require 'ostruct'

module S3Website
  class DiffHelper
    def self.resolve_files_to_upload(s3_bucket, site_dir, config)
      objects = []
      list = nil
      with_progress_indicator('Downloading list of the objects in a bucket') { |progress_indicator|
        while list.nil? || list[:truncated]
          list = s3_bucket.client.list_objects(:bucket_name => s3_bucket.name, :marker => objects.last ? objects.last.key : '')
          objects.concat(list[:contents].map { |o|
            OpenStruct.new({
              :key => o[:key],
              :etag => o[:etag],
              :last_modified => o[:last_modified],
              :size => o[:size]
            })
          })
          progress_indicator.render_next_step
        end
      }

      # ignore objects in the bucket that match ignore_on_server regex
      # otherwise those objects are requested (sometimes just HEAD sometimes a full GET)
      # only to be ignored later
      regexps_to_ignore = S3Website::Uploader.ignore_regexps(config['ignore_on_server'])
      filtered_bucket = OpenStruct.new({
        :objects => objects.reject { |s3_object|
          regexps_to_ignore.any? do |ignore_regexp|
            Regexp.new(ignore_regexp).match s3_object.key
          end
        }
      })

      with_progress_indicator('Calculating diff') { |progress_indicator|
        s3_data_source = Filey::DataSources::AwsSdkS3.new(filtered_bucket, config) { |filey|
          progress_indicator.render_next_step
        }
        fs_data_source = Filey::DataSources::FileSystem.new(site_dir) { |filey|
          progress_indicator.render_next_step
        }

        changed_local_files = Filey::Comparison.list_changed(
          fs_data_source,
          s3_data_source
        )
        new_local_files = Filey::Comparison.list_missing(
          fs_data_source,
          s3_data_source
        )
        [
          reject_blacklisted(changed_local_files, config),
          reject_blacklisted(new_local_files, config)
        ]
      }
    end

    private

    def self.reject_blacklisted(file_paths, config)
      (normalise file_paths).reject { |f| Upload.is_blacklisted(f, config) }
    end

    def self.with_progress_indicator(diff_msg)
      progress_indicator = DiffProgressIndicator.new(diff_msg, "... done\n")
      result = yield progress_indicator
      progress_indicator.finish
      result
    end

    def self.normalise(fileys)
      fileys.map { |filey|
        filey.full_path.sub(/\.\//, '')
      }
    end

    class DiffProgressIndicator
      def initialize(init_msg, end_msg)
        @end_msg = end_msg
        @ordinal_direction = 'n' # start from north
        print init_msg
        print '   '
        render_next_step
      end

      def render_next_step
        @ordinal_direction = DiffProgressIndicator.next_ordinal_direction @ordinal_direction
        print("\b\b" + DiffProgressIndicator.render_ordinal_direction(@ordinal_direction) + ' ')
      end

      def finish
        print "\b\b"
        print @end_msg
      end

      private

      def self.render_ordinal_direction(ordinal_direction)
        case ordinal_direction
        when 'n'
          '|'
        when 'ne'
          '/'
        when 'e'
          '-'
        when 'se'
          '\\'
        when 's'
          '|'
        when 'sw'
          '/'
        when 'w'
          '-'
        when 'nw'
          '\\'
        else
          raise 'Unknown ordinal direction ' + ordinal_direction
        end
      end

      def self.next_ordinal_direction(current_ordinal_direction)
        case current_ordinal_direction
        when 'n'
          'ne'
        when 'ne'
          'e'
        when 'e'
          'se'
        when 'se'
          's'
        when 's'
          'sw'
        when 'sw'
          'w'
        when 'w'
          'nw'
        when 'nw'
          'n'
        else
          raise 'Unknown ordinal direction ' + current_ordinal_direction
        end
      end
    end
  end
end