feat(gateway): add Slack gateway webhook flow

surfsense_backend/app/routes/gateway_webhook_routes.py

@@ -2,24 +2,32 @@
 
 from __future__ import annotations
 
+import hashlib
 import hmac
+import json
 import logging
+import time
 import uuid
 from datetime import UTC, datetime
 from typing import Any
-from urllib.parse import quote
+from urllib.parse import quote, urlencode
+from uuid import UUID
 
+import httpx
 from fastapi import APIRouter, Depends, HTTPException, Request
 from pydantic import BaseModel
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
-from starlette.responses import Response
+from starlette.responses import JSONResponse, RedirectResponse, Response
 
 from app.config import config
 from app.db import (
     ExternalChatAccount,
+    ExternalChatAccountMode,
     ExternalChatBinding,
     ExternalChatBindingState,
+    ExternalChatHealthStatus,
+    ExternalChatPeerKind,
     ExternalChatPlatform,
     User,
     get_async_session,
@@ -27,19 +35,92 @@ from app.db import (
 from app.gateway.accounts import (
     get_or_create_system_telegram_account,
     get_or_create_system_whatsapp_account,
+    get_slack_account_by_team,
 )
 from app.gateway.bindings import resume_binding, revoke_binding
-from app.gateway.inbox import persist_inbound_event, telegram_event_dedupe_key
+from app.gateway.inbox import (
+    persist_inbound_event,
+    slack_event_dedupe_key,
+    telegram_event_dedupe_key,
+)
 from app.gateway.pairing import generate_pairing_code, pairing_expires_at
+from app.gateway.slack.adapter import slack_user_peer_id
 from app.observability.metrics import (
     record_gateway_inbox_write,
     record_gateway_webhook_parse_error,
 )
 from app.users import current_active_user
+from app.utils.oauth_security import OAuthStateManager, TokenEncryption
 
 router = APIRouter(prefix="/gateway", tags=["gateway"])
 logger = logging.getLogger(__name__)
 
+SLACK_AUTHORIZATION_URL = "https://slack.com/oauth/v2/authorize"
+SLACK_TOKEN_URL = "https://slack.com/api/oauth.v2.access"
+SLACK_BOT_SCOPES = [
+    "app_mentions:read",
+    "chat:write",
+    "channels:read",
+    "groups:read",
+    "im:write",
+    "users:read",
+    "team:read",
+]
+_state_manager: OAuthStateManager | None = None
+_token_encryption: TokenEncryption | None = None
+
+
+def _get_state_manager() -> OAuthStateManager:
+    global _state_manager
+    if _state_manager is None:
+        if not config.SECRET_KEY:
+            raise HTTPException(status_code=500, detail="SECRET_KEY is not configured")
+        _state_manager = OAuthStateManager(config.SECRET_KEY)
+    return _state_manager
+
+
+def _get_token_encryption() -> TokenEncryption:
+    global _token_encryption
+    if _token_encryption is None:
+        if not config.SECRET_KEY:
+            raise HTTPException(status_code=500, detail="SECRET_KEY is not configured")
+        _token_encryption = TokenEncryption(config.SECRET_KEY)
+    return _token_encryption
+
+
+def _slack_redirect_uri() -> str:
+    if config.GATEWAY_SLACK_REDIRECT_URI:
+        return config.GATEWAY_SLACK_REDIRECT_URI
+    base = config.BACKEND_URL or ""
+    return f"{base.rstrip('/')}/api/v1/gateway/slack/callback"
+
+
+def _slack_frontend_redirect(space_id: int, *, success: bool = False, error: str | None = None) -> RedirectResponse:
+    qs = "slack_gateway=connected" if success else f"error={error or 'slack_gateway_failed'}"
+    return RedirectResponse(
+        url=f"{config.NEXT_FRONTEND_URL}/dashboard/{space_id}/user-settings?{qs}"
+    )
+
+
+def verify_slack_signature(*, signing_secret: str, timestamp: str | None, signature: str | None, body: bytes) -> bool:
+    if not signing_secret or not timestamp or not signature:
+        return False
+    try:
+        ts = int(timestamp)
+    except ValueError:
+        return False
+    if abs(time.time() - ts) > 60 * 5:
+        return False
+    base = b"v0:" + timestamp.encode() + b":" + body
+    digest = hmac.new(signing_secret.encode(), base, hashlib.sha256).hexdigest()
+    expected = f"v0={digest}"
+    return hmac.compare_digest(expected, signature)
+
+
+def _slack_event_kind(payload: dict[str, Any]) -> str:
+    event_type = str((payload.get("event") or {}).get("type") or "")
+    return "message" if event_type in {"app_mention", "message"} else "other"
+
 
 class StartBindingRequest(BaseModel):
     platform: ExternalChatPlatform = ExternalChatPlatform.TELEGRAM
@@ -67,6 +148,213 @@ def _telegram_message(payload: dict[str, Any]) -> dict[str, Any] | None:
     return payload.get("message") or payload.get("edited_message")
 
