# frozen_string_literal: true

module Gitlab
  module Usage
    class MetricDefinition
      METRIC_SCHEMA_PATH = Rails.root.join('config', 'metrics', 'schema.json')

      attr_reader :path
      attr_reader :attributes

      def initialize(path, opts = {})
        @path = path
        @attributes = opts
      end

      def key
        key_path
      end

      def to_h
        attributes
      end

      def validate!
        self.class.schemer.validate(attributes.stringify_keys).map do |error|
          Gitlab::ErrorTracking.track_and_raise_for_dev_exception(Metric::InvalidMetricError.new("#{error["details"] || error['data_pointer']} for `#{path}`"))
        end
      end

      alias_method :to_dictionary, :to_h

      class << self
        def paths
          @paths ||= [Rails.root.join('config', 'metrics', '**', '*.yml')]
        end

        def definitions
          @definitions ||= load_all!
        end

        def schemer
          @schemer ||= ::JSONSchemer.schema(Pathname.new(METRIC_SCHEMA_PATH))
        end

        private

        def load_all!
          paths.each_with_object({}) do |glob_path, definitions|
            load_all_from_path!(definitions, glob_path)
          end
        end

        def load_from_file(path)
          definition = File.read(path)
          definition = YAML.safe_load(definition)
          definition.deep_symbolize_keys!

          self.new(path, definition).tap(&:validate!)
        rescue => e
          Gitlab::ErrorTracking.track_and_raise_for_dev_exception(Metric::InvalidMetricError.new(e.message))
        end

        def load_all_from_path!(definitions, glob_path)
          Dir.glob(glob_path).each do |path|
            definition = load_from_file(path)

            if previous = definitions[definition.key]
              Gitlab::ErrorTracking.track_and_raise_for_dev_exception(Metric::InvalidMetricError.new("Metric '#{definition.key}' is already defined in '#{previous.path}'"))
            end

            definitions[definition.key] = definition
          end
        end
      end

      private

      def method_missing(method, *args)
        attributes[method] || super
      end
    end
  end
end

Gitlab::Usage::MetricDefinition.prepend_if_ee('EE::Gitlab::Usage::MetricDefinition')