/*

 * Copyright (c) 2005, 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.tools.script.shell;

import java.io.*;

import java.net.*;

import java.text.*;

import java.util.*;

import javax.script.*;

/**

 * This is the main class for Java script shell.

 */

public class Main {

    /**

     * main entry point to the command line tool

     * @param args command line argument array

     */

    public static void main(String[] args) {

        // parse command line options

        String[] scriptArgs = processOptions(args);

        // process each script command

        for (Command cmd : scripts) {

            cmd.run(scriptArgs);

        }

        System.exit(EXIT_SUCCESS);

    }

    // Each -e or -f or interactive mode is represented

    // by an instance of Command.

    private static interface Command {

        public void run(String[] arguments);

    }

    /**

     * Parses and processes command line options.

     * @param args command line argument array

     */

    private static String[] processOptions(String[] args) {

        // current scripting language selected

        String currentLanguage = DEFAULT_LANGUAGE;

        // current script file encoding selected

        String currentEncoding = null;

        // check for -classpath or -cp first

        checkClassPath(args);

        // have we seen -e or -f ?

        boolean seenScript = false;

        // have we seen -f - already?

        boolean seenStdin = false;

        for (int i=0; i < args.length; i++) {

            String arg = args[i];

            if (arg.equals("-classpath") ||

                    arg.equals("-cp")) {

                // handled already, just continue

                i++;

                continue;

            }

            // collect non-option arguments and pass these as script arguments

            if (!arg.startsWith("-")) {

                int numScriptArgs;

                int startScriptArg;

                if (seenScript) {

                    // if we have seen -e or -f already all non-option arguments

                    // are passed as script arguments

                    numScriptArgs = args.length - i;

                    startScriptArg = i;

                } else {

                    // if we have not seen -e or -f, first non-option argument

                    // is treated as script file name and rest of the non-option

                    // arguments are passed to script as script arguments

                    numScriptArgs = args.length - i - 1;

                    startScriptArg = i + 1;

                    ScriptEngine se = getScriptEngine(currentLanguage);

                    addFileSource(se, args[i], currentEncoding);

                }

                // collect script arguments and return to main

                String[] result = new String[numScriptArgs];

                System.arraycopy(args, startScriptArg, result, 0, numScriptArgs);

                return result;

            }

            if (arg.startsWith("-D")) {

                String value = arg.substring(2);

                int eq = value.indexOf('=');

                if (eq != -1) {

                    System.setProperty(value.substring(0, eq),

                            value.substring(eq + 1));

                } else {

                        System.setProperty(value, "");

                    } else {

                        // do not allow empty property name

                        usage(EXIT_CMD_NO_PROPNAME);

                    }

                }

                continue;

            } else if (arg.equals("-?") ||

                       arg.equals("-h") ||

                       arg.equals("--help") ||

                       // -help: legacy.

                       arg.equals("-help")) {

                usage(EXIT_SUCCESS);

            } else if (arg.equals("-e")) {

                seenScript = true;

                if (++i == args.length)

                    usage(EXIT_CMD_NO_SCRIPT);

                ScriptEngine se = getScriptEngine(currentLanguage);

                addStringSource(se, args[i]);

                continue;

            } else if (arg.equals("-encoding")) {

                if (++i == args.length)

                    usage(EXIT_CMD_NO_ENCODING);

                currentEncoding = args[i];

                continue;

            } else if (arg.equals("-f")) {

                seenScript = true;

                if (++i == args.length)

                    usage(EXIT_CMD_NO_FILE);

                ScriptEngine se = getScriptEngine(currentLanguage);

                if (args[i].equals("-")) {

                    if (seenStdin) {

                        usage(EXIT_MULTIPLE_STDIN);

                    } else {

                        seenStdin = true;

                    }

                    addInteractiveMode(se);

                } else {

                    addFileSource(se, args[i], currentEncoding);

                }

                continue;

            } else if (arg.equals("-l")) {

                if (++i == args.length)

                    usage(EXIT_CMD_NO_LANG);

                currentLanguage = args[i];

                continue;

            } else if (arg.equals("-q")) {

                listScriptEngines();

            }

            // some unknown option...

            usage(EXIT_UNKNOWN_OPTION);

        }

        if (! seenScript) {

            ScriptEngine se = getScriptEngine(currentLanguage);

            addInteractiveMode(se);

        }

        return new String[0];

    }

    /**

     * Adds interactive mode Command

     * @param se ScriptEngine to use in interactive mode.

