from typing import Optional
from datetime import datetime
from fastapi import APIRouter, Depends, HTTPException, status, Query
from sqlalchemy.orm import Session

from app.core.database import get_db
from app.models import User, Notification
from app.schemas.notification import (
    NotificationResponse, NotificationListResponse, UnreadCountResponse
)
from app.middleware.auth import get_current_user

router = APIRouter(tags=["notifications"])


def notification_to_response(notification: Notification) -> NotificationResponse:
    """Convert Notification model to NotificationResponse."""
    return NotificationResponse(
        id=notification.id,
        type=notification.type,
        reference_type=notification.reference_type,
        reference_id=notification.reference_id,
        title=notification.title,
        message=notification.message,
        is_read=notification.is_read,
        created_at=notification.created_at,
        read_at=notification.read_at,
    )


@router.get("/api/notifications", response_model=NotificationListResponse)
async def list_notifications(
    is_read: Optional[bool] = Query(None, description="Filter by read status"),
    limit: int = Query(50, ge=1, le=100, description="Number of notifications to return"),
    offset: int = Query(0, ge=0, description="Offset for pagination"),
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """List notifications for the current user."""
    query = db.query(Notification).filter(Notification.user_id == current_user.id)

    if is_read is not None:
        query = query.filter(Notification.is_read == is_read)

    total = query.count()
    unread_count = db.query(Notification).filter(
        Notification.user_id == current_user.id,
        Notification.is_read == False,
    ).count()

    notifications = query.order_by(Notification.created_at.desc()).offset(offset).limit(limit).all()

    return NotificationListResponse(
        notifications=[notification_to_response(n) for n in notifications],
        total=total,
        unread_count=unread_count,
    )


@router.get("/api/notifications/unread-count", response_model=UnreadCountResponse)
async def get_unread_count(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Get count of unread notifications."""
    count = db.query(Notification).filter(
        Notification.user_id == current_user.id,
        Notification.is_read == False,
    ).count()

    return UnreadCountResponse(unread_count=count)


@router.put("/api/notifications/{notification_id}/read", response_model=NotificationResponse)
async def mark_as_read(
    notification_id: str,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Mark a notification as read."""
    notification = db.query(Notification).filter(
        Notification.id == notification_id,
        Notification.user_id == current_user.id,
    ).first()

    if not notification:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Notification not found",
        )

    if not notification.is_read:
        notification.is_read = True
        notification.read_at = datetime.utcnow()
        db.commit()
        db.refresh(notification)

    return notification_to_response(notification)


@router.put("/api/notifications/read-all", response_model=dict)
async def mark_all_as_read(
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    """Mark all notifications as read."""
    now = datetime.utcnow()

    updated_count = db.query(Notification).filter(
        Notification.user_id == current_user.id,
        Notification.is_read == False,
    ).update({
        Notification.is_read: True,
        Notification.read_at: now,
    })

    db.commit()

    return {"updated_count": updated_count}