package org.daisy.pipeline.common.calabash.impl;
   
   import java.util.Map;
   import java.util.NoSuchElementException;
   import java.util.function.Consumer;
   
   import javax.xml.namespace.QName;
   import static javax.xml.stream.XMLStreamConstants.START_ELEMENT;
   import javax.xml.stream.XMLStreamException;
  import javax.xml.stream.XMLStreamReader;
  
  import com.google.common.collect.ImmutableMap;
  
  import org.daisy.common.transform.InputValue;
  import org.daisy.common.transform.OutputValue;
  import org.daisy.common.transform.TransformerException;
  import org.daisy.common.transform.XMLInputValue;
  import org.daisy.common.transform.XMLTransformer;
  import org.daisy.common.xproc.XProcError;
  
  public class ErrorReporter implements XMLTransformer {
  
  	private final static QName _SOURCE = new QName("source");
  	private static final QName C_ERROR = new QName("http://www.w3.org/ns/xproc-step", "error");
  
  	private final Consumer<XProcError> reporter;
  
  	ErrorReporter(Consumer<XProcError> reporter) {
  		this.reporter = reporter;
  	}
  
  	@Override
  	public Runnable transform(Map<QName,InputValue<?>> input, Map<QName,OutputValue<?>> output) {
  		input = XMLTransformer.validateInput(input, ImmutableMap.of(_SOURCE, InputType.MANDATORY_NODE_SEQUENCE));
  		output = XMLTransformer.validateOutput(output, null);
  		XMLInputValue<?> source = (XMLInputValue<?>)input.get(_SOURCE);
  		return () -> report(source.asXMLStreamReader());
  	}
  
  	private void report(XMLStreamReader reader) throws TransformerException {
  		try {
  			while (true)
  				try {
  					int event = reader.next();
  					switch (event) {
  					case START_ELEMENT:
  						if (C_ERROR.equals(reader.getName())) {
  							XProcError xprocError = XProcError.parse(reader);
  							reporter.accept(xprocError);
  						}
  						break;
  					default:
  					}
  				} catch (NoSuchElementException e) {
  					break;
  				}
  		} catch (XMLStreamException e) {
  			throw new TransformerException(e);
  		}
  	}
  }