mcp-nextcloud/nextcloud_mcp_server/auth/browser_oauth_routes.py

"""Browser-based OAuth login routes for admin UI.

Separate from MCP OAuth flow - these routes establish browser sessions
for accessing admin UI endpoints like /app.
"""

import hashlib
import logging
import os
import secrets
import time
from base64 import urlsafe_b64encode
from html import escape as html_escape
from urllib.parse import urlencode
from urllib.parse import urlparse as parse_url

import httpx
from starlette.requests import Request
from starlette.responses import HTMLResponse, JSONResponse, RedirectResponse

from nextcloud_mcp_server.auth.token_utils import (
    IdTokenVerificationError,
    verify_id_token,
)
from nextcloud_mcp_server.auth.userinfo_routes import (
    _get_userinfo_endpoint,
    _query_idp_userinfo,
)

from ..http import nextcloud_httpx_client

logger = logging.getLogger(__name__)


def _should_use_secure_cookies() -> bool:
    """Determine if cookies should have secure flag.

    Checks COOKIE_SECURE env var first, then auto-detects from NEXTCLOUD_HOST.

    Returns:
        True if cookies should be secure (HTTPS), False otherwise
    """
    # Explicit configuration takes precedence
    explicit = os.getenv("COOKIE_SECURE", "").lower()
    if explicit == "true":
        return True
    if explicit == "false":
        return False

    # Auto-detect from NEXTCLOUD_HOST protocol
    nextcloud_host = os.getenv("NEXTCLOUD_HOST", "")
    return nextcloud_host.startswith("https://")


async def oauth_login(request: Request) -> RedirectResponse | JSONResponse:
    """Browser OAuth login endpoint - redirects to IdP for authentication.

    This is separate from the MCP OAuth flow (/oauth/authorize).
    Creates a browser session with refresh token for admin UI access.

    Query parameters:
        next: Optional URL to redirect to after login (default: /user/page)

    Returns:
        302 redirect to IdP authorization endpoint
    """
    oauth_ctx = request.app.state.oauth_context
    if not oauth_ctx:
        # BasicAuth mode - no login needed, redirect to app
        return RedirectResponse("/app", status_code=302)

    storage = oauth_ctx["storage"]
    oauth_client = oauth_ctx["oauth_client"]
    oauth_config = oauth_ctx["config"]

    # Debug: Log oauth_config contents
    logger.info(f"oauth_login called - oauth_config keys: {oauth_config.keys()}")
    logger.info(f"oauth_login called - client_id: {oauth_config.get('client_id')}")
    logger.info(f"oauth_login called - oauth_client: {oauth_client is not None}")

    # Get redirect URL from query params (default to /app)
    next_url = request.query_params.get("next", "/app")
    logger.info(f"oauth_login - next_url: {next_url}")

    # Generate state for CSRF protection
    state = secrets.token_urlsafe(32)

    # Build OAuth authorization URL
    mcp_server_url = oauth_config["mcp_server_url"]
    callback_uri = f"{mcp_server_url}/oauth/callback"

    # Request only basic OIDC scopes for browser session.
    # offline_access is added conditionally below based on IdP discovery.
    # Note: Nextcloud app scopes (notes.read, etc.) are for MCP client access tokens,
    # not for the MCP server's own browser authentication
    scopes = "openid profile email"

    # Generate PKCE values for ALL modes (both external and integrated IdP require PKCE)
    code_verifier = secrets.token_urlsafe(32)
    digest = hashlib.sha256(code_verifier.encode()).digest()
    code_challenge = urlsafe_b64encode(digest).decode().rstrip("=")

    # Store code_verifier in session for retrieval during callback (using state as key)
    await storage.store_oauth_session(
        session_id=state,  # Use state as session ID
        client_id="browser-ui",
        client_redirect_uri=next_url,  # Store the redirect URL for after auth
        state=state,
        code_challenge=code_challenge,
        code_challenge_method="S256",
        mcp_authorization_code=code_verifier,  # Store code_verifier here temporarily
        flow_type="browser",
        ttl_seconds=600,  # 10 minutes
    )

    if oauth_client:
        # External IdP mode (Keycloak)
        if not oauth_client.authorization_endpoint:
            await oauth_client.discover()

