[Glitch] Revamp post filtering system

Port front-end changes from 02851848e9 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/reducers/filters.js

@@ -1,10 +1,34 @@
-import { FILTERS_FETCH_SUCCESS } from '../actions/filters';
-import { List as ImmutableList, fromJS } from 'immutable';
+import { FILTERS_IMPORT } from '../actions/importer';
+import { Map as ImmutableMap, is, fromJS } from 'immutable';
 
-export default function filters(state = ImmutableList(), action) {
+const normalizeFilter = (state, filter) => {
+  const normalizedFilter = fromJS({
+    id: filter.id,
+    title: filter.title,
+    context: filter.context,
+    filter_action: filter.filter_action,
+    expires_at: filter.expires_at ? Date.parse(filter.expires_at) : null,
+  });
+
+  if (is(state.get(filter.id), normalizedFilter)) {
+    return state;
+  } else {
+    return state.set(filter.id, normalizedFilter);
+  }
+};
+
+const normalizeFilters = (state, filters) => {
+  filters.forEach(filter => {
+    state = normalizeFilter(state, filter);
+  });
+
+  return state;
+};
+
+export default function filters(state = ImmutableMap(), action) {
   switch(action.type) {
-  case FILTERS_FETCH_SUCCESS:
-    return fromJS(action.filters);
+  case FILTERS_IMPORT:
+    return normalizeFilters(state, action.filters);
   default:
     return state;
   }