python
from flask import Flask, render_template, request, jsonify, send_file
from ics import Calendar, Event
from datetime import datetime
import io

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/generate', methods=['POST'])
def generate_ics():
    try:
        data = request.get_json()
        events_data = data.get('events', [])
        
        cal = Calendar()
        
        for event_data in events_data:
            event = Event()
            event.name = event_data.get('title', 'Untitled Event')
            event.location = event_data.get('location', '')
            event.description = event_data.get('description', '')
            
            # Parse dates based on all-day flag
            is_all_day = event_data.get('allDay', False)
            
            if is_all_day:
                start_str = event_data.get('start')
                end_str = event_data.get('end')
                
                # Parse date strings (format depends on browser locale)
                start_date = datetime.strptime(start_str.split('T')[0], '%Y-%m-%d').date()
                end_date = datetime.strptime(end_str.split('T')[0], '%Y-%m-%d').date()
                
                event.begin = start_date
                event.end = end_date
                event.all_day = True
            else:
                # Parse datetime strings
                start_str = event_data.get('start')
                end_str = event_data.get('end')
                
                # Handle different datetime formats from different browsers
                for fmt in ('%Y-%m-%dT%H:%M', '%m/%d/%Y, %I:%M:%S %p', '%Y-%m-%d %H:%M:%S'):
                    try:
                        start_dt = datetime.strptime(start_str, fmt)
                        end_dt = datetime.strptime(end_str, fmt)
                        event.begin = start_dt
                        event.end = end_dt
                        break
                    except ValueError:
                        continue
            
            cal.events.add(event)
        
        # Create in-memory file
        ics_file = io.BytesIO()
        ics_file.write(str(cal).encode('utf-8'))
        ics_file.seek(0)
        
        return send_file(
            ics_file,
            as_attachment=True,
            download_name='calendar_events.ics',
            mimetype='text/calendar'
        )
        
    except Exception as e:
        print(f"Error generating ICS: {str(e)}")
        return jsonify({'error': str(e)}), 500

if __name__ == '__main__':
    app.run(debug=True)

</html>