        # Check if IdP supports offline_access via server metadata from discovery
        idp_metadata = getattr(oauth_client, "server_metadata", None) or {}
        idp_scopes = idp_metadata.get("scopes_supported")
        if idp_scopes is None or "offline_access" in idp_scopes:
            scopes += " offline_access"

        # Get Nextcloud resource URI for audience (background sync needs Nextcloud-scoped tokens)
        nextcloud_resource_uri = oauth_config.get(
            "nextcloud_resource_uri", oauth_config.get("nextcloud_host")
        )

        idp_params = {
            "client_id": oauth_client.client_id,
            "redirect_uri": callback_uri,
            "response_type": "code",
            "scope": scopes,
            "state": state,
            "code_challenge": code_challenge,
            "code_challenge_method": "S256",
            "prompt": "consent",  # Ensure refresh token
            "resource": nextcloud_resource_uri,  # Request tokens for Nextcloud API access
        }

        auth_url = f"{oauth_client.authorization_endpoint}?{urlencode(idp_params)}"
        logger.info(f"Redirecting to external IdP login: {auth_url.split('?')[0]}")
    else:
        # Integrated mode (Nextcloud OIDC)
        discovery_url = oauth_config.get("discovery_url")
        if not discovery_url:
            return JSONResponse(
                {
                    "error": "server_error",
                    "error_description": "OAuth discovery URL not configured",
                },
                status_code=500,
            )

        # Fetch authorization endpoint
        async with nextcloud_httpx_client() as http_client:
            response = await http_client.get(discovery_url)
            response.raise_for_status()
            discovery = response.json()
            authorization_endpoint = discovery["authorization_endpoint"]

        # Include offline_access only if the IdP advertises it (or if
        # scopes_supported is absent from the discovery document).
        # IdPs like AWS Cognito provide refresh tokens automatically without
        # supporting the offline_access scope.
        idp_scopes = discovery.get("scopes_supported")
        if idp_scopes is None or "offline_access" in idp_scopes:
            scopes += " offline_access"

        # Replace internal Docker hostname with public URL
        public_issuer = os.getenv("NEXTCLOUD_PUBLIC_ISSUER_URL")
        if public_issuer:
            internal_parsed = parse_url(oauth_config["nextcloud_host"])
            auth_parsed = parse_url(authorization_endpoint)

            if auth_parsed.hostname == internal_parsed.hostname:
                public_parsed = parse_url(public_issuer)
                authorization_endpoint = (
                    f"{public_parsed.scheme}://{public_parsed.netloc}{auth_parsed.path}"
                )

        # Get Nextcloud resource URI for audience (background sync needs Nextcloud-scoped tokens)
        nextcloud_resource_uri = oauth_config.get(
            "nextcloud_resource_uri", oauth_config.get("nextcloud_host")
        )

        idp_params = {
            "client_id": oauth_config["client_id"],
            "redirect_uri": callback_uri,
            "response_type": "code",
            "scope": scopes,
            "state": state,
            "code_challenge": code_challenge,
            "code_challenge_method": "S256",
            "prompt": "consent",  # Ensure refresh token
            "resource": nextcloud_resource_uri,  # Request tokens for Nextcloud API access
        }

        # Debug: Log full parameters
        logger.info(f"Building Nextcloud OIDC auth URL with params: {idp_params}")

        auth_url = f"{authorization_endpoint}?{urlencode(idp_params)}"
        logger.info(f"Redirecting to Nextcloud OIDC login: {auth_url}")

    return RedirectResponse(auth_url, status_code=302)


async def oauth_login_callback(request: Request) -> RedirectResponse | HTMLResponse:
    """Browser OAuth callback - IdP redirects here after authentication.

    Exchanges authorization code for tokens, stores refresh token,
    sets session cookie, and redirects to original destination.

