from fastapi import APIRouter, Depends, HTTPException, Query
from sqlalchemy.orm import Session
from sqlalchemy import desc, func
from typing import List, Optional
from datetime import datetime

from database import get_db
from models.user import User
from models.notification import Notification, UserNotificationPreference, NotificationType
from schemas.notification import (
    NotificationResponse,
    NotificationMarkRead,
    NotificationPreferencesResponse,
    NotificationPreferencesUpdate,
    NotificationStats
)
from utils.auth import get_current_user

router = APIRouter(prefix="/notifications", tags=["notifications"])


@router.get("", response_model=List[NotificationResponse])
def get_notifications(
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=100),
    unread_only: bool = Query(False),
    type_filter: Optional[NotificationType] = None,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Get notifications for the current user."""
    query = db.query(Notification).filter(Notification.user_id == current_user.id)
    
    if unread_only:
        query = query.filter(Notification.read == False)
    
    if type_filter:
        query = query.filter(Notification.type == type_filter)
    
    notifications = query.order_by(desc(Notification.created_at)).offset(skip).limit(limit).all()
    return notifications


@router.get("/stats", response_model=NotificationStats)
def get_notification_stats(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Get notification statistics for the current user."""
    total = db.query(Notification).filter(Notification.user_id == current_user.id).count()
    unread = db.query(Notification).filter(
        Notification.user_id == current_user.id,
        Notification.read == False
    ).count()
    
    # Get counts by type
    by_type_query = db.query(
        Notification.type,
        func.count(Notification.id).label('count')
    ).filter(
        Notification.user_id == current_user.id,
        Notification.read == False
    ).group_by(Notification.type).all()
    
    by_type = {str(type_): count for type_, count in by_type_query}
    
    return NotificationStats(total=total, unread=unread, by_type=by_type)


@router.post("/mark-read")
def mark_notifications_read(
    data: NotificationMarkRead,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Mark notifications as read."""
    notifications = db.query(Notification).filter(
        Notification.id.in_(data.notification_ids),
        Notification.user_id == current_user.id
    ).all()
    
    if not notifications:
        raise HTTPException(status_code=404, detail="No notifications found")
    
    for notification in notifications:
        notification.read = True
        notification.read_at = datetime.utcnow()
    
    db.commit()
    
    return {"message": f"Marked {len(notifications)} notifications as read"}


@router.post("/mark-all-read")
def mark_all_notifications_read(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Mark all notifications as read for the current user."""
    count = db.query(Notification).filter(
        Notification.user_id == current_user.id,
        Notification.read == False
    ).update({
        "read": True,
        "read_at": datetime.utcnow()
    })
    
    db.commit()
    
    return {"message": f"Marked {count} notifications as read"}


@router.delete("/{notification_id}")
def delete_notification(
    notification_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Delete a notification."""
    notification = db.query(Notification).filter(
        Notification.id == notification_id,
        Notification.user_id == current_user.id
    ).first()
    
    if not notification:
        raise HTTPException(status_code=404, detail="Notification not found")
    
    db.delete(notification)
    db.commit()
    
    return {"message": "Notification deleted"}


@router.get("/preferences", response_model=NotificationPreferencesResponse)
def get_notification_preferences(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Get notification preferences for the current user."""
    preferences = db.query(UserNotificationPreference).filter(
        UserNotificationPreference.user_id == current_user.id
    ).first()
    
    if not preferences:
        # Create default preferences
        preferences = UserNotificationPreference(user_id=current_user.id)
        db.add(preferences)
        db.commit()
        db.refresh(preferences)
    
    return preferences


@router.put("/preferences", response_model=NotificationPreferencesResponse)
def update_notification_preferences(
    data: NotificationPreferencesUpdate,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user)
):
    """Update notification preferences for the current user."""
    preferences = db.query(UserNotificationPreference).filter(
        UserNotificationPreference.user_id == current_user.id
    ).first()
    
    if not preferences:
        preferences = UserNotificationPreference(user_id=current_user.id)
        db.add(preferences)
    
    # Update all fields
    for field, value in data.model_dump().items():
        setattr(preferences, field, value)
    
    preferences.updated_at = datetime.utcnow()
    
    db.commit()
    db.refresh(preferences)
    
    return preferences