/*
    * Copyright 2001-2005 The Apache Software Foundation.
    *
    * 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.logging.log4j.catalog.api.dao;
  
  import java.io.ByteArrayOutputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URL;
  import java.net.URLConnection;
  import java.time.Instant;
  import java.time.LocalDateTime;
  import java.time.ZoneId;
  import java.util.Collection;
  import java.util.Map;
  
  import com.fasterxml.jackson.core.JsonFactory;
  import com.fasterxml.jackson.core.JsonParser;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.catalog.api.CatalogData;
  import org.apache.logging.log4j.util.LoaderUtil;
  
  /**
   * Reads the catalog from the local file system.
   */
  public class ClassPathCatalogReader extends AbstractCatalogReader {
  
      private static final Logger LOGGER = LogManager.getLogger(ClassPathCatalogReader.class);
      private static final String BASEDIR = "baseDir";
  
      private static final String CATALOG_ATTRIBUTE_NAME = "catalogFile";
      private static final String DEFAULT_CATALOG_FILE = "catalog.json";
  
      private final String catalog;
      private final LocalDateTime lastUpdated;
  
      public ClassPathCatalogReader(Map<String, String> attributes) throws IOException {
          String catalogFile = attributes != null ?
              attributes.getOrDefault(CATALOG_ATTRIBUTE_NAME, DEFAULT_CATALOG_FILE) : DEFAULT_CATALOG_FILE;
          Collection<URL> catalogs = LoaderUtil.findResources(catalogFile);
          URL catalogURL;
          if (catalogs.size() == 0) {
              LOGGER.error("No catalog named {} could be found on the class path", catalogFile);
              throw new FileNotFoundException("No catalog named " + catalogFile + " could be found");
          } else if (catalogs.size() > 1) {
              catalogURL = catalogs.stream().findFirst().get();
              LOGGER.warn("Multiple catalogs named {} were found. Using {}", catalogFile, catalogURL.toString());
          } else {
              catalogURL = catalogs.stream().findFirst().get();
          }
  
          catalog = readCatalog(catalogURL);
          LocalDateTime localDateTime = null;
          try {
              URLConnection connection = catalogURL.openConnection();
              localDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(connection.getLastModified()),
                      ZoneId.systemDefault());
          } catch (IOException ioe) {
              LOGGER.warn("Unable to open connection to {}", catalogURL.toString());
          }
          lastUpdated = localDateTime;
          JsonFactory factory = new JsonFactory();
          factory.enable(JsonParser.Feature.ALLOW_COMMENTS);
          ObjectMapper objectMapper = new ObjectMapper(factory);
          catalogData = objectMapper.readValue(catalog, CatalogData.class);
      }
  
      private String readCatalog(URL catalogUrl) throws IOException {
          try (InputStream is = catalogUrl.openStream()) {
              ByteArrayOutputStream baos = new ByteArrayOutputStream();
              byte[] buffer = new byte[1024];
              int length;
              while ((length = is.read(buffer)) != -1) {
                  baos.write(buffer, 0, length);
              }
              return baos.toString("UTF-8");
          }
      }
  
      public ClassPathCatalogReader() throws IOException {
          this(null);
      }
  
      @Override
     public String readCatalog() {
         return catalog;
     }
 
     @Override
     public LocalDateTime getLastUpdated() {
         return lastUpdated;
     }
 }