    Query parameters:
        code: Authorization code from IdP
        state: State parameter
        error: Error code (if authorization failed)

    Returns:
        302 redirect to next URL with session cookie
    """
    # Check for errors
    error = request.query_params.get("error")
    if error:
        error_description = request.query_params.get(
            "error_description", "Authorization failed"
        )
        logger.error(f"OAuth login error: {error} - {error_description}")
        login_url = str(request.url_for("oauth_login"))
        return HTMLResponse(
            f"""
            <!DOCTYPE html>
            <html>
            <head><title>Login Failed</title></head>
            <body>
                <h1>Login Failed</h1>
                <p>Error: {error}</p>
                <p>{error_description}</p>
                <p><a href="{login_url}">Try again</a></p>
            </body>
            </html>
            """,
            status_code=400,
        )

    # Extract code and state
    code = request.query_params.get("code")
    state = request.query_params.get("state")

    if not code or not state:
        return HTMLResponse(
            """
            <!DOCTYPE html>
            <html>
            <head><title>Invalid Request</title></head>
            <body>
                <h1>Invalid Request</h1>
                <p>Missing code or state parameter</p>
            </body>
            </html>
            """,
            status_code=400,
        )

    # Get OAuth context
    oauth_ctx = request.app.state.oauth_context
    storage = oauth_ctx["storage"]
    oauth_client = oauth_ctx["oauth_client"]
    oauth_config = oauth_ctx["config"]

    # Retrieve code_verifier and redirect URL from session storage
    code_verifier = ""
    next_url = "/app"  # Default redirect
    oauth_session = await storage.get_oauth_session(state)
    if oauth_session:
        # code_verifier was stored in mcp_authorization_code field
        code_verifier = oauth_session.get("mcp_authorization_code", "")
        # next_url was stored in client_redirect_uri field
        next_url = oauth_session.get("client_redirect_uri", "/app")
        # Clean up the temporary session
        # Note: We don't have delete_oauth_session method, but it will expire after TTL

    # Exchange authorization code for tokens
    mcp_server_url = oauth_config["mcp_server_url"]
    callback_uri = f"{mcp_server_url}/oauth/callback"

    try:
        if oauth_client:
            # External IdP mode (Keycloak)
            # Use PKCE if we have a code_verifier
            if not oauth_client.token_endpoint:
                await oauth_client.discover()

            token_params = {
                "grant_type": "authorization_code",
                "code": code,
                "redirect_uri": callback_uri,
                "client_id": oauth_client.client_id,
                "client_secret": oauth_client.client_secret,
            }

            # Add code_verifier if we have one (PKCE)
            if code_verifier:
                token_params["code_verifier"] = code_verifier

            async with nextcloud_httpx_client() as http_client:
                response = await http_client.post(
                    oauth_client.token_endpoint,
                    data=token_params,
                )
                response.raise_for_status()
                token_data = response.json()
        else:
            # Integrated mode (Nextcloud OIDC)
            discovery_url = oauth_config.get("discovery_url")
            async with nextcloud_httpx_client() as http_client:
                response = await http_client.get(discovery_url)
                response.raise_for_status()
                discovery = response.json()
                token_endpoint = discovery["token_endpoint"]

            token_params = {
                "grant_type": "authorization_code",
                "code": code,
                "redirect_uri": callback_uri,
                "client_id": oauth_config["client_id"],
                "client_secret": oauth_config["client_secret"],
            }

            # Add code_verifier for PKCE (required by Nextcloud OIDC)
            if code_verifier:
                token_params["code_verifier"] = code_verifier

            async with nextcloud_httpx_client() as http_client:
                response = await http_client.post(
                    token_endpoint,
                    data=token_params,
                )
                response.raise_for_status()
                token_data = response.json()

    except httpx.HTTPStatusError as e:
        error_body = (
            e.response.text if hasattr(e.response, "text") else str(e.response.content)
        )
        logger.error(
            f"Token exchange failed: HTTP {e.response.status_code} - {error_body}"
        )
        return HTMLResponse(
            f"""
            <!DOCTYPE html>
            <html>
            <head><title>Login Failed</title></head>
            <body>
                <h1>Login Failed</h1>
                <p>Failed to exchange authorization code for tokens</p>
                <p>HTTP {e.response.status_code}: {error_body}</p>
            </body>
            </html>
            """,
            status_code=500,
        )
    except Exception as e:
        logger.error(f"Token exchange failed: {e}")
        return HTMLResponse(
            f"""
            <!DOCTYPE html>
            <html>
            <head><title>Login Failed</title></head>
            <body>
                <h1>Login Failed</h1>
                <p>Failed to exchange authorization code for tokens</p>
                <p>Error: {e}</p>
            </body>
            </html>
            """,
            status_code=500,
        )

    refresh_token = token_data.get("refresh_token")
    id_token = token_data.get("id_token")

    logger.info(f"Token exchange response keys: {token_data.keys()}")
    logger.info(f"Refresh token present: {refresh_token is not None}")
    logger.info(f"ID token present: {id_token is not None}")

