/*
    * This file is part of dependency-check-core.
    *
    * 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.
   *
   * Copyright (c) 2018 Paul Irwin. All Rights Reserved.
   */
  package org.owasp.dependencycheck.data.nuget;
  
  import org.owasp.dependencycheck.utils.XmlUtils;
  import org.w3c.dom.Document;
  import org.w3c.dom.NamedNodeMap;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  import org.xml.sax.SAXException;
  
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.ParserConfigurationException;
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathExpressionException;
  import javax.xml.xpath.XPathFactory;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  import org.owasp.dependencycheck.utils.InterpolationUtil;
  import org.owasp.dependencycheck.utils.InterpolationUtil.SyntaxStyle;
  
  /**
   * Parses a MSBuild project file for NuGet references using XPath.
   *
   * @author paulirwin
   */
  public class XPathMSBuildProjectParser {
  
      /**
       * Parses the given stream for MSBuild PackageReference elements.
       *
       * @param stream the input stream to parse
       * @param props the Directory.Build.props properties
       * @param centrallyManaged a map of centrally managed package references
       * @return a collection of discovered NuGet package references
       * @throws MSBuildProjectParseException if an exception occurs
       */
      public List<NugetPackageReference> parse(InputStream stream, Properties props,
              Map<String, String> centrallyManaged) throws MSBuildProjectParseException {
          try {
              final DocumentBuilder db = XmlUtils.buildSecureDocumentBuilder();
              final Document d = db.parse(stream);
  
              final XPath xpath = XPathFactory.newInstance().newXPath();
              final List<NugetPackageReference> packages = new ArrayList<>();
  
              final NodeList nodeList = (NodeList) xpath.evaluate("//PackageReference", d, XPathConstants.NODESET);
  
              if (nodeList == null) {
                  throw new MSBuildProjectParseException("Unable to parse MSBuild project file");
              }
  
              for (int i = 0; i < nodeList.getLength(); i++) {
                  final Node node = nodeList.item(i);
                  final NamedNodeMap attrs = node.getAttributes();
  
                  final Node includeAttr = attrs.getNamedItem("Include");
                  if (includeAttr == null) {
                      // Issue 5144 work-around for NPE on packageReferences other than includes
                      continue;
                  }
                  final String include = includeAttr.getNodeValue();
                  String version = null;
  
                  if (centrallyManaged.containsKey(include)) {
                      if (attrs.getNamedItem("VersionOverride") != null) {
                          version = attrs.getNamedItem("VersionOverride").getNodeValue();
                      } else {
                          version = centrallyManaged.get(include);
                      }
                  } else if (attrs.getNamedItem("Version") != null) {
                      version = attrs.getNamedItem("Version").getNodeValue();
                  } else if (xpath.evaluate("Version", node, XPathConstants.NODE) instanceof Node) {
                      version = ((Node) xpath.evaluate("Version", node, XPathConstants.NODE)).getTextContent();
                  }
  
                  if (include != null && version != null) {
  
                      final NugetPackageReference npr = new NugetPackageReference();
 
                     npr.setId(include);
                     npr.setVersion(InterpolationUtil.interpolate(version, props, SyntaxStyle.MSBUILD));
 
                     packages.add(npr);
                 }
             }
 
             return packages;
         } catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException | MSBuildProjectParseException e) {
             throw new MSBuildProjectParseException("Unable to parse MSBuild project file", e);
         }
     }
 
 }