# ISO <<Class>> ConventionalUnit
# writer output in XML

# History:
# 	Stan Smith 2014-12-03 original script

class ConventionalUnit

	def initialize(xml)
		@xml = xml
	end

	def writeXML(hConv)

		# create and identity for the unit
		$idCount = $idCount.succ
		unitID = 'unit' + $idCount

		@xml.tag!('gml:ConventionalUnit', {'gml:id' => unitID}) do
		    @xml.tag!('gml:identifier', {'codeSpace' => hConv[:codeSpace]}, hConv[:identifier])
			@xml.tag!('gml:name', hConv[:name])
			@xml.tag!('gml:catalogSymbol', hConv[:catalogSymbol])
			@xml.tag!('gml:conversionToPreferredUnit', {'uom' => hConv[:preferredUnit]}) do

				# two methods of conversion are available
				# factor and formula
				if !hConv[:factor].nil?
					# factor:
					#    y = factor * x
					#    y is in preferred units
					#    x is in provided units
					#    factor is conversion to preferred units
					@xml.tag!('gml:factor', hConv[:factor])
				else
					# formula:
					#    y = (a + bx) / (c + dx)
					#    y is in preferred units
					#    x is in provided units
					#    a,b,c,d are constants to convert to preferred units
					@xml.tag!('gml:formula') do
						@xml.tag!('gml:a', hConv[:a])
						@xml.tag!('gml:b', hConv[:b])
						@xml.tag!('gml:c', hConv[:c])
						@xml.tag!('gml:d', hConv[:d])
					end
				end

			end
		end

	end

end