fix: scroll misbehaving + fixed jump to middle (#547)

* fix: scroll misbehaving + fixed jump to middle

* add test

* fixx

* fix nil

lua/telescope/actions/init.lua

@@ -80,7 +80,11 @@ end
 
 function actions.move_to_middle(prompt_bufnr)
   local current_picker = actions.get_current_picker(prompt_bufnr)
-  current_picker:set_selection(p_scroller.middle(nil, current_picker.max_results, nil))
+  current_picker:set_selection(p_scroller.middle(
+    current_picker.sorting_strategy,
+    current_picker.max_results,
+    current_picker.manager:num_results()
+  ))
 end
 
 function actions.move_to_bottom(prompt_bufnr)

lua/telescope/actions/set.lua

@@ -28,6 +28,7 @@ local set = setmetatable({}, {
 set.shift_selection = function(prompt_bufnr, change)
   local count = vim.v.count
   count = count == 0 and 1 or count
+  count = a.nvim_get_mode().mode == "n" and count or 1
   action_state.get_current_picker(prompt_bufnr):move_selection(change * count)
 end
 

lua/telescope/pickers/scroller.lua

@@ -81,7 +81,15 @@ scroller.top = function(sorting_strategy, max_results, num_results)
 end
 
 scroller.middle = function(sorting_strategy, max_results, num_results)
-  return math.floor(max_results/2)
+  local mid_pos
+
+  if sorting_strategy == 'ascending' then
+    mid_pos = math.floor(num_results / 2)
+  else
+    mid_pos = math.floor(max_results - num_results / 2)
+  end
+
+  return (num_results < max_results) and mid_pos or math.floor(max_results / 2)
 end
 
 scroller.bottom = function(sorting_strategy, max_results, num_results)

lua/tests/automated/scroller_spec.lua

@@ -114,18 +114,16 @@ describe('scroller', function()
 
 
   describe('should give top, middle and bottom index', function()
-    it('should handle middle index', function()
-      eq(5, p_scroller.middle(nil, 11, nil))
-      eq(10, p_scroller.middle(nil, 20, nil))
-      eq(12, p_scroller.middle(nil, 25, nil))
-    end)
-
     it('should handle ascending', function()
       eq(0, p_scroller.top('ascending', 20, 1000))
       eq(19, p_scroller.bottom('ascending', 20, 1000))
 
       eq(0, p_scroller.top('ascending', 20, 10))
       eq(9, p_scroller.bottom('ascending', 20, 10))
+
+      eq(5, p_scroller.middle('ascending', 11, 100))
+      eq(10, p_scroller.middle('ascending', 20, 100))
+      eq(12, p_scroller.middle('ascending', 25, 100))
     end)
 
     it('should handle descending', function()
@@ -134,6 +132,10 @@ describe('scroller', function()
 
       eq(10, p_scroller.top('descending', 20, 10))
       eq(19, p_scroller.bottom('descending', 20, 10))
+
+      eq(25, p_scroller.middle('descending', 30, 10))
+      eq(50, p_scroller.middle('descending', 60, 20))
+      eq(105, p_scroller.middle('descending', 120, 30))
     end)
   end)
 end)