M5-T10: add paho MQTT client with lifespan connect/reconnect and mqtt/test endpoint

app/api/routes/api/config.py

@@ -9,12 +9,14 @@ from sqlalchemy.orm import Session
 from app.api.routes.api.deps import require_csrf, require_session
 from app.config import Settings, get_settings
 from app.dependencies import get_app_settings, get_db
+from app.integrations.mqtt import MQTT_SETTINGS_KEYS, mqtt_manager
 from app.schemas.config import (
     ConfigField,
     ConfigResponse,
     ConfigSection,
     ConfigUpdateRequest,
     ConfigUpdateResponse,
+    MqttTestResponse,
     SmtpTestResponse,
 )
 from app.services.auth import AuthenticatedSession
@@ -58,7 +60,12 @@ def put_config(
 
     - Blank secret value keeps the existing stored value (no change).
     - Invalid values return 422 and nothing is written to the database.
+    - If MQTT-related settings changed, the MQTT client reconnects automatically.
     """
+    # Detect whether any MQTT-related key is being submitted (non-secret change
+    # or non-blank secret change) so we know to reconnect after saving.
+    mqtt_keys_submitted = any(k.lower() in MQTT_SETTINGS_KEYS for k in body.updates)
+
     try:
         save_config_updates(db, body.updates, settings)
     except ConfigSaveError as exc:
@@ -70,6 +77,12 @@ def put_config(
 
     # Re-read settings after save (save_config_updates clears the settings cache)
     refreshed_settings = get_settings()
+
+    # Reconnect MQTT client if any MQTT setting was updated.
+    if mqtt_keys_submitted:
+        logger.info("MQTT settings changed — triggering reconnect.")
+        mqtt_manager.reconnect(refreshed_settings)
+
     sections_raw = build_config_sections(db, refreshed_settings)
     return ConfigUpdateResponse(sections=_sections_from_raw(sections_raw))
 
