<?xml version="1.0" encoding="UTF-8"?>
<!--
Relational pipes
Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
-->
<xsl:stylesheet version="1.0"
				xmlns="tag:globalcode.info,2018:relpipe"
				xmlns:sparql="http://www.w3.org/2005/sparql-results#"
				xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
				xmlns:fn="http://www.w3.org/2005/xpath-functions"
				xmlns:xs="http://www.w3.org/2001/XMLSchema"
				exclude-result-prefixes="fn sparql xs">
	<xsl:output
		method="xml"
		indent="yes"
		encoding="UTF-8"/>

	<xsl:param name="relation" select="'rdf'"/>

	<xsl:template match="/sparql:sparql">
		<relpipe>
			<relation>
				<name>
					<xsl:value-of select="$relation"/>
				</name>
				<attributes-metadata>
					<xsl:for-each select="sparql:head/sparql:variable">
						<attribute-metadata name="{@name}" type="string"/>
						<!-- here we can optionally append additional attributes with some metadata -->
					</xsl:for-each>
				</attributes-metadata>
				
				<xsl:for-each select="sparql:results/sparql:result">
					<xsl:variable name="record" select="."/>
					<record>
						<xsl:for-each select="/sparql:sparql/sparql:head/sparql:variable">
							<xsl:variable name="attribute" select="@name"/>
							<xsl:call-template name="record">
								<xsl:with-param name="record" select="$record"/>
								<xsl:with-param name="attribute" select="$attribute"/>
							</xsl:call-template>
						</xsl:for-each>
					</record>
				</xsl:for-each>
				
			</relation>
		</relpipe>
	</xsl:template>
	
	<xsl:template name="record">
		<xsl:param name="record"/>
		<xsl:param name="attribute"/>
		<attribute>
			<xsl:value-of select="$record/sparql:binding[@name=$attribute]"/>
			<!-- here we can optionally append additional attributes with some metadata -->
			<!--
				<sparql:binding name="…attribute…">
					<sparql:uri>…value…</sparql:uri>
					<sparql:literal xml:lang="it">…value…</sparql:literal>
				</sparql:binding>
			-->
		</attribute>
	</xsl:template>

</xsl:stylesheet>