thoughtbot/paperclip

module Paperclip
  module Storage
    # The default place to store attachments is in the filesystem. Files on the local
    # filesystem can be very easily served by Apache without requiring a hit to your app.
    # They also can be processed more easily after they've been saved, as they're just
    # normal files. There are two Filesystem-specific options for has_attached_file:
    # * +path+: The location of the repository of attachments on disk. This can (and, in
    #   almost all cases, should) be coordinated with the value of the +url+ option to
    #   allow files to be saved into a place where Apache can serve them without
    #   hitting your app. Defaults to
    #   ":rails_root/public/:attachment/:id/:style/:basename.:extension"
    #   By default this places the files in the app's public directory which can be served
    #   directly. If you are using capistrano for deployment, a good idea would be to
    #   make a symlink to the capistrano-created system directory from inside your app's
    #   public directory.
    #   See Paperclip::Attachment#interpolate for more information on variable interpolaton.
    #     :path => "/var/app/attachments/:class/:id/:style/:basename.:extension"
    # * +override_file_permissions+: This allows you to override the file permissions for files
    #   saved by paperclip. If you set this to an explicit octal value (0755, 0644, etc) then
    #   that value will be used to set the permissions for an uploaded file. The default is 0666.
    #   If you set :override_file_permissions to false, the chmod will be skipped. This allows
    #   you to use paperclip on filesystems that don't understand unix file permissions, and has the 
    #   added benefit of using the storage directories default umask on those that do.
    module Filesystem
      def self.extended base
      end

      def exists?(style_name = default_style)
        if original_filename
          File.exist?(path(style_name))
        else
          false
        end
      end

      def flush_writes #:nodoc:
        @queued_for_write.each do |style_name, file|
          FileUtils.mkdir_p(File.dirname(path(style_name)))
          begin
            move_file(file.path, path(style_name))
          rescue SystemCallError
            File.open(path(style_name), "wb") do |new_file|
              while chunk = file.read(16 * 1024)
                new_file.write(chunk)
              end
            end
          end
          unless @options[:override_file_permissions] == false
            resolved_chmod = (@options[:override_file_permissions] & ~0111) || (0666 & ~File.umask)
            FileUtils.chmod( resolved_chmod, path(style_name) )
          end
          file.rewind
        end

        after_flush_writes # allows attachment to clean up temp files

        @queued_for_write = {}
      end

      def flush_deletes #:nodoc:
        @queued_for_delete.each do |path|
          begin
            log("deleting #{path}")
            FileUtils.rm(path) if File.exist?(path)
          rescue Errno::ENOENT => e
            # ignore file-not-found, let everything else pass
          end
          begin
            while(true)
              path = File.dirname(path)
              FileUtils.rmdir(path)
              break if File.exist?(path) # Ruby 1.9.2 does not raise if the removal failed.
            end
          rescue Errno::EEXIST, Errno::ENOTEMPTY, Errno::ENOENT, Errno::EINVAL, Errno::ENOTDIR, Errno::EACCES
            # Stop trying to remove parent directories
          rescue SystemCallError => e
            log("There was an unexpected error while deleting directories: #{e.class}")
            # Ignore it
          end
        end
        @queued_for_delete = []
      end

      def copy_to_local_file(style, local_dest_path)
        FileUtils.cp(path(style), local_dest_path)
      end

      private

      def move_file(src, dest)
        # Support hardlinked files
        if File.identical?(src, dest)
          File.unlink(src)
        else
          FileUtils.mv(src, dest)
        end
      end
    end

  end
end