Fix and improve tag search menu

Show also "empty tags", where the count is 0. Before only tags with a
count > 0 were displayed. When searching this is fine, but when using
drag&drop to attach tags to items, it is good to see all. They can be
hidden via a button.

The tags are now ordered by their count descending, but regarding to
the overall count – not the current view. Otherwise the tags are
reordered when clicking on them, which is confusing. Also it then
shows the "more important" (most used) tags first, even when the
result is a subset.

A fix was made related to updating the menu. When coming back from
the detail view where a tag with prior count=0 was associated, the
menu didn't show it, because it relied on a previous state, where this
tag were not included.

modules/webapp/src/main/elm/Comp/SearchMenu.elm

@@ -24,6 +24,7 @@ import Api.Model.ItemSearch exposing (ItemSearch)
 import Api.Model.PersonList exposing (PersonList)
 import Api.Model.ReferenceList exposing (ReferenceList)
 import Api.Model.SearchStats exposing (SearchStats)
+import Api.Model.TagList exposing (TagList)
 import Comp.CustomFieldMultiInput
 import Comp.DatePicker
 import Comp.Dropdown exposing (isDropdownChangeMsg)
@@ -84,7 +85,7 @@ type TextSearchModel
 
 init : Flags -> Model
 init flags =
-    { tagSelectModel = Comp.TagSelect.init Comp.TagSelect.emptySelection []
+    { tagSelectModel = Comp.TagSelect.init [] []
     , tagSelection = Comp.TagSelect.emptySelection
     , directionModel =
         Comp.Dropdown.makeSingleList
@@ -358,6 +359,7 @@ type Msg
     | CustomFieldMsg Comp.CustomFieldMultiInput.Msg
     | SetSource String
     | GetStatsResp (Result Http.Error SearchStats)
+    | GetAllTagsResp (Result Http.Error SearchStats)
 
 
 type alias NextState =
@@ -424,7 +426,7 @@ updateDrop ddm flags settings msg model =
             { model = mdp
             , cmd =
                 Cmd.batch
-                    [ Api.itemSearchStats flags (getItemSearch model) GetStatsResp
+                    [ Api.itemSearchStats flags Api.Model.ItemSearch.empty GetAllTagsResp
                     , Api.getOrgLight flags GetOrgResp
                     , Api.getEquipments flags "" GetEquipResp
                     , Api.getPersons flags "" GetPersonResp
@@ -437,7 +439,7 @@ updateDrop ddm flags settings msg model =
 
         ResetForm ->
             { model = resetModel model
-            , cmd = Cmd.none
+            , cmd = Api.itemSearchStats flags Api.Model.ItemSearch.empty GetAllTagsResp
             , stateChange = True
             , dragDrop = DD.DragDropData ddm Nothing
             }
@@ -473,12 +475,29 @@ updateDrop ddm flags settings msg model =
         SetTag id ->
             resetAndSet (TagSelectMsg (Comp.TagSelect.toggleTag id))
 
+        GetAllTagsResp (Ok stats) ->
+            let
+                tagSel =
+                    Comp.TagSelect.modifyAll stats.tagCloud.items model.tagSelectModel
+            in
+            { model = { model | tagSelectModel = tagSel }
+            , cmd = Cmd.none
+            , stateChange = False
+            , dragDrop = DD.DragDropData ddm Nothing
+            }
+
+        GetAllTagsResp (Err _) ->
+            { model = model
+            , cmd = Cmd.none
+            , stateChange = False
+            , dragDrop = DD.DragDropData ddm Nothing
+            }
+
         GetStatsResp (Ok stats) ->
             let
                 selectModel =
                     List.sortBy .count stats.tagCloud.items
-                        |> List.reverse
-                        |> Comp.TagSelect.modify model.tagSelection model.tagSelectModel
+                        |> Comp.TagSelect.modifyCount model.tagSelectModel
 
                 model_ =
                     { model
@@ -567,7 +586,7 @@ updateDrop ddm flags settings msg model =
         TagSelectMsg m ->
             let
                 ( m_, sel, ddd ) =
-                    Comp.TagSelect.updateDrop ddm m model.tagSelectModel
+                    Comp.TagSelect.updateDrop ddm model.tagSelection m model.tagSelectModel
             in
             { model =
                 { model
@@ -968,14 +987,26 @@ viewDrop ddd flags settings model =
                 , ( "invisible hidden", fieldHidden Data.Fields.Tag && fieldHidden Data.Fields.Folder )
                 ]
             ]
-            [ optional [ Data.Fields.Tag ] <|
-                Html.map TagSelectMsg (Comp.TagSelect.viewTagsDrop ddd.model settings model.tagSelectModel)
-            , optional [ Data.Fields.Tag ] <|
-                Html.map TagSelectMsg (Comp.TagSelect.viewCats settings model.tagSelectModel)
-            , optional [ Data.Fields.Folder ] <|
-                Html.map FolderSelectMsg
-                    (Comp.FolderSelect.viewDrop ddd.model settings.searchMenuFolderCount model.folderList)
-            ]
+            ((if fieldVisible Data.Fields.Tag then
+                List.map (Html.map TagSelectMsg)
+                    (Comp.TagSelect.viewAll
+                        ddd.model
+                        settings
+                        model.tagSelection
+                        model.tagSelectModel
+                    )
+
+              else
+                []
+             )
+                ++ [ optional [ Data.Fields.Folder ] <|
+                        Html.map FolderSelectMsg
+                            (Comp.FolderSelect.viewDrop ddd.model
+                                settings.searchMenuFolderCount
+                                model.folderList
+                            )
+                   ]
+            )
         , div
             [ classList
                 [ ( segmentClass, True )