#!/usr/bin/env python3
"""Quick email validation utility. Validates email format without external dependencies."""

import re
from typing import NamedTuple

class EmailValidationResult(NamedTuple):
    """Result of email validation."""
    is_valid: bool
    normalized: str | None
    error: str | None = None

def validate_email(email: str) -> EmailValidationResult:
    """Validate email address format.
    
    Args:
        email: Email address to validate
        
    Returns:
        EmailValidationResult with validation status
    """
    if not email:
        return EmailValidationResult(False, None, "Email is empty")
    
    email = email.strip().lower()
    
    # Basic RFC 5322-inspired pattern
    pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
    
    if not re.match(pattern, email):
        return EmailValidationResult(False, None, "Invalid email format")
    
    local, _, domain = email.rpartition('@')
    
    if len(local) > 64:
        return EmailValidationResult(False, None, "Local part too long (>64 chars)")
    
    if len(domain) > 253:
        return EmailValidationResult(False, None, "Domain part too long (>253 chars)")
    
    # Check for consecutive dots
    if '..' in email:
        return EmailValidationResult(False, None, "Consecutive dots not allowed")
    
    return EmailValidationResult(True, email)

if __name__ == "__main__":
    test_emails = [
        "test@example.com",
        "  USER@Example.COM  ",
        "invalid-email",
        "bad..email@example.com",
        "",
        "valid.email+tag@subdomain.example.org"
    ]
    
    print("Email Validation Results:")
    print("-" * 60)
    for email in test_emails:
        result = validate_email(email)
        status = "✓ VALID" if result.is_valid else f"✗ INVALID: {result.error}"
        print(f"{email!r:45} -> {status}")