Implement user-engine portal foundation

src/user_engine/web.py

@@ -0,0 +1,230 @@
+"""Dependency-free WSGI transport for the user-engine portal.
+
+Authentication is deliberately delegated to KeyCape (or another OIDC-aware
+edge).  The application accepts claims only when the edge presents a shared
+authentication marker configured at process start.  This keeps passwords,
+MFA material, provider administration credentials, and browser sessions out
+of user-engine.
+"""
+
+from __future__ import annotations
+
+from dataclasses import asdict, is_dataclass
+from enum import Enum
+from html import escape
+import json
+import secrets
+from typing import Any, Callable, Iterable, Mapping
+from urllib.parse import parse_qs
+
+from user_engine.domain import AccountStatus
+from user_engine.errors import AuthorizationDenied, ConflictError, NotFoundError, ValidationError
+from user_engine.service import UserEngineService
+
+StartResponse = Callable[[str, list[tuple[str, str]]], Any]
+
+
+def _jsonable(value: Any) -> Any:
+    if is_dataclass(value):
+        return {key: _jsonable(item) for key, item in asdict(value).items()}
+    if isinstance(value, Enum):
+        return value.value
+    if isinstance(value, Mapping):
+        return {str(key): _jsonable(item) for key, item in value.items()}
+    if isinstance(value, (tuple, list)):
+        return [_jsonable(item) for item in value]
+    if hasattr(value, "isoformat"):
+        return value.isoformat()
+    return value
+
+
+class PortalApplication:
+    """Small, auditable HTTP adapter over :class:`UserEngineService`."""
+
+    def __init__(
+        self,
+        service: UserEngineService,
+        *,
+        trusted_proxy_secret: str,
+        login_url: str,
+        public_registration: bool = True,
+    ) -> None:
+        if len(trusted_proxy_secret) < 24:
+            raise ValueError("trusted proxy secret must contain at least 24 characters")
+        self.service = service
+        self.trusted_proxy_secret = trusted_proxy_secret
+        self.login_url = login_url
+        self.public_registration = public_registration
+
+    def __call__(self, environ: Mapping[str, Any], start_response: StartResponse) -> Iterable[bytes]:
+        correlation_id = environ.get("HTTP_X_REQUEST_ID") or f"corr_{secrets.token_hex(12)}"
+        try:
+            return self._dispatch(environ, start_response, str(correlation_id))
+        except (ValidationError, ConflictError) as exc:
+            return self._error(start_response, "400 Bad Request", "invalid_request", str(exc), correlation_id)
+        except AuthorizationDenied:
+            return self._error(start_response, "403 Forbidden", "access_denied", "Access denied.", correlation_id)
+        except NotFoundError:
+            return self._error(start_response, "404 Not Found", "not_found", "Resource not found.", correlation_id)
+        except (json.JSONDecodeError, UnicodeDecodeError):
+            return self._error(start_response, "400 Bad Request", "invalid_json", "Malformed request body.", correlation_id)
+
+    def _dispatch(self, environ: Mapping[str, Any], start_response: StartResponse, correlation_id: str) -> Iterable[bytes]:
+        method = str(environ.get("REQUEST_METHOD", "GET")).upper()
+        path = str(environ.get("PATH_INFO", "/")).rstrip("/") or "/"
+        if path == "/healthz":
+            return self._json(start_response, "200 OK", _jsonable(self.service.health()), correlation_id)
+        if path == "/readyz":
+            report = self.service.readiness()
+            return self._json(start_response, "200 OK" if report.ready else "503 Service Unavailable", _jsonable(report), correlation_id)
+        if path == "/login":
+            start_response("303 See Other", [("Location", self.login_url), *self._security_headers(correlation_id)])
+            return [b""]
+        if path == "/" and method == "GET":
+            actor = self._optional_actor(environ)
+            return self._html(start_response, self._home(actor), correlation_id)
+
+        actor = self._actor(environ)
+        if path == "/api/v1/me" and method == "GET":
