module Gitlab
  module Ci
    class Config
      module Entry
        ##
        # This mixin is responsible for adding DSL, which purpose is to
        # simplifly process of adding child nodes.
        #
        # This can be used only if parent node is a configuration entry that
        # holds a hash as a configuration value, for example:
        #
        # job:
        #   script: ...
        #   artifacts: ...
        #
        module Configurable
          extend ActiveSupport::Concern

          included do
            include Validatable

            validations do
              validates :config, type: Hash
            end
          end

          def compose!(deps = nil)
            return unless valid?

            self.class.nodes.each do |key, factory|
              factory
                .value(config[key])
                .with(key: key, parent: self)

              entries[key] = factory.create!
            end

            yield if block_given?

            entries.each_value do |entry|
              entry.compose!(deps)
            end
          end

          class_methods do
            def nodes
              Hash[(@nodes || {}).map { |key, factory| [key, factory.dup] }]
            end

            private

            def entry(key, entry, metadata)
              factory = Entry::Factory.new(entry)
                .with(description: metadata[:description])

              (@nodes ||= {}).merge!(key.to_sym => factory)
            end

            def helpers(*nodes)
              nodes.each do |symbol|
                define_method("#{symbol}_defined?") do
                  entries[symbol]&.specified?
                end

                define_method("#{symbol}_value") do
                  return unless entries[symbol] && entries[symbol].valid?

                  entries[symbol].value
                end
              end
            end
          end
        end
      end
    end
  end
end