source: trunk/java-utils/src/main/java/de/ugoe/cs/util/console/TextConsole.java @ 1297

//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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 de.ugoe.cs.util.console;

import java.io.IOException;
import java.nio.charset.Charset;
import java.util.logging.Level;

import de.ugoe.cs.util.console.listener.IErrorListener;
import de.ugoe.cs.util.console.listener.IExceptionListener;
import de.ugoe.cs.util.console.listener.IOutputListener;
import de.ugoe.cs.util.console.listener.ITraceListener;

/**
 * <p>
 * Implements a simple console observer that prints normal text to
 * {@code stdout}, errors to {@code stderr} and reads from {@code stdin}.
 * </p>
 * 
 * @author Steffen Herbold
 * @version 1.0
 */
public class TextConsole implements IOutputListener, IErrorListener,
                ITraceListener, IExceptionListener {
        
        /**
         * <p>Defines the trace level used by this console.</p>
         */
        private Level traceLevel;
        
        /**
         * <p>
         * Creates a new text console and automatically registers it as observer. The trace level is {@link Level#WARNING}.
         * </p>
         */
        public TextConsole() {
            this(Level.WARNING);
        }

        /**
         * <p>
         * Creates a new text console and automatically registers it as observer.
         * </p>
         * @param traceLevel trace level used by this text console
         */
        public TextConsole(Level traceLevel) {
                Console.getInstance().registerOutputListener(this);
                Console.getInstance().registerErrorListener(this);
                Console.getInstance().registerTraceListener(this);
                Console.getInstance().registerExceptionListener(this);
                this.traceLevel = traceLevel;
        }

        /**
         * <p>
         * Prints messages to {@code stdout}.
         * </p>
         * 
         * @see ConsoleObserver#outputMsg(java.lang.String)
         */
        public void outputMsg(String newMessage) {
                System.out.print(newMessage);
        }

        /**
         * <p>
         * Prints messages to {@code stderr}.
         * </p>
         * 
         * @see ConsoleObserver#errorMsg(String)
         */
        @Override
        public void errorMsg(String errMessage) {
                System.err.print(errMessage);
        }

        /**
         * <p>
         * Prints the stacktrace of an exception to {@code stderr}.
         * </p>
         * 
         * @see ConsoleObserver#logException(Exception)
         */
        @Override
        public void logException(Exception e) {
                System.err.println(e.getMessage());
        }

        /**
         * <p>
         * Prints messages to {@code stdout}. These messages are only printed, if
         * the console is run in debug mode.
         * </p>
         */
        @Override
        public void traceMsg(String traceMessage, Level level) {
                if (level.intValue()>=traceLevel.intValue()) {
                        System.out.print("[" + level.toString() + "] " + traceMessage);
                }
        }

        /**
         * <p>
         * Starts a new TextConsole. If the text console is started, it can be used
         * not only to print message, but also to execute commands by reading
         * {@code stdin}.
         * </p>
         */
        public void run() {
                CommandExecuter exec = CommandExecuter.getInstance();
                while (true) {
                        System.out.print("> ");
                        String command = getCommand().trim();
                        if (!command.equals("")) {
                                exec.exec(command);
                        }
                }
        }

        /**
         * <p>
         * Reads a new command from {@code stdin}.
         * </p>
         * 
         * @return a string with a command
         */
        protected String getCommand() {
                byte[] buffer = new byte[1024];
                int bytesRead = 0;
                String command;
                try {
                        bytesRead = System.in.read(buffer);
                } catch (IOException e) {

                }
                if (bytesRead == 0) {
                        command = "";
                } else {
                        command = new String(buffer, Charset.defaultCharset());
                }
                return command;
        }

}