"""
Weekly Digest Email Service
Sends weekly digest emails to users who have email_digest enabled.
Run via cron job: 0 9 * * 0 (Sunday at 9am)
"""
import os
import sys

# Add backend to path
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from datetime import datetime, timedelta
from sqlmodel import Session, select, func
from database import engine
from models import User, Show, Performance, Review, Rating, ChaseSong, Attendance


def get_weekly_stats(session: Session, user_id: int, start_date: datetime, end_date: datetime):
    """Get user's activity stats for the week"""
    
    # Shows attended this week
    shows_attended = session.exec(
        select(func.count(Attendance.id))
        .where(Attendance.user_id == user_id)
        .where(Attendance.created_at >= start_date)
        .where(Attendance.created_at < end_date)
    ).one() or 0
    
    # Reviews written this week
    reviews_written = session.exec(
        select(func.count(Review.id))
        .where(Review.user_id == user_id)
        .where(Review.created_at >= start_date)
        .where(Review.created_at < end_date)
    ).one() or 0
    
    # Ratings given this week
    ratings_given = session.exec(
        select(func.count(Rating.id))
        .where(Rating.user_id == user_id)
        .where(Rating.created_at >= start_date)
        .where(Rating.created_at < end_date)
    ).one() or 0
    
    # Check for caught chase songs
    chase_caught = session.exec(
        select(func.count(ChaseSong.id))
        .where(ChaseSong.user_id == user_id)
        .where(ChaseSong.caught_at >= start_date)
        .where(ChaseSong.caught_at < end_date)
    ).one() or 0
    
    return {
        "shows_attended": shows_attended,
        "reviews_written": reviews_written,
        "ratings_given": ratings_given,
        "chase_caught": chase_caught
    }


def get_community_highlights(session: Session, start_date: datetime, end_date: datetime):
    """Get community highlights for the week"""
    
    # New shows added
    new_shows = session.exec(
        select(func.count(Show.id))
        .where(Show.date >= start_date.date())
        .where(Show.date < end_date.date())
    ).one() or 0
    
    # Total reviews this week
    total_reviews = session.exec(
        select(func.count(Review.id))
        .where(Review.created_at >= start_date)
        .where(Review.created_at < end_date)
    ).one() or 0
    
    # Most reviewed performance this week
    top_perf = session.exec(
        select(Performance.id, func.count(Review.id).label("count"))
        .join(Review, Review.performance_id == Performance.id)
        .where(Review.created_at >= start_date)
        .where(Review.created_at < end_date)
        .group_by(Performance.id)
        .order_by(func.count(Review.id).desc())
        .limit(1)
    ).first()
    
    return {
        "new_shows": new_shows,
        "total_reviews": total_reviews,
        "top_performance_id": top_perf[0] if top_perf else None
    }


def send_digest_email(user, stats: dict, highlights: dict, frontend_url: str):
    """Send the weekly digest email to a user"""
    from services.email_service import email_service
    
    subject = "Your Weekly Elmeg Digest"
    
    # Build activity section
    activity_items = []
    if stats["shows_attended"] > 0:
        activity_items.append(f"🎵 Attended {stats['shows_attended']} show{'s' if stats['shows_attended'] > 1 else ''}")
    if stats["reviews_written"] > 0:
        activity_items.append(f"✍️ Wrote {stats['reviews_written']} review{'s' if stats['reviews_written'] > 1 else ''}")
    if stats["ratings_given"] > 0:
        activity_items.append(f"⭐ Gave {stats['ratings_given']} rating{'s' if stats['ratings_given'] > 1 else ''}")
    if stats["chase_caught"] > 0:
        activity_items.append(f"🎯 Caught {stats['chase_caught']} chase song{'s' if stats['chase_caught'] > 1 else ''}!")
    
