/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.maven.plugins.jar;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Optional;
  
  import org.apache.maven.toolchain.Toolchain;
  import org.codehaus.plexus.util.cli.CommandLineException;
  import org.codehaus.plexus.util.cli.CommandLineUtils;
  import org.codehaus.plexus.util.cli.Commandline;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Component provided JDK specification based on toolchains.
   */
  @Named
  @Singleton
  class ToolchainsJdkSpecification {
  
      private final Logger logger = LoggerFactory.getLogger(ToolchainsJdkSpecification.class);
  
      private final Map<Path, String> cache = new HashMap<>();
  
      public synchronized Optional<String> getJDKSpecification(Toolchain toolchain) {
          Optional<Path> javacPath = getJavacPath(toolchain);
          return javacPath.map(path -> cache.computeIfAbsent(path, this::getSpecForPath));
      }
  
      private Optional<Path> getJavacPath(Toolchain toolchain) {
          return Optional.ofNullable(toolchain.findTool("javac")).map(Paths::get).map(this::getCanonicalPath);
      }
  
      private Path getCanonicalPath(Path path) {
          try {
              return path.toRealPath();
          } catch (IOException e) {
              if (path.getParent() != null) {
                  return getCanonicalPath(path.getParent()).resolve(path.getFileName());
              } else {
                  throw new UncheckedIOException(e);
              }
          }
      }
  
      private String getSpecForPath(Path path) {
          try {
              Commandline cl = new Commandline(path.toString());
              cl.createArg().setValue("-version");
              CommandLineUtils.StringStreamConsumer out = new CommandLineUtils.StringStreamConsumer();
              CommandLineUtils.StringStreamConsumer err = new CommandLineUtils.StringStreamConsumer();
              CommandLineUtils.executeCommandLine(cl, out, err);
              String version = out.getOutput().trim();
              if (version.isEmpty()) {
                  version = err.getOutput().trim();
              }
              if (version.startsWith("javac ")) {
                  version = version.substring(6);
                  if (version.startsWith("1.")) {
                      version = version.substring(0, 3);
                  } else {
                      version = version.substring(0, 2);
                  }
                  return version;
              } else {
                  logger.warn("Unrecognized output form " + path + " -version - " + version);
                  return null;
              }
          } catch (CommandLineException | IndexOutOfBoundsException e) {
              logger.warn("Failed to execute: " + path + " - " + e.getMessage());
              return null;
          }
      }
  }