     */

    private static void addInteractiveMode(final ScriptEngine se) {

        scripts.add(new Command() {

            public void run(String[] args) {

                setScriptArguments(se, args);

                processSource(se, "-", null);

            }

        });

    }

    /**

     * Adds script source file Command

     * @param se ScriptEngine used to evaluate the script file

     * @param fileName script file name

     * @param encoding script file encoding

     */

    private static void addFileSource(final ScriptEngine se,

            final String fileName,

            final String encoding) {

        scripts.add(new Command() {

            public void run(String[] args) {

                setScriptArguments(se, args);

                processSource(se, fileName, encoding);

            }

        });

    }

    /**

     * Adds script string source Command

     * @param se ScriptEngine to be used to evaluate the script string

     * @param source Script source string

     */

    private static void addStringSource(final ScriptEngine se,

            final String source) {

        scripts.add(new Command() {

            public void run(String[] args) {

                setScriptArguments(se, args);

                String oldFile = setScriptFilename(se, "<string>");

                try {

                    evaluateString(se, source);

                } finally {

                    setScriptFilename(se, oldFile);

                }

            }

        });

    }

    /**

     * Prints list of script engines available and exits.

     */

    private static void listScriptEngines() {

        List<ScriptEngineFactory> factories = engineManager.getEngineFactories();

        for (ScriptEngineFactory factory: factories) {

            getError().println(getMessage("engine.info",

                    new Object[] { factory.getLanguageName(),

                            factory.getLanguageVersion(),

                            factory.getEngineName(),

                            factory.getEngineVersion()

            }));

        }

        System.exit(EXIT_SUCCESS);

    }

    /**

     * Processes a given source file or standard input.

     * @param se ScriptEngine to be used to evaluate

     * @param filename file name, can be null

     * @param encoding script file encoding, can be null

     */

    private static void processSource(ScriptEngine se, String filename,

            String encoding) {

        if (filename.equals("-")) {

            BufferedReader in = new BufferedReader

                    (new InputStreamReader(getIn()));

            boolean hitEOF = false;

            String prompt = getPrompt(se);

            se.put(ScriptEngine.FILENAME, "<STDIN>");

            while (!hitEOF) {

                getError().print(prompt);

                String source = "";

                try {

                    source = in.readLine();

                } catch (IOException ioe) {

                    getError().println(ioe.toString());

                }

                if (source == null) {

                    hitEOF = true;

                    break;

                }

                Object res = evaluateString(se, source, false);

                if (res != null) {

                    res = res.toString();

                    if (res == null) {

                        res = "null";

                    }

                    getError().println(res);

                }

            }

        } else {

            FileInputStream fis = null;

            try {

                fis = new FileInputStream(filename);

            } catch (FileNotFoundException fnfe) {

                getError().println(getMessage("file.not.found",

                        new Object[] { filename }));

                        System.exit(EXIT_FILE_NOT_FOUND);

            }

            evaluateStream(se, fis, filename, encoding);

        }

    }

    /**

     * Evaluates given script source

     * @param se ScriptEngine to evaluate the string

     * @param script Script source string

     * @param exitOnError whether to exit the process on script error

     */

    private static Object evaluateString(ScriptEngine se,

            String script, boolean exitOnError) {

        try {

            return se.eval(script);

        } catch (ScriptException sexp) {

            getError().println(getMessage("string.script.error",

                    new Object[] { sexp.getMessage() }));

                    if (exitOnError)

                        System.exit(EXIT_SCRIPT_ERROR);

        } catch (Exception exp) {

            exp.printStackTrace(getError());

            if (exitOnError)

                System.exit(EXIT_SCRIPT_ERROR);

        }

        return null;

    }

    /**

     * Evaluate script string source and exit on script error

     * @param se ScriptEngine to evaluate the string

     * @param script Script source string

     */

    private static void evaluateString(ScriptEngine se, String script) {

        evaluateString(se, script, true);

    }

    /**

     * Evaluates script from given reader

     * @param se ScriptEngine to evaluate the string

     * @param reader Reader from which is script is read

     * @param name file name to report in error.

     */

    private static Object evaluateReader(ScriptEngine se,

            Reader reader, String name) {

        String oldFilename = setScriptFilename(se, name);

        try {

            return se.eval(reader);

        } catch (ScriptException sexp) {

            getError().println(getMessage("file.script.error",

                    new Object[] { name, sexp.getMessage() }));

                    System.exit(EXIT_SCRIPT_ERROR);

        } catch (Exception exp) {

            exp.printStackTrace(getError());

            System.exit(EXIT_SCRIPT_ERROR);

        } finally {

            setScriptFilename(se, oldFilename);

        }

        return null;

    }

    /**

     * Evaluates given input stream

     * @param se ScriptEngine to evaluate the string

     * @param is InputStream from which script is read

     * @param name file name to report in error

     */

    private static Object evaluateStream(ScriptEngine se,

            InputStream is, String name,

            String encoding) {

        BufferedReader reader = null;

        if (encoding != null) {

            try {

                reader = new BufferedReader(new InputStreamReader(is,

                        encoding));

