import httpx
from typing import Optional
from app.core.config import settings


class AuthAPIError(Exception):
    """Exception raised when external auth API returns an error."""
    def __init__(self, message: str, status_code: int = 400):
        self.message = message
        self.status_code = status_code
        super().__init__(self.message)


class AuthAPIConnectionError(Exception):
    """Exception raised when unable to connect to auth API."""
    pass


async def verify_credentials(email: str, password: str) -> dict:
    """
    Verify user credentials against the external auth API.

    Args:
        email: User's email address
        password: User's password

    Returns:
        dict: User info from auth API if successful

    Raises:
        AuthAPIError: If credentials are invalid
        AuthAPIConnectionError: If unable to connect to auth API
    """
    try:
        async with httpx.AsyncClient(timeout=10.0) as client:
            response = await client.post(
                f"{settings.AUTH_API_URL}/api/auth/login",
                json={"username": email, "password": password},
            )

            if response.status_code == 200:
                return response.json()
            elif response.status_code == 401:
                raise AuthAPIError("Invalid credentials", 401)
            else:
                raise AuthAPIError(
                    f"Authentication failed: {response.text}",
                    response.status_code
                )
    except httpx.ConnectError:
        raise AuthAPIConnectionError("Unable to connect to authentication service")
    except httpx.TimeoutException:
        raise AuthAPIConnectionError("Authentication service timeout")


async def validate_token(token: str) -> Optional[dict]:
    """
    Validate a token with the external auth API.

    Args:
        token: The auth token to validate

    Returns:
        dict: Token payload if valid, None if invalid
    """
    try:
        async with httpx.AsyncClient(timeout=10.0) as client:
            response = await client.get(
                f"{settings.AUTH_API_URL}/api/auth/validate",
                headers={"Authorization": f"Bearer {token}"},
            )

            if response.status_code == 200:
                return response.json()
            return None
    except (httpx.ConnectError, httpx.TimeoutException):
        return None