from typing import List, Optional
import re
from pydantic import EmailStr, validator
from models import Intern

def validate_phone_number(phone_number: str) -> bool:
    """
    Validate a phone number format.

    Args:
        phone_number: The phone number to validate

    Returns:
        bool: True if phone number format is valid, False otherwise
    """
    pattern = r'^\+?\d{10,13}$'
    return bool(re.match(pattern, phone_number))

def get_all_interns(db_session) -> List[Intern]:
    """
    Get a list of all interns from the database.

    Args:
        db_session: The database session

    Returns:
        List[Intern]: A list of Intern objects
    """
    return db_session.query(Intern).all()

def get_intern_by_email(db_session, email: EmailStr) -> Optional[Intern]:
    """
    Get an intern by their email address.

    Args:
        db_session: The database session
        email: Email to search for

    Returns:
        Intern object if found, None otherwise
    """
    return db_session.query(Intern).filter(Intern.email == email).first()

class InternBase:
    first_name: str
    last_name: str
    email: EmailStr
    phone_number: str
    track: str
    bio: Optional[str] = None

    @validator('phone_number')
    def validate_phone_number(cls, phone_number):
        if not validate_phone_number(phone_number):
            raise ValueError('Invalid phone number format')
        return phone_number

def create_intern(db_session, intern_data: InternBase) -> Intern:
    """
    Create a new intern in the database.

    Args:
        db_session: The database session
        intern_data: The data for the new intern

    Returns:
        Intern: The created Intern object
    """
    existing_intern = get_intern_by_email(db_session, intern_data.email)
    if existing_intern:
        raise ValueError('Email already registered')

    new_intern = Intern(**intern_data.dict())
    db_session.add(new_intern)
    db_session.commit()
    db_session.refresh(new_intern)

    return new_intern