# = Database Utilities 
#
# A collection of database utilities.
#
# code: 
# George Moschovitis  <gm@navel.gr>
#
# (c) 2004 Navel, all rights reserved.
# $Id$

module N; 

require "n/properties"
require "n/utils/array"
require "n/utils/time"

# = DbUtils
#	
# A collection of Database utilities.
# Additional backend specific utilities are defined in
# the backend implementations.
#
module DbUtils

	# Escape an sql string
	#
	def self.escape(str)
		# defined in the backend
	end
	
	# Escape bytes
	#
	def self.escape_bytes(bytes)
		# defined in the backend
	end
	
	# The name of the SQL table where entities of this class are stored.
	# The Module separators are replaced with _ and NOT stripped out so 
	# that we can convert back to the original notation if needed.
	#
	def self.sql_table(klass)
		return "#{klass}".gsub(/::/, "_").downcase
	end
	
	# Convert a ruby time to an sql timestamp.
	# 
	def self.sql_timestamp(time = Time.now)
		# defined in the backend
	end
	
	# Output YYY-mm-dd
	#
	def self.sql_date(date)
		# defined in the backend
	end
	
	# Parse sql datetime
	#
	def self.parse_sql_timestamp(str)
		# defined in the backend
	end
	
	# Input YYYY-mm-dd
	#
	def self.parse_sql_date(str)
		# defined in the backend
	end

	# Return an sql string evaluator for the property.
	# No need to optimize this, used only to precalculate code.
	#
	# FIXME: add extra handling for float.
	#
	def self.write_prop(p)
		if String == p.klass
			return "'#\{DbUtils.escape(@#{p.symbol})\}'"
		elsif Time == p.klass
			return %|#\{@#{p.symbol} ? "'#\{DbUtils.sql_timestamp(@#{p.symbol})\}'" : 'NULL'\}|
		elsif Date == p.klass
			return %|#\{@#{p.symbol} ? "'#\{DbUtils.sql_date(@#{p.symbol})\}'" : 'NULL'\}|
		elsif Object == p.klass or Array == p.klass or Hash == p.klass
			#return "'#\{DbUtils.escape_bytes(Marshal.dump(@#{p.symbol}))\}'"
			return "'#\{DbUtils.escape_bytes(Marshal.dump(@#{p.symbol}))\}'"
		else
			# Fixnum, TrueClass
			return "#\{@#{p.symbol} || 'NULL'\}"
		end
	end

	# Return an evaluator for reading the property
	# No need to optimize this, used only to precalculate code.
	#
	def self.read_prop(p)
		# defined in the backend
	end
end

end # namespace