/**
    * Copyright 2005-2013 The Kuali Foundation
    *
    * Licensed under the Educational Community License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.opensource.org/licenses/ecl2.php
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.kuali.rice.kew.rule.xmlrouting;
  
  import org.apache.commons.lang.StringUtils;
  import org.kuali.rice.kew.api.WorkflowRuntimeException;
  import org.kuali.rice.kew.api.rule.RuleExtension;
  import org.kuali.rice.kew.xml.xstream.XStreamSafeSearchFunction;
  import org.w3c.dom.Node;
  
  import javax.xml.namespace.QName;
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathFunction;
  import javax.xml.xpath.XPathFunctionResolver;
  import java.util.List;
  import java.util.Map;
  
  /**
   * A function resolver for XPath functions provided by KEW.
   *
   * @author Kuali Rice Team (rice.collab@kuali.org)
   */
  public class WorkflowFunctionResolver implements XPathFunctionResolver {
  	
  	private List<RuleExtension> ruleExtensions;
  	private Node rootNode;
  	private XPath xpath;
  
  
  	public XPathFunction resolveFunction(QName fname, int arity) {
  		if (fname == null) {
  			throw new NullPointerException("The function name cannot be null.");
  		}
  		if (fname.equals(new QName("http://nothingfornowwf.com", "ruledata", "wf"))) {
  			if (ruleExtensions == null) {
  				throw new IllegalArgumentException("There are no rule extensions.");
  			}
  			return new XPathFunction() {
  				public Object evaluate(List args) {
  					if (args.size() == 1) {
  						String name = (String) args.get(0);
  						for (RuleExtension ruleExtension : ruleExtensions) {
  						    for (Map.Entry<String, String> entry : ruleExtension.getExtensionValuesMap().entrySet()) {
  						        if (entry.getKey().equals(name)) {
  						            return entry.getValue();
  						        }
  						    }
  						}
  					}
  					return "";
  				}
  			};
  		} else if (fname.equals(new QName("http://nothingfornowwf.com", "xstreamsafe", "wf"))) {
  			return new XStreamSafeSearchFunction(rootNode, this.getXpath());
  		} else if (fname.equals(new QName("http://nothingfornowwf.com", "upper-case", "wf"))) {
  			return new UpperCaseFunction();
  		} else if (fname.equals(new QName("http://nothingfornowwf.com", "field", "wf"))) {
  			return new XPathFunction() {
  				public Object evaluate(java.util.List args) {
  					if (args.size() == 1) {
  						String name = (String) args.get(0);
  						try {
  							return field(name);
  						} catch (Exception e) {
  							throw new WorkflowRuntimeException("Failed to find field to validate.", e);
  						}
  					}
  					return "";
  				}
  			};
  		} else if (fname.equals(new QName("http://nothingfornowwf.com", "empty", "wf"))) {
  			return new XPathFunction() {
  				public Object evaluate(java.util.List args) {
  					return empty(args.get(0));
  				}
  			};
  		} else {
  			return null;
  		}
  	}
  
  	public String field(String fieldName) throws Exception {
  	    return xpath.evaluate("//edlContent/data/version[@current='true']/field[@name='" + fieldName + "']/value", rootNode);
  	}
  	    
  	    
 	public boolean empty(Object object) {
 	    if (object instanceof String) {
 	    	return StringUtils.isBlank((String)object);
 	    }
 	    return object == null;
 	}
 
 	public List<RuleExtension> getRuleExtensions() {
         return this.ruleExtensions;
     }
 
     public void setRuleExtensions(List<RuleExtension> ruleExtensions) {
         this.ruleExtensions = ruleExtensions;
     }
 
     public Node getRootNode() {
 		return rootNode;
 	}
 
 	public void setRootNode(Node rootNode) {
 		this.rootNode = rootNode;
 	}
 	
 
 	public XPath getXpath() {
 		return xpath;
 	}
 
 	public void setXpath(XPath xpath) {
 		this.xpath = xpath;
 	}
 }