/*
    * 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
    *
   *   https://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.commons.exec;
  
  import java.io.Closeable;
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  import java.util.Map;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ThreadFactory;
  import java.util.function.Supplier;
  
  import org.apache.commons.exec.launcher.CommandLauncher;
  import org.apache.commons.exec.launcher.CommandLauncherFactory;
  
  /**
   * The default class to start a subprocess. The implementation allows to
   * <ul>
   * <li>set a current working directory for the subprocess</li>
   * <li>provide a set of environment variables passed to the subprocess</li>
   * <li>capture the subprocess output of stdout and stderr using an ExecuteStreamHandler</li>
   * <li>kill long-running processes using an ExecuteWatchdog</li>
   * <li>define a set of expected exit values</li>
   * <li>terminate any started processes when the main process is terminating using a ProcessDestroyer</li>
   * </ul>
   *
   * The following example shows the basic usage:
   *
   * <pre>
   * Executor exec = DefaultExecutor.builder().get();
   * CommandLine cl = new CommandLine("ls -l");
   * int exitValue = exec.execute(cl);
   * </pre>
   */
  public class DefaultExecutor implements Executor {
  
      /**
       * Constructs a new {@link DefaultExecutor}.
       *
       * @param <T> The builder type.
       * @since 1.4.0
       */
      public static class Builder<T extends Builder<T>> implements Supplier<DefaultExecutor> {
  
          /**
           * Error stream handler.
           */
          private ExecuteStreamHandler executeStreamHandler;
  
          /**
           * Thread factory.
           */
          private ThreadFactory threadFactory;
  
          /**
           * Working directory path.
           */
          private Path workingDirectory;
  
          /**
           * Constructs a new instance.
           */
          public Builder() {
              // empty
          }
  
          /**
           * Returns this instance typed as the subclass type {@code T}.
           * <p>
           * This is the same as the expression:
           * </p>
           * <pre>
           * (B) this
           * </pre>
           *
           * @return {@code this} instance typed as the subclass type {@code T}.
           */
          @SuppressWarnings("unchecked")
          T asThis() {
             return (T) this;
         }
 
         /**
          * Creates a new configured DefaultExecutor.
          *
          * @return a new configured DefaultExecutor.
          */
         @Override
         public DefaultExecutor get() {
             return new DefaultExecutor(this);
         }
 
         ExecuteStreamHandler getExecuteStreamHandler() {
             return executeStreamHandler;
         }
 
         ThreadFactory getThreadFactory() {
             return threadFactory;
         }
 
         Path getWorkingDirectoryPath() {
             return workingDirectory;
         }
 
         /**
          * Sets the PumpStreamHandler.
          *
          * @param executeStreamHandler the ExecuteStreamHandler, null resets to the default.
          * @return {@code this} instance.
          */
         public T setExecuteStreamHandler(final ExecuteStreamHandler executeStreamHandler) {
             this.executeStreamHandler = executeStreamHandler;
             return asThis();
         }
 
         /**
          * Sets the ThreadFactory.
          *
          * @param threadFactory the ThreadFactory, null resets to the default.
          * @return {@code this} instance.
          */
         public T setThreadFactory(final ThreadFactory threadFactory) {
             this.threadFactory = threadFactory;
             return asThis();
         }
 
         /**
          * Sets the working directory.
          *
          * @param workingDirectory the working directory., null resets to the default.
          * @return {@code this} instance.
          */
         public T setWorkingDirectory(final File workingDirectory) {
             this.workingDirectory = workingDirectory != null ? workingDirectory.toPath() : null;
             return asThis();
         }
 
         /**
          * Sets the working directory.
          *
          * @param workingDirectory the working directory., null resets to the default.
          * @return {@code this} instance.
          * @since 1.5.0
          */
         public T setWorkingDirectory(final Path workingDirectory) {
             this.workingDirectory = workingDirectory;
             return asThis();
         }
 
     }
 
     /**
      * Creates a new builder.
      *
      * @return a new builder.
      * @since 1.4.0
      */
     public static Builder<?> builder() {
         return new Builder<>();
     }
 
     /** The first exception being caught to be thrown to the caller. */
     private IOException exceptionCaught;
 
     /** Taking care of output and error stream. */
     private ExecuteStreamHandler executeStreamHandler;
 