 
+@router.get("/slack/install")
+async def install_slack_gateway(
+    search_space_id: int,
+    user: User = Depends(current_active_user),
+) -> dict[str, str]:
+    if not config.GATEWAY_SLACK_CLIENT_ID:
+        raise HTTPException(status_code=500, detail="Slack gateway OAuth is not configured")
+    state = _get_state_manager().generate_secure_state(search_space_id, user.id)
+    auth_params = {
+        "client_id": config.GATEWAY_SLACK_CLIENT_ID,
+        "scope": ",".join(SLACK_BOT_SCOPES),
+        "redirect_uri": _slack_redirect_uri(),
+        "state": state,
+    }
+    return {"auth_url": f"{SLACK_AUTHORIZATION_URL}?{urlencode(auth_params)}"}
+
+
+@router.get("/slack/callback")
+async def slack_gateway_callback(
+    code: str | None = None,
+    error: str | None = None,
+    state: str | None = None,
+    session: AsyncSession = Depends(get_async_session),
+) -> RedirectResponse:
+    space_id = None
+    if state:
+        try:
+            state_data = _get_state_manager().validate_state(state)
+            space_id = int(state_data["space_id"])
+        except Exception:
+            state_data = None
+    else:
+        state_data = None
+
+    if error:
+        return _slack_frontend_redirect(space_id or 0, error="slack_gateway_oauth_denied")
+    if not code or state_data is None:
+        raise HTTPException(status_code=400, detail="Invalid Slack gateway OAuth callback")
+    if not config.GATEWAY_SLACK_CLIENT_ID or not config.GATEWAY_SLACK_CLIENT_SECRET:
+        raise HTTPException(status_code=500, detail="Slack gateway OAuth is not configured")
+
+    user_id = UUID(state_data["user_id"])
+    token_payload = {
+        "client_id": config.GATEWAY_SLACK_CLIENT_ID,
+        "client_secret": config.GATEWAY_SLACK_CLIENT_SECRET,
+        "code": code,
+        "redirect_uri": _slack_redirect_uri(),
+    }
+    async with httpx.AsyncClient(timeout=30.0) as client:
+        token_response = await client.post(
+            SLACK_TOKEN_URL,
+            data=token_payload,
+            headers={"Content-Type": "application/x-www-form-urlencoded"},
+        )
+    token_response.raise_for_status()
+    token_json = token_response.json()
+    if not token_json.get("ok", False):
+        raise HTTPException(
+            status_code=400,
+            detail=f"Slack gateway OAuth failed: {token_json.get('error', 'unknown_error')}",
+        )
+
+    bot_token = token_json.get("access_token")
+    team = token_json.get("team") or {}
+    team_id = team.get("id")
+    if not bot_token or not team_id:
+        raise HTTPException(status_code=400, detail="Slack gateway OAuth returned incomplete data")
+
+    bot_user_id = token_json.get("bot_user_id")
+    app_id = token_json.get("app_id")
+    authed_user = token_json.get("authed_user") or {}
+    authed_slack_user_id = authed_user.get("id")
+    enc = _get_token_encryption()
+    credentials = {
+        "bot_token": bot_token,
+        "token_type": token_json.get("token_type", "bot"),
+        "scope": token_json.get("scope"),
+    }
+    cursor_state = {
+        "team_id": team_id,
+        "team_name": team.get("name"),
+        "enterprise_id": (token_json.get("enterprise") or {}).get("id"),
+        "app_id": app_id,
+        "bot_user_id": bot_user_id,
+        "scope": token_json.get("scope"),
+    }
+
+    account = await get_slack_account_by_team(session, team_id=team_id)
+    if account is None:
+        account = ExternalChatAccount(
+            platform=ExternalChatPlatform.SLACK,
+            mode=ExternalChatAccountMode.CLOUD_SHARED,
+            is_system_account=True,
+            encrypted_credentials=enc.encrypt_token(json.dumps(credentials)),
+            bot_username="SurfSense",
+            cursor_state=cursor_state,
+            health_status=ExternalChatHealthStatus.UNKNOWN,
+        )
+        session.add(account)
+        await session.flush()
+    else:
+        account.encrypted_credentials = enc.encrypt_token(json.dumps(credentials))
+        account.cursor_state = {**(account.cursor_state or {}), **cursor_state}
+        account.health_status = ExternalChatHealthStatus.UNKNOWN
+
+    if authed_slack_user_id:
+        peer_id = slack_user_peer_id(team_id, authed_slack_user_id)
+        existing_binding_result = await session.execute(
+            select(ExternalChatBinding).where(
