webmail-client/backend/app/plugins/sdk.py

"""The plugin SDK — the ONLY ``app.*`` surface a plugin may import (SPEC §11).

Everything a plugin needs is reached through :func:`sdk`, which returns a
:class:`PluginSdk` bound to the plugin's name: a plugin-scoped DB session, the
event bus (publishing under ``plugin.{name}.*``), the blob store, outbox
draft/send helpers, the settings accessor, an SSRF-guarded HTTP client
(§10.6), and the namespaced KV store (§11).

The frozen contract types (:class:`Plugin`, :class:`UiManifest`, :class:`JobSpec`,
…) are re-exported here so plugin packages import only from ``app.plugins.sdk``.
"""

from __future__ import annotations

import uuid
from contextlib import AbstractAsyncContextManager
from dataclasses import dataclass
from typing import Annotated, Any

from fastapi import Depends
from sqlalchemy.ext.asyncio import AsyncSession

from app.accounts.ssrf import guarded_get
from app.config import Settings, get_settings
from app.events import get_event_bus
from app.identity.deps import current_user, require_csrf
from app.indexer import blobstore
from app.models import User
from app.outbox import service as outbox_service
from app.plugins.actions import PluginActions, PluginMessages
from app.plugins.db import plugin_session
from app.plugins.kv import PluginKvStore
from app.plugins.types import (
    Hook,
    JobFunc,
    JobSpec,
    Page,
    PageNav,
    Plugin,
    Slot,
    UiManifest,
)
from app.queue import enqueue_job

__all__ = [
    "CurrentUserId",
    "Hook",
    "JobFunc",
    "JobSpec",
    "Page",
    "PageNav",
    "Plugin",
    "PluginSdk",
    "Slot",
    "UiManifest",
    "blobstore",
    "require_csrf",
    "sdk",
]


async def _current_user_id(user: Annotated[User, Depends(current_user)]) -> uuid.UUID:
    return user.id


# Auth for plugin routers (plugins must not import app.identity directly, SPEC §11):
# `CurrentUserId` resolves the authenticated user's id; `require_csrf` guards mutating
# routes. Use with the RLS-scoped `sdk(name).session(user_id)`.
CurrentUserId = Annotated[uuid.UUID, Depends(_current_user_id)]


@dataclass(frozen=True)
class PluginSdk:
    """A lightweight facade over shared services, scoped to one plugin.

    Cheap to construct (wraps process-wide singletons + the plugin name), so
    handlers/routes obtain it on demand via ``sdk("<name>")``."""

    name: str

    # --- config -------------------------------------------------------------
    @property
    def settings(self) -> Settings:
        return get_settings()

    # --- database -----------------------------------------------------------
    def session(self, user_id: uuid.UUID) -> AbstractAsyncContextManager[AsyncSession]:
        """An RLS-enforced transactional session scoped to ``user_id`` (SPEC §11.1).

        Row-level security limits every query to this user's rows on ``plg_*``
        tables — even a query that forgets ``WHERE user_id`` cannot leak or write
        across users (see :mod:`app.plugins.db`)."""
        return plugin_session(user_id)

    def kv(self, user_id: uuid.UUID) -> PluginKvStore:
        """The namespaced KV store for this plugin and ``user_id`` (SPEC §11)."""
        return PluginKvStore(self.name, user_id)

    # --- events -------------------------------------------------------------
    async def publish(self, event: str, payload: dict[str, object]) -> None:
        """Publish ``plugin.{name}.{event}`` on the bus (payload needs ``user_id``)."""
        await get_event_bus().publish(f"plugin.{self.name}.{event}", payload)

    # --- background jobs ----------------------------------------------------
    async def enqueue(self, job_func: JobFunc, **kwargs: Any) -> None:
        """Enqueue one of this plugin's jobs on the shared worker (SPEC §11.2).

        ``job_func`` must be a job declared in this plugin's ``jobs=[...]``. Pass
        ``user_id=`` for singleton jobs so the per-user lock applies."""
        await enqueue_job(f"plg.{self.name}.{job_func.__name__}", **kwargs)

    # --- blob store ---------------------------------------------------------
    @property
    def blob(self) -> object:
        """The blob store (``store``/``load``/``exists``/``remove``), keyed by user."""
        return blobstore

    # --- outbox -------------------------------------------------------------
    @property
    def outbox(self) -> object:
        """Draft/send helpers (``upsert_draft``, ``create_outbox``, …)."""
        return outbox_service

    # --- messages -----------------------------------------------------------
    @property
    def messages(self) -> PluginMessages:
        """Read a user's message envelope (subject/sender/flags) for matching."""
        return PluginMessages()

    @property
    def actions(self) -> PluginActions:
        """User-scoped message actions (``set_flags``) — e.g. for filter rules."""
        return PluginActions()

    # --- outbound HTTP ------------------------------------------------------
    async def http_get(self, url: str) -> str | None:
        """GET ``url`` through the §10.6 SSRF guard (blocks private IPs/oversize)."""
        return await guarded_get(url)


def sdk(name: str) -> PluginSdk:
    """Return the SDK facade bound to plugin ``name`` (SPEC §11)."""
    return PluginSdk(name)