package org.apache.struts2.dispatcher.mapper;

import com.opensymphony.xwork2.config.ConfigurationManager;
import com.opensymphony.xwork2.inject.Container;
import com.opensymphony.xwork2.inject.Inject;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts2.StrutsConstants;

import javax.servlet.http.HttpServletRequest;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * <!-- START SNIPPET: description -->
 * 
 * A prefix based action mapper that is capable of delegating to other {@link ActionMapper}s based on the request's prefix
 *
 * It is configured through struts.xml
 *
 * For example, with the following entries in struts.properties
 *
 * <pre>
 * <constant name="struts.mapper.class" value="org.apache.struts2.dispatcher.mapper.PrefixBasedActionMapper"/>
 * <constant name="struts.mapper.prefixMapping" value="/communities:pseudoRestful,/communityTags:pseudoRestful,/events:pseudoRestful,/mediaList:pseudoRestful,/users:pseudoRestful,/community:struts,/communityTag:struts,/event:struts,/media:struts,/user:struts,:struts"/>
 * </pre>
 * <p/>
 * When {@link PrefixBasedActionMapper#getMapping(HttpServletRequest, ConfigurationManager)} or
 * {@link PrefixBasedActionMapper#getUriFromActionMapping(ActionMapping)} is invoked,
 * {@link PrefixBasedActionMapper} will check each possible prefix (url prefix terminating just before a /) to find the most specific ActionMapper that returns a mapping when asked to map the request.  If none are found, null is returned for both
 * {@link PrefixBasedActionMapper#getMapping(HttpServletRequest, ConfigurationManager)} and
 * {@link PrefixBasedActionMapper#getUriFromActionMapping(ActionMapping)} methods.
 * <p/>
 *
 * <!-- END SNIPPET: description -->
 *
 * @see ActionMapper
 * @see ActionMapping
 *
 */
public class PrefixBasedActionMapper extends DefaultActionMapper implements ActionMapper {
  protected transient final Log log = LogFactory.getLog(getClass());
  protected Container container;
  protected Map<String,ActionMapper> actionMappers = new HashMap<String,ActionMapper>();

  @Inject
  public void setContainer(Container container) {
    this.container = container;
  }

  @Inject(StrutsConstants.PREFIX_BASED_MAPPER_CONFIGURATION)
  public void setPrefixBasedActionMappers(String list) {
    if (list != null) {
      String[] mappers = list.split(",");
      for (String mapper : mappers) {
        String[] thisMapper = mapper.split(":");
        if ((thisMapper != null) && (thisMapper.length == 2)) {
          String mapperPrefix = thisMapper[0].trim();
          String mapperName = thisMapper[1].trim();
          Object obj = container.getInstance(ActionMapper.class, mapperName);
          if (obj != null) {
            actionMappers.put(mapperPrefix, (ActionMapper) obj);
          } else if (log.isDebugEnabled()) {
            log.debug("invalid PrefixBasedActionMapper config entry: " + mapper);
          }
        }
      }
    }
  }


  @SuppressWarnings("unchecked")
  public ActionMapping getMapping(HttpServletRequest request, ConfigurationManager configManager) {
    String uri = getUri(request);
    for (int lastIndex = uri.lastIndexOf('/'); lastIndex > (-1); lastIndex = uri.lastIndexOf('/', lastIndex-1)) {
      ActionMapper actionMapper = actionMappers.get(uri.substring(0,lastIndex));
      if (actionMapper != null) {
        ActionMapping actionMapping = actionMapper.getMapping(request, configManager);
        if (log.isDebugEnabled()) {
          log.debug("Using ActionMapper "+actionMapper);
        }
        if (actionMapping != null) {
          if (log.isDebugEnabled()) {
            if (actionMapping.getParams() != null) {
              log.debug("ActionMapper found mapping. Parameters: "+actionMapping.getParams());
              for (Map.Entry<String,Object> mappingParameterEntry : ((Map<String,Object>)(actionMapping.getParams())).entrySet()) {
                Object paramValue = mappingParameterEntry.getValue();
                if (paramValue == null) {
                  log.debug(mappingParameterEntry.getKey()+" : null!");
                } else if (paramValue instanceof String[]) {
                  log.debug(mappingParameterEntry.getKey()+" : (String[]) "+Arrays.toString((String[])paramValue));
                } else if (paramValue instanceof String) {
                  log.debug(mappingParameterEntry.getKey()+" : (String) "+(String)paramValue);
                } else {
                  log.debug(mappingParameterEntry.getKey()+" : (Object) "+(paramValue.toString()));
                }
              }
            }
          }
          return actionMapping;
        } else if (log.isDebugEnabled()) {
          log.debug("ActionMapper "+actionMapper+" failed to return an ActionMapping");
        }
      }
    }
    if (log.isDebugEnabled()) {
      log.debug("no ActionMapper found");
    }
    return null;
  }

  public String getUriFromActionMapping(ActionMapping mapping) {
    String namespace = mapping.getNamespace();
    for (int lastIndex = namespace.length(); lastIndex > (-1); lastIndex = namespace.lastIndexOf('/', lastIndex-1)) {
      ActionMapper actionMapper = actionMappers.get(namespace.substring(0,lastIndex));
      if (actionMapper != null) {
        String uri = actionMapper.getUriFromActionMapping(mapping);
        if (log.isDebugEnabled()) {
          log.debug("Using ActionMapper "+actionMapper);
        }
        if (uri != null) {
          return uri;
        } else if (log.isDebugEnabled()) {
          log.debug("ActionMapper "+actionMapper+" failed to return an ActionMapping (null)");
        }
      }
    }
    if (log.isDebugEnabled()) {
      log.debug("ActionMapper failed to return a uri");
    }
    return null;
  }
}