add ability to fetch file from remote (#34)

Author: dpsk

README.rdoc

@@ -72,6 +72,11 @@ Images for a specific cell can be obtained with images_at method:
 
 Creek will most likely return nil for a cell with images if there is no other text cell in that row - you can use *images_at* method for retrieving images in that cell.
 
+== Remote files
+
+    remote_url = 'http://dev-builds.libreoffice.org/tmp/test.xlsx'
+    Creek::Book.new remote_url, remote: true
+
 == Contributing
 
 Contributions are welcomed. You can fork a repository, add your code changes to the forked branch, ensure all existing unit tests pass, create new unit tests cover your new changes and finally create a pull request.

lib/creek/book.rb

@@ -1,6 +1,7 @@
 require 'zip/filesystem'
 require 'nokogiri'
 require 'date'
+require 'open-uri'
 
 module Creek
 
@@ -19,6 +20,7 @@ def initialize path, options = {}
         extension = File.extname(options[:original_filename] || path).downcase
         raise 'Not a valid file format.' unless (['.xlsx', '.xlsm'].include? extension)
       end
+      path = open(path) if options[:remote]
       @files = Zip::File.open path
       @shared_strings = SharedStrings.new(self)
     end

spec/test_spec.rb

@@ -15,6 +15,14 @@
     open_book.should raise_error 'Not a valid file format.'
   end
 
+  it 'Fail to open remote file' do
+    lambda { Creek::Book.new 'http://dev-builds.libreoffice.org/tmp/test.xlsx' }.should raise_error
+  end
+
+  it 'Opens remote file with remote flag' do
+    lambda { Creek::Book.new 'http://dev-builds.libreoffice.org/tmp/test.xlsx', remote: true }.should_not raise_error
+  end
+
   it 'Check file extension of original_filename if passed.' do
     path = 'spec/fixtures/temp_string_io_file_path_with_no_extension'
     lambda { Creek::Book.new path, :original_filename => 'invalid.xls' }.should raise_error 'Not a valid file format.'