#--
# Copyright: Copyright (c) 2010-2011 RightScale, Inc.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# 'Software'), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#++

module RightScraper
  module Retrievers

    # Base class for retrievers that want to do version control operations
    # (CVS, SVN, etc.). Subclasses can get away with implementing only
    # Retrievers::Base#available? and #do_checkout but to support incremental
    # operation need to implement #exists? and #do_update, in addition to
    # Retrievers::Base#ignorable_paths.
    class CheckoutBasedRetriever < Base

      # Check out repository into the directory.  Occurs between
      # variable initialization and beginning scraping.
      def retrieve
        raise RetrieverError.new("retriever is unavailable") unless available?
        if exists?
          begin
            @logger.operation(:updating) do
              do_update
            end
          rescue Exception => e
            @logger.note_error(e, :updating, "switching to using checkout")
            FileUtils.remove_entry_secure basedir
            @logger.operation(:checkout) do
              do_checkout
            end
          end
        else
          @logger.operation(:checkout) do
            do_checkout
          end
        end
      end

      # Return true if a checkout exists.
      #
      # === Returns
      # Boolean:: true if the checkout already exists (and thus
      #           incremental updating can occur).
      def exists?
        false
      end

      # Perform an incremental update of the checkout.  Subclasses that
      # want to handle incremental updating need to override this.
      def do_update
        do_checkout
      end

      # Perform a de novo full checkout of the repository.  Subclasses
      # must override this to do anything useful.
      def do_checkout
        FileUtils.mkdir_p(@repo_dir)
      end

    end
  end
end