module LiquidInterpolatable
  extend ActiveSupport::Concern

  def interpolate_options(options, payload)
    case options.class.to_s
    when 'String'
      interpolate_string(options, payload)
    when 'ActiveSupport::HashWithIndifferentAccess', 'Hash'
      duped_options = options.dup
      duped_options.each do |key, value|
        duped_options[key] = interpolate_options(value, payload)
      end
    when 'Array'
      options.collect do |value|
        interpolate_options(value, payload)
      end
    end
  end

  def interpolate_string(string, payload)
    Liquid::Template.parse(string).render!(payload, registers: {agent: self})
  end

  require 'uri'
  # Percent encoding for URI conforming to RFC 3986.
  # Ref: http://tools.ietf.org/html/rfc3986#page-12
  module Filters
    def uri_escape(string)
      CGI::escape string
    end
  end
  Liquid::Template.register_filter(LiquidInterpolatable::Filters)

  module Tags
    class Credential < Liquid::Tag
      def initialize(tag_name, name, tokens)
        super
        @credential_name = name.strip
      end

      def render(context)
        credential = context.registers[:agent].credential(@credential_name)
        raise "No user credential named '#{@credential_name}' defined" if credential.nil?
        credential
      end
    end
  end
  Liquid::Template.register_tag('credential', LiquidInterpolatable::Tags::Credential)
end