# frozen_string_literal: true

module Gitlab
  module Ci
    class Config
      module Interpolation
        ##
        # Interpolation::Context is a class that represents the data that can be used
        # when performing string interpolation on a CI configuration.
        #
        class Context
          ContextTooComplexError = Class.new(StandardError)
          NotSymbolizedContextError = Class.new(StandardError)

          MAX_DEPTH = 3

          attr_reader :variables

          def initialize(data, variables:)
            @data = data
            @variables = Ci::Variables::Collection.fabricate(variables)

            raise ContextTooComplexError if depth > MAX_DEPTH
          end

          def valid?
            errors.none?
          end

          ##
          # This method is here because `Context` will be responsible for validating specs, inputs and defaults.
          #
          def errors
            []
          end

          def depth
            deep_depth(@data)
          end

          def fetch(field)
            @data.fetch(field)
          end

          def key?(name)
            @data.key?(name)
          end

          def to_h
            @data.to_h
          end

          private

          def deep_depth(data, depth = 0)
            values = data.values.map do |value|
              if value.is_a?(Hash)
                deep_depth(value, depth + 1)
              else
                depth + 1
              end
            end

            values.max.to_i
          end

          def self.fabricate(context, variables: [])
            case context
            when Hash
              new(context, variables: variables)
            when Interpolation::Context
              context
            else
              raise ArgumentError, 'unknown interpolation context'
            end
          end
        end
      end
    end
  end
end
