#// Usage: jjs -scripting javashell.js

/*

 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.

 * 

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 

 *   - Redistributions of source code must retain the above copyright

 *     notice, this list of conditions and the following disclaimer.

 * 

 *   - Redistributions in binary form must reproduce the above copyright

 *     notice, this list of conditions and the following disclaimer in the

 *     documentation and/or other materials provided with the distribution.

 * 

 *   - Neither the name of Oracle nor the names of its

 *     contributors may be used to endorse or promote products derived

 *     from this software without specific prior written permission.

 * 

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

// Simple Java "shell" with which you can try out

// your few liner Java code leaving imports, main etc.

// And you can leave even compilation as this script

// takes care boilerplate+compile step for you.

// Java types used

var Arrays = Java.type("java.util.Arrays");

var BufferedReader = Java.type("java.io.BufferedReader");

var FileWriter = Java.type("java.io.FileWriter");

var LocalDateTime = Java.type("java.time.LocalDateTime");

var InputStreamReader = Java.type("java.io.InputStreamReader");

var PrintWriter = Java.type("java.io.PrintWriter");

var ProcessBuilder = Java.type("java.lang.ProcessBuilder");

var System = Java.type("java.lang.System");

// read multiple lines of input from stdin till user

// enters an empty line

function input(endMarker, prompt) {

    if (!endMarker) {

        endMarker = "";

    }

    if (!prompt) {

        prompt = " >> ";

    }

    var str = "";

    var reader = new BufferedReader(new InputStreamReader(System.in));

    var line;

    while (true) {

        System.out.print(prompt);

        line = reader.readLine();

        if (line == null || line == endMarker) {

            break;

        }

        str += line + "\n";

    }

    return str;

}

// write the string to the given file

function writeTo(file, str) {

    var w = new PrintWriter(new FileWriter(file));

    try {

        w.print(str);

    } finally {

        w.close();

    }

}

// generate Java code with user's input

// put inside generated main method

function generate(className) {

    var usercode = input();

    if (usercode == "") {

        return false;

    }

    var fullcode = <<EOF

// userful imports, add more here if you want

// more imports.

import static java.lang.System.*;

import java.io.*;

import java.net.*;

import java.math.*;

import java.nio.file.*;

import java.time.*;

import java.time.chrono.*;

import java.time.format.*;

import java.time.temporal.*;

import java.time.zone.*;

import java.util.*;

import java.util.concurrent.*;

import java.util.function.*;

import java.util.stream.*;

public class ${className} {

   public static void main(String[] args) throws Exception {

       ${usercode}

   }

}

EOF

    writeTo("${className}.java", fullcode);

    return true;

}

// execute code command

function exec(args) {

    // build child process and start it!

    new ProcessBuilder(Arrays.asList(args.split(' ')))

         .inheritIO()

         .start()

         .waitFor();

}

// generate unique name

function uniqueName() {

    var now = LocalDateTime.now().toString();

    // replace unsafe chars with '_' 

    return "JavaShell" + now.replace(/-|:|\./g, '_');

}

// read-compile-run loop

while(true) {

    var className = uniqueName();

    if (generate(className)) {

        exec("javac ${className}.java");

        exec("java ${className}");

    } else {

        break;

    }

}