+            return self._json(start_response, "200 OK", _jsonable(self.service.me(self._claims(environ), correlation_id=correlation_id)), correlation_id)
+        if path == "/api/v1/registrations" and method == "POST":
+            if not self.public_registration:
+                raise AuthorizationDenied("public registration disabled")
+            body = self._body(environ)
+            session = self.service.start_registration(
+                actor,
+                tenant=body.get("tenant"),
+                correlation_id=correlation_id,
+            )
+            return self._json(start_response, "201 Created", _jsonable(session), correlation_id)
+        if path.startswith("/api/v1/registrations/") and path.endswith("/complete") and method == "POST":
+            registration_id = path.split("/")[4]
+            body = self._body(environ)
+            result = self.service.complete_registration(
+                actor,
+                registration_id,
+                display_name=body.get("display_name"),
+                primary_email=body.get("primary_email"),
+                correlation_id=correlation_id,
+            )
+            return self._json(start_response, "200 OK", _jsonable(result), correlation_id)
+        if path.startswith("/api/v1/tenants/") and path.endswith("/users") and method == "GET":
+            tenant = path.split("/")[4]
+            self.service.resolve_tenant_context(actor, tenant)
+            memberships = self.service.store.memberships_for_tenant(tenant)
+            offset, limit = self._page(environ)
+            items = memberships[offset : offset + limit]
+            payload = {"items": _jsonable(items), "offset": offset, "limit": limit, "total": len(memberships)}
+            return self._json(start_response, "200 OK", payload, correlation_id)
+        if path.startswith("/api/v1/tenants/") and "/users/" in path and method == "PATCH":
+            parts = path.split("/")
+            tenant, user_id = parts[4], parts[6]
+            body = self._body(environ)
+            status = AccountStatus(str(body["status"]))
+            result = self.service.set_tenant_account_status(
+                actor, user_id, status, tenant=tenant, correlation_id=correlation_id
+            )
+            return self._json(start_response, "200 OK", _jsonable(result), correlation_id)
+        if path.startswith("/admin/") and method == "GET":
+            tenant = path.split("/")[2]
+            self.service.resolve_tenant_context(actor, tenant)
+            memberships = self.service.store.memberships_for_tenant(tenant)
+            return self._html(start_response, self._admin(tenant, memberships), correlation_id)
+        return self._error(start_response, "404 Not Found", "not_found", "Resource not found.", correlation_id)
+
+    def _claims(self, environ: Mapping[str, Any]) -> Mapping[str, Any]:
+        marker = str(environ.get("HTTP_X_USER_ENGINE_PROXY_SECRET", ""))
+        if not secrets.compare_digest(marker, self.trusted_proxy_secret):
+            raise AuthorizationDenied("untrusted identity source")
+        raw = environ.get("HTTP_X_VERIFIED_OIDC_CLAIMS")
+        if not raw:
+            raise AuthorizationDenied("verified claims required")
+        claims = json.loads(str(raw))
+        if not isinstance(claims, dict):
+            raise AuthorizationDenied("verified claims must be an object")
+        return claims
+
+    def _actor(self, environ: Mapping[str, Any]) -> Any:
+        return self.service.identity_adapter.normalize(self._claims(environ))
+
+    def _optional_actor(self, environ: Mapping[str, Any]) -> Any | None:
+        try:
+            return self._actor(environ)
+        except (AuthorizationDenied, json.JSONDecodeError, ValidationError):
+            return None
+
+    @staticmethod
+    def _body(environ: Mapping[str, Any]) -> Mapping[str, Any]:
+        length = min(int(environ.get("CONTENT_LENGTH") or 0), 65536)
+        payload = environ["wsgi.input"].read(length) if length else b"{}"
+        value = json.loads(payload.decode("utf-8"))
+        if not isinstance(value, dict):
