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 # Needed for the default implementation of get_page_data.
  20 require 'net/http'
  21
  22 # Necessary in a lot of subclasses; plus, we need it
  23 # to parse the server name out of our URL.
  24 require 'uri'
  25
  26 # Needed to download.. things.
  27 require 'net/http'
  28
  29 # This class keeps track of all its subclasses
  30 # We use this to loop through every "website" in an
  31 # attempt to determine to which site a URL belongs.
  32 class Website
  33
  34   protected;
  35
  36   @url = nil
  37
  38
  39   def self.inherited(subclass)
  40     if superclass.respond_to? :inherited
  41       superclass.inherited(subclass)
  42     end
  43
  44     # Every time we're subclassed, add the new
  45     # subclass to our list of subclasses.
  46     @subclasses ||= []
  47     @subclasses << subclass
  48   end
  49
  50
  51   def server
  52     # Get the HTTP server portion of our URI
  53     uri = URI.parse(@url)
  54     return uri.host
  55   end
  56
  57
  58
  59   def get_page_data(url)
  60     # A naive implementation that just grabs the
  61     # data from a page.
  62     uri = URI.parse(url)
  63
  64     response = Net::HTTP.start(uri.host, uri.port) do |http|
  65       http.get(uri.request_uri, self.headers)
  66     end
  67
  68     return response.body
  69   end
  70
  71
  72
  73   public;
  74
  75   # Additional headers used when requesting data from the website.
  76   # These aren't passed as a parameter because the (final)
  77   # downloaders need them as well.
  78   attr_accessor :headers
  79
  80   def initialize(url)
  81     @url = url
  82     self.headers = { 'User-Agent' => Configuration::USER_AGENT }
  83   end
  84
  85
  86   def self.create(url)
  87     # Factory method returning an instance of
  88     # the appropriate subclass.
  89
  90     # Check the URL against each website's class.
  91     # The class will know whether or not the URL
  92     # "belongs" to its website.
  93     @subclasses.each do |w|
  94       if w.owns_url?(url)
  95         return w.new(url)
  96       end
  97     end
  98
  99     # If nothing matched, we don't return an instance
 100     # of anything.
 101     return nil
 102   end
 103
 104
 105   # Abstract definition. Each subclass of Website
 106   # should support it on its own.
 107   def self.owns_url?(url)
 108     raise NotImplementedError
 109   end
 110
 111
 112   # Same here. Abstract.
 113   def get_video_url()
 114     raise NotImplementedError
 115   end
 116
 117
 118   # The website class should be responsible for determining the
 119   # video's filename. By default, we can take the last component
 120   # of the video URL, but in some cases, subclasses will want
 121   # to override this behavior.
 122   def get_video_filename()
 123     # Use whatever comes after the final front slash.
 124     file_and_params = get_video_url().split('/').pop()
 125
 126     # Unless it contains URL parameters. We don't want those.
 127     return file_and_params unless file_and_params.include?('?')
 128
 129     # There must be some parameters. Strip them off.
 130     param_start_idx = file_and_params.index('?')
 131     return file_and_params[0...(param_start_idx)]
 132   end
 133
 134 end