package org.daisy.pipeline.css.saxon.impl;
   
   import net.sf.saxon.expr.XPathContext;
   import net.sf.saxon.lib.ExtensionFunctionCall;
   import net.sf.saxon.lib.ExtensionFunctionDefinition;
   import net.sf.saxon.om.Sequence;
   import net.sf.saxon.om.StructuredQName;
   import net.sf.saxon.trans.XPathException;
   import net.sf.saxon.value.BooleanValue;
  import net.sf.saxon.value.SequenceType;
  
  import org.daisy.pipeline.css.Medium;
  
  import org.osgi.service.component.annotations.Component;
  
  @Component(
  	name = "pf:media-query-matches",
  	service = { ExtensionFunctionDefinition.class }
  )
  public class MediaQueryMatchesDefinition extends ExtensionFunctionDefinition {
  
  	private static final StructuredQName funcname = new StructuredQName(
  		"pf",
  		"http://www.daisy.org/ns/pipeline/functions",
  		"media-query-matches");
  
  	public StructuredQName getFunctionQName() {
  		return funcname;
  	}
  
  	@Override
  	public int getMinimumNumberOfArguments() {
  		return 2;
  	}
  
  	@Override
  	public int getMaximumNumberOfArguments() {
  		return 2;
  	}
  
  	public SequenceType[] getArgumentTypes() {
  		return new SequenceType[] {
  			SequenceType.SINGLE_STRING,
  			SequenceType.SINGLE_STRING
  		};
  	}
  
  	public SequenceType getResultType(SequenceType[] suppliedArgumentTypes) {
  		return SequenceType.SINGLE_BOOLEAN;
  	}
  
  	public ExtensionFunctionCall makeCallExpression() {
  		return new ExtensionFunctionCall() {
  			public Sequence call(XPathContext context, Sequence[] arguments) throws XPathException {
  				try {
  					String mediaQuery = arguments[0].head().getStringValue();
  					Medium medium = Medium.parse(arguments[1].head().getStringValue());
  					return BooleanValue.get(medium.matches(mediaQuery));
  				} catch (Throwable e) {
  					throw new XPathException("Unexpected error in pf:media-query-matches", e);
  				}
  			}
  		};
  	}
  }