/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  /**
   * 
   */
  package org.mycore.restapi.v1.utils;
  
  import static org.mycore.datamodel.niofs.MCRAbstractFileSystem.SEPARATOR;
  import static org.mycore.datamodel.niofs.MCRAbstractFileSystem.SEPARATOR_STRING;
  
  import java.io.IOException;
  import java.nio.file.FileVisitResult;
  import java.nio.file.Path;
  import java.nio.file.SimpleFileVisitor;
  import java.nio.file.attribute.BasicFileAttributes;
  
  import org.mycore.datamodel.metadata.MCRObjectID;
  import org.mycore.datamodel.niofs.MCRContentTypes;
  import org.mycore.datamodel.niofs.MCRFileAttributes;
  import org.mycore.datamodel.niofs.MCRPath;
  import org.mycore.frontend.filter.MCRSecureTokenV2FilterConfig;
  import org.mycore.frontend.jersey.MCRJerseyUtil;
  
  import com.google.gson.stream.JsonWriter;
  
  import jakarta.ws.rs.core.Application;
  import jakarta.ws.rs.core.UriInfo;
  
  /**
   * @author Thomas Scheffler (yagee)
   *
   */
  public class MCRJSONFileVisitor extends SimpleFileVisitor<Path> {
  
      private JsonWriter jw;
  
      private String baseURL;
  
      private String objId;
  
      private String derId;
  
      public MCRJSONFileVisitor(JsonWriter jw, MCRObjectID objId, MCRObjectID derId, UriInfo info, Application app) {
          super();
          this.jw = jw;
          this.baseURL = MCRJerseyUtil.getBaseURL(info, app);
          this.objId = objId.toString();
          this.derId = derId.toString();
      }
  
      @Override
      public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
          jw.beginObject();
          writePathInfo(dir, attrs);
          jw.name("children").beginArray();
          return super.preVisitDirectory(dir, attrs);
      }
  
      private void writePathInfo(Path path, BasicFileAttributes attrs) throws IOException {
          MCRPath mcrPath = MCRPath.toMCRPath(path);
          MCRPath relativePath = mcrPath.getRoot().relativize(mcrPath);
          boolean isRoot = mcrPath.getNameCount() == 0;
          jw.name("type").value(attrs.isDirectory() ? "directory" : "file");
          if (isRoot) {
              jw.name("mycoreobject").value(objId);
              jw.name("mycorederivate").value(mcrPath.getOwner());
          }
          jw.name("name").value(isRoot ? "" : mcrPath.getFileName().toString());
          jw.name("path")
              .value(attrs.isDirectory() ? toStringValue(relativePath) : SEPARATOR_STRING + relativePath);
          if (!isRoot) {
              jw.name("parentPath").value(toStringValue(relativePath.getParent()));
          }
          addBasicAttributes(path, attrs);
      }
  
      private void addBasicAttributes(Path path, BasicFileAttributes attrs) throws IOException {
          jw.name("size").value(attrs.size());
          jw.name("time").beginObject();
          jw.name("created").value(attrs.creationTime().toString());
          jw.name("modified").value(attrs.lastModifiedTime().toString());
          jw.name("accessed").value(attrs.lastAccessTime().toString());
          jw.endObject();
         if (attrs.isRegularFile()) {
             jw.name("contentType").value(MCRContentTypes.probeContentType(path));
             if (attrs instanceof MCRFileAttributes) {
                 jw.name("md5").value(((MCRFileAttributes<?>) attrs).md5sum());
             }
         }
     }
 
     @Override
     public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
         MCRPath mcrPath = MCRPath.toMCRPath(file);
         MCRPath relativePath = mcrPath.getRoot().relativize(mcrPath);
         jw.beginObject();
         writePathInfo(file, attrs);
         jw.name("extension").value(getFileExtension(file.getFileName().toString()));
         jw.name("href").value(MCRSecureTokenV2FilterConfig.getFileNodeServletSecured(MCRObjectID.getInstance(derId),
             relativePath.toString(), this.baseURL));
         jw.endObject();
         return super.visitFile(file, attrs);
     }
 
     private static String getFileExtension(String fileName) {
         if (fileName.endsWith(".")) {
             return "";
         }
         int pos = fileName.lastIndexOf(".");
         return pos == -1 ? "" : fileName.substring(pos + 1);
     }
 
     @Override
     public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
         jw.endArray();
         jw.endObject();
         return super.postVisitDirectory(dir, exc);
     }
 
     private static String toStringValue(MCRPath relativePath) {
         if (relativePath == null) {
             return SEPARATOR_STRING;
         }
         String pathString = relativePath.toString();
         if (pathString.isEmpty()) {
             return SEPARATOR_STRING;
         }
         if (pathString.equals(SEPARATOR_STRING)) {
             return pathString;
         }
         return SEPARATOR + pathString + SEPARATOR;
     }
 
 }