[web] Add reducer and actions for option editor.

web/src/js/ducks/ui/index.js

@@ -2,10 +2,12 @@ import { combineReducers } from 'redux'
 import flow from './flow'
 import header from './header'
 import modal from './modal'
+import option from './option'
 
 // TODO: Just move ducks/ui/* into ducks/?
 export default combineReducers({
     flow,
     header,
-    modal
+    modal,
+    option,
 })

web/src/js/ducks/ui/option.js

@@ -0,0 +1,39 @@
+export const OPTION_UPDATE_START   = 'UI_OPTION_UPDATE_START'
+export const OPTION_UPDATE_SUCCESS = 'UI_OPTION_UPDATE_SUCCESS'
+export const OPTION_UPDATE_ERROR   = 'UI_OPTION_UPDATE_ERROR'
+
+const defaultState = {
+    /* optionName -> {isUpdating, value (client-side), error} */
+}
+
+export default function reducer(state = defaultState, action) {
+    switch (action.type) {
+        case OPTION_UPDATE_START:
+            return {
+                ...state,
+                [action.option]: {
+                    isUpdate: true,
+                    value: action.value,
+                    error: false,
+                }
+            }
+
+        case OPTION_UPDATE_SUCCESS:
+            let s = {...state}
+            delete s[action.option]
+            return s
+
+        case OPTION_UPDATE_ERROR:
+            return {
+                ...state,
+                [action.option]: {
+                    ...state[action.option],
+                    isUpdating: false,
+                    error: action.error
+                }
+            }
+
+        default:
+            return state
+    }
+}