.")

# Authentication
authority = f'https://login.microsoftonline.com/{tenant_id}'
scopes = ['https://graph.microsoft.com/Calendars.Read']

app = msal.PublicClientApplication(client_id, authority=authority)
flow = app.initiate_device_flow(scopes=scopes)
if 'user_code' not in flow:
    raise Exception("Failed to create device flow")
print(flow['message'])
token_response = app.acquire_token_by_device_flow(flow)

if 'access_token' not in token_response:
    raise Exception("Failed to acquire token")

access_token = token_response['access_token']

# Fetch events with pagination and expand recurring events
headers = {'Authorization': f'Bearer {access_token}'}
events_url = 'https://graph.microsoft.com/v1.0/me/events?$top=100&$expand=instances'
events = []

while events_url:
    response = requests.get(events_url, headers=headers)
    response_data = response.json()
    events.extend(response_data.get('value', []))
    events_url = response_data.get('@odata.nextLink')

# Save events to a file in iCalendar format
with open('outlook_events.ics', 'w') as f:
    f.write("BEGIN:VCALENDAR\nVERSION:2.0\n")
    for event in events:
        if 'start' in event and 'end' in event:
            start = parser.isoparse(event['start']['dateTime'])
            end = parser.isoparse(event['end']['dateTime'])
            f.write(f"BEGIN:VEVENT\nSUMMARY:{event['subject']}\n")
            f.write(f"DTSTART:{start.strftime('%Y%m%dT%H%M%S')}\n")
            f.write(f"DTEND:{end.strftime('%Y%m%dT%H%M%S')}\n")
            f.write("END:VEVENT\n")
    f.write("END:VCALENDAR\n")