    activity_html = ""
    if activity_items:
        activity_html = "<ul>" + "".join([f"<li>{item}</li>" for item in activity_items]) + "</ul>"
    else:
        activity_html = "<p style='color: #666;'>No activity this week. Get out there and catch some shows!</p>"
    
    html_content = f"""
    <html>
        <body style="font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif; line-height: 1.6; color: #333; background-color: #f5f5f5; padding: 20px;">
            <div style="max-width: 600px; margin: 0 auto; background: white; border-radius: 12px; padding: 40px; box-shadow: 0 2px 8px rgba(0,0,0,0.1);">
                <h2 style="color: #2563eb; margin-top: 0;">Weekly Digest</h2>
                
                <h3 style="color: #374151; border-bottom: 2px solid #e5e7eb; padding-bottom: 8px;">Your Activity</h3>
                {activity_html}
                
                <h3 style="color: #374151; border-bottom: 2px solid #e5e7eb; padding-bottom: 8px; margin-top: 30px;">Community Highlights</h3>
                <ul>
                    <li>🆕 {highlights['new_shows']} new show{'s' if highlights['new_shows'] != 1 else ''} added</li>
                    <li>📝 {highlights['total_reviews']} review{'s' if highlights['total_reviews'] != 1 else ''} written by the community</li>
                </ul>
                
                <div style="margin: 30px 0; text-align: center;">
                    <a href="{frontend_url}" style="background: linear-gradient(135deg, #2563eb, #4f46e5); color: white; padding: 14px 32px; text-decoration: none; border-radius: 8px; font-weight: 600; display: inline-block;">Visit Elmeg</a>
                </div>
                
                <hr style="border: 0; border-top: 1px solid #eee; margin: 30px 0;">
                <p style="font-size: 12px; color: #999; margin-bottom: 0;">You're receiving this because you enabled weekly digests. <a href="{frontend_url}/settings" style="color: #2563eb;">Manage preferences</a></p>
            </div>
        </body>
    </html>
    """
    
    text_content = f"""
Weekly Elmeg Digest

YOUR ACTIVITY:
- Attended {stats['shows_attended']} shows
- Wrote {stats['reviews_written']} reviews
- Gave {stats['ratings_given']} ratings
- Caught {stats['chase_caught']} chase songs

COMMUNITY HIGHLIGHTS:
- {highlights['new_shows']} new shows added
- {highlights['total_reviews']} reviews written

Visit Elmeg: {frontend_url}

To disable weekly digests, visit {frontend_url}/settings
    """
    
    return email_service.send_email(user.email, subject, html_content, text_content)


def send_weekly_digests():
    """Main function to send all weekly digest emails"""
    print("=" * 60)
    print("WEEKLY DIGEST EMAIL SENDER")
    print("=" * 60)
    
    # Calculate date range (last 7 days)
    end_date = datetime.utcnow()
    start_date = end_date - timedelta(days=7)
    
    print(f"Period: {start_date.date()} to {end_date.date()}")
    
    from services.email_service import email_service
    frontend_url = email_service.frontend_url
    
    with Session(engine) as session:
        # Get community highlights (shared across all emails)
        highlights = get_community_highlights(session, start_date, end_date)
        print(f"Community stats: {highlights['new_shows']} shows, {highlights['total_reviews']} reviews")
        
        # Find all users with email_digest enabled
        users_with_digest = session.exec(
            select(User)
            .where(User.is_active == True)
            .where(User.email_verified == True)
        ).all()
        
        sent_count = 0
        skipped_count = 0
        
        for user in users_with_digest:
            # Check if user has digest enabled
            if not user.preferences or not user.preferences.email_digest:
                skipped_count += 1
                continue
            
            # Get user's stats
            stats = get_weekly_stats(session, user.id, start_date, end_date)
            
            # Send the digest
            try:
                success = send_digest_email(user, stats, highlights, frontend_url)
                if success:
                    sent_count += 1
                    print(f"  ✓ Sent to {user.email}")
                else:
                    print(f"  ✗ Failed for {user.email}")
            except Exception as e:
                print(f"  ✗ Error for {user.email}: {e}")
        
        print(f"\n✓ Sent {sent_count} digest emails, skipped {skipped_count}")


if __name__ == "__main__":
    send_weekly_digests()