/*
 * Copyright (C) 2014 Red Hat, Inc. and/or its affiliates.
 *
 * 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.jboss.errai.forge.facet.module;

import org.jboss.errai.forge.config.ProjectConfig;
import org.jboss.errai.forge.config.ProjectProperty;
import org.jboss.errai.forge.constant.ModuleVault.Module;
import org.jboss.errai.forge.facet.resource.AbstractXmlResourceFacet;
import org.jboss.errai.forge.xml.ElementFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import java.io.File;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

/**
 * A base facet for facets which must add GWT module dependencies via the
 * "inherit" tag. Concrete subclasses must assign a {@link Collection} of
 * {@link Module Modules} they wish to inherit to
 * {@link AbstractModuleFacet#modules}.
 * 
 * @author Max Barkley <mbarkley@redhat.com>
 */
public abstract class AbstractModuleFacet extends AbstractXmlResourceFacet {

  /**
   * A collection of GWT modules to inherit in this project.
   */
  protected Collection<Module> modules;

  protected final String xPathRootExpression = "/module";

  /**
   * Generate xml {@link Element Elements} for inheriting the given
   * {@link Module Modules}.
   * 
   * @param modules
   *          The modules to generate {@link Element Elements} for.
   * @param doc
   *          Used to generate the {@link Element Elements}.
   */
  protected Collection<Node> generateInsertElements(final Collection<Module> modules, final Document doc)
          throws ParserConfigurationException {
    final Collection<Node> retVal = new ArrayList<Node>(modules.size());
    for (final Module mod : modules) {
      final Element elem = doc.createElement("inherits");
      elem.setAttribute("name", mod.getLogicalName());
      retVal.add(elem);
    }

    return retVal;
  }

  @Override
  protected Map<XPathExpression, Node> getRemovalMap(final XPath xPath, final ElementFactory elemFactory) {
    return new HashMap<XPathExpression, Node>(0);
  }

  @Override
  protected Map<XPathExpression, Collection<Node>> getElementsToInsert(final XPath xPath, final ElementFactory elemFactory)
          throws ParserConfigurationException, XPathExpressionException {
    final XPathExpression parentExpression = xPath.compile(xPathRootExpression);
    final Collection<Node> nodes = new ArrayList<Node>(modules.size());
    for (final Module module : modules) {
      final Element inherits = elemFactory.createElement("inherits");
      inherits.setAttribute("name", module.getLogicalName());
      nodes.add(inherits);
    }

    final Map<XPathExpression, Collection<Node>> retVal = new HashMap<XPathExpression, Collection<Node>>(1);
    retVal.put(parentExpression, nodes);

    return retVal;
  }

  @Override
  protected Map<XPathExpression, Node> getReplacements(final XPath xPath, final ElementFactory elemFactory)
          throws ParserConfigurationException {
    return new HashMap<XPathExpression, Node>(0);
  }

  /**
   * @return The absolute path of the GWT module used in this project.
   */
  public File getModuleFile() {
    return getProject().getFacet(ProjectConfig.class).getProjectProperty(ProjectProperty.MODULE_FILE, File.class);
  }

  @Override
  protected String getRelPath() {
    final File module = getProject().getFacet(ProjectConfig.class).getProjectProperty(ProjectProperty.MODULE_FILE,
            File.class);
    if (module != null)
      return module.getPath();
    else
      return null;
  }

}