package at.gv.egovernment.moa.spss.api.xmlbind;

import java.text.ParseException;
import java.util.Date;

import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

import at.gv.egovernment.moa.util.Base64Utils;
import at.gv.egovernment.moa.util.Constants;
import at.gv.egovernment.moa.util.DOMUtils;
import at.gv.egovernment.moa.util.DateTimeUtils;
import at.gv.egovernment.moa.util.XPathUtils;

import at.gv.egovernment.moa.spss.MOAApplicationException;
import at.gv.egovernment.moa.spss.api.SPSSFactory;
import at.gv.egovernment.moa.spss.api.common.Content;
import at.gv.egovernment.moa.spss.api.common.MetaInfo;
import at.gv.egovernment.moa.spss.api.common.XMLDataObjectAssociation;

/**
 * Utility methods for parsing XML requests definied in the MOA XML schema.
 * 
 * @author Patrick Peck
 * @version $Id$
 */
public class RequestParserUtils {
  //
  // XPath expressions for parsing parts of a request
  //
  private static final String MOA = Constants.MOA_PREFIX + ":";
  private static final String REFERENCE_ATTR_NAME = "Reference";
  private static final String MIME_TYPE_XPATH = MOA + "MimeType";
  private static final String DESCRIPTION_XPATH = MOA + "Description";
  private static final String XML_ASSOC_CONTENT_XPATH = MOA + "Content";
  private static final String CONTENT_XPATH =
    MOA + "Base64Content | " + MOA + "XMLContent";
  private static final String ANY_OTHER_XPATH =
    "*[namespace-uri() != \"" + Constants.MOA_NS_URI + "\"]";

  /**
   * Parse a <code>XMLDataObjectAssociationType</code> kind of DOM element.
   * 
   * @param assocElem The <code>XMLDataObjectAssociationType</code> kind of
   * DOM elmeent to parse. 
   * @return The <code>XMLDataObjectAssociation</code> API object containing
   * the data from the <code>XMLDataObjectAssociationType</code> DOM element.
   */
  public static XMLDataObjectAssociation parseXMLDataObjectAssociation(Element assocElem) {
    SPSSFactory factory = SPSSFactory.getInstance();
    MetaInfo metaInfo = parseMetaInfo(assocElem);
    Element contentElem =
      (Element) XPathUtils.selectSingleNode(assocElem, XML_ASSOC_CONTENT_XPATH);
    Content content = parseContent(contentElem);

    return factory.createXMLDataObjectAssociation(metaInfo, content);
  }

  /**
   * Parse a <code>MetaInfoType</code> kind of DOM element.
   * 
   * @param metaInfoElem The <code>MetaInfoType</code> kind of DOM element.
   * @return The <code>MetaInfo</code> API object containing the data from
   * the <code>metaInfoElem</code>.
   */
  public static MetaInfo parseMetaInfo(Element metaInfoElem) {
    SPSSFactory factory = SPSSFactory.getInstance();
    String mimeType =
      XPathUtils.getElementValue(metaInfoElem, MIME_TYPE_XPATH, null);
    String description =
      XPathUtils.getElementValue(metaInfoElem, DESCRIPTION_XPATH, null);
    NodeList anyOther =
      XPathUtils.selectNodeList(metaInfoElem, ANY_OTHER_XPATH);

    return factory.createMetaInfo(mimeType, description, anyOther);
  }

  /**
   * Parse a <code>ContentOptionalRefType</code> or 
   * <code>ContentRequiredRefType</code> kind of DOM element.
   * @param contentParentElem The DOM element being the parent of the 
   * content element.
   * @return The <code>Content</code> API object containing the data from
   * the given DOM element.
   */
  public static Content parseContent(Element contentParentElem) {
    SPSSFactory factory = SPSSFactory.getInstance();
    String referenceURI =
      contentParentElem.hasAttribute(REFERENCE_ATTR_NAME)
        ? contentParentElem.getAttribute(REFERENCE_ATTR_NAME)
        : null;
    Element contentElem =
      (Element) XPathUtils.selectSingleNode(contentParentElem, CONTENT_XPATH);

    if (contentElem == null) {
      return factory.createContent(referenceURI);
    }

    if ("Base64Content".equals(contentElem.getLocalName())) {
      String base64String = DOMUtils.getText(contentElem);
      return factory.createContent(
        Base64Utils.decodeToStream(base64String, true),
        referenceURI);
    } else { // "XMLContent".equals(contentElem.getLocalName())
      return factory.createContent(contentElem.getChildNodes(), referenceURI);
    }
  }

  /**
   * Get the signing time from a Verfiy(CMS|XML)SignatureRequest.
   * 
   * @param requestElem A <code>Verify(CMS|XML)SignatureRequest</code> DOM 
   * element.
   * @param dateTimeXPath The XPath to lookup the <code>DateTime</code> element
   * within the request.
   * @return Date The date and time corresponding to the <code>DateTime</code>
   * element in the request. If no <code>DateTime</code> element exists in the
   * request, <code>null</code> is returned.
   * @throws MOAApplicationException An error occurred during a parsing the
   * <code>DateTime</code> element or creating the return value.
   */
  public static Date parseDateTime(Element requestElem, String dateTimeXPath)
    throws MOAApplicationException {

    Element dateTimeElem;
    String dateTimeText;

    // select the DateTime element
    dateTimeElem =
      (Element) XPathUtils.selectSingleNode(requestElem, dateTimeXPath);

    // parse a date from the element value
    if (dateTimeElem != null) {
      dateTimeText = DOMUtils.getText(dateTimeElem);
      try {
        return DateTimeUtils.parseDateTime(dateTimeText);
      } catch (ParseException e) {
        throw new MOAApplicationException(
          "1104",
          new Object[] { dateTimeText });
      }
    } else {
      return null;
    }
  }

}