"""
Session ID generation service.
Feature: 012-profile-contact-ui
"""

import re
import uuid


def generate_profile_session_id(user_id: str) -> str:
    """
    Generate profile session ID: {user_id}_session

    Args:
        user_id: HuggingFace username

    Returns:
        Profile session ID string

    Raises:
        ValueError: If user_id is empty or contains invalid characters
    """
    if not user_id:
        raise ValueError("user_id cannot be empty")

    # Validate user_id format (alphanumeric + hyphens/underscores)
    if not re.match(r"^[a-zA-Z0-9_-]+$", user_id):
        raise ValueError(
            "user_id must contain only alphanumeric characters, hyphens, and underscores"
        )

    return f"{user_id}_session"


def generate_contact_session_id(user_id: str) -> str:
    """
    Generate contact session ID: UUID_v4
    
    Note: Returns pure UUID format (without user_id prefix) to maintain 
    compatibility with PostgreSQL UUID type in the backend API.

    Args:
        user_id: HuggingFace username (validated but not included in session_id)

    Returns:
        Contact session ID string (pure UUID format)

    Raises:
        ValueError: If user_id is empty or contains invalid characters
    """
    if not user_id:
        raise ValueError("user_id cannot be empty")

    # Validate user_id format (alphanumeric + hyphens/underscores)
    if not re.match(r"^[a-zA-Z0-9_-]+$", user_id):
        raise ValueError(
            "user_id must contain only alphanumeric characters, hyphens, and underscores"
        )

    # Generate UUID v4 (cryptographically random)
    # Return pure UUID without prefix to match PostgreSQL UUID type
    return str(uuid.uuid4())