module Vcloud

  class QueryRunner
    def initialize
      @fsi = Vcloud::Fog::ServiceInterface.new
    end

    def run(type=nil, options={})
      raise ArgumentError, "Query API :format option is not supported" if options[:format]
      get_all_results(type, options)
    end

    def available_query_types
      query_body = @fsi.get_execute_query()
      get_entity_types_in_record_format(query_body)
    end

  private

    def get_entity_types_in_record_format(query_body)
      query_links = query_body.fetch(:Link).select do |link|
        link[:rel] == 'down'
      end
      entity_types = []
      query_links.each do |link|
        (entity_type, query_format) = extract_query_type_and_format_from_link(link)
        entity_types << entity_type if query_format == 'records'
      end
      entity_types
    end

    def extract_query_type_and_format_from_link(link)
        href  = Nokogiri::XML.fragment(link[:href])
        query = CGI.parse(URI.parse(href.text).query)
        query_format = query['format'].first
        query_type = query['type'].first
        [query_type, query_format]
    end

    def get_all_results(type, options)
      results = []
      (1..get_num_pages(type, options)).each do |page|
        results += get_results_page(page, type, options) || []
      end
      results
    end

    def get_num_pages(type, options)
      body = @fsi.get_execute_query(type, options)
      last_page = body[:lastPage] || 1
      raise "Invalid lastPage (#{last_page}) in query results" unless last_page.is_a? Integer
      last_page.to_i
    end

    def get_results_page(page, type, options)
      body = @fsi.get_execute_query(type, options.merge({:page=>page}))

      record_key = key_of_first_record_or_reference(body)
      body[record_key] = [body[record_key]] if body[record_key].is_a?(Hash)
      body[record_key]
    end

    def key_of_first_record_or_reference(body)
      body.keys.detect { |key| key.to_s =~ /Record|Reference$/ }
    end
  end
end