src/uri_utilities.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 require 'open-uri'
  20 require 'vendor/ruby-progressbar/progressbar'
  21
  22 # Just a couple of convenience methods for URIs.
  23 # These could be monkey-patched in, but with only
  24 # a few methods, that'd be asking (unnecessarily)
  25 # for trouble.
  26 class UriUtilities
  27
  28   def initialize()
  29     @pbar = nil
  30   end
  31
  32   def content_length_callback(content_length)
  33     if content_length && (0 < content_length)
  34       @pbar = ProgressBar.new("Download", content_length)
  35       @pbar.instance_eval { @bar_mark = '=' }
  36       @pbar.file_transfer_mode
  37     end
  38   end
  39
  40   def progress_callback(size)
  41     @pbar.set(size) if @pbar
  42   end
  43
  44
  45   # Download the given URI object to <outfile_name>.
  46   # Should use the progress_proc parameter to show
  47   # a progress bar using the Ruby/ProgressBar library.
  48   def download_with_progress_bar(uri, outfile_name, headers = {})
  49     # We wrap the whole thing in a begin/rescue so that
  50     # we can clean up afterwards in case of an error.
  51     begin
  52       File.open(outfile_name, 'wb') do |outfile|
  53         # Convert our methods to Proc objects.
  54         content_length_callback = method(:content_length_callback)
  55         progress_callback = method(:progress_callback)
  56
  57         # So that they can be passed as arguments to open().
  58         open_params = { :content_length_proc => content_length_callback,
  59                         :progress_proc => progress_callback}
  60
  61         # Add the headers as additional parameters to the open() call.
  62         open_params.merge!(headers)
  63
  64         uri.open(open_params) do |video_file|
  65           outfile.write(video_file.read)
  66         end
  67       end
  68
  69       # Toss out an empty line to get rid of the progress bar.
  70       # Normally, it would remain on the shell's "current" line.
  71       puts ''
  72
  73     rescue Errno::EACCES => e
  74       # Don't delete the file if it's unwritable.
  75       raise(e)
  76     rescue => e
  77       # Here we get rid of the output file if there was an error.
  78       # We test File.exists? first since the first line, the open()
  79       # call, could theoretically fail.
  80       File.delete(outfile_name) if File.exists?(outfile_name)
  81       raise(e)
  82     end
  83   end
  84
  85 end