/**
    *    Copyright 2009-2015 the original author or authors.
    *
    *    Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
    *
   *    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.apache.ibatis.builder.xml;
  
  import org.apache.ibatis.builder.BuilderException;
  import org.apache.ibatis.builder.IncompleteElementException;
  import org.apache.ibatis.builder.MapperBuilderAssistant;
  import org.apache.ibatis.parsing.PropertyParser;
  import org.apache.ibatis.parsing.XNode;
  import org.apache.ibatis.session.Configuration;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  import java.util.Properties;
  
  /**
   * @author Frank D. Martinez [mnesarco]
   */
  public class XMLIncludeTransformer {
  
    private final Configuration configuration;
    private final MapperBuilderAssistant builderAssistant;
  
    public XMLIncludeTransformer(Configuration configuration, MapperBuilderAssistant builderAssistant) {
      this.configuration = configuration;
      this.builderAssistant = builderAssistant;
    }
  
    public void applyIncludes(Node source) {
      Properties variablesContext = new Properties();
      Properties configurationVariables = configuration.getVariables();
      if (configurationVariables != null) {
        variablesContext.putAll(configurationVariables);
      }
      applyIncludes(source, variablesContext);
    }
  
    /**
     * Recursively apply includes through all SQL fragments.
     * @param source Include node in DOM tree
     * @param variablesContext Current context for static variables with values
     */
    private void applyIncludes(Node source, final Properties variablesContext) {
      if (source.getNodeName().equals("include")) {
        // new full context for included SQL - contains inherited context and new variables from current include node
        Properties fullContext;
  
        String refid = getStringAttribute(source, "refid");
        // replace variables in include refid value
        refid = PropertyParser.parse(refid, variablesContext);
        Node toInclude = findSqlFragment(refid);
        Properties newVariablesContext = getVariablesContext(source, variablesContext);
        if (!newVariablesContext.isEmpty()) {
          // merge contexts
          fullContext = new Properties();
          fullContext.putAll(variablesContext);
          fullContext.putAll(newVariablesContext);
        } else {
          // no new context - use inherited fully
          fullContext = variablesContext;
        }
        applyIncludes(toInclude, fullContext);
        if (toInclude.getOwnerDocument() != source.getOwnerDocument()) {
          toInclude = source.getOwnerDocument().importNode(toInclude, true);
        }
        source.getParentNode().replaceChild(toInclude, source);
        while (toInclude.hasChildNodes()) {
          toInclude.getParentNode().insertBefore(toInclude.getFirstChild(), toInclude);
        }
        toInclude.getParentNode().removeChild(toInclude);
      } else if (source.getNodeType() == Node.ELEMENT_NODE) {
        NodeList children = source.getChildNodes();
        for (int i=0; i<children.getLength(); i++) {
          applyIncludes(children.item(i), variablesContext);
        }
      } else if (source.getNodeType() == Node.ATTRIBUTE_NODE && !variablesContext.isEmpty()) {
        // replace variables in all attribute values
        source.setNodeValue(PropertyParser.parse(source.getNodeValue(), variablesContext));
      } else if (source.getNodeType() == Node.TEXT_NODE && !variablesContext.isEmpty()) {
        // replace variables ins all text nodes
        source.setNodeValue(PropertyParser.parse(source.getNodeValue(), variablesContext));
      }
    }
  
    private Node findSqlFragment(String refid) {
      refid = builderAssistant.applyCurrentNamespace(refid, true);
     try {
       XNode nodeToInclude = configuration.getSqlFragments().get(refid);
       return nodeToInclude.getNode().cloneNode(true);
     } catch (IllegalArgumentException e) {
       throw new IncompleteElementException("Could not find SQL statement to include with refid '" + refid + "'", e);
     }
   }
 
   private String getStringAttribute(Node node, String name) {
     return node.getAttributes().getNamedItem(name).getNodeValue();
   }
 
   /**
    * Read placholders and their values from include node definition. 
    * @param node Include node instance
    * @param inheritedVariablesContext Current context used for replace variables in new variables values
    * @return variables context from include instance (no inherited values)
    */
   private Properties getVariablesContext(Node node, Properties inheritedVariablesContext) {
     Properties variablesContext = new Properties();
     NodeList children = node.getChildNodes();
     for (int i = 0; i < children.getLength(); i++) {
       Node n = children.item(i);
       if (n.getNodeType() == Node.ELEMENT_NODE) {
         String name = getStringAttribute(n, "name");
         String value = getStringAttribute(n, "value");
         // Replace variables inside
         value = PropertyParser.parse(value, inheritedVariablesContext);
         // Push new value
         Object originalValue = variablesContext.put(name, value);
         if (originalValue != null) {
           throw new BuilderException("Variable " + name + " defined twice in the same include definition");
         }
       }
     }
     return variablesContext;
   }
   
 }