#!/usr/bin/env python3
"""
One-time Backfill Script: Send notifications for existing listings matching alerts.

This script:
1. Fetches all active search_alerts
2. Fetches all published listings 
3. Checks each listing against each alert
4. Sends DM notifications for matches (avoiding duplicates)

Usage:
    cd python-Backend/lojiz-backend/AIDA
    python -m scripts.backfill_alerts

Or run as standalone:
    python scripts/backfill_alerts.py
"""

import asyncio
import sys
import os

# Add parent directory to path for imports
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from datetime import datetime
from typing import List, Dict, Any

async def run_backfill():
    """Main backfill function."""
    # Import after path setup
    from app.database import get_db, connect_db, disconnect_db
    from app.models.search_alert import SearchAlert
    from app.services.alert_service import check_listing_matches_alert, notify_user_of_match
    
    print("="*60)
    print(" ALERT BACKFILL SCRIPT")
    print("="*60)
    print(f"Started at: {datetime.now().isoformat()}")
    print()
    
    # Initialize DB Connection
    await connect_db()
    
    try:
        db = await get_db()
        
        # 1. Fetch all active alerts
        print(" Fetching active search alerts...")
        alerts_cursor = db.search_alerts.find({"is_active": True})
        alerts = [SearchAlert(**doc) async for doc in alerts_cursor]
        print(f"   Found {len(alerts)} active alerts")
        
        if not alerts:
            print("   No active alerts found. Nothing to backfill.")
            return
        
        # Print alert summary
        for alert in alerts:
            print(f"   - User {alert.user_id}: '{alert.user_query}'")
        print()
        
        # 2. Fetch all published listings
        print(" Fetching published listings...")
        listings_cursor = db.listings.find({"status": "active"})
        listings = await listings_cursor.to_list(length=1000)  # Limit for safety
        print(f"   Found {len(listings)} active listings")
        print()
        
        if not listings:
            print("   No active listings found. Nothing to match.")
            return
        
        # 3. Check each listing against each alert
        print(" Checking matches...")
        matches_found = 0
        notifications_sent = 0
        skipped_duplicates = 0
        
        for listing in listings:
            listing_id = str(listing["_id"])
            listing_title = listing.get("title", "Untitled")
            listing_location = listing.get("location", "Unknown")
            
            for alert in alerts:
                # Check if this alert already received notification for this listing
                # (We store notified listing IDs in alert to prevent duplicate notifications)
                notified_listings = alert.notified_listing_ids or []
                if listing_id in notified_listings:
                    skipped_duplicates += 1
                    continue
                
                # Check if listing matches alert criteria
                if await check_listing_matches_alert(listing, alert):
                    matches_found += 1
                    print(f"   MATCH: '{listing_title}' ({listing_location}) -> User {alert.user_id}")
                    
                    try:
                        # Send notification
                        await notify_user_of_match(alert, listing)
                        notifications_sent += 1
                        
                        # Mark listing as notified for this alert (prevent duplicates)
                        await db.search_alerts.update_one(
                            {"_id": alert.id},
                            {"$addToSet": {"notified_listing_ids": listing_id}}
                        )
                        
                        print(f"      Notification sent!")
                        
                    except Exception as e:
                        print(f"      Failed to notify: {e}")
        
        # 4. Summary
        print()
        print("="*60)
        print(" BACKFILL SUMMARY")
        print("="*60)
        print(f"   Alerts processed:     {len(alerts)}")
        print(f"   Listings checked:     {len(listings)}")
        print(f"   Matches found:        {matches_found}")
        print(f"   Notifications sent:   {notifications_sent}")
        print(f"   Duplicates skipped:   {skipped_duplicates}")
        print()
        print(f"Completed at: {datetime.now().isoformat()}")
        print("="*60)
        
    finally:
        await disconnect_db()


if __name__ == "__main__":
    print("\n" + " Starting Alert Backfill Script..." + "\n")
    asyncio.run(run_backfill())
    print("\n" + " Script completed!" + "\n")