+                ExternalChatBinding.account_id == account.id,
+                ExternalChatBinding.external_peer_id == peer_id,
+                ExternalChatBinding.state.in_(
+                    [ExternalChatBindingState.BOUND, ExternalChatBindingState.SUSPENDED]
+                ),
+            )
+        )
+        binding = existing_binding_result.scalars().first()
+        if binding is None:
+            session.add(
+                ExternalChatBinding(
+                    account_id=account.id,
+                    user_id=user_id,
+                    search_space_id=space_id,
+                    state=ExternalChatBindingState.BOUND,
+                    external_peer_id=peer_id,
+                    external_peer_kind=ExternalChatPeerKind.DIRECT,
+                    external_username=authed_slack_user_id,
+                    external_metadata={
+                        "kind": "slack_user",
+                        "team_id": team_id,
+                        "slack_user_id": authed_slack_user_id,
+                    },
+                )
+            )
+        elif binding.user_id == user_id:
+            binding.search_space_id = space_id
+            binding.external_metadata = {
+                **(binding.external_metadata or {}),
+                "kind": "slack_user",
+                "team_id": team_id,
+                "slack_user_id": authed_slack_user_id,
+            }
+
+    await session.commit()
+    return _slack_frontend_redirect(space_id, success=True)
+
+
+@router.post("/webhooks/slack")
+async def slack_webhook(
+    request: Request,
+    session: AsyncSession = Depends(get_async_session),
+) -> Response:
+    body = await request.body()
+    if not verify_slack_signature(
+        signing_secret=config.GATEWAY_SLACK_SIGNING_SECRET or "",
+        timestamp=request.headers.get("X-Slack-Request-Timestamp"),
+        signature=request.headers.get("X-Slack-Signature"),
+        body=body,
+    ):
+        raise HTTPException(status_code=403, detail="Invalid Slack signature")
+
+    try:
+        payload = json.loads(body.decode())
+    except ValueError:
+        record_gateway_webhook_parse_error()
+        return Response(status_code=200)
+
+    if payload.get("type") == "url_verification":
+        return JSONResponse({"challenge": payload.get("challenge", "")})
+    if payload.get("type") != "event_callback":
+        return Response(status_code=200)
+
+    event = payload.get("event") or {}
+    event_id = payload.get("event_id")
+    team_id = payload.get("team_id") or event.get("team")
+    if not event_id or not team_id:
+        return Response(status_code=200)
+
+    account = await get_slack_account_by_team(session, team_id=str(team_id))
+    if account is None:
+        logger.warning("Ignoring Slack event for uninstalled team_id=%s", team_id)
+        return Response(status_code=200)
+
+    bot_user_id = (account.cursor_state or {}).get("bot_user_id")
+    if event.get("bot_id") or (bot_user_id and event.get("user") == bot_user_id):
+        return Response(status_code=200)
+
+    try:
+        inbox_id = await persist_inbound_event(
+            session,
+            account_id=account.id,
+            platform=ExternalChatPlatform.SLACK,
+            event_dedupe_key=slack_event_dedupe_key(event_id),
+            external_event_id=str(event_id),
+            external_message_id=str(event.get("ts")) if event.get("ts") else None,
+            event_kind=_slack_event_kind(payload),
+            raw_payload=payload,
+            request_id=f"gateway_{uuid.uuid4().hex[:16]}",
+        )
+        await session.commit()
+        record_gateway_inbox_write(platform="slack", dedup_skipped=inbox_id is None)
+    except Exception:
+        await session.rollback()
+        logger.exception("Slack webhook persistence failed team_id=%s", team_id)
+    return Response(status_code=200)
+
+
 async def _resolve_webhook_account(
     session: AsyncSession,
     *,
@@ -207,6 +495,7 @@ async def list_bindings(
             "search_space_id": binding.search_space_id,
             "external_display_name": binding.external_display_name,
             "external_username": binding.external_username,
+            "external_metadata": binding.external_metadata,
             "suspended_reason": binding.suspended_reason,
         }
         for binding, account in result.all()