src/website.rb

   1 #
   2 # Copyright Michael Orlitzky
   3 #
   4 # http://michael.orlitzky.com/
   5 #
   6 # This program is free software: you can redistribute it and/or modify
   7 # it under the terms of the GNU General Public License as published by
   8 # the Free Software Foundation, either version 3 of the License, or
   9 # (at your option) any later version.
  10 #
  11 # This program is distributed in the hope that it will be useful,
  12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14 # GNU General Public License for more details.
  15 #
  16 # http://www.fsf.org/licensing/licenses/gpl.html
  17 #
  18
  19 # Necessary in a lot of subclasses; plus, we need it
  20 # to parse the server name out of our URL.
  21 require 'uri'
  22
  23 # Needed to download.. things.
  24 require 'net/http'
  25
  26 # This class keeps track of all its subclasses
  27 # We use this to loop through every "website" in an
  28 # attempt to determine to which site a URL belongs.
  29 class Website
  30
  31   protected;
  32
  33   @url = nil
  34
  35
  36   def self.inherited(subclass)
  37     if superclass.respond_to? :inherited
  38       superclass.inherited(subclass)
  39     end
  40
  41     # Every time we're subclassed, add the new
  42     # subclass to our list of subclasses.
  43     @subclasses ||= []
  44     @subclasses << subclass
  45   end
  46
  47
  48   def server
  49     # Get the HTTP server portion of our URI
  50     uri = URI.parse(@url)
  51     return uri.host
  52   end
  53
  54
  55
  56   def get_page_data(url)
  57     # A naive implementation that just grabs the
  58     # data from a page.
  59     uri = URI.parse(url)
  60
  61     response = Net::HTTP.start(uri.host, uri.port) do |http|
  62       http.get(uri.request_uri)
  63     end
  64
  65     return response.body
  66   end
  67
  68
  69
  70   public;
  71
  72   def initialize(url)
  73     @url = url
  74   end
  75
  76
  77   def self.create(url)
  78     # Factory method returning an instance of
  79     # the appropriate subclass.
  80
  81     # Check the URL against each website's class.
  82     # The class will know whether or not the URL
  83     # "belongs" to its website.
  84     @subclasses.each do |w|
  85       if w.owns_url?(url)
  86         return w.new(url)
  87       end
  88     end
  89
  90     # If nothing matched, we don't return an instance
  91     # of anything.
  92     return nil
  93   end
  94
  95
  96   # Abstract definition. Each subclass of Website
  97   # should support it on its own.
  98   def self.owns_url?(url)
  99     raise NotImplementedError
 100   end
 101
 102
 103   # Same here. Abstract.
 104   def get_video_url()
 105     raise NotImplementedError
 106   end
 107
 108
 109   # The website class should be responsible for determining the
 110   # video's filename. By default, we can take the last component
 111   # of the video URL, but in some cases, subclasses will want
 112   # to override this behavior.
 113   def get_video_filename()
 114     # Use whatever comes after the final front slash.
 115     return get_video_url().split('/').pop()
 116   end
 117
 118 end