UI: manage SC state from one source

Make sure that sample changer state is managed by the SET_SC_STATE
action only.

Previously the sample changer state was set by two different actions,
one originating from SampleChanger HW object and the other from
SampleChangerMaint HW object.

That creates problems, as the state can potentionally be set to different
values by these two objects. Let the SampleChanger HW object be the
source of truth for the current sample changer state.

mxcube3/routes/signals.py

@@ -187,12 +187,18 @@ def sc_contents_update():
     server.emit("sc_contents_update")
 
 
-def sc_maintenance_update(state_list, cmd_state, message):
+def sc_maintenance_update(*args):
+    if len(args) == 3:
+        # be backward compatible with older HW objects,
+        # which are emitting signal with 3 arguments
+        _, cmd_state, message = args
+    else:
+        cmd_state, message = args
+
     try:
         server.emit(
             "sc_maintenance_update",
             {
-                "state": json.dumps(state_list),
                 "commands_state": json.dumps(cmd_state),
                 "message": message,
             },

ui/src/reducers/sampleChanger.js

@@ -118,12 +118,6 @@ export default (state = INITIAL_STATE, action) => {
     case 'SET_SC_SELECTED_DROP': {
       return { ...state, selectedDrop: action.drop_index };
     }
-    case 'SET_SC_GLOBAL_STATE': {
-      return {
-        ...state,
-        state: JSON.parse(action.data.state).state,
-      };
-    }
     default: {
       return state;
     }

ui/src/reducers/sampleChangerMaintenance.js

@@ -20,8 +20,6 @@ export default (state = INITIAL_STATE, action) => {
     case 'SET_SC_GLOBAL_STATE': {
       return {
         ...state,
-        state: JSON.parse(action.data.state),
-        global_state: JSON.parse(action.data.global_state),
         commands_state: JSON.parse(action.data.commands_state),
         message: action.data.message,
       };