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 # This class keeps track of all its subclasses
  24 # We use this to loop through every "website" in an
  25 # attempt to determine to which site a URL belongs.
  26 class Website
  27
  28   protected;
  29
  30   @url = nil
  31
  32
  33   def self.inherited(subclass)
  34     if superclass.respond_to? :inherited
  35       superclass.inherited(subclass)
  36     end
  37
  38     # Every time we're subclassed, add the new
  39     # subclass to our list of subclasses.
  40     @subclasses ||= []
  41     @subclasses << subclass
  42   end
  43
  44
  45   def server
  46     # Get the HTTP server portion of our URI
  47     uri = URI.parse(@url)
  48     return uri.host
  49   end
  50
  51
  52   public;
  53
  54   def initialize(url)
  55     @url = url
  56   end
  57
  58
  59   def self.create(url)
  60     # Factory method returning an instance of
  61     # the appropriate subclass.
  62
  63     # Check the URL against each website's class.
  64     # The class will know whether or not the URL
  65     # "belongs" to its website.
  66     @subclasses.each do |w|
  67       if w.owns_url?(url)
  68         return w.new(url)
  69       end
  70     end
  71
  72     # If nothing matched, we don't return an instance
  73     # of anything.
  74     return nil
  75   end
  76
  77
  78   # Abstract definition. Each subclass of Website
  79   # should support it on its own.
  80   def self.owns_url?(url)
  81     raise NotImplementedError
  82   end
  83
  84
  85   # Same here. Abstract.
  86   def get_video_url()
  87     raise NotImplementedError
  88   end
  89
  90
  91   # The website class should be responsible for determining the
  92   # video's filename. By default, we can take the last component
  93   # of the video URL, but in some cases, subclasses will want
  94   # to override this behavior.
  95   def get_video_filename()
  96     # Use whatever comes after the final front slash.
  97     return get_video_url().split('/').pop()
  98   end
  99
 100 end