module Calais
  class Client
    attr_accessor :license_id
    attr_accessor :content
    attr_accessor :content_type, :output_format
    attr_accessor :allow_distribution, :allow_search, :submitter, :external_id
    attr_accessor :external_metadata
    
    def initialize(options={}, &block)
      options.each {|k,v| send("#{k}=", v)}
      yield(self) if block_given?
    end
    
    def call(method, times=1)
      method = method.intern unless method.is_a?(Symbol)
      raise ArgumentError.new("Unknown method: #{method}") unless AVAILABLE_METHODS.keys.include? method
      
      post_args = {
        "licenseID" => @license_id,
        "content" => @content,
        "paramsXML" => params_xml
      }
      
      url = URI.parse(POST_URL + AVAILABLE_METHODS[method])
      resp, data = Net::HTTP.post_form(url, post_args)
      
      handle_response(resp, data, method, times)
    end
    
    def self.process_data(data, error=nil)
      Calais::Response.new(data, error)
    end
    
    private
      def handle_response(resp, data, method, times)
        if resp.is_a? Net::HTTPOK
          [data, nil]
        elsif times >= MAX_RETRIES
          [data, "Too many retries: #{times}"]
        else
          call(method, times+1)
        end
      end
      
      def params_xml
        content_type = @content_type && AVAILABLE_CONTENT_TYPES.keys.include?(@content_type) ? AVAILABLE_CONTENT_TYPES[@content_type] : AVAILABLE_CONTENT_TYPES[DEFAULT_CONTENT_TYPE]
        output_format = @output_format && AVAILABLE_OUTPUT_FORMATS.keys.include?(@output_format) ? AVAILABLE_OUTPUT_FORMATS[@output_format] : AVAILABLE_OUTPUT_FORMATS[DEFAULT_OUTPUT_FORMAT]
        allow_distribution = @allow_distribution ? "true" : "false"
        allow_search = @allow_search ? "true" : "false"
        submitter = @submitter || DEFAULT_SUBMITTER
        external_id = @external_id || Digest::SHA1.hexdigest(@content.inspect)
        external_metadata = @external_metadata || ""
        
        xml  = %[<c:params xmlns:c="http://s.opencalais.com/1/pred/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">]
        xml += %[<c:processingDirectives c:contentType="#{content_type}" c:outputFormat="#{output_format}"></c:processingDirectives>]
        xml += %[<c:userDirectives c:allowDistribution="#{allow_distribution}" c:allowSearch="#{allow_search}" c:externalID="#{external_id}" c:submitter="#{submitter}"></c:userDirectives>]
        xml += %[<c:externalMetadata>#{external_metadata}</c:externalMetadata>]
        xml += %[</c:params>]
      end
  end
end