     /** Worker thread for asynchronous execution. */
     private Thread executorThread;
 
     /** The exit values considered to be successful. */
     private int[] exitValues;
 
     /** Launches the command in a new process. */
     private final CommandLauncher launcher;
 
     /** Optional cleanup of started processes. */
     private ProcessDestroyer processDestroyer;
 
     /**
      * The thread factory.
      */
     private final ThreadFactory threadFactory;
 
     /** Monitoring of long-running processes. */
     private ExecuteWatchdog watchdog;
 
     /** The working directory of the process. */
     private Path workingDirectory;
 
     /**
      * Constructs a default {@code PumpStreamHandler} and sets the working directory of the subprocess to the current working directory.
      *
      * The {@code PumpStreamHandler} pumps the output of the subprocess into our {@code System.out} and {@code System.err} to avoid into our {@code System.out}
      * and {@code System.err} to avoid a blocked or deadlocked subprocess (see {@link Process Process}).
      *
      * @deprecated Use {@link Builder#get()}.
      */
     @Deprecated
     public DefaultExecutor() {
         this(builder().setExecuteStreamHandler(new PumpStreamHandler()).setWorkingDirectory(Paths.get(".")));
     }
 
     DefaultExecutor(final Builder<?> builder) {
         this.threadFactory = builder.threadFactory != null ? builder.threadFactory : Executors.defaultThreadFactory();
         this.executeStreamHandler = builder.executeStreamHandler != null ? builder.executeStreamHandler : new PumpStreamHandler();
         this.workingDirectory = builder.workingDirectory != null ? builder.workingDirectory : Paths.get(".");
         this.launcher = CommandLauncherFactory.createVMLauncher();
         this.exitValues = new int[0];
     }
 
     private void checkWorkingDirectory() throws IOException {
         checkWorkingDirectory(workingDirectory);
     }
 
     private void checkWorkingDirectory(final File directory) throws IOException {
         if (directory != null && !directory.exists()) {
             throw new IOException(directory + " doesn't exist.");
         }
     }
 
     private void checkWorkingDirectory(final Path directory) throws IOException {
         if (directory != null && !Files.exists(directory)) {
             throw new IOException(directory + " doesn't exist.");
         }
     }
 
     /**
      * Closes the Closeable, remembering any exception.
      *
      * @param closeable the {@link Closeable} to close.
      */
     private void closeCatch(final Closeable closeable) {
         try {
             closeable.close();
         } catch (final IOException e) {
             setExceptionCaught(e);
         }
     }
 
     /**
      * Closes the streams belonging to the given Process.
      *
      * @param process the {@link Process}.
      */
     @SuppressWarnings("resource")
     private void closeProcessStreams(final Process process) {
         closeCatch(process.getInputStream());
         closeCatch(process.getOutputStream());
         closeCatch(process.getErrorStream());
     }
 
     /**
      * Creates a thread waiting for the result of an asynchronous execution.
      *
      * @param runnable the runnable passed to the thread.
      * @param name     the name of the thread.
      * @return the thread
      */
     protected Thread createThread(final Runnable runnable, final String name) {
         return ThreadUtil.newThread(threadFactory, runnable, name, false);
     }
 
     /**
      * @see org.apache.commons.exec.Executor#execute(CommandLine)
      */
     @Override
     public int execute(final CommandLine command) throws ExecuteException, IOException {
         return execute(command, (Map<String, String>) null);
     }
 
     /**
      * @see org.apache.commons.exec.Executor#execute(CommandLine, org.apache.commons.exec.ExecuteResultHandler)
      */
     @Override
     public void execute(final CommandLine command, final ExecuteResultHandler handler) throws ExecuteException, IOException {
         execute(command, null, handler);
     }
 
     /**
      * @see org.apache.commons.exec.Executor#execute(CommandLine, java.util.Map)
      */
     @Override
     public int execute(final CommandLine command, final Map<String, String> environment) throws ExecuteException, IOException {
         checkWorkingDirectory();
         return executeInternal(command, environment, workingDirectory, executeStreamHandler);
     }
 
