package org.trails.engine.encoders;

 import org.apache.tapestry.TapestryUtils;

 import org.apache.tapestry.engine.ServiceEncoder;

 import org.apache.tapestry.engine.ServiceEncoding;

 import org.trails.Trails;

 import org.trails.io.ClassDescriptorSqueezerStrategy;

 import org.trails.services.ServiceConstants;

 /**

  * A specialized encoder for the TrailsPageService that encodes the necessary parameters into the servlet path allowing

  * the use of rest like URLs to access the service.

  */

 public class PagesEncoder implements ServiceEncoder

 {

         private static final char PATH_SEPARATOR = '/';

         private String path = "/trails";

         private String entitySqzrPrefix;

         private String entitySqzrDelimiter;

         public void encode(ServiceEncoding encoding)

         {

                 if (!isTrailsPageService(encoding))

                         return;

                 StringBuilder builder = new StringBuilder(path);

                 String pageType = encoding.getParameterValue(ServiceConstants.PAGE_TYPE);

                 builder.append(PATH_SEPARATOR).append(pageType);

                 String className = abbreviateSqueezedClassDescripor(encoding.getParameterValue(ServiceConstants.CLASS_DESCRIPTOR));

                 builder.append(PATH_SEPARATOR).append(className);

                 String entity = encoding.getParameterValue(ServiceConstants.MODEL);

                 if (entity != null)

                 {

                         builder.append(PATH_SEPARATOR).append(abbreviateSqueezedEntity(entity, className));

                 }

                 encoding.setServletPath(builder.toString());

                 encoding.setParameterValue(ServiceConstants.SERVICE, null);

                 encoding.setParameterValue(ServiceConstants.PAGE_TYPE, null);

                 encoding.setParameterValue(ServiceConstants.CLASS_DESCRIPTOR, null);

                 encoding.setParameterValue(ServiceConstants.MODEL, null);

         }

         private boolean isTrailsPageService(ServiceEncoding encoding)

         {

                 String service = encoding.getParameterValue(ServiceConstants.SERVICE);

                 return service.equals(Trails.TRAILS_PAGES_SERVICE);

         }

         public void decode(ServiceEncoding encoding)

         {

                 String servletPath = encoding.getServletPath();

                 if (!servletPath.equals(path))

                         return;

                 String pathInfo = encoding.getPathInfo();

                 String[] params = TapestryUtils.split(pathInfo.substring(1), PATH_SEPARATOR);

 //                String params = pathInfo.substring(1);

                 encoding.setParameterValue(ServiceConstants.SERVICE, Trails.TRAILS_PAGES_SERVICE);

                 encoding.setParameterValue(ServiceConstants.PAGE_TYPE, params[0]);

                 String simpleClassName = params[1];

                 encoding.setParameterValue(ServiceConstants.CLASS_DESCRIPTOR, unAbbreviateSqueezedClassDescripor(simpleClassName));

                 if (params.length > 2)

                         encoding.setParameterValue(ServiceConstants.MODEL, unAbbreviateSqueezedEntity(

                                         pathInfo.substring(params[0].length() + params[1].length() + 3), simpleClassName));

         }

         private String abbreviateSqueezedClassDescripor(String squeezedClassDescripor)

         {

                 return squeezedClassDescripor.substring(ClassDescriptorSqueezerStrategy.PREFIX.length());

         }

         private String unAbbreviateSqueezedClassDescripor(String string)

         {

                 return ClassDescriptorSqueezerStrategy.PREFIX + string;

         }

         private String abbreviateSqueezedEntity(String squeezedEntity, String className)

         {

                 final int prefixLenght = entitySqzrPrefix.length() + className.length() + entitySqzrDelimiter.length();

                 return squeezedEntity.length() > prefixLenght ? squeezedEntity.substring(prefixLenght) : "";

         }

         private String unAbbreviateSqueezedEntity(String string, String className)

         {

                 return new StringBuilder()

                                 .append(entitySqzrPrefix)

                                 .append(className)

                                 .append(entitySqzrDelimiter)

                                 .append(string)

                                 .toString();

         }

         public void setEntitySqzrPrefix(String entitySqzrPrefix)

         {

                 this.entitySqzrPrefix = entitySqzrPrefix;

         }

         public void setEntitySqzrDelimiter(String entitySqzrDelimiter)

         {

                 this.entitySqzrDelimiter = entitySqzrDelimiter;

         }

         public void setPath(String path)

         {

                 // fix broken path if doesn't start with /

                 this.path = !path.startsWith(String.valueOf(PATH_SEPARATOR)) ? PATH_SEPARATOR + path : path;

         }

 }