            } catch (UnsupportedEncodingException uee) {

                getError().println(getMessage("encoding.unsupported",

                        new Object[] { encoding }));

                        System.exit(EXIT_NO_ENCODING_FOUND);

            }

        } else {

            reader = new BufferedReader(new InputStreamReader(is));

        }

        return evaluateReader(se, reader, name);

    }

    /**

     * Prints usage message and exits

     * @param exitCode process exit code

     */

    private static void usage(int exitCode) {

        getError().println(getMessage("main.usage",

                new Object[] { PROGRAM_NAME }));

                System.exit(exitCode);

    }

    /**

     * Gets prompt for interactive mode

     * @return prompt string to use

     */

    private static String getPrompt(ScriptEngine se) {

        List<String> names = se.getFactory().getNames();

        return names.get(0) + "> ";

    }

    /**

     * Get formatted, localized error message

     */

    private static String getMessage(String key, Object[] params) {

        return MessageFormat.format(msgRes.getString(key), params);

    }

    // input stream from where we will read

    private static InputStream getIn() {

        return System.in;

    }

    // stream to print error messages

    private static PrintStream getError() {

        return System.err;

    }

    // get current script engine

    private static ScriptEngine getScriptEngine(String lang) {

        ScriptEngine se = engines.get(lang);

        if (se == null) {

            se = engineManager.getEngineByName(lang);

            if (se == null) {

                getError().println(getMessage("engine.not.found",

                        new Object[] { lang }));

                        System.exit(EXIT_ENGINE_NOT_FOUND);

            }

            // initialize the engine

            initScriptEngine(se);

            // to avoid re-initialization of engine, store it in a map

            engines.put(lang, se);

        }

        return se;

    }

    // initialize a given script engine

    private static void initScriptEngine(ScriptEngine se) {

        // put engine global variable

        se.put("engine", se);

        // load init.<ext> file from resource

        List<String> exts = se.getFactory().getExtensions();

        InputStream sysIn = null;

        ClassLoader cl = Thread.currentThread().getContextClassLoader();

        for (String ext : exts) {

            try {

                sysIn = Main.class.getModule().getResourceAsStream("com/sun/tools/script/shell/init." + ext);

            } catch (IOException ioe) {

                throw new RuntimeException(ioe);

            }

            if (sysIn != null) break;

        }

        if (sysIn != null) {

            evaluateStream(se, sysIn, "<system-init>", null);

        }

    }

    /**

     * Checks for -classpath, -cp in command line args. Creates a ClassLoader

     * and sets it as Thread context loader for current thread.

     *

     * @param args command line argument array

     */

    private static void checkClassPath(String[] args) {

        String classPath = null;

        for (int i = 0; i < args.length; i++) {

            if (args[i].equals("-classpath") ||

                    args[i].equals("-cp")) {

                if (++i == args.length) {

                    // just -classpath or -cp with no value

                    usage(EXIT_CMD_NO_CLASSPATH);

                } else {

                    classPath = args[i];

                }

            }

        }

        if (classPath != null) {

            /* We create a class loader, configure it with specified

             * classpath values and set the same as context loader.

             * Note that ScriptEngineManager uses context loader to

             * load script engines. So, this ensures that user defined

             * script engines will be loaded. For classes referred

             * from scripts, Rhino engine uses thread context loader

             * but this is script engine dependent. We don't have

             * script engine independent solution anyway. Unless we

             * know the class loader used by a specific engine, we

             * can't configure correct loader.

             */

            URL[] urls = pathToURLs(classPath);

            URLClassLoader loader = new URLClassLoader(urls);

            Thread.currentThread().setContextClassLoader(loader);

        }

        // now initialize script engine manager. Note that this has to

        // be done after setting the context loader so that manager

        // will see script engines from user specified classpath

        engineManager = new ScriptEngineManager();

    }

    /**

     * Utility method for converting a search path string to an array

     * of directory and JAR file URLs.

     *

     * @param path the search path string

     * @return the resulting array of directory and JAR file URLs

     */

    private static URL[] pathToURLs(String path) {

        String[] components = path.split(File.pathSeparator);

        URL[] urls = new URL[components.length];

        int count = 0;

        while(count < components.length) {

            URL url = fileToURL(new File(components[count]));

            if (url != null) {

                urls[count++] = url;

            }

        }

        if (urls.length != count) {

            URL[] tmp = new URL[count];

            System.arraycopy(urls, 0, tmp, 0, count);

            urls = tmp;

        }

        return urls;

    }

    /**

     * Returns the directory or JAR file URL corresponding to the specified

     * local file name.

     *

     * @param file the File object

     * @return the resulting directory or JAR file URL, or null if unknown

     */

    private static URL fileToURL(File file) {