# frozen_string_literal: true

module AnsibleDocGenerator
  class DocGenerator
    class Interpolator
      class VariableExtractor

        class MissingInterpolationError < StandardError; end

        attr_reader :input, :task, :role_path

        def initialize input, task, role_path
          @input = input
          @task = task
          @role_path = role_path
          @filters = {
            join: ', '
          }
        end

        def call
          output = input

          input.scan(/#\{[^\}]+\}/).each do |interpolation|
            new_string = get_string(interpolation)
            output.gsub!(interpolation, new_string)
          end

          output
        end

        private

        def get_string interpolation
          variable_match = interpolation.match(/#\{([^\}]+)\}/)[1]
          yaml_path, filters = variable_match.split('|')
          set_filters(filters)
          yaml_value = dig(task, yaml_path.gsub(/\s/, '').split('>'))

          case yaml_value
          when String then yaml_value
          when Array then yaml_value.join(@filters[:join])
          else interpolation
          end
        rescue MissingInterpolationError => e
          raise e, "Interpolation not found:\n - #{interpolation}\n - #{task}\n - #{role_path}"
        end

        def set_filters(filters)
          return if filters.nil?
          filter_name, filter_value = filters.split(':')
          @filters[filter_name.gsub(/\s/, '').to_sym] = eval(filter_value)
        end

        def dig task, keys
          head, *tail = keys
          new_task = task[head]

          raise MissingInterpolationError if new_task.nil?

          if tail == []
            return new_task
          elsif new_task.is_a?(String) && tail != []
            return scan_in_inline_syntax(new_task, tail.first)
          else
            dig(new_task, tail)
          end
        end

        def scan_in_inline_syntax string, key
          input = StringScanner.new(string)

          # Scan until the key we are looking for
          input.scan_until(/#{key}=/)
          # Scan until the next key or until the end
          output = input.scan_until(/\s{1}\S+=/) || input.scan(/.*/)
          # Remove the next key part
          output.gsub(/\s{1}\S+=/, '')
        end

      end
    end
  end
end