/*
 * Copyright  2000-2004 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.tools.ant.taskdefs;

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

/**
 * Copies standard output and error of subprocesses to standard output and
 * error of the parent process.
 *
 * @since Ant 1.2
 */
public class PumpStreamHandler implements ExecuteStreamHandler {

    private Thread outputThread;
    private Thread errorThread;
    private Thread inputThread;

    private OutputStream out;
    private OutputStream err;
    private InputStream input;

    /**
     * Construct a new <CODE>PumpStreamHandler</CODE>.
     * @param out the output <CODE>OutputStream</CODE>.
     * @param err the error <CODE>OutputStream</CODE>.
     * @param input the input <CODE>InputStream</CODE>.
     */
    public PumpStreamHandler(OutputStream out, OutputStream err,
                             InputStream input) {
        this.out = out;
        this.err = err;
        this.input = input;
    }

    /**
     * Construct a new <CODE>PumpStreamHandler</CODE>.
     * @param out the output <CODE>OutputStream</CODE>.
     * @param err the error <CODE>OutputStream</CODE>.
     */
    public PumpStreamHandler(OutputStream out, OutputStream err) {
        this(out, err, null);
    }

    /**
     * Construct a new <CODE>PumpStreamHandler</CODE>.
     * @param outAndErr the output/error <CODE>OutputStream</CODE>.
     */
    public PumpStreamHandler(OutputStream outAndErr) {
        this(outAndErr, outAndErr);
    }

    /**
     * Construct a new <CODE>PumpStreamHandler</CODE>.
     */
    public PumpStreamHandler() {
        this(System.out, System.err);
    }

    /**
     * Set the <CODE>InputStream</CODE> from which to read the
     * standard output of the process.
     * @param is the <CODE>InputStream</CODE>.
     */
    public void setProcessOutputStream(InputStream is) {
        createProcessOutputPump(is, out);
    }

    /**
     * Set the <CODE>InputStream</CODE> from which to read the
     * standard error of the process.
     * @param is the <CODE>InputStream</CODE>.
     */
    public void setProcessErrorStream(InputStream is) {
        if (err != null) {
            createProcessErrorPump(is, err);
        }
    }

    /**
     * Set the <CODE>OutputStream</CODE> by means of which
     * input can be sent to the process.
     * @param os the <CODE>OutputStream</CODE>.
     */
    public void setProcessInputStream(OutputStream os) {
        if (input != null) {
            inputThread = createPump(input, os, true);
        } else {
            try {
                os.close();
            } catch (IOException e) {
                //ignore
            }
        }
    }

    /**
     * Start the <CODE>Thread</CODE>s.
     */
    public void start() {
        outputThread.start();
        errorThread.start();
        if (inputThread != null) {
            inputThread.start();
        }
    }

    /**
     * Stop pumping the streams.
     */
    public void stop() {
        try {
            outputThread.join();
        } catch (InterruptedException e) {
            // ignore
        }
        try {
            errorThread.join();
        } catch (InterruptedException e) {
            // ignore
        }

        if (inputThread != null) {
            try {
                inputThread.join();
            } catch (InterruptedException e) {
                // ignore
            }
        }

        try {
            err.flush();
        } catch (IOException e) {
            // ignore
        }
        try {
            out.flush();
        } catch (IOException e) {
            // ignore
        }
    }

    /**
     * Get the error stream.
     * @return <CODE>OutputStream</CODE>.
     */
    protected OutputStream getErr() {
        return err;
    }

    /**
     * Get the output stream.
     * @return <CODE>OutputStream</CODE>.
     */
    protected OutputStream getOut() {
        return out;
    }

    /**
     * Create the pump to handle process output.
     * @param is the <CODE>InputStream</CODE>.
     * @param os the <CODE>OutputStream</CODE>.
     */
    protected void createProcessOutputPump(InputStream is, OutputStream os) {
        outputThread = createPump(is, os);
    }

    /**
     * Create the pump to handle error output.
     * @param is the <CODE>InputStream</CODE>.
     * @param os the <CODE>OutputStream</CODE>.
     */
    protected void createProcessErrorPump(InputStream is, OutputStream os) {
        errorThread = createPump(is, os);
    }

    /**
     * Creates a stream pumper to copy the given input stream to the
     * given output stream.
     */
    protected Thread createPump(InputStream is, OutputStream os) {
        return createPump(is, os, false);
    }

    /**
     * Creates a stream pumper to copy the given input stream to the
     * given output stream.
     */
    protected Thread createPump(InputStream is, OutputStream os,
                                boolean closeWhenExhausted) {
        final Thread result
            = new Thread(new StreamPumper(is, os, closeWhenExhausted));
        result.setDaemon(true);
        return result;
    }

}