    # Resolve the discovery URL + audience used for THIS auth request so
    # we can verify the ID token signature + claims (issue #626 finding 1).
    if oauth_client:
        # External IdP path
        verification_audience = oauth_client.client_id
        verification_discovery_url = getattr(oauth_client, "discovery_url", None)
    else:
        # Integrated Nextcloud OIDC path
        verification_audience = oauth_config["client_id"]
        verification_discovery_url = oauth_config.get("discovery_url")

    if not verification_discovery_url:
        logger.error("Cannot verify ID token: no discovery_url available")
        return HTMLResponse(
            "<h1>Login Failed</h1><p>OIDC discovery URL not configured</p>",
            status_code=500,
        )

    try:
        userinfo = await verify_id_token(
            id_token,
            discovery_url=verification_discovery_url,
            expected_audience=verification_audience,
        )
    except IdTokenVerificationError as e:
        logger.error("ID token verification failed: %s", e)
        # html_escape: defense-in-depth. The exception text is currently
        # server-constructed, but escape on the success path too so any
        # future error wrapping that includes IdP response text can't
        # smuggle markup into the login-failure page.
        return HTMLResponse(
            f"<h1>Login Failed</h1><p>ID token failed verification: {html_escape(str(e))}</p>",
            status_code=400,
        )

    user_id = userinfo["sub"]
    username = userinfo.get("preferred_username") or userinfo.get("email")
    logger.info("Browser login successful: %s (sub=%s)", username, user_id)

    # Calculate refresh token expiration from token response
    refresh_expires_in = token_data.get("refresh_expires_in")
    refresh_expires_at = None
    if refresh_expires_in:
        refresh_expires_at = int(time.time()) + refresh_expires_in
        logger.info(
            f"Refresh token expires in {refresh_expires_in}s (at timestamp {refresh_expires_at})"
        )

    # Extract granted scopes
    granted_scopes = (
        token_data.get("scope", "").split() if token_data.get("scope") else None
    )

    # Store refresh token (for background jobs ONLY)
    if refresh_token:
        logger.info(f"Storing refresh token for user_id: {user_id}")
        logger.info(f"  State parameter (provisioning_client_id): {state[:16]}...")
        logger.info(f"  Granted scopes: {granted_scopes}")
        logger.info(f"  Expires at: {refresh_expires_at}")
        await storage.store_refresh_token(
            user_id=user_id,
            refresh_token=refresh_token,
            expires_at=refresh_expires_at,
            flow_type="browser",  # Browser-based login flow
            provisioning_client_id=state,  # Store state for unified session lookup
            scopes=granted_scopes,
        )
        logger.info(f"✓ Refresh token stored successfully for user_id: {user_id}")
        logger.info(
            f"  Token can now be found via provisioning_client_id={state[:16]}..."
        )
    else:
        logger.warning("No refresh token in token response - cannot store session")

    # Query and cache user profile (for browser UI display)
    access_token = token_data.get("access_token")
    if access_token:
        try:
            # Get the OAuth context to determine correct userinfo endpoint
            oauth_ctx = getattr(request.app.state, "oauth_context", {})
            userinfo_endpoint = await _get_userinfo_endpoint(oauth_ctx)

            if userinfo_endpoint:
                # Query userinfo endpoint with fresh access token
                profile_data = await _query_idp_userinfo(
                    access_token, userinfo_endpoint
                )

                if profile_data:
                    # Cache profile for browser UI (no token needed to display)
                    await storage.store_user_profile(user_id, profile_data)
                    logger.info(f"✓ User profile cached for {user_id}")
                else:
                    logger.warning(f"Failed to query userinfo endpoint for {user_id}")
            else:
                logger.warning("Could not determine userinfo endpoint")
        except Exception as e:
            logger.error(f"Error caching user profile: {e}")
            # Continue anyway - profile cache is optional for browser UI

