simple-flickr.rb

require 'json'
require 'hpricot'
require 'open-uri'

module SimpleFlickr

  AUTH_URL = 'http://flickr.com/services/auth/'.freeze
  API_URL  = 'http://api.flickr.com/services/rest/'.freeze

  # USAGE
  # it's pretty dead simple
  # 1) create an instance with a given api_key: flickr = Rublickr::Flickr.new('your_api_key',:format => json)
  # 2) makes an API call: flick.photosets.getList(:user_id => '12037949754@N01')
  # PS.:
  # I didn't implemente authorized calls support yet. Will do soonish.
  # I grabbed a piece of code (the xml response dealing from net-flickr gem
  # For Flickr API reference visit http://www.flickr.com/services/api/
  class Flickr

#    attr_reader :options, :api_key, :api_secret
    attr_reader :options, :api_key

    # I chose to don't give support for auth API calls for now. Will do when necessary.
#    def initialize(api_key, api_secret = nil, options = {})
    def initialize(api_key, options = {})
      @api_key       = api_key
#      @api_secret    = api_secret
      @options       = options
      @meth          = ['flickr']
      @http_response = nil
    end

    def call(*args)
      api_method = @meth.join('.')
      @meth = ['flickr']
      self.get_response(api_method, @options.merge(args.first || {})).to_response
    end

    def method_missing(method, *args)
      methstr = method.id2name
      @meth << methstr
      return self if args.empty?
      self.call(*args)
    end

    def to_response
      return nil if @http_response.nil?

      begin
        if @options[:format] == 'json'
          raw_response = @http_response.read[/^(?:[a-z_$][0-9a-z_$]+)?\(?(.*)\)?$/i, 1]
          raw_response = raw_response[0..-2] if raw_response[-1].chr == ')'
          response = JSON.parse(raw_response)
        else
          response = Hpricot::XML(@http_response.read)
        end
      end

      if @options[:format].nil? || @options[:format] == 'xml'
        unless rsp = response.at('/rsp')
          raise 'Invalid Flickr API response'
        end

        if rsp['stat'] == 'ok'
          return rsp
        elsif rsp['stat'] == 'fail'
          raise rsp.at('/err')['msg']
        else
          raise 'Invalid Flickr API response'
        end
      end

      response
    end

    # only non-authorized calls for now
    def url_generator(method, params = {})
      parameters = parameterize(params)
      API_URL + "?" + "method=#{method}&api_key=#{@api_key}" + (parameters.empty? ? '' : "&#{parameters}")
    end

    def parameterize(params)
      params.map {|k,v| "#{k}=#{v}"}.join('&')
    end

    def get_response(method, params = {})
      @http_response = (open(url_generator(method, params)) rescue nil)
      self
    end

  end

end