fix google docs for xlsx

We use a very old version of the google docs api, and according to the
api docs (https://developers.google.com/google-apps/documents-list/),
when selecting an export format to download a spreadsheet, it should
not matter whether you specify 'xls' or 'xlsx', you should get the same
file.  However, in manual testing, this is not true.  For old files,
there are slight differences between the binary files that are
downloaded between the two specified file extensions, and for new files,
specifying 'xls' returns an error rather than a file, while 'xlsx' still
works.

One option would be to switch all spreadsheet downloads from google
docs. Since the binaries were slightly different on older docs, in
order to prevent changing old behavior (and because this whole api has
to be totally replaced in the next few months), I decided to implement
this as a fallback exception, where it still tries 'xls' first but if
that option fails, then it falls back to trying 'xlsx'.

fixes CNVS-16689

test plan:
- authenticate a user with google docs
- create a new spreadsheet in google drive
- create an assignment that accepts google docs submissions
- go to submit the assignment, and choose the spreadsheet
- submit the assignment
- it should submit successfully

Change-Id: Ic93ff6267de33106fb8e3bb3bd23d14c90f3563c
Reviewed-on: https://gerrit.instructure.com/48014
Reviewed-by: Brad Horrocks <bhorrocks@instructure.com>
Tested-by: Jenkins
QA-Review: Adam Stone <astone@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>

gems/google_docs/lib/google_docs/connection.rb

@@ -57,14 +57,27 @@ module GoogleDocs
       access_token = retrieve_access_token
       entry = fetch_list(access_token).entries.map { |e| GoogleDocs::Entry.new(e) }.find { |e| e.document_id == document_id }
       if entry
-        response = access_token.get(entry.download_url)
-        response = access_token.get(response['Location']) if response.is_a?(Net::HTTPFound)
+        response = fetch_entry(access_token, entry)
+
+        # some new google spreadsheets will not download as plain 'xls', so
+        # retry the download as 'xlsx'
+        if response.is_a?(Net::HTTPBadRequest) && entry.extension == 'xls'
+          entry.reset_extension_as_xlsx
+          response = fetch_entry(access_token, entry)
+        end
+
         [response, entry.display_name, entry.extension]
       else
         [nil, nil, nil]
       end
     end
 
+    def fetch_entry(access_token, entry)
+      response = access_token.get(entry.download_url)
+      response = access_token.get(response['Location']) if response.is_a?(Net::HTTPFound)
+      response
+    end
+
     def fetch_list(access_token)
       response = access_token.get('https://docs.google.com/feeds/documents/private/full')
       Atom::Feed.load_feed(response.body)

gems/google_docs/lib/google_docs/entry.rb

@@ -95,6 +95,10 @@ module GoogleDocs
       }
     end
 
+    def reset_extension_as_xlsx
+      @extension = 'xlsx'
+    end
+
     private
 
     def set_document_id_from(entry)

gems/google_docs/spec/google_docs/connection_spec.rb

@@ -240,6 +240,30 @@ describe GoogleDocs::Connection do
       doc_array = google_docs.download(doc_id)
       doc_array.should == [nil, nil, nil]
     end
+
+    it "attempts as 'xlsx' if 'xls' fails" do
+      doc_id = 'spreadsheet:0AiN8C_VHrPxkdEF6YmQyc3p2Qm02ODhJWGJnUmJYY2c'
+      src = 'https://docs.google.com/feeds/download/spreadsheets/Export?key=0AiN8C_VHrPxkdEF6YmQyc3p2Qm02ODhJWGJnUmJYY2c'
+      xls_src = [src, "exportFormat=xls", "format=xls"].join('&')
+      xlsx_src = [src, "exportFormat=xlsx", "format=xlsx"].join('&')
+
+      access_token = mock_access_token
+
+      document_response = mock()
+      access_token.expects(:get).with(xlsx_src).returns(document_response)
+      bad_req = Net::HTTPBadRequest.new(1.0, 400, "Bad Request")
+      access_token.expects(:get).with(xls_src).returns(bad_req)
+
+      fetch_list_response = mock()
+      fetch_list_response.expects(:body).returns(xml_doc_list_many)
+      access_token.expects(:get).with(xml_schema_id).returns(fetch_list_response)
+
+      google_docs = GoogleDocs::Connection.new(token, secret)
+      doc_array = google_docs.download(doc_id)
+      doc_array[0].should == document_response
+      doc_array[1].should == 'Sprint Teams'
+      doc_array[2].should == 'xlsx'
+    end
   end
 
   describe "#create_doc" do

gems/google_docs/spec/google_docs/entry_spec.rb

@@ -50,6 +50,13 @@ describe GoogleDocs::Entry do
       entry = GoogleDocs::Entry.new(entry_feed)
       entry.extension.should == "doc"
     end
+
+    it "can be reset/forced to 'xlsx'" do
+      entry = GoogleDocs::Entry.new(entry_feed)
+      entry.extension.should == "doc"
+      entry.reset_extension_as_xlsx
+      entry.extension.should == "xlsx"
+    end
   end
 
   describe '#download_url' do