=begin
                  Arachni
  Copyright (c) 2010-2012 Tasos "Zapotek" Laskos <tasos.laskos@gmail.com>

  This is free software; you can copy and distribute and modify
  this program under the term of the GPL v2.0 License
  (See LICENSE file for details)

=end

require 'tmpdir'

module Arachni
module Database

    #
    # Base class for Database data structures
    #
    # Provides helper methods for data structures to be implemented related to
    # objecting dumping, loading, unique filename generation, etc.
    #
    # @author: Tasos "Zapotek" Laskos
    #                                      <tasos.laskos@gmail.com>
    #                                      <zapotek@segfault.gr>
    # @version: 0.1
    # @abstract
    #
    class Base

        #
        # @param    [Object]    serializer   any object that responds to 'dump' and 'load'.<br/>
        #                                       Will default to YAML.
        #
        def initialize( serializer = nil )
            @serializer = serializer
            if !@serializer
                @serializer = Marshal
            end
        end

        private

        #
        # Dumps the object to a unique file and returns its path.
        #
        # The path can be used as a reference to the original value
        # by way of passing it to load().
        #
        # @param    [Object]    obj
        #
        # @return   [String]    filepath
        #
        def dump( obj, &block )
            f = File.open( get_unique_filename, 'w' )

            serialized = serialize( obj )
            f.write( serialized )

            block.call( serialized ) if block_given?

            f.path
        ensure
            f.close
        end

        #
        # Loads the object stored in filepath.
        #
        # @param    [String]    filepath
        #
        # @return   [Object]
        #
        def load( filepath )
            unserialize( IO.read( filepath ) )
        end

        #
        # Deletes a file.
        #
        # @param    [String]    filepath
        #
        def delete_file( filepath )
            File.delete( filepath ) if File.exist?( filepath )
        end

        #
        # Loads the object in file and then removes it from the file-system.
        #
        # @param    [String]    filepath
        #
        # @return   [Object]
        #
        def load_and_delete_file( filepath )
            obj = load( filepath )
            delete_file( filepath )
            return obj
        end

        def serialize( obj )
            serializer.dump( obj )
        end

        def unserialize( obj )
            serializer.load( obj )
        end

        def serializer
            @serializer
        end

        def get_unique_filename
            while( File.exist?( path = generate_filename ) );end
            return path
        end

        def generate_filename
            s = ""
            10.times { s << ( 65 + rand( 26 ) ) }
            ( Dir.tmpdir + "/#{self.class.name}_" + s ).gsub( '::', '_' )
        end

    end

end
end