1 files changed, 121 insertions, 0 deletions
diff --git a/web/src/js/ducks/utils/list.js b/web/src/js/ducks/utils/list.js
new file mode 100644
index 00000000..37b2ae3a
--- /dev/null
+++ b/web/src/js/ducks/utils/list.js
@@ -0,0 +1,121 @@
+import {fetchApi} from "../../utils";
+
+const ADD = "ADD"
+const REQUEST_LIST = "REQUEST_LIST"
+const RECEIVE_LIST = "RECEIVE_LIST"
+
+
+const defaultState = {
+    list: [],
+    isFetching: false,
+    actionsDuringFetch: [],
+    byId: {},
+    indexOf: {},
+};
+
+export default function makeList(actionType, fetchURL) {
+    function reduceList(state = defaultState, action = {}) {
+
+        if (action.type !== actionType) {
+            return state
+        }
+
+        // Handle cases where we finished fetching or are still fetching.
+        if (action.cmd === RECEIVE_LIST) {
+            let s = {
+                isFetching: false,
+                actionsDuringFetch: [],
+                list: action.list,
+                byId: {},
+                indexOf: {}
+            }
+            for (let i = 0; i < action.list.length; i++) {
+                let item = action.list[i]
+                s.byId[item.id] = item
+                s.indexOf[item.id] = i
+            }
+            for (action of state.actionsDuringFetch) {
+                s = reduceList(s, action)
+            }
+            return s
+        } else if (state.isFetching) {
+            return {
+                ...state,
+                actionsDuringFetch: [...state.actionsDuringFetch, action]
+            }
+        }
+
+        switch (action.cmd) {
+            case ADD:
+                return {
+                    list: [...state.list, action.item],
+                    byId: {...state.byId, [action.item.id]: action.item},
+                    indexOf: {...state.indexOf, [action.item.id]: state.list.length},
+                }
+
+            case REQUEST_LIST:
+                return {
+                    ...defaultState,
+                    isFetching: true
+                }
+
+            default:
+                console.debug("unknown action", action.type)
+                return state
+        }
+    }
+
+    function addToList(item) {
+        return {
+            type: actionType,
+            cmd: ADD,
+            item
+        }
+    }
+
+
+    function updateList(action) {
+        /* This action creater takes all WebSocket events */
+        return dispatch => {
+            switch (action.cmd) {
+                case "add":
+                    return dispatch(addToList(action.data))
+                case "reset":
+                    return dispatch(fetchList())
+                default:
+                    console.error("unknown list update", action)
+            }
+        }
+    }
+
+    function requestList() {
+        return {
+            type: actionType,
+            cmd: REQUEST_LIST,
+        }
+    }
+
+    function receiveList(list) {
+        return {
+            type: actionType,
+            cmd: RECEIVE_LIST,
+            list
+        }
+    }
+
+    function fetchList() {
+        return dispatch => {
+
+            dispatch(requestList())
+
+            fetchApi(fetchURL).then(response => {
+                return response.json().then(json => {
+                    dispatch(receiveList(json.data))
+                })
+            })
+        }
+    }
+
+
+    return {reduceList, addToList, updateList, fetchList}
+}
+\ No newline at end of file