+            raise ValidationError("request body must be an object")
+        return value
+
+    @staticmethod
+    def _page(environ: Mapping[str, Any]) -> tuple[int, int]:
+        query = parse_qs(str(environ.get("QUERY_STRING", "")))
+        offset = max(0, int(query.get("offset", ["0"])[0]))
+        limit = max(1, min(100, int(query.get("limit", ["25"])[0])))
+        return offset, limit
+
+    def _home(self, actor: Any | None) -> str:
+        identity = (
+            f"<p>Signed in as <strong>{escape(actor.preferred_username)}</strong>.</p>"
+            if actor is not None
+            else f'<p><a class="button" href="/login">Sign in with KeyCape</a></p>'
+        )
+        return self._page_html(
+            "Identity & access",
+            "<h1>Your account, on your terms.</h1>"
+            "<p>Join a tenant, complete onboarding, and manage access without exposing credentials to applications.</p>"
+            + identity,
+        )
+
+    def _admin(self, tenant: str, memberships: tuple[Any, ...]) -> str:
+        rows = "".join(
+            f"<tr><td>{escape(item.user_id)}</td><td>{escape(item.kind)}</td><td>{escape(item.scope_id)}</td></tr>"
+            for item in memberships
+        ) or '<tr><td colspan="3">No members yet.</td></tr>'
+        return self._page_html(
+            f"{tenant} users",
+            f"<h1>{escape(tenant)} users</h1><table><thead><tr><th>User</th><th>Role</th><th>Scope</th></tr></thead><tbody>{rows}</tbody></table>",
+        )
+
+    @staticmethod
+    def _page_html(title: str, body: str) -> str:
+        return f"""<!doctype html><html lang="en"><head><meta charset="utf-8">
+<meta name="viewport" content="width=device-width,initial-scale=1">
+<title>{escape(title)} · Railiance</title><style>
+:root{{--ink:#17201c;--paper:#f5f1e8;--accent:#195b47;--line:#c8c1b3}}
+*{{box-sizing:border-box}}body{{margin:0;background:var(--paper);color:var(--ink);font:18px/1.55 system-ui,sans-serif}}
+header,main{{max-width:68rem;margin:auto;padding:1.25rem}}header{{border-bottom:1px solid var(--line)}}
+h1{{font:clamp(2.2rem,7vw,5.5rem)/.98 Georgia,serif;max-width:13ch}}a{{color:var(--accent)}}
+.button{{display:inline-block;background:var(--accent);color:white;padding:.8rem 1.15rem;border-radius:.3rem;text-decoration:none}}
+table{{width:100%;border-collapse:collapse;background:#fff}}th,td{{padding:.75rem;text-align:left;border-bottom:1px solid var(--line)}}
+a:focus-visible{{outline:3px solid #e59f24;outline-offset:3px}}@media(max-width:640px){{body{{font-size:16px}}}}
+</style></head><body><header><strong>Railiance identity</strong></header><main>{body}</main></body></html>"""
+
+    def _html(self, start_response: StartResponse, body: str, correlation_id: str) -> list[bytes]:
+        data = body.encode()
+        start_response("200 OK", [("Content-Type", "text/html; charset=utf-8"), ("Content-Length", str(len(data))), *self._security_headers(correlation_id)])
+        return [data]
+
+    def _json(self, start_response: StartResponse, status: str, payload: Any, correlation_id: str) -> list[bytes]:
+        data = json.dumps(payload, separators=(",", ":"), default=str).encode()
+        start_response(status, [("Content-Type", "application/json"), ("Content-Length", str(len(data))), *self._security_headers(correlation_id)])
+        return [data]
+
+    def _error(self, start_response: StartResponse, status: str, code: str, message: str, correlation_id: str) -> list[bytes]:
+        return self._json(start_response, status, {"error": {"code": code, "message": message, "correlation_id": correlation_id}}, correlation_id)
+
+    @staticmethod
+    def _security_headers(correlation_id: str) -> list[tuple[str, str]]:
+        return [
+            ("X-Request-ID", correlation_id),
+            ("Cache-Control", "no-store"),
+            ("X-Content-Type-Options", "nosniff"),
+            ("Referrer-Policy", "no-referrer"),
+            ("Content-Security-Policy", "default-src 'none'; style-src 'unsafe-inline'; form-action 'self'; frame-ancestors 'none'; base-uri 'none'"),
+        ]