"""
Demo authentication module for SmartTrip AI.

NOTE: This is intentionally simple for demo purposes.
In production, replace with a proper auth system using hashed passwords
stored in a database (e.g., bcrypt + PostgreSQL/Supabase).
"""

from typing import Optional, Dict, List

# ---------------------------------------------------------------------------
# Hardcoded demo credentials (shown on the UI as well)
# ---------------------------------------------------------------------------
DEMO_USERS: Dict[str, Dict] = {
    "user1": {
        "password": "user123",
        "role": "user",
        "display_name": "User One",
    },
    "user2": {
        "password": "user123",
        "role": "user",
        "display_name": "User Two",
    },
    "user3": {
        "password": "user123",
        "role": "user",
        "display_name": "User Three",
    },
    "admin": {
        "password": "admin123",
        "role": "admin",
        "display_name": "Administrator",
    },
}


def authenticate(username: str, password: str) -> Optional[Dict]:
    """
    Verify credentials and return user data dict on success, None on failure.
    """
    user = DEMO_USERS.get(username.strip())
    if user and user["password"] == password:
        return {
            "username": username.strip(),
            "role": user["role"],
            "display_name": user["display_name"],
        }
    return None


def get_all_users() -> List[str]:
    """Return list of all non-admin usernames."""
    return [k for k, v in DEMO_USERS.items() if v["role"] == "user"]


def is_admin(role: str) -> bool:
    return role == "admin"


def get_demo_credentials_md() -> str:
    """Return a markdown table of demo credentials for display in the UI."""
    return """
**👤 Regular Users**

| Username | Password |
|:---------|:---------|
| user1    | user123  |
| user2    | user123  |
| user3    | user123  |

**🛡️ Admin**

| Username | Password  |
|:---------|:----------|
| admin    | admin123  |
"""