@@ -117,3 +130,174 @@ def post_smtp_test(
         status_code=status.HTTP_200_OK,
         content={"result": "success", "message": "Test email sent successfully."},
     )
+
+
+# ---------------------------------------------------------------------------
+# POST /api/config/mqtt/test — M5-T10
+# ---------------------------------------------------------------------------
+
+class _MqttConfigurationError(ValueError):
+    """Raised when MQTT settings are incomplete or disabled."""
+
+
+class _MqttConnectionError(RuntimeError):
+    """Raised when MQTT broker connection or publish fails."""
+
+
+@router.post(
+    "/config/mqtt/test",
+    responses={
+        200: {"model": MqttTestResponse},
+        400: {"model": MqttTestResponse},
+        502: {"model": MqttTestResponse},
+    },
+)
+def post_mqtt_test(
+    settings: Settings = Depends(get_app_settings),
+    _auth: AuthenticatedSession = Depends(require_session),
+    _csrf: None = Depends(require_csrf),
+) -> JSONResponse:
+    """
+    Test MQTT broker connectivity by attempting to connect and publishing a
+    test message to ``<ha_discovery_prefix>/home-automation/test``.
+
+    The message is visible in MQTT Explorer (or any subscriber) so users can
+    confirm the full broker publish path is working.
+
+    Three possible outcomes:
+    - 200 { "result": "success", "message": ... }
+    - 400 { "result": "config-error", "message": ... }   (not configured)
+    - 502 { "result": "failed", "message": ... }          (connection/publish error)
+
+    MQTT credentials are never echoed in the response.
+    """
+    try:
+        _run_mqtt_test(settings)
+    except _MqttConfigurationError as exc:
+        logger.warning("MQTT test rejected due to configuration: %s", exc)
+        return JSONResponse(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            content={"result": "config-error", "message": str(exc)},
+        )
+    except _MqttConnectionError as exc:
+        logger.warning("MQTT test connection/publish failed: %s", exc)
+        return JSONResponse(
+            status_code=status.HTTP_502_BAD_GATEWAY,
+            content={"result": "failed", "message": str(exc)},
+        )
+
+    return JSONResponse(
+        status_code=status.HTTP_200_OK,
+        content={
+            "result": "success",
+            "message": (
+                f"Test message published to "
+                f"{settings.ha_discovery_prefix}/home-automation/test."
+            ),
+        },
+    )
+
+
+def _run_mqtt_test(settings: Settings) -> None:
+    """Attempt a transient MQTT connection and publish a test message.
+
+    Raises
+    ------
+    _MqttConfigurationError
+        When MQTT is not enabled or broker host is not configured.
+    _MqttConnectionError
+        When the broker is unreachable or the publish fails.
+    """
+    import socket
+
+    import paho.mqtt.client as mqtt
+
+    if not settings.mqtt_broker_host:
+        raise _MqttConfigurationError("MQTT broker host is not configured.")
+
+    test_topic = f"{settings.ha_discovery_prefix}/home-automation/test"
+    test_payload = '{"source": "home-automation", "event": "mqtt_test"}'
+
+    connected_event = __import__("threading").Event()
+    published_event = __import__("threading").Event()
+    connect_error: list[str] = []
+
+    client = mqtt.Client(
+        callback_api_version=mqtt.CallbackAPIVersion.VERSION2,
+        client_id="home-automation-test",
+    )
+
+    def _on_connect(
+        _client: mqtt.Client,
+        _userdata: object,
+        _flags: mqtt.ConnectFlags,
+        reason_code: mqtt.ReasonCode,
+        _properties: mqtt.Properties | None,
+    ) -> None:
+        if reason_code.is_failure:
+            connect_error.append(f"Broker refused connection: {reason_code}")
+        connected_event.set()
+
+    def _on_publish(
+        _client: mqtt.Client,
+        _userdata: object,
+        _mid: int,
+        _reason_code: mqtt.ReasonCode,
+        _properties: mqtt.Properties | None,
+    ) -> None:
+        published_event.set()
+
+    client.on_connect = _on_connect
+    client.on_publish = _on_publish
+
+    if settings.mqtt_tls_enabled:
+        try:
+            client.tls_set()
+        except Exception as exc:
+            raise _MqttConnectionError(f"TLS setup failed: {exc}") from exc
+
+    if settings.mqtt_username:
+        client.username_pw_set(
+            username=settings.mqtt_username,
+            password=settings.mqtt_password or None,
+        )
+
+    client.loop_start()
+    try:
+        try:
+            client.connect(
+                host=settings.mqtt_broker_host,
+                port=settings.mqtt_broker_port,
+                keepalive=10,
+            )
+        except (OSError, socket.error) as exc:
+            # Sanitise: ensure password never leaks into the error message.
+            msg = _sanitize_mqtt_error(str(exc), settings.mqtt_password)
+            raise _MqttConnectionError(f"Cannot reach broker: {msg}") from exc
+
+        # Wait up to 5 s for connection acknowledgement.
+        if not connected_event.wait(timeout=5):
+            raise _MqttConnectionError("Broker connection timed out (5 s).")
+
+        if connect_error:
+            raise _MqttConnectionError(connect_error[0])
+
+        # Publish test message.
+        client.publish(test_topic, payload=test_payload, qos=1, retain=False)
+        # Wait up to 5 s for the publish ACK (QoS 1).
+        if not published_event.wait(timeout=5):
+            raise _MqttConnectionError("Publish timed out (5 s) — broker reachable but no ACK.")
+
+    finally:
+        try:
+            client.disconnect()
+        except Exception:
+            pass
+        client.loop_stop()
+
+
+def _sanitize_mqtt_error(message: str, password: str | None) -> str:
+    """Replace *password* in *message* with ``[redacted]``."""
+    if password:
+        return message.replace(password, "[redacted]")
+    return message