     /**
      * @see org.apache.commons.exec.Executor#execute(CommandLine, java.util.Map, org.apache.commons.exec.ExecuteResultHandler)
      */
     @Override
     public void execute(final CommandLine command, final Map<String, String> environment, final ExecuteResultHandler handler)
             throws ExecuteException, IOException {
         checkWorkingDirectory();
         if (watchdog != null) {
             watchdog.setProcessNotStarted();
         }
         executorThread = createThread(() -> {
             int exitValue = INVALID_EXITVALUE;
             try {
                 exitValue = executeInternal(command, environment, workingDirectory, executeStreamHandler);
                 handler.onProcessComplete(exitValue);
             } catch (final ExecuteException e) {
                 handler.onProcessFailed(e);
             } catch (final Exception e) {
                 handler.onProcessFailed(new ExecuteException("Execution failed", exitValue, e));
             }
         }, "CommonsExecDefaultExecutor");
         getExecutorThread().start();
     }
 
     /**
      * Execute an internal process. If the executing thread is interrupted while waiting for the child process to return the child process will be killed.
      *
      * @param command          the command to execute.
      * @param environment      the execution environment.
      * @param workingDirectory the working directory.
      * @param streams          process the streams (in, out, err) of the process.
      * @return the exit code of the process.
      * @throws IOException executing the process failed.
      */
     private int executeInternal(final CommandLine command, final Map<String, String> environment, final Path workingDirectory,
             final ExecuteStreamHandler streams) throws IOException {
         final Process process;
         exceptionCaught = null;
         try {
             process = launch(command, environment, workingDirectory);
         } catch (final IOException e) {
             if (watchdog != null) {
                 watchdog.failedToStart(e);
             }
             throw e;
         }
         try {
             setStreams(streams, process);
         } catch (final IOException e) {
             process.destroy();
             if (watchdog != null) {
                 watchdog.failedToStart(e);
             }
             throw e;
         }
         streams.start();
         try {
             // add the process to the list of those to destroy if the VM exits
             if (getProcessDestroyer() != null) {
                 getProcessDestroyer().add(process);
             }
             // associate the watchdog with the newly created process
             if (watchdog != null) {
                 watchdog.start(process);
             }
             int exitValue = INVALID_EXITVALUE;
             try {
                 exitValue = process.waitFor();
             } catch (final InterruptedException e) {
                 process.destroy();
             } finally {
                 // see https://bugs.sun.com/view_bug.do?bug_id=6420270
                 // see https://issues.apache.org/jira/browse/EXEC-46
                 // Process.waitFor should clear interrupt status when throwing InterruptedException
                 // but we have to do that manually
                 Thread.interrupted();
             }
             if (watchdog != null) {
                 watchdog.stop();
             }
             try {
                 streams.stop();
             } catch (final IOException e) {
                 setExceptionCaught(e);
             }
             closeProcessStreams(process);
             if (getExceptionCaught() != null) {
                 throw getExceptionCaught();
             }
             if (watchdog != null) {
                 try {
                     watchdog.checkException();
                 } catch (final IOException e) {
                     throw e;
                 } catch (final Exception e) {
                     throw new IOException(e);
                 }
             }
             if (isFailure(exitValue)) {
                 throw new ExecuteException("Process exited with an error: " + exitValue, exitValue);
             }
             return exitValue;
         } finally {
             // remove the process to the list of those to destroy if the VM exits
             if (getProcessDestroyer() != null) {
                 getProcessDestroyer().remove(process);
             }
         }
     }
 
     /**
      * Gets the first IOException being thrown.
      *
      * @return the first IOException being caught.
      */
     private IOException getExceptionCaught() {
         return exceptionCaught;
     }
 
     /**
      * Gets the worker thread being used for asynchronous execution.
      *
      * @return the worker thread.
      */
     protected Thread getExecutorThread() {
         return executorThread;
     }
 
     /**
      * @see org.apache.commons.exec.Executor#getProcessDestroyer()
      */
     @Override
     public ProcessDestroyer getProcessDestroyer() {
         return processDestroyer;
     }
 
     /**
      * @see org.apache.commons.exec.Executor#getStreamHandler()
      */
     @Override
     public ExecuteStreamHandler getStreamHandler() {
         return executeStreamHandler;
     }
 
