1 files changed, 106 insertions, 0 deletions
diff --git a/lib/gitlab/usage/metrics/names_suggestions/generator.rb b/lib/gitlab/usage/metrics/names_suggestions/generator.rb
new file mode 100644
index 00000000000..33f025770e0
--- /dev/null
+++ b/lib/gitlab/usage/metrics/names_suggestions/generator.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Usage
+    module Metrics
+      module NamesSuggestions
+        class Generator < ::Gitlab::UsageData
+          FREE_TEXT_METRIC_NAME = "<please fill metric name>"
+
+          class << self
+            def generate(key_path)
+              uncached_data.deep_stringify_keys.dig(*key_path.split('.'))
+            end
+
+            private
+
+            def count(relation, column = nil, batch: true, batch_size: nil, start: nil, finish: nil)
+              name_suggestion(column: column, relation: relation, prefix: 'count')
+            end
+
+            def distinct_count(relation, column = nil, batch: true, batch_size: nil, start: nil, finish: nil)
+              name_suggestion(column: column, relation: relation, prefix: 'count_distinct', distinct: :distinct)
+            end
+
+            def redis_usage_counter
+              FREE_TEXT_METRIC_NAME
+            end
+
+            def alt_usage_data(*)
+              FREE_TEXT_METRIC_NAME
+            end
+
+            def redis_usage_data_totals(counter)
+              counter.fallback_totals.transform_values { |_| FREE_TEXT_METRIC_NAME}
+            end
+
+            def sum(relation, column, *rest)
+              name_suggestion(column: column, relation: relation, prefix: 'sum')
+            end
+
+            def estimate_batch_distinct_count(relation, column = nil, *rest)
+              name_suggestion(column: column, relation: relation, prefix: 'estimate_distinct_count')
+            end
+
+            def add(*args)
+              "add_#{args.join('_and_')}"
+            end
+
+            def name_suggestion(relation:, column: nil, prefix: nil, distinct: nil)
+              parts = [prefix]
+
+              if column
+                parts << parse_target(column)
+                parts << 'from'
+              end
+
+              source = parse_source(relation)
+              constraints = parse_constraints(relation: relation, column: column, distinct: distinct)
+
+              if constraints.include?(source)
+                parts << "<adjective describing: '#{constraints}'>"
+              end
+
+              parts << source
+              parts.compact.join('_')
+            end
+
+            def parse_constraints(relation:, column: nil, distinct: nil)
+              connection = relation.connection
+              ::Gitlab::Usage::Metrics::NamesSuggestions::RelationParsers::Constraints
+                .new(connection)
+                .accept(arel(relation: relation, column: column, distinct: distinct), collector(connection))
+                .value
+            end
+
+            def parse_target(column)
+              if column.is_a?(Arel::Attribute)
+                "#{column.relation.name}.#{column.name}"
+              else
+                column
+              end
+            end
+
+            def parse_source(relation)
+              relation.table_name
+            end
+
+            def collector(connection)
+              Arel::Collectors::SubstituteBinds.new(connection, Arel::Collectors::SQLString.new)
+            end
+
+            def arel(relation:, column: nil, distinct: nil)
+              column ||= relation.primary_key
+
+              if column.is_a?(Arel::Attribute)
+                relation.select(column.count(distinct)).arel
+              else
+                relation.select(relation.all.table[column].count(distinct)).arel
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end