#434

backend/app/services/counts_pivot_layout.rb

@@ -10,7 +10,21 @@ class CountsPivotLayout
     (1...keys.length).select { order.first(_1).sort == keys.first(_1).sort }
   end
 
-  def self.headers(values, depths, next_values: nil, grand: false)
+  def self.label_key(row_count, column_count, row_depth, column_depth)
+    total = row_count + column_count
+    collapsed = total - row_depth - column_depth
+    return nil if collapsed.zero?
+    return 'grandTotal' if total >= 3 && collapsed == total
+    if (collapsed == 1 &&
+        ((row_count > 1 && row_depth < row_count) ||
+         (column_count > 1 && column_depth < column_count)))
+      return 'subtotal'
+    end
+    'singleTotal'
+  end
+
+  def self.headers(values, depths, next_values: nil, grand: false, axis_count: nil,
+                   other_count: 0, direction: :row)
     result = []
     values.each_with_index do |tuple, index|
       result << { values: tuple, kind: 'data' }
@@ -23,6 +37,15 @@ class CountsPivotLayout
       end
     end
     result << { values: [], kind: 'grand_total' } if grand
+    count = axis_count || values.first&.length || 0
+    result.each do |header|
+      depth = header[:values].length
+      label = if header[:kind] != 'data'
+                direction == :row ? label_key(count, other_count, depth, other_count) :
+                    label_key(other_count, count, other_count, depth)
+              end
+      header.merge!(depth:, axis_count: count, label_key: label)
+    end
     result
   end
 end