     /**
      * Gets the thread factory. Z
      *
      * @return the thread factory.
      */
     ThreadFactory getThreadFactory() {
         return threadFactory;
     }
 
     /**
      * @see org.apache.commons.exec.Executor#getWatchdog()
      */
     @Override
     public ExecuteWatchdog getWatchdog() {
         return watchdog;
     }
 
     /**
      * @see org.apache.commons.exec.Executor#getWorkingDirectory()
      */
     @Override
     public File getWorkingDirectory() {
         return workingDirectory.toFile();
     }
 
     /** @see org.apache.commons.exec.Executor#isFailure(int) */
     @Override
     public boolean isFailure(final int exitValue) {
         if (exitValues == null) {
             return false;
         }
         if (exitValues.length == 0) {
             return launcher.isFailure(exitValue);
         }
         for (final int exitValue2 : exitValues) {
             if (exitValue2 == exitValue) {
                 return false;
             }
         }
         return true;
     }
 
     /**
      * Creates a process that runs a command.
      *
      * @param command          the command to run.
      * @param env              the environment for the command.
      * @param workingDirectory the working directory for the command.
      * @return the process started.
      * @throws IOException forwarded from the particular launcher used.
      */
     protected Process launch(final CommandLine command, final Map<String, String> env, final File workingDirectory) throws IOException {
         if (launcher == null) {
             throw new IllegalStateException("CommandLauncher cannot be null");
         }
         checkWorkingDirectory(workingDirectory);
         return launcher.exec(command, env, workingDirectory);
     }
 
     /**
      * Creates a process that runs a command.
      *
      * @param command          the command to run.
      * @param env              the environment for the command.
      * @param workingDirectory the working directory for the command.
      * @return the process started.
      * @throws IOException forwarded from the particular launcher used.
      * @since 1.5.0
      */
     protected Process launch(final CommandLine command, final Map<String, String> env, final Path workingDirectory) throws IOException {
         if (launcher == null) {
             throw new IllegalStateException("CommandLauncher cannot be null");
         }
         checkWorkingDirectory(workingDirectory);
         return launcher.exec(command, env, workingDirectory);
     }
 
     /**
      * Sets the first IOException thrown.
      *
      * @param e the IOException.
      */
     private void setExceptionCaught(final IOException e) {
         if (exceptionCaught == null) {
             exceptionCaught = e;
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @see org.apache.commons.exec.Executor#setExitValue(int)
      */
     @Override
     public void setExitValue(final int value) {
         setExitValues(new int[] {value});
     }
 
     /** @see org.apache.commons.exec.Executor#setExitValues(int[]) */
     @Override
     public void setExitValues(final int[] values) {
         exitValues = values == null ? null : (int[]) values.clone();
     }
 
     /**
      * @see org.apache.commons.exec.Executor#setProcessDestroyer(ProcessDestroyer)
      */
     @Override
     public void setProcessDestroyer(final ProcessDestroyer processDestroyer) {
         this.processDestroyer = processDestroyer;
     }
 
     /**
      * @see org.apache.commons.exec.Executor#setStreamHandler(org.apache.commons.exec.ExecuteStreamHandler)
      */
     @Override
     public void setStreamHandler(final ExecuteStreamHandler streamHandler) {
         this.executeStreamHandler = streamHandler;
     }
 
     @SuppressWarnings("resource")
     private void setStreams(final ExecuteStreamHandler streams, final Process process) throws IOException {
         streams.setProcessInputStream(process.getOutputStream());
         streams.setProcessOutputStream(process.getInputStream());
         streams.setProcessErrorStream(process.getErrorStream());
     }
 
     /**
      * @see org.apache.commons.exec.Executor#setWatchdog(org.apache.commons.exec.ExecuteWatchdog)
      */
     @Override
     public void setWatchdog(final ExecuteWatchdog watchdog) {
         this.watchdog = watchdog;
     }
 
     /**
      * Sets the working directory.
      *
      * @see org.apache.commons.exec.Executor#setWorkingDirectory(java.io.File)
      * @deprecated Use {@link Builder#setWorkingDirectory(File)}.
      */
     @Deprecated
     @Override
     public void setWorkingDirectory(final File workingDirectory) {
         this.workingDirectory = workingDirectory != null ? workingDirectory.toPath() : null;
     }
 
 }