require File.join(File.dirname(__FILE__), 'stored_file')

module Milton
  module Storage
    # How Milton deals with a file stored on disk...
    class DiskFile < StoredFile
      class << self
        # Creates the given directory and sets it to the mode given in
        # options[:chmod]
        def recreate_directory(directory, options)
          return true if File.exists?(directory)
          FileUtils.mkdir_p(directory)
          FileUtils.chmod(options[:storage_options][:chmod], directory)
        end
      end

      # Returns the full path and filename to the file with the given options.
      # If no options are given then returns the path and filename to the
      # original file.
      def path
        File.join(dirname, filename)
      end

      # Returns the full directory path up to the file, w/o the filename.
      def dirname
        File.join(root_path, partitioned_path)
      end

      # Returns true if the file exists on the underlying file system.
      def exists?
        File.exist?(path)
      end
      
      # Writes the given source file to this file's path.
      def store(source)
        Milton.log "storing #{source} to disk at #{path}"
        self.class.recreate_directory(dirname, options)
        File.cp(source, path)
        FileUtils.chmod(options[:storage_options][:chmod], path)
      end
      
      # Removes the file from the underlying file system and any derivatives of
      # the file.
      def destroy
        Milton.log "destroying path #{dirname}"
        FileUtils.rm_rf dirname if File.exists?(dirname)
      end
      
      # Copies this file to the given location on disk.
      def copy(destination)
        Milton.log "copying #{path} to #{destination}"
        FileUtils.cp(path, destination)
      end
      
      # Returns the mime type of the file.
      def mime_type
        Milton.syscall("file -Ib #{path}").gsub(/\n/,"")
      end

      protected

      # Partitioner that takes an id, pads it up to 12 digits then splits
      # that into 4 folders deep, each 3 digits long.
      # 
      # i.e.
      #   000/000/012/139
      # 
      # Scheme allows for 1000 billion files while never storing more than
      # 1000 files in a single folder.
      #
      # Can overwrite this method to provide your own partitioning scheme.
      def partitioned_path
        # TODO: there's probably some fancy 1-line way to do this...
        padded = ("0"*(12-id.to_s.size)+id.to_s).split('')
        File.join(*[0, 3, 6, 9].collect{ |i| padded.slice(i, 3).join })
      end

      # The full path to the root of where files will be stored on disk.
      def root_path
        options[:storage_options][:root]
      end
    end
  end
end