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Groovy: A powerful, dynamic language for the JVM
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/*
 *  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.codehaus.groovy.tools.shell

import org.codehaus.groovy.runtime.InvokerHelper
import org.codehaus.groovy.tools.shell.util.CommandArgumentParser
import org.codehaus.groovy.tools.shell.util.Logger
import org.fusesource.jansi.Ansi

import static org.fusesource.jansi.Ansi.ansi

/**
 * A simple shell for invoking commands from a command-line.
 *
 * @author Jason Dillon
 */
class Shell
{
    protected final Logger log = Logger.create(this.class)

    final CommandRegistry registry = new CommandRegistry()

    final IO io

    Shell(final IO io) {
        assert(io != null)

        this.io = io
    }

    Shell() {
        this(new IO())
    }



    /**
     * @param line the line to parse
     * @param parsedArgs accumulate the rest of the line after the command
     */
    Command findCommand(final String line, List parsedArgs = null) {
        assert line

        //
        // TODO: Introduce something like 'boolean Command.accepts(String)' to ask
        //       commands if they can take the line?
        //
        //       Would like to get '!66' to invoke the 'history recall' bits, but currently has
        //       to be '! 66' for it to work with an alias like:
        //
        //           alias ! history recall
        //
        //       Or maybe allow commands to register specific syntax hacks into the registry?
        //       then ask the registry for the command for a given line?
        //

        // command id is first word, unless empty
        Command command = null;
        List linetokens = line.trim().tokenize()
        assert linetokens.size() > 0

        if (linetokens[0].length() > 0) {
            command = registry.find(linetokens[0])
            if (command != null && linetokens.size() > 1 && parsedArgs != null) {
                List args = CommandArgumentParser.parseLine(line, parsedArgs == null ? 1 : -1)
                parsedArgs.addAll(args[1..-1])
            }
        }
        return command
    }

    boolean isExecutable(final String line) {
        return findCommand(line) != null
    }

    Object execute(final String line) {
        assert line

        List args = []
        Command command = findCommand(line, args)

        def result = null

        if (command) {

            log.debug("Executing command($command.name): $command; w/args: $args")
            try {
                result = command.execute(args)
            } catch (CommandException e) {
                io.err.println(ansi().a(Ansi.Attribute.INTENSITY_BOLD).fg(Ansi.Color.RED).a(e.message).reset())
            }
            log.debug("Result: ${InvokerHelper.toString(result)}")
        }

        return result
    }

    Command register(final Command command) {
        return registry.register(command)
    }

    /**
     * this should probably be deprecated
     */
    def leftShift(final String line) {
        return execute(line)
    }


    Command leftShift(final Command command) {
        return register(command)
    }
}