    # Create a server-side browser session: a random opaque session_id is
    # mapped to the verified user_id in `browser_sessions`. The cookie value
    # is the session_id (never the raw user_id — see issue #626 finding 2).
    session_id = secrets.token_urlsafe(32)
    session_ttl = 86400 * 30  # 30 days
    await storage.create_browser_session(
        session_id=session_id, user_id=user_id, ttl_seconds=session_ttl
    )

    response = RedirectResponse(next_url, status_code=302)
    response.set_cookie(
        key="mcp_session",
        value=session_id,
        max_age=session_ttl,
        httponly=True,
        secure=_should_use_secure_cookies(),
        samesite="lax",
    )

    logger.info("Session cookie set for user %s (sid=%s…)", username, session_id[:8])
    return response


async def oauth_logout(request: Request) -> RedirectResponse:
    """Browser OAuth logout — invalidate session and revoke refresh token.

    Issue #626 finding 4: prior implementation only cleared the cookie,
    leaving the refresh token in storage (valid up to 90 days). This now:
      1. Resolves the user_id for the current browser session_id.
      2. Calls the IdP `revocation_endpoint` for the stored refresh token
         when the IdP advertises one.
      3. Deletes the stored refresh token regardless of revocation success.
      4. Deletes the browser_sessions row so the cookie is unusable even
         if it leaks.
      5. Clears the cookie on the response.

    Query parameters:
        next: Optional URL to redirect to after logout (default: /oauth/login)
    """
    next_url = request.query_params.get("next", "/oauth/login")
    session_id = request.cookies.get("mcp_session")

    oauth_ctx = getattr(request.app.state, "oauth_context", None)
    storage = oauth_ctx.get("storage") if oauth_ctx else None

    if session_id and storage and oauth_ctx:
        try:
            user_id = await storage.get_browser_session_user(session_id)
            if user_id:
                token_data = await storage.get_refresh_token(user_id)
                refresh_token = token_data.get("refresh_token") if token_data else None

                if refresh_token:
                    await _revoke_refresh_token_at_idp(oauth_ctx, refresh_token)
                    await storage.delete_refresh_token(user_id)
                    logger.info("Refresh token revoked + deleted for user %s", user_id)

            await storage.delete_browser_session(session_id)
        except Exception as e:
            # Logout must always succeed locally; log and continue.
            logger.warning("Logout cleanup failed (continuing): %s", e)

    response = RedirectResponse(next_url, status_code=302)
    response.delete_cookie("mcp_session")

    logger.info("User logged out, session cookie cleared")
    return response


async def _revoke_refresh_token_at_idp(oauth_ctx: dict, refresh_token: str) -> None:
    """Best-effort RFC 7009 revocation against the IdP.

    Silent on failure: revoking remotely is a defense-in-depth step on top
    of deleting the local copy, and we don't want logout to error if the
    IdP is unreachable or doesn't advertise a revocation endpoint.
    """
    try:
        discovery_url = oauth_ctx.get("discovery_url") or os.getenv(
            "OIDC_DISCOVERY_URL",
            f"{os.getenv('NEXTCLOUD_HOST', '')}/.well-known/openid-configuration",
        )
        if not discovery_url:
            return

        async with nextcloud_httpx_client() as http_client:
            discovery_response = await http_client.get(discovery_url)
            discovery_response.raise_for_status()
            discovery = discovery_response.json()
            revocation_endpoint = discovery.get("revocation_endpoint")
            if not revocation_endpoint:
                logger.debug("IdP advertises no revocation_endpoint; skipping")
                return

            client_id = oauth_ctx.get("client_id") or os.getenv("OIDC_CLIENT_ID")
            client_secret = oauth_ctx.get("client_secret") or os.getenv(
                "OIDC_CLIENT_SECRET"
            )
            if not (client_id and client_secret):
                logger.debug("No OIDC client credentials available for revocation")
                return

            response = await http_client.post(
                revocation_endpoint,
                data={
                    "token": refresh_token,
                    "token_type_hint": "refresh_token",
                },
                auth=(client_id, client_secret),
            )
            if response.status_code >= 400:
                logger.warning(
                    "Refresh token revocation returned HTTP %s", response.status_code
                )
    except Exception as e:
        logger.warning("Refresh token revocation failed: %s", e)