// adds a #power_set method to Hash class

# The Array power set is stolen from http://snippets.dzone.com/posts/show/3524
class Array
  # Returns the "power set" for this Array. This means that an array with all
  # subsets of the array's elements will be returned.
  def power_set
    # the power set line is stolen from http://johncarrino.net/blog/2006/08/11/powerset-in-ruby/
    inject([[]]){|c,y|r=[];c.each{|i|r<<i;r<<i+[y]};r}
  end
end

class Hash
  def power_set
    # Returns the "power set" for this Hash. This means that a array with hashes of all
    # subsets of the hash's (key => value) pairs will be returned.
    # Example:
    # >> {:feedback_type=>"", :language_code=>"", :comment=>""}.power_set
    #
    # [{}, {:comment=>""}, {:language_code=>""}, {:language_code=>"", :comment=>""}, {:feedback_type=>""}, {:feedback_type=>"", :comment=>""}, {:feedback_type=>"", :language_code=>""}, {:feedback_type=>"", :language_code=>"", :comment=>""}]
    
    hash_to_array = self.to_a
    array_power_set = hash_to_array.power_set
    hash_power_set = array_power_set.collect { |pairs| pairs.inject({}) { |hash,pair| hash[pair[0]] = pair[1]; hash } }
    hash_power_set
  end
end

When you have a huge label with thousands of messages, Gmail can't handle deleting all of them at a time (it says it can, but for me it's never worked). This solves the problem.

I wrote it more as a practice to get familiar with FireWatir, so it's not very pretty or anything and it's a bit slow. If you have doubts on how to use or suggestions on how to improve it please feel free to contact me.

By the way, it assumes Gmail is in German. Replace that string with the one that comes up for your language.

def empty_label(label)
  # you need a Firefox instance already running with JSSh installed and listening
  ff = Firefox.new
  # Goes to Gmail in HTML
  ff.goto('http://mail.google.com/mail/h/x4odcwnm5f5v/?s=l&l=#{label}')
  a = []
  # doing 'c.set' didn't work for me here so I had to do this hack of getting the value
  # and then acquiring the element thorugh ff.checkbox(:value,value)
  ff.checkboxes.each {|c| a << c.value}

  while a.length > 0 do
    c = []
    a.each {|v| c << ff.checkbox(:value,v)}
    # checks all checkboxes
    c.each {|e| e.set}
    # clicks the drop-down entry for deleting
    ff.select_list(:name,'tact').select('In den Papierkorb verschieben')
    ff.button(:name,'nvp_tbu_go').click
    a = []
    ff.checkboxes.each {|c| a << c.value}
  end
end