#!/usr/bin/env python3
"""
Generate calendar.ics and README.md from meetings.yaml
"""

import yaml
from datetime import datetime, timedelta
from zoneinfo import ZoneInfo
import hashlib


def load_meetings(yaml_file='meetings.yaml'):
    """Load meetings from YAML file"""
    with open(yaml_file, 'r') as f:
        data = yaml.safe_load(f)
    return data['meetings']


def filter_meetings(meetings, months=3):
    """Filter meetings to show only those within the last/next N months"""
    now = datetime.now()
    cutoff_past = now - timedelta(days=30 * months)
    cutoff_future = now + timedelta(days=30 * months)

    filtered = []
    for meeting in meetings:
        meeting_date = datetime.strptime(meeting['date'], '%Y-%m-%d')
        if cutoff_past <= meeting_date <= cutoff_future:
            filtered.append(meeting)

    return sorted(filtered, key=lambda m: m['date'])


def generate_ics(meetings, output_file='calendar.ics'):
    """Generate iCalendar file from meetings"""
    lines = [
        'BEGIN:VCALENDAR',
        'VERSION:2.0',
        'PRODID:-//Linux Cast User Group//Events//EN',
        'CALSCALE:GREGORIAN',
        'METHOD:PUBLISH',
        'X-WR-CALNAME:Linux Cast User Group Meetings',
        'X-WR-TIMEZONE:America/New_York',
        'X-WR-CALDESC:Bi-monthly meetings for the Linux Cast User Group',
        ''
    ]

    for meeting in meetings:
        # Parse date and time
        date_str = meeting['date']
        time_str = meeting['time']
        tz_str = meeting['timezone']

        dt = datetime.strptime(f"{date_str} {time_str}", '%Y-%m-%d %H:%M')
        tz = ZoneInfo(tz_str)
        dt_local = dt.replace(tzinfo=tz)

        # Convert to UTC for iCalendar
        dt_utc = dt_local.astimezone(ZoneInfo('UTC'))
        dt_end_utc = dt_utc + timedelta(hours=1)

        # Generate unique ID
        uid_base = f"{date_str}-{meeting['title']}"
        uid = hashlib.md5(uid_base.encode()).hexdigest()

        # Format timestamps
        dtstamp = datetime.now(ZoneInfo('UTC')).strftime('%Y%m%dT%H%M%SZ')
        dtstart = dt_utc.strftime('%Y%m%dT%H%M%SZ')
        dtend = dt_end_utc.strftime('%Y%m%dT%H%M%SZ')

        lines.extend([
            'BEGIN:VEVENT',
            f'UID:{uid}@thelinuxcast.org',
            f'DTSTAMP:{dtstamp}',
            f'DTSTART:{dtstart}',
            f'DTEND:{dtend}',
            f'SUMMARY:Linux Cast User Group: {meeting["title"]}',
            f'DESCRIPTION:{meeting["title"]}\\n\\n{meeting["description"]}',
            f'LOCATION:{meeting.get("location", "Online")}',
            'STATUS:CONFIRMED',
            'END:VEVENT',
            ''
        ])

    lines.append('END:VCALENDAR')

    with open(output_file, 'w') as f:
        f.write('\n'.join(lines))

    print(f"Generated {output_file}")


def generate_readme(meetings, output_file='README.md'):
    """Generate README.md from meetings"""
    now = datetime.now()

    # Separate past and upcoming meetings
    past_meetings = []
    upcoming_meetings = []

    for meeting in meetings:
        meeting_date = datetime.strptime(meeting['date'], '%Y-%m-%d')
        if meeting_date < now:
            past_meetings.append(meeting)
        else:
            upcoming_meetings.append(meeting)

    # Sort
    past_meetings = sorted(past_meetings, key=lambda m: m['date'], reverse=True)
    upcoming_meetings = sorted(upcoming_meetings, key=lambda m: m['date'])

    lines = [
        '# Linux Cast User Group Meetings',
        '',
        '**[Subscribe to Calendar](calendar.ics)** | **[Download ICS](calendar.ics)**',
        '',
    ]

    # Upcoming events
    if upcoming_meetings:
        lines.append('## Upcoming Events')
        lines.append('')

        for meeting in upcoming_meetings:
            dt = datetime.strptime(f"{meeting['date']} {meeting['time']}", '%Y-%m-%d %H:%M')
            formatted_date = dt.strftime('%B %d, %Y at %I:%M %p')

            lines.extend([
                f"### {meeting['title']}",
                f"- **Date:** {formatted_date} EST",
                f"- **Location:** {meeting.get('location', 'Online')}",
                f"- **Description:** {meeting['description']}",
                ''
            ])

    # Recent past events
    if past_meetings:
        lines.append('## Recent Past Events')
        lines.append('')

        for meeting in past_meetings:
            dt = datetime.strptime(f"{meeting['date']} {meeting['time']}", '%Y-%m-%d %H:%M')
            formatted_date = dt.strftime('%B %d, %Y at %I:%M %p')

            lines.extend([
                f"### {meeting['title']}",
                f"- **Date:** {formatted_date} EST",
                f"- **Location:** {meeting.get('location', 'Online')}",
                f"- **Description:** {meeting['description']}",
                ''
            ])

    with open(output_file, 'w') as f:
        f.write('\n'.join(lines))

    print(f"Generated {output_file}")


def main():
    """Main function"""
    print("Loading meetings from meetings.yaml...")
    meetings = load_meetings()

    print(f"Found {len(meetings)} total meetings")

    # Filter to 3 months
    filtered_meetings = filter_meetings(meetings, months=3)
    print(f"Filtered to {len(filtered_meetings)} meetings within 3 months")

    # Generate files
    generate_ics(filtered_meetings)
    generate_readme(filtered_meetings)

    print("Done!")


if __name__ == '__main__':
    main()