1 files changed, 7 insertions, 175 deletions

diff --git a/lib/gitlab/usage/metrics/names_suggestions/generator.rb b/lib/gitlab/usage/metrics/names_suggestions/generator.rb
index 49581169452..a669b43f395 100644
--- a/lib/gitlab/usage/metrics/names_suggestions/generator.rb
+++ b/lib/gitlab/usage/metrics/names_suggestions/generator.rb
@@ -5,10 +5,6 @@ module Gitlab
     module Metrics
       module NamesSuggestions
         class Generator < ::Gitlab::UsageData
-          FREE_TEXT_METRIC_NAME = "<please fill metric name>"
-          REDIS_EVENT_METRIC_NAME = "<please fill metric name, suggested format is: {subject}_{verb}{ing|ed}_{object} eg: users_creating_epics or merge_requests_viewed_in_single_file_mode>"
-          CONSTRAINTS_PROMPT_TEMPLATE = "<adjective describing: '%{constraints}'>"
-
           class << self
             def generate(key_path)
               uncached_data.deep_stringify_keys.dig(*key_path.split('.'))
@@ -17,200 +13,36 @@ module Gitlab
             private
 
             def count(relation, column = nil, batch: true, batch_size: nil, start: nil, finish: nil)
-              name_suggestion(column: column, relation: relation, prefix: 'count')
+              Gitlab::Usage::Metrics::NameSuggestion.for(:count, column: column, relation: relation)
             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)
+              Gitlab::Usage::Metrics::NameSuggestion.for(:distinct_count, column: column, relation: relation)
             end
 
             def redis_usage_counter
-              REDIS_EVENT_METRIC_NAME
+              Gitlab::Usage::Metrics::NameSuggestion.for(:redis)
             end
 
             def alt_usage_data(*)
-              FREE_TEXT_METRIC_NAME
+              Gitlab::Usage::Metrics::NameSuggestion.for(:alt)
             end
 
             def redis_usage_data_totals(counter)
-              counter.fallback_totals.transform_values { |_| REDIS_EVENT_METRIC_NAME }
+              counter.fallback_totals.transform_values { |_| Gitlab::Usage::Metrics::NameSuggestion.for(:redis) }
             end
 
             def sum(relation, column, *rest)
-              name_suggestion(column: column, relation: relation, prefix: 'sum')
+              Gitlab::Usage::Metrics::NameSuggestion.for(:sum, column: column, relation: relation)
             end
 
             def estimate_batch_distinct_count(relation, column = nil, *rest)
-              name_suggestion(column: column, relation: relation, prefix: 'estimate_distinct_count')
+              Gitlab::Usage::Metrics::NameSuggestion.for(:estimate_batch_distinct_count, column: column, relation: relation)
             end
 
