"""WorkOS AuthKit helpers for the FastAPI web app."""

from __future__ import annotations

from dataclasses import dataclass
from functools import lru_cache
from os import getenv
from typing import Any

from fastapi import Request
from workos import WorkOSClient
from workos.session import seal_session_from_auth_response


@dataclass(frozen=True)
class AuthConfig:
    """Runtime configuration for WorkOS AuthKit."""

    api_key: str
    client_id: str
    cookie_password: str
    redirect_uri: str
    logout_redirect_uri: str
    session_cookie_name: str
    organization_id: str

    @property
    def secure_cookies(self) -> bool:
        return self.redirect_uri.startswith("https://")


@dataclass(frozen=True)
class AuthSession:
    """Normalized auth session passed through the app."""

    user_id: str
    email: str
    first_name: str | None
    last_name: str | None
    role_slugs: set[str]
    organization_id: str | None
    raw_user: Any
    raw_session: Any

    @property
    def display_name(self) -> str:
        parts = [part for part in (self.first_name, self.last_name) if part]
        return " ".join(parts) if parts else self.email

    @property
    def is_admin(self) -> bool:
        return "admin" in self.role_slugs


@dataclass(frozen=True)
class CallbackResult:
    """Result of exchanging a WorkOS callback code."""

    sealed_session: str
    next_path: str


def safe_next_path(value: str | None, default: str = "/dashboard") -> str:
    """Allow only local relative redirect targets."""
    if value and value.startswith("/") and not value.startswith("//"):
        return value
    return default


def build_authorization_url(next_path: str) -> str:
    """Build the WorkOS hosted login URL."""
    config = get_auth_config()
    return get_workos_client().user_management.get_authorization_url(
        provider="authkit",
        redirect_uri=config.redirect_uri,
        state=safe_next_path(next_path),
        organization_id=config.organization_id,
    )


def exchange_code(request: Request) -> CallbackResult:
    """Exchange a WorkOS callback code for a sealed session cookie value."""
    code = request.query_params.get("code")
    if not code:
        raise ValueError("Missing authentication code.")

    config = get_auth_config()
    auth_response = get_workos_client().user_management.authenticate_with_code(
        code=code,
        ip_address=_request_ip(request),
        user_agent=request.headers.get("user-agent"),
    )
    sealed_session = seal_session_from_auth_response(
        access_token=auth_response.access_token,
        refresh_token=auth_response.refresh_token,
        user=auth_response.user.to_dict(),
        impersonator=auth_response.impersonator.to_dict()
        if auth_response.impersonator is not None
        else None,
        cookie_password=config.cookie_password,
    )

    return CallbackResult(
        sealed_session=sealed_session,
        next_path=safe_next_path(request.query_params.get("state")),
    )


def get_current_session(request: Request) -> AuthSession | None:
    """Load the current signed-in WorkOS session from the sealed cookie."""
    cookie_name = getenv("WORKOS_SESSION_COOKIE_NAME", "workos_session")
    sealed_session = request.cookies.get(cookie_name)
    if not sealed_session:
        return None

    config = get_auth_config()
    try:
        session = get_workos_client().user_management.load_sealed_session(
            session_data=sealed_session,
            cookie_password=config.cookie_password,
        )
        auth_response = session.authenticate()
    except ValueError:
        return None
    if not getattr(auth_response, "authenticated", False):
        return None

    user = auth_response.user or {}
    organization_id = getattr(auth_response, "organization_id", None)
    if config.organization_id and organization_id != config.organization_id:
        return None
    role_slugs = set(getattr(auth_response, "roles", None) or [])
    role = getattr(auth_response, "role", None)
    if role:
        role_slugs.add(role)

    return AuthSession(
        user_id=_user_field(user, "id") or "",
        email=_user_field(user, "email") or "",
        first_name=_user_field(user, "first_name"),
        last_name=_user_field(user, "last_name"),
        role_slugs=role_slugs,
        organization_id=organization_id,
        raw_user=user,
        raw_session=auth_response,
    )


def get_logout_url(request: Request) -> str:
    """Return the WorkOS logout URL for the current sealed session."""
    config = get_auth_config()
    sealed_session = request.cookies.get(config.session_cookie_name)
    if not sealed_session:
        return config.logout_redirect_uri

    try:
        session = get_workos_client().user_management.load_sealed_session(
            session_data=sealed_session,
            cookie_password=config.cookie_password,
        )
        return session.get_logout_url(return_to=config.logout_redirect_uri)
    except ValueError:
        return config.logout_redirect_uri


@lru_cache(maxsize=1)
def get_auth_config() -> AuthConfig:
    """Load and validate WorkOS environment configuration."""
    values = {
        "WORKOS_API_KEY": getenv("WORKOS_API_KEY"),
        "WORKOS_CLIENT_ID": getenv("WORKOS_CLIENT_ID"),
        "WORKOS_COOKIE_PASSWORD": getenv("WORKOS_COOKIE_PASSWORD"),
        "WORKOS_ORGANIZATION_ID": getenv("WORKOS_ORGANIZATION_ID"),
    }
    missing = [name for name, value in values.items() if not value]
    if missing:
        raise RuntimeError(
            "Missing WorkOS configuration: " + ", ".join(sorted(missing))
        )

    return AuthConfig(
        api_key=values["WORKOS_API_KEY"] or "",
        client_id=values["WORKOS_CLIENT_ID"] or "",
        cookie_password=values["WORKOS_COOKIE_PASSWORD"] or "",
        redirect_uri=getenv("WORKOS_REDIRECT_URI", "http://localhost:8000/callback"),
        logout_redirect_uri=getenv("WORKOS_LOGOUT_REDIRECT_URI", "http://localhost:8000/"),
        session_cookie_name=getenv("WORKOS_SESSION_COOKIE_NAME", "workos_session"),
        organization_id=values["WORKOS_ORGANIZATION_ID"] or "",
    )


@lru_cache(maxsize=1)
def get_workos_client():
    """Create and cache the WorkOS SDK client."""
    config = get_auth_config()
    return WorkOSClient(api_key=config.api_key, client_id=config.client_id)


def _request_ip(request: Request) -> str | None:
    if request.client is None:
        return None
    return request.client.host


def _user_field(user: Any, key: str) -> Any:
    if isinstance(user, dict):
        return user.get(key)
    return getattr(user, key, None)