/*
    * Themis: Java Project Framework
    * Copyright 2012-2026. Tony Washer
    *
    * 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 io.github.tonywasher.joceanus.themis.lethe.analysis;
  
  import io.github.tonywasher.joceanus.oceanus.base.OceanusException;
  import io.github.tonywasher.joceanus.themis.exc.ThemisDataException;
  import io.github.tonywasher.joceanus.themis.exc.ThemisIOException;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.xml.sax.SAXException;
  
  import javax.xml.XMLConstants;
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.parsers.ParserConfigurationException;
  import java.io.BufferedInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * Maven pom.xml parser.
   */
  public class ThemisAnalysisMaven {
      /**
       * Project filename.
       */
      public static final String POM = "pom.xml";
  
      /**
       * Document name.
       */
      private static final String DOC_NAME = "project";
  
      /**
       * Parent element.
       */
      private static final String EL_PARENT = "parent";
  
      /**
       * Modules element.
       */
      private static final String EL_MODULES = "modules";
  
      /**
       * Module element.
       */
      private static final String EL_MODULE = "module";
  
      /**
       * Dependencies element.
       */
      private static final String EL_DEPENDENCIES = "dependencies";
  
      /**
       * Dependency element.
       */
      private static final String EL_DEPENDENCY = "dependency";
  
      /**
       * The Id.
       */
      private final ThemisAnalysisMavenId theId;
  
      /**
       * The modules.
       */
      private final List<String> theModules;
  
      /**
       * The dependencies.
       */
      private final List<ThemisAnalysisMavenId> theDependencies;
  
      /**
       * Constructor.
       *
       * @param pInputStream the input stream to read
       * @throws OceanusException on error
       */
      public ThemisAnalysisMaven(final InputStream pInputStream) throws OceanusException {
          /* Create the module list */
         theModules = new ArrayList<>();
         theDependencies = new ArrayList<>();
 
         /* Protect against exceptions */
         try (BufferedInputStream myInBuffer = new BufferedInputStream(pInputStream)) {
             final DocumentBuilderFactory myFactory = DocumentBuilderFactory.newInstance();
             myFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
             myFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
             myFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
             final DocumentBuilder myBuilder = myFactory.newDocumentBuilder();
 
             /* Build the document from the input stream */
             final Document myDocument = myBuilder.parse(myInBuffer);
             theId = parseProjectFile(myDocument);
 
             /* Handle exceptions */
         } catch (IOException
                  | ParserConfigurationException
                  | SAXException e) {
             throw new ThemisIOException("Exception accessing Pom file", e);
         }
     }
 
     @Override
     public String toString() {
         return theId.toString();
     }
 
     /**
      * Obtain the list of modules.
      *
      * @return the list
      */
     public ThemisAnalysisMavenId getMavenId() {
         return theId;
     }
 
     /**
      * Obtain the list of modules.
      *
      * @return the list
      */
     public List<String> getModules() {
         return theModules;
     }
 
     /**
      * Parse the project file.
      *
      * @param pDocument the document
      * @return the MavenId
      * @throws OceanusException on error
      */
     public ThemisAnalysisMavenId parseProjectFile(final Document pDocument) throws OceanusException {
         /* Access the document element */
         final Element myDoc = pDocument.getDocumentElement();
 
         /* Check that the document name is correct */
         if (!Objects.equals(myDoc.getNodeName(), DOC_NAME)) {
             throw new ThemisDataException("Invalid document type");
         }
 
         /* Obtain parent definition if any */
         final Element myParentEl = getElement(myDoc, EL_PARENT);
         final ThemisAnalysisMavenId myParent = myParentEl == null
                 ? null
                 : new ThemisAnalysisMavenId(myParentEl);
 
         /* Obtain our mavenId */
         final ThemisAnalysisMavenId myId = new ThemisAnalysisMavenId(myDoc, myParent);
 
         /* Process modules */
         final Element myModules = getElement(myDoc, EL_MODULES);
         processModules(myModules);
 
         /* Process dependencies */
         final Element myDependencies = getElement(myDoc, EL_DEPENDENCIES);
         processDependencies(myDependencies, myId);
 
         /* Return the Id */
         return myId;
     }
 
     /**
      * Obtain element value.
      *
      * @param pElement the element
      * @param pValue   the value name
      * @return the value
      */
     static String getElementValue(final Element pElement,
                                   final String pValue) {
         /* Return null if no element */
         if (pElement == null) {
             return null;
         }
 
         /* Loop through the children */
         for (Node myChild = pElement.getFirstChild();
              myChild != null;
              myChild = myChild.getNextSibling()) {
             /* Return result if we have a match */
             if (myChild instanceof Element
                     && pValue.equals(myChild.getNodeName())) {
                 return myChild.getTextContent();
             }
         }
 
         /* Not found */
         return null;
     }
 
     /**
      * Obtain element value.
      *
      * @param pElement the element
      * @param pValue   the value name
      * @return the value
      */
     static Element getElement(final Element pElement,
                               final String pValue) {
         /* Return null if no element */
         if (pElement == null) {
             return null;
         }
 
         /* Loop through the children */
         for (Node myChild = pElement.getFirstChild();
              myChild != null;
              myChild = myChild.getNextSibling()) {
             /* Return result if we have a match */
             if (myChild instanceof Element myElement
                     && pValue.equals(myChild.getNodeName())) {
                 return myElement;
             }
         }
 
         /* Not found */
         return null;
     }
 
     /**
      * Process modules.
      *
      * @param pModules the modules
      */
     private void processModules(final Element pModules) {
         /* Return if no element */
         if (pModules == null) {
             return;
         }
 
         /* Loop through the children */
         for (Node myChild = pModules.getFirstChild();
              myChild != null;
              myChild = myChild.getNextSibling()) {
             /* Return result if we have a match */
             if (myChild instanceof Element
                     && EL_MODULE.equals(myChild.getNodeName())) {
                 theModules.add(myChild.getTextContent());
             }
         }
     }
 
     /**
      * Process dependencies.
      *
      * @param pDependencies the dependencies
      * @param pParent       the parentId
      */
     private void processDependencies(final Element pDependencies,
                                      final ThemisAnalysisMavenId pParent) {
         /* Return if no element */
         if (pDependencies == null) {
             return;
         }
 
         /* Loop through the children */
         for (Node myChild = pDependencies.getFirstChild();
              myChild != null;
              myChild = myChild.getNextSibling()) {
             /* Return result if we have a match */
             if (myChild instanceof Element myElement
                     && EL_DEPENDENCY.equals(myChild.getNodeName())) {
                 theDependencies.add(new ThemisAnalysisMavenId(myElement, pParent));
             }
         }
     }
 }