package at.knowcenter.wag.egov.egiz.pdf;

import java.util.HashMap;

import javax.xml.datatype.DatatypeFactory;
import javax.xml.datatype.XMLGregorianCalendar;

import org.apache.log4j.Logger;

import at.gv.egiz.pdfas.exceptions.ErrorCode;
import at.gv.egiz.pdfas.framework.signator.SignatorInformation;
import at.gv.egiz.pdfas.utils.OgnlUtil;
import at.knowcenter.wag.egov.egiz.cfg.SettingsReader;
import at.knowcenter.wag.egov.egiz.exceptions.PresentableException;
import at.knowcenter.wag.egov.egiz.exceptions.SettingsException;
import at.knowcenter.wag.egov.egiz.sig.SignatureObject;

import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.PdfDate;
import com.lowagie.text.pdf.PdfDictionary;
import com.lowagie.text.pdf.PdfName;
import com.lowagie.text.pdf.PdfSignature;
import com.lowagie.text.pdf.PdfSignatureAppearance;
import com.lowagie.text.pdf.PdfStamper;
import com.lowagie.text.pdf.PdfString;

/**
 * Helper class for creating adobe signature attributes.
 * 
 * @author dferbas
 *
 */
public class AdobeSignatureHelper {
   private static final String ADOBE_SIGN_FIELDNAME_KEY = "adobeSignFieldName";

   private static final String ADOBE_SIG_ENABLED_KEY = "adobeSignEnabled";

   private static Logger logger = Logger.getLogger(AdobeSignatureHelper.class);
   
   public static final String ADOBE_SIG_FILTER = "Adobe.PDF-AS";
   
   public static final String ADOBE_SIG_TEXT_KEY = "adobeSignText";

   /**
    * Writes Adobe-pdf signature entry with itext
    * 
    * @param stamper
    * @param si
    * @param so
    * @param atp
    * @throws PresentableException
    */
   public static void createAdobeSignatureField(PdfStamper stamper, SignatorInformation si,
         SignatureObject so, ActualTablePos atp) throws PresentableException {

      try {
         logger.info("create adobe signature field");
         PdfSignatureAppearance sap = stamper.getSignatureAppearance();

         String fieldName = getAdobeFieldName(so.getSignatureTypeDefinition().getType());
         // find field num
         int nexSigNum = 1;
         String finalFieldName = fieldName + " #" + nexSigNum;
         while (stamper.getAcroFields().getField(finalFieldName) != null) {
            nexSigNum++;
            finalFieldName = fieldName + " #" + nexSigNum;
         }

         sap.setCrypto(null, null, null, null);
         // supress overlay text for visible signatures
         sap.setLayer2Text("");
         sap.setLayer4Text("");

         // the following line marks the sig block as adobe sig
         // sap.setVisibleSignature(createRectangleFromTablePos(iui.actualTablePos),
         // iui.actualTablePos.page, "PDF-AS-Signatur");
         sap.setVisibleSignature(new Rectangle(0, 0, 0, 0), atp.page, finalFieldName);
         String subfilter = "unknown";
         if (so != null && so.getKZ() != null) {
            subfilter = so.getKZ().toString();
         } else if (si != null) {
            subfilter = si.getSignSignatureObject().kz;
         }
         PdfSignature sig = new PdfSignature(new PdfName(ADOBE_SIG_FILTER), new PdfName(subfilter));
         // the following fields are not shown by the reader, because its is no
         // Standard filter
         // sig.setLocation("location is not visible");
         // sig.setReason("reason is not visible");
         // sig.setContact("contact is not visible");
         // sig.setDate(new PdfDate());
         if (si != null) {
            XMLGregorianCalendar c = DatatypeFactory.newInstance().newXMLGregorianCalendar(
                  si.getSignSignatureObject().date);
            sig.setDate(new PdfDate(c.toGregorianCalendar()));
         }
         sig.setName(getAdobeSignText(so.getSignatureTypeDefinition().getType(), si));
         sap.setCryptoDictionary(sig);

         // content element is mandatory but empty
         HashMap exc = new HashMap();
         exc.put(PdfName.CONTENTS, new Integer(2));
         sap.preClose(exc); // *2+2

         PdfDictionary dic = new PdfDictionary();
         dic.put(PdfName.CONTENTS, new PdfString((String) null).setHexWriting(true));
         sap.close(dic);
      } catch (Exception ex) {
         logger.error("error", ex);
         throw new PresentableException(ErrorCode.CANNOT_WRITE_PDF,
               "Error creating adobe signature attribute", ex);
      }
   }
   

   /**
    * Returns if adobe signature is enabled for the passed signature profile.
    * Config key: {@value #ADOBE_SIG_ENABLED_KEY}
    * @param sigProfile
    * @return
    */
   public static boolean isAdobeSignatureFieldEnabled(String sigProfile) {
      return "true".equalsIgnoreCase(
            getDefaultableConfigProperty(sigProfile, ADOBE_SIG_ENABLED_KEY, "false"));
   }

   protected static Rectangle createRectangleFromTablePos(ActualTablePos pos) {
      return new Rectangle(pos.x, pos.y, pos.x + pos.width, pos.y - pos.height);
   }
   
   private static String getAdobeFieldName(String sigProfile) {
      return getDefaultableConfigProperty(sigProfile, ADOBE_SIGN_FIELDNAME_KEY, "PDF-AS-Signatur");
   }
   
   private static String getDefaultableConfigProperty(String sigProfile, String propName, String defaultValue) {      
      String confVal;
      try {
         confVal = SettingsReader.getInstance().getSetting(
               "sig_obj." + sigProfile + "." + propName,
               "default." + propName,
               defaultValue);
      } catch (SettingsException e) {
         logger.warn("error reading " + propName  + " from config. Using default: " + defaultValue, e);
         return defaultValue;
      }
      return confVal;            
   }

   /**
    * Evaluate name for adobe signature field. Get from config. Evaluate ognl if
    * ok.
    * 
    * @param sigProfile
    * @param si
    * @return
    */
   private static String getAdobeSignText(String sigProfile, SignatorInformation si) {
      String defaultName = "PDF-AS";
      try {
         logger.debug("reading adobe sig name for profile: " + sigProfile);
         String propKey = ADOBE_SIG_TEXT_KEY + ".textual";
         if (si == null) {
            propKey = propKey.replaceAll("textual", "binary");
         }
         String adobeStr = getDefaultableConfigProperty(sigProfile, propKey, defaultName);
       
         HashMap ognlCtx = new HashMap();
         OgnlUtil ognl = new OgnlUtil(ognlCtx);
         if (ognl.containsExpression(adobeStr)) {
            if (si == null) {
               logger
                     .error(ADOBE_SIG_TEXT_KEY
                           + " ognl expressions not allowed for binary signatures (SignatorInformation not available)");
               return defaultName;
            }
            ognlCtx.put("si", si);
            ognlCtx.put("sso", si.getSignSignatureObject());
            String res = ognl.compileMessage(adobeStr);
            return res;
         } else {
            return adobeStr;
         }

      } catch (Exception ex) {
         logger.warn("error creating adobe sign text, using default '" + defaultName + "'", ex);
         return defaultName;
      }
   }

}