require 'active_support'
require 'net/http'
require 'json'

module Itunes

  class Search
    include Enumerable
  
    @@config = {
      :endpoint => 'http://phobos.apple.com/WebObjects/MZSearch.woa/wa/itmsSearch',
      :default_parameters => {
        :output => 'json',
        :media => 'music'
      }
    }
  
    cattr_accessor :config
    
    attr_reader :size, :results
  
    def initialize(term, options={})
      result = get({
        :term => term
      }.merge(self.class.config[:default_parameters]).merge(options))
      
      parse(result)
    end
    
    def each
      results.each do |track|
        yield track
      end
    end
    
    
    protected
    
    def parse(json)
      source = JSON.load(json)
      @size = source['resultCount']
      @results = source['results'].collect do |result|
        Track.new result
      end
    end
      
    
    def get(params)
      Net::HTTP.get(compose(self.class.config[:endpoint], params))
    end
    
    def compose(base, params)
      URI.parse([base, build_params(params)].join('?'))
    end
    
    def build_params(params)
      params.collect { |key, value| 
        "#{key.to_s}=#{CGI::escape(value.to_s)}" if value
      }.compact.join "&"
    end
    
  end
  
  class Track
    
    FIELD_MAP = { 
                  :artist => 'artistName', 
                  :title => 'itemName', 
                  :album => 'itemParentName', 
                  :genre => 'primaryGenreName',
                  :song_url => 'itemLinkUrl', 
                  :album_url => 'itemParentLinkUrl', 
                  :artist_url => 'artistLinkUrl',
                  :preview_url => 'previewUrl',
                  :small_image_url => 'artworkUrl60', 
                  :large_image_url => 'artworkUrl100'
                }
    
    attr_reader *FIELD_MAP.keys
    
    def initialize(source)
      unpack(source)
    end
    
    protected
    
    def unpack(source_data)
      FIELD_MAP.each do |dest, source|
        instance_variable_set "@#{dest}".to_sym, source_data[source]
      end
    end
    
  end
  
end