             def add(*args)
               "add_#{args.join('_and_')}"
             end
-
-            def name_suggestion(relation:, column: nil, prefix: nil, distinct: nil)
-              # rubocop: disable CodeReuse/ActiveRecord
-              relation = relation.unscope(where: :created_at)
-              # rubocop: enable CodeReuse/ActiveRecord
-
-              parts = [prefix]
-              arel_column = arelize_column(relation, column)
-
-              # nil as column indicates that the counting would use fallback value of primary key.
-              # Because counting primary key from relation is the conceptual equal to counting all
-              # records from given relation, in order to keep name suggestion more condensed
-              # primary key column is skipped.
-              # eg: SELECT COUNT(id) FROM issues would translate as count_issues and not
-              # as count_id_from_issues since it does not add more information to the name suggestion
-              if arel_column != Arel::Table.new(relation.table_name)[relation.primary_key]
-                parts << arel_column.name
-                parts << 'from'
-              end
-
-              arel = arel_query(relation: relation, column: arel_column, distinct: distinct)
-              constraints = parse_constraints(relation: relation, arel: arel)
-
-              # In some cases due to performance reasons metrics are instrumented with joined relations
-              # where relation listed in FROM statement is not the one that includes counted attribute
-              # in such situations to make name suggestion more intuitive source should be inferred based
-              # on the relation that provide counted attribute
-              # EG: SELECT COUNT(deployments.environment_id) FROM clusters
-              #       JOIN deployments ON deployments.cluster_id = cluster.id
-              # should be translated into:
-              #   count_environment_id_from_deployments_with_clusters
-              # instead of
-              #   count_environment_id_from_clusters_with_deployments
-              actual_source = parse_source(relation, arel_column)
-
-              append_constraints_prompt(actual_source, [constraints], parts)
-
-              parts << actual_source
-              parts += process_joined_relations(actual_source, arel, relation, constraints)
-              parts.compact.join('_').delete('"')
-            end
-
-            def append_constraints_prompt(target, constraints, parts)
-              applicable_constraints = constraints.select { |constraint| constraint.include?(target) }
-              return unless applicable_constraints.any?
-
-              parts << CONSTRAINTS_PROMPT_TEMPLATE % { constraints: applicable_constraints.join(' AND ') }
-            end
-
-            def parse_constraints(relation:, arel:)
-              connection = relation.connection
-              ::Gitlab::Usage::Metrics::NamesSuggestions::RelationParsers::Constraints
-                .new(connection)
-                .accept(arel, collector(connection))
-                .value
-            end
-
-            # TODO: joins with `USING` keyword
-            def process_joined_relations(actual_source, arel, relation, where_constraints)
-              joins = parse_joins(connection: relation.connection, arel: arel)
-              return [] unless joins.any?
-
-              sources = [relation.table_name, *joins.map { |join| join[:source] }]
-              joins = extract_joins_targets(joins, sources)
-
-              relations = if actual_source != relation.table_name
-                            build_relations_tree(joins + [{ source: relation.table_name }], actual_source)
-                          else
-                            # in case where counter attribute comes from joined relations, the relations
-                            # diagram has to be built bottom up, thus source and target are reverted
-                            build_relations_tree(joins + [{ source: relation.table_name }], actual_source, source_key: :target, target_key: :source)
-                          end
-
-              collect_join_parts(relations: relations[actual_source], joins: joins, wheres: where_constraints)
-            end
-
-            def parse_joins(connection:, arel:)
-              ::Gitlab::Usage::Metrics::NamesSuggestions::RelationParsers::Joins
-                .new(connection)
-                .accept(arel)
-            end
-
-            def extract_joins_targets(joins, sources)
-              joins.map do |join|
-                source_regex = /(#{join[:source]})\.(\w+_)*id/i
-
-                tables_except_src = (sources - [join[:source]]).join('|')
-                target_regex = /(?<target>#{tables_except_src})\.(\w+_)*id/i
-
-                join_cond_regex = /(#{source_regex}\s+=\s+#{target_regex})|(#{target_regex}\s+=\s+#{source_regex})/i
-                matched = join_cond_regex.match(join[:constraints])
-
-                if matched
-                  join[:target] = matched[:target]
-                  join[:constraints].gsub!(/#{join_cond_regex}(\s+(and|or))*/i, '')
-                end
-
-                join
-              end
-            end
-
-            def build_relations_tree(joins, parent, source_key: :source, target_key: :target)
-              return [] if joins.blank?
-
-              tree = {}
-              tree[parent] = []
-
-              joins.each do |join|
-                if join[source_key] == parent
-                  tree[parent] << build_relations_tree(joins - [join], join[target_key], source_key: source_key, target_key: target_key)
-                end
-              end
-              tree
-            end
-
-            def collect_join_parts(relations:, joins:, wheres:, parts: [], conjunctions: %w[with having including].cycle)
-              conjunction = conjunctions.next
-              relations.each do |subtree|
-                subtree.each do |parent, children|
-                  parts << "<#{conjunction}>"
-                  join_constraints = joins.find { |join| join[:source] == parent }&.dig(:constraints)
-                  append_constraints_prompt(parent, [wheres, join_constraints].compact, parts)
-                  parts << parent
-                  collect_join_parts(relations: children, joins: joins, wheres: wheres, parts: parts, conjunctions: conjunctions)
-                end
-              end
-              parts
-            end
-
-            def arelize_column(relation, column)
-              case column
-              when Arel::Attribute
-                column
-              when NilClass
-                Arel::Table.new(relation.table_name)[relation.primary_key]
-              when String
-                if column.include?('.')
-                  table, col = column.split('.')
-                  Arel::Table.new(table)[col]
-                else
-                  Arel::Table.new(relation.table_name)[column]
-                end
-              when Symbol
-                arelize_column(relation, column.to_s)
-              end
-            end
-
-            def parse_source(relation, column)
-              column.relation.name || relation.table_name
-            end
-
-            def collector(connection)
-              Arel::Collectors::SubstituteBinds.new(connection, Arel::Collectors::SQLString.new)
-            end
-
-            def arel_query(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