(core) add `+` button to the filter bar

Summary:
 - Adds a + button to the filter. Button triggers a menu that allow to
add one of the column that does not already have a filter set.

Caveats:
 - for now menu only allows to choose from visible column.
 - This diff introduces a slight change of behavior of how filter works:
     - Filter used to be automatically removed when user set them to all
inclusive (ie: by clicking the `All` button).
     - With this diff, it is no longer the case.
     - indeed, when filter are added to the filter bar with the `+` btn they are initially in the `all inclusive` state, hence would have been removed with the above mention behaviour.

Test Plan: Added new test to nbrowser/FilterBar

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2776

app/client/ui/ColumnFilterMenu.ts

@@ -264,6 +264,7 @@ export function createFilterMenu(openCtl: IOpenController, sectionFilter: Sectio
   const labelGetter = tableData.getRowPropFunc(field.displayColModel().colId())!;
   const formatter = field.createVisibleColFormatter();
   const valueMapFunc = (rowId: number) => formatter.formatAny(labelGetter(rowId));
+  const activeFilterBar = field.viewSection.peek().activeFilterBar;
 
   const valueCounts: Map<CellValue, {label: string, count: number}> = new Map();
   // TODO: as of now, this is not working for non text-or-numeric columns, ie: for Date column it is
@@ -282,7 +283,8 @@ export function createFilterMenu(openCtl: IOpenController, sectionFilter: Sectio
     onClose: () => openCtl.close(),
     doSave: (reset: boolean = false) => {
       const spec = columnFilter.makeFilterJson();
-      field.activeFilter(spec === allInclusive ? '' : spec);
+      // If filter is moot and filter bar is hidden, let's remove the filter.
+      field.activeFilter((spec === allInclusive && !activeFilterBar.peek()) ? '' : spec);
       if (reset) {
         sectionFilter.resetTemporaryRows();
       }

app/client/ui/FilterBar.ts

@@ -1,14 +1,17 @@
+import { allInclusive } from "app/client/models/ColumnFilter";
 import { ViewFieldRec, ViewSectionRec } from "app/client/models/DocModel";
 import { attachColumnFilterMenu } from "app/client/ui/ColumnFilterMenu";
 import { cssButton, cssButtonGroup } from "app/client/ui2018/buttons";
 import { colors, testId } from "app/client/ui2018/cssVars";
 import { icon } from "app/client/ui2018/icons";
+import { menu, menuItemAsync } from "app/client/ui2018/menus";
 import { dom, IDisposableOwner, IDomArgs, styled } from "grainjs";
 
 export function filterBar(_owner: IDisposableOwner, viewSection: ViewSectionRec) {
   return cssFilterBar(
     testId('filter-bar'),
     dom.forEach(viewSection.filteredFields, (field) => makeFilterField(viewSection, field)),
+    makePlusButton(viewSection),
     cssSpacer(),
     dom.maybe(viewSection.filterSpecChanged, () => [
       primaryButton(
@@ -30,18 +33,38 @@ function makeFilterField(viewSection: ViewSectionRec, field: ViewFieldRec) {
       testId('btn'),
       cssIcon('FilterSimple'),
       cssMenuTextLabel(dom.text(field.label)),
-      cssBtn.cls('-disabled', field.activeFilter.isSaved),
+      cssBtn.cls('-saved', field.activeFilter.isSaved),
       attachColumnFilterMenu(viewSection, field, {placement: 'bottom-start', attach: 'body'}),
     ),
     deleteButton(
       testId('delete'),
       cssIcon('CrossSmall'),
-      cssBtn.cls('-disabled', field.activeFilter.isSaved),
+      cssBtn.cls('-saved', field.activeFilter.isSaved),
       dom.on('click', () => field.activeFilter('')),
     )
   );
 }
 
+function makePlusButton(viewSectionRec: ViewSectionRec) {
+  return dom.domComputed((use) => {
+    const fields = use(use(viewSectionRec.viewFields).getObservable());
+    const anyFilter = fields.find((f) => use(f.isFiltered));
+    return cssPlusButton(
+      cssBtn.cls('-saved'),
+      cssIcon('Plus'),
+      menu(() => fields.map((f) => (
+        menuItemAsync(
+          () => f.activeFilter(allInclusive),
+          f.label.peek(),
+          dom.cls('disabled', f.isFiltered)
+        )
+      ))),
+      anyFilter ? null : cssPlusLabel('Add Filter'),
+      testId('add-filter-btn')
+    );
+  });
+}
+
 const cssFilterBar = styled('div', `
   display: flex;
   flex-direction: row;
@@ -75,13 +98,13 @@ const cssBtn = styled('div', `
   .${cssFilterBar.className} > & {
     margin: 0 4px;
   }
-  &-disabled {
+  &-saved {
     color:        ${colors.light};
     --icon-color: ${colors.light};
     background-color: ${colors.slate};
     border-color: ${colors.slate};
   }
-  &-disabled:hover {
+  &-saved:hover {
     background-color: ${colors.darkGrey};
     border-color: ${colors.darkGrey};
   }
@@ -100,3 +123,9 @@ const cssSpacer = styled('div', `
   width: 8px;
   flex-shrink: 0;
 `);
+const cssPlusButton = styled(primaryButton, `
+  padding: 3px 3px
+`);
+const cssPlusLabel = styled('span', `
+  margin: 0 12px 0 4px;
+`);