=begin
    Copyright 2010-2012 Tasos Laskos <tasos.laskos@gmail.com>

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
=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>
    #                                      
    # @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