"""
Authentication and SSO support for enterprise deployments.
"""

from __future__ import annotations

from abc import ABC, abstractmethod
from typing import Dict, Optional

from ..types import JSONDict


class AuthenticationProvider(ABC):
    """Abstract base class for authentication providers."""

    @abstractmethod
    def authenticate(self, credentials: JSONDict) -> Optional[Dict[str, str]]:
        """
        Authenticate a user with credentials.

        Args:
            credentials: Authentication credentials (e.g., username/password, token)

        Returns:
            User info dict with at least 'user_id' and 'email', or None if authentication fails
        """
        pass

    @abstractmethod
    def validate_token(self, token: str) -> Optional[Dict[str, str]]:
        """
        Validate an authentication token.

        Args:
            token: Authentication token

        Returns:
            User info dict if token is valid, None otherwise
        """
        pass


class SSOProvider(AuthenticationProvider):
    """
    SSO provider for enterprise authentication.

    Supports SAML, OAuth2, and OpenID Connect protocols.
    """

    def __init__(
        self,
        provider_type: str = "oauth2",
        issuer_url: Optional[str] = None,
        client_id: Optional[str] = None,
        client_secret: Optional[str] = None,
        redirect_uri: Optional[str] = None,
    ) -> None:
        """
        Initialize SSO provider.

        Args:
            provider_type: Type of SSO ("oauth2", "saml", "oidc")
            issuer_url: Identity provider URL
            client_id: OAuth2/OIDC client ID
            client_secret: OAuth2/OIDC client secret
            redirect_uri: OAuth2 redirect URI
        """
        self.provider_type = provider_type
        self.issuer_url = issuer_url
        self.client_id = client_id
        self.client_secret = client_secret
        self.redirect_uri = redirect_uri

    def authenticate(self, credentials: JSONDict) -> Optional[Dict[str, str]]:
        """
        Authenticate via SSO.

        For OAuth2/OIDC, expects 'code' in credentials.
        For SAML, expects 'saml_response' in credentials.
        """
        if self.provider_type == "oauth2" or self.provider_type == "oidc":
            code = credentials.get("code")
            if not code:
                return None

            # In a real implementation, exchange code for token
            # This is a placeholder that would integrate with OAuth2/OIDC libraries
            # For now, return a mock user
            return {
                "user_id": "sso_user_123",
                "email": "user@example.com",
                "name": "SSO User",
            }
        elif self.provider_type == "saml":
            saml_response = credentials.get("saml_response")
            if not saml_response:
                return None

            # In a real implementation, parse and validate SAML response
            # This is a placeholder
            return {
                "user_id": "saml_user_123",
                "email": "user@example.com",
                "name": "SAML User",
            }
        else:
            raise ValueError(f"Unsupported SSO provider type: {self.provider_type}")

    def validate_token(self, token: str) -> Optional[Dict[str, str]]:
        """
        Validate SSO token (JWT for OAuth2/OIDC, assertion for SAML).
        """
        if self.provider_type == "oauth2" or self.provider_type == "oidc":
            # In a real implementation, decode and validate JWT
            # This is a placeholder
            if token.startswith("valid_"):
                return {
                    "user_id": "token_user_123",
                    "email": "user@example.com",
                    "name": "Token User",
                }
            return None
        elif self.provider_type == "saml":
            # In a real implementation, validate SAML assertion
            # This is a placeholder
            if token.startswith("saml_"):
                return {
                    "user_id": "saml_token_user_123",
                    "email": "user@example.com",
                    "name": "SAML Token User",
                }
            return None
        else:
            raise ValueError(f"Unsupported SSO provider type: {self.provider_type}")


class BasicAuthProvider(AuthenticationProvider):
    """Basic username/password authentication provider."""

    def __init__(self, user_store: Dict[str, str]) -> None:
        """
        Initialize basic auth provider.

        Args:
            user_store: Dict mapping username to password hash
        """
        self.user_store = user_store

    def authenticate(self, credentials: JSONDict) -> Optional[Dict[str, str]]:
        """Authenticate with username and password."""
        username = credentials.get("username")
        password = credentials.get("password")

        if not username or not password:
            return None

        # In a real implementation, hash and compare passwords
        # This is a simplified version
        if username in self.user_store and self.user_store[username] == password:
            return {
                "user_id": username,
                "email": f"{username}@example.com",
                "name": username,
            }
        return None

    def validate_token(self, token: str) -> Optional[Dict[str, str]]:
        """Basic auth doesn't use tokens."""
        return None


def authenticate_user(
    provider: AuthenticationProvider,
    credentials: JSONDict,
) -> Optional[Dict[str, str]]:
    """
    Authenticate a user using the provided authentication provider.

    Args:
        provider: Authentication provider instance
        credentials: User credentials

    Returns:
        User info dict if authentication succeeds, None otherwise
    """
    return provider.authenticate(credentials)

