require_relative "./configuration"

module Axe
  class FindsPage
    WEBDRIVER_NAMES = [:page, :browser, :driver, :webdriver]

    class << self
      alias :in :new
    end

    def initialize(world)
      @world = world
    end

    def page
      from_configuration || implicit or raise "A page/browser/webdriver must be configured"
    end

    private

    def configuration
      Axe::Configuration.instance
    end

    def from_configuration
      if configuration.page.is_a?(String) || configuration.page.is_a?(Symbol)
        from_world(configuration.page)
      else
        configuration.page
      end
    end

    def implicit
      WEBDRIVER_NAMES.map(&method(:from_world)).drop_while(&:nil?).first
    end

    def from_world(name)
      via_method(name) || via_ivar(name)
    end

    def via_method(name)
      @world.__send__(name) if @world.respond_to?(name)
    end

    def via_ivar(name)
      name = ensure_ivar_format(name)
      @world.instance_variable_get(name) if @world.instance_variables.include?(name)
    end

    def ensure_ivar_format(name)
      # ensure leading '@'
      name.to_s.sub(/^([^@])/, '@\1').to_sym
    end
  end
end