groovy/modules/process/src/main/com/baulsupp/process/JavaProcess.java

package com.baulsupp.process;

import java.io.IOException;
import java.io.OutputStream;

public class JavaProcess implements AppProcess {      
  private String[] command;
  private Process process;
  
  private boolean errHandled = false;
  private boolean outHandled = false;
  private boolean inHandled = false;

  private JavaProcess(String[] command) throws IOException {
    this.command = command;
    process = Runtime.getRuntime().exec(command);
  }

  public static JavaProcess createProcess(String command, String[] args) throws IOException { 
    String[] commandArgs = concat(command, args);
       
    return new JavaProcess(commandArgs);
  }

  private static String[] concat(String command, String[] args) {
    String[] commandArgs = new String[args.length + 1];
    commandArgs[0] = command;
    System.arraycopy(args, 0, commandArgs, 1, args.length);
    return commandArgs;
  }

  public void start() throws IOException {    
    if (!inHandled) {
      process.getOutputStream().close();
    }

    // Should we throw away, it would make it explicit to direct the output somewhere.
    if (!outHandled)
      IOUtil.pumpAsync(process.getInputStream(), StandardStreams.stderr().getStream());
      
    if (!errHandled)
      IOUtil.pumpAsync(process.getErrorStream(), StandardStreams.stderr().getStream());
  }

  public Sink getInput() {
    return new InSink();
  }

  public Source getOutput() {
    return new OutSource();
  }

  public Source getError() {
    return new ErrSource();
  }

  public int result() {
    try {
      return process.waitFor();
    } catch (InterruptedException e) {
      throw new RuntimeException(e);
    }
  }

  public boolean hadError() {
    return result() != 0;
  }
  
  public class InSink extends Sink {
    public OutputStream getStream() {
      inHandled = true;
      return process.getOutputStream();
    }

    public boolean providesStream() {
      return true;
    }
  }
  
  public class OutSource extends Source {
    public void connect(Sink sink) {
      if (sink.providesStream()) {
        outHandled = true;
        // TODO handle result
        IOUtil.pumpAsync(process.getInputStream(), sink.getStream());
      } else if (sink.receivesStream()) {
        outHandled = true;
        sink.setStream(process.getInputStream());  
      } else {
        throw new UnsupportedOperationException("sink type unknown");  
      }
    }
  }
  
  public class ErrSource extends Source {
    public void connect(Sink sink) {
      if (sink.providesStream()) {
        errHandled = true;
        // TODO handle result
        IOUtil.pumpAsync(process.getInputStream(), sink.getStream());
      } else if (sink.receivesStream()) {
        errHandled = true;
        sink.setStream(process.getInputStream());  
      } else {
        throw new UnsupportedOperationException("sink type unknown");  
      }
    }
  }
}