1 files changed, 68 insertions, 0 deletions
diff --git a/lib/gitlab/ci/config/normalizer/matrix_strategy.rb b/lib/gitlab/ci/config/normalizer/matrix_strategy.rb
new file mode 100644
index 00000000000..db21274a9ed
--- /dev/null
+++ b/lib/gitlab/ci/config/normalizer/matrix_strategy.rb
@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    class Config
+      class Normalizer
+        class MatrixStrategy
+          class << self
+            def applies_to?(config)
+              config.is_a?(Hash) && config.key?(:matrix)
+            end
+
+            def build_from(job_name, initial_config)
+              config = expand(initial_config[:matrix])
+              total = config.size
+
+              config.map.with_index do |vars, index|
+                new(job_name, index.next, vars, total)
+              end
+            end
+
+            # rubocop: disable CodeReuse/ActiveRecord
+            def expand(config)
+              config.flat_map do |config|
+                values = config.values
+
+                values[0]
+                  .product(*values.from(1))
+                  .map { |vals| config.keys.zip(vals).to_h }
+              end
+            end
+            # rubocop: enable CodeReuse/ActiveRecord
+          end
+
+          def initialize(job_name, instance, variables, total)
+            @job_name = job_name
+            @instance = instance
+            @variables = variables.to_h
+            @total = total
+          end
+
+          def attributes
+            {
+              name: name,
+              instance: instance,
+              variables: variables,
+              parallel: { total: total }
+            }
+          end
+
+          def name_with_details
+            vars = variables.map { |key, value| "#{key}=#{value}"}.join('; ')
+
+            "#{job_name} (#{vars})"
+          end
+
+          def name
+            "#{job_name} #{instance}/#{total}"
+          end
+
+          private
+
+          attr_reader :job_name, :instance, :variables, :total
+        end
+      end
+    end
+  end
+end