"""
Email validation utilities - Format and DNS validation
"""
import re
import socket
from typing import Tuple

def validate_email_format(email: str) -> Tuple[bool, str]:
    """
    Validate email format using regex.
    Returns (is_valid, error_message)
    """
    if not email or not email.strip():
        return False, "Email is empty"
    
    email = email.strip().lower()
    
    # Basic email regex pattern
    pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
    
    if not re.match(pattern, email):
        return False, f"Invalid email format: {email}"
    
    return True, ""


def validate_email_domain(email: str) -> Tuple[bool, str]:
    """
    Validate that the email domain has valid MX or A records.
    Returns (is_valid, error_message)
    """
    try:
        domain = email.split('@')[1]
        
        # Try to get MX records first
        try:
            socket.getaddrinfo(domain, None, socket.AF_INET)
            return True, ""
        except socket.gaierror:
            pass
        
        # If no A record, try with 'mail.' prefix (common mail server)
        try:
            socket.getaddrinfo(f"mail.{domain}", None, socket.AF_INET)
            return True, ""
        except socket.gaierror:
            pass
        
        return False, f"Domain does not exist: {domain}"
        
    except Exception as e:
        return False, f"Domain validation error: {str(e)}"


def validate_email(email: str) -> Tuple[bool, str]:
    """
    Full email validation - format and domain.
    Returns (is_valid, error_message)
    """
    # First check format
    is_valid, error = validate_email_format(email)
    if not is_valid:
        return False, error
    
    # Then check domain
    is_valid, error = validate_email_domain(email)
    if not is_valid:
        return False, error
    
    return True, ""