"""
Geolocation Verification Module for Attendr
Implements KR Rule #2: Geolocation Verification
∀x[(Student(x) ∧ IsWithinAllowedArea(x)) → VerifiedLocation(x)]
"""

from utils import haversine_distance, validate_coordinates
from models import Classroom, db
from config import Config
import logging

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)


class GeolocationModule:
    """Handles all geolocation verification operations"""
    
    def __init__(self, default_radius=None):
        """
        Initialize geolocation module
        
        Args:
            default_radius: Default radius in meters for geofencing
        """
        self.default_radius = default_radius or Config.GEOLOCATION_RADIUS_METERS
        logger.info(f"Geolocation Module initialized with default radius={self.default_radius}m")
    
    def get_classroom_location(self, classroom_id):
        """
        Get classroom GPS coordinates and radius
        
        Args:
            classroom_id: ID of the classroom
            
        Returns:
            tuple: (latitude, longitude, radius) or (None, None, None) if not found
        """
        try:
            classroom = Classroom.query.get(classroom_id)
            
            if not classroom:
                logger.warning(f"Classroom {classroom_id} not found")
                return None, None, None
            
            radius = classroom.radius_meters or self.default_radius
            logger.info(f"Classroom {classroom.name}: lat={classroom.latitude}, lon={classroom.longitude}, radius={radius}m")
            
            return classroom.latitude, classroom.longitude, radius
            
        except Exception as e:
            logger.error(f"Error fetching classroom location: {str(e)}")
            return None, None, None
    
    def calculate_distance(self, lat1, lon1, lat2, lon2):
        """
        Calculate distance between two GPS coordinates
        
        Args:
            lat1, lon1: First coordinate
            lat2, lon2: Second coordinate
            
        Returns:
            Distance in meters
        """
        try:
            distance = haversine_distance(lat1, lon1, lat2, lon2)
            logger.info(f"Distance calculated: {distance:.2f} meters")
            return distance
        except Exception as e:
            logger.error(f"Distance calculation error: {str(e)}")
            return None
    
    def is_within_allowed_area(self, student_lat, student_lon, classroom_id):
        """
        Check if student is within allowed classroom area
        Implements: IsWithinAllowedArea(x)
        
        Args:
            student_lat: Student's latitude
            student_lon: Student's longitude
            classroom_id: ID of the classroom
            
        Returns:
            tuple: (is_within: bool, distance: float, error_message: str or None)
        """
        try:
            # Validate student coordinates
            valid, error = validate_coordinates(student_lat, student_lon)
            if not valid:
                logger.warning(f"Invalid student coordinates: {error}")
                return False, None, error
            
            # Get classroom location
            class_lat, class_lon, radius = self.get_classroom_location(classroom_id)
            
            if class_lat is None:
                return False, None, "Classroom location not found"
            
            # Calculate distance
            distance = self.calculate_distance(
                float(student_lat), 
                float(student_lon),
                class_lat, 
                class_lon
            )
            
            if distance is None:
                return False, None, "Failed to calculate distance"
            
            # Check if within radius
            is_within = distance <= radius
            
            logger.info(f"Location verification: within_area={is_within}, distance={distance:.2f}m, allowed_radius={radius}m")
            
            if is_within:
                return True, distance, None
            else:
                return False, distance, f"You are {distance:.0f}m away from the classroom (max allowed: {radius}m)"
                
        except Exception as e:
            logger.error(f"Location verification error: {str(e)}")
            return False, None, f"Location verification failed: {str(e)}"
    
    def verify_location(self, student_lat, student_lon, classroom_id):
        """
        Complete location verification process
        Implements: Student(x) ∧ IsWithinAllowedArea(x) → VerifiedLocation(x)
        
        Args:
            student_lat: Student's latitude
            student_lon: Student's longitude
            classroom_id: ID of the classroom
            
        Returns:
            dict: Verification result with status, distance, and message
        """
        is_within, distance, error = self.is_within_allowed_area(
            student_lat, 
            student_lon, 
            classroom_id
        )
        
        result = {
            'verified': is_within,
            'distance': distance,
            'message': None,
            'error': error
        }
        
        if is_within:
            result['message'] = f"Location verified! You are {distance:.0f}m from the classroom."
        elif error:
            result['message'] = error
        
        return result
    
    def get_all_classrooms(self):
        """
        Get all available classrooms
        
        Returns:
            List of classroom dictionaries
        """
        try:
            classrooms = Classroom.query.all()
            return [classroom.to_dict() for classroom in classrooms]
        except Exception as e:
            logger.error(f"Error fetching classrooms: {str(e)}")
            return []
    
    def add_classroom(self, name, building, latitude, longitude, radius_meters=None):
        """
        Add a new classroom to the system
        
        Args:
            name: Classroom name
            building: Building name
            latitude: GPS latitude
            longitude: GPS longitude
            radius_meters: Geofencing radius (optional)
            
        Returns:
            tuple: (success, classroom_dict or error_message)
        """
        try:
            # Validate coordinates
            valid, error = validate_coordinates(latitude, longitude)
            if not valid:
                return False, error
            
            # Create classroom
            classroom = Classroom(
                name=name,
                building=building,
                latitude=float(latitude),
                longitude=float(longitude),
                radius_meters=radius_meters or self.default_radius
            )
            
            db.session.add(classroom)
            db.session.commit()
            
            logger.info(f"Classroom added: {name} in {building}")
            return True, classroom.to_dict()
            
        except Exception as e:
            db.session.rollback()
            logger.error(f"Error adding classroom: {str(e)}")
            return False, f"Failed to add classroom: {str(e)}"


# Singleton instance
geolocation_module = GeolocationModule()