package org.daisy.pipeline.braille.css.saxon.impl;
   
   import java.util.ArrayList;
   import java.util.List;
   
   import net.sf.saxon.expr.XPathContext;
   import net.sf.saxon.lib.ExtensionFunctionCall;
   import net.sf.saxon.lib.ExtensionFunctionDefinition;
   import net.sf.saxon.om.NodeInfo;
  import net.sf.saxon.om.Sequence;
  import net.sf.saxon.om.StructuredQName;
  import net.sf.saxon.s9api.XdmItem;
  import net.sf.saxon.s9api.XdmNode;
  import net.sf.saxon.trans.XPathException;
  import net.sf.saxon.value.SequenceType;
  
  import org.daisy.common.saxon.SaxonInputValue;
  import org.daisy.common.saxon.SaxonOutputValue;
  import org.daisy.common.transform.TransformerException;
  
  import org.osgi.service.component.annotations.Component;
  
  @Component(
  	name = "css:render-table-by",
  	service = { ExtensionFunctionDefinition.class }
  )
  public class RenderTableByDefinition extends ExtensionFunctionDefinition {
  	
  	private static final String XMLNS_CSS = "http://www.daisy.org/ns/pipeline/braille-css";
  	
  	private static final StructuredQName funcname = new StructuredQName("css", XMLNS_CSS, "render-table-by");
  	
  	public StructuredQName getFunctionQName() {
  		return funcname;
  	}
  	
  	public SequenceType[] getArgumentTypes() {
  		return new SequenceType[] {
  			SequenceType.SINGLE_STRING,
  			SequenceType.SINGLE_NODE // SINGLE_ELEMENT_NODE
  		};
  	}
  	
  	public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
  		return SequenceType.SINGLE_NODE; // SINGLE_ELEMENT_NODE
  	}
  	
  	public ExtensionFunctionCall makeCallExpression() {
  		return new ExtensionFunctionCall() {
  			public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
  				try {
  					String axes = arguments[0].head().getStringValue();
  					NodeInfo tableElement = (NodeInfo)arguments[1].head();
  					
  					// FIXME: why does this not work?
  					// URI base = new URI(tableElement.getBaseURI());
  					List<XdmItem> result = new ArrayList<>();
  					new TableAsList(axes)
  					.transform(
  						new SaxonInputValue(tableElement),
  						new SaxonOutputValue(result::add, context.getConfiguration()))
  					.run();
  					if (result.size() != 1 || !(result.get(0) instanceof XdmNode))
  						throw new RuntimeException(); // should not happen
  					return ((XdmNode)result.get(0)).getUnderlyingNode();
  				} catch (TransformerException e) {
  					throw new XPathException(e.getMessage(), e.getCause());
  				} catch (Throwable e) {
  					throw new XPathException("Unexpected error in css:render-table-by", e);
  				}
  			}
  		};
  	}
  }