/*
 * Copyright (c) 2010, 2013, 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 jdk.nashorn.tools;

import jdk.nashorn.api.scripting.NashornException;
import jdk.nashorn.internal.codegen.Compiler;
import jdk.nashorn.internal.codegen.Compiler.CompilationPhases;
import jdk.nashorn.internal.ir.Expression;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.debug.ASTWriter;
import jdk.nashorn.internal.ir.debug.PrintVisitor;
import jdk.nashorn.internal.objects.Global;
import jdk.nashorn.internal.objects.NativeSymbol;
import jdk.nashorn.internal.parser.Parser;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.ErrorManager;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.Property;
import jdk.nashorn.internal.runtime.ScriptEnvironment;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.ScriptRuntime;
import jdk.nashorn.internal.runtime.ScriptingFunctions;
import jdk.nashorn.internal.runtime.Symbol;
import jdk.nashorn.internal.runtime.arrays.ArrayLikeIterator;
import jdk.nashorn.internal.runtime.options.Options;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
import java.io.StringReader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.ResourceBundle;

import static jdk.nashorn.internal.runtime.Source.sourceFor;

Command line Shell for processing JavaScript files.
/**
 * Command line Shell for processing JavaScript files.
 */
public class Shell implements PartialParser {

    
Resource name for properties file
/**
     * Resource name for properties file
     */
    private static final String MESSAGE_RESOURCE = "jdk.nashorn.tools.resources.Shell";
    
Shell message bundle.
/**
     * Shell message bundle.
     */
    protected static final ResourceBundle bundle = ResourceBundle.getBundle(MESSAGE_RESOURCE, Locale.getDefault());

    
Exit code for command line tool - successful
/**
     * Exit code for command line tool - successful
     */
    public static final int SUCCESS = 0;
    
Exit code for command line tool - error on command line
/**
     * Exit code for command line tool - error on command line
     */
    public static final int COMMANDLINE_ERROR = 100;
    
Exit code for command line tool - error compiling script
/**
     * Exit code for command line tool - error compiling script
     */
    public static final int COMPILATION_ERROR = 101;
    
Exit code for command line tool - error during runtime
/**
     * Exit code for command line tool - error during runtime
     */
    public static final int RUNTIME_ERROR = 102;
    
Exit code for command line tool - i/o error
/**
     * Exit code for command line tool - i/o error
     */
    public static final int IO_ERROR = 103;
    
Exit code for command line tool - internal error
/**
     * Exit code for command line tool - internal error
     */
    public static final int INTERNAL_ERROR = 104;

    
Constructor
/**
     * Constructor
     */
    protected Shell() {
    