Fix: scroller for descending (#327)

lua/telescope/pickers.lua

@@ -126,7 +126,8 @@ function Picker:new(opts)
 
 
   obj.scroller = p_scroller.create(
-    get_default(opts.scroll_strategy, config.values.scroll_strategy)
+    get_default(opts.scroll_strategy, config.values.scroll_strategy),
+    obj.sorting_strategy
   )
 
   return obj

lua/telescope/pickers/scroller.lua

@@ -1,10 +1,33 @@
-
 local scroller = {}
 
-scroller.create = function(strategy)
+local calc_count_fn = function(sorting_strategy)
+  if sorting_strategy == 'ascending' then
+    return function(a, b) return math.min(a, b) end
+  else
+    return function(a, b, row)
+      if a == b or not row then
+        return math.max(a, b)
+      else
+        local x = a - b
+        if row < x then
+          return math.max(a, b) - 1, true
+        elseif row == a then
+          return x, true
+        else
+          return math.max(a, b)
+        end
+      end
+    end
+  end
+end
+
+scroller.create = function(strategy, sorting_strategy)
+  local calc_count = calc_count_fn(sorting_strategy)
+
   if strategy == 'cycle' then
     return function(max_results, num_results, row)
-      local count = math.min(max_results, num_results)
+      local count, b = calc_count(max_results, num_results, row)
+      if b then return count end
 
       if row >= count then
         return 0
@@ -16,7 +39,7 @@ scroller.create = function(strategy)
     end
   elseif strategy == 'limit' or strategy == nil then
     return function(max_results, num_results, row)
-      local count = math.min(max_results, num_results)
+      local count = calc_count(max_results, num_results)
 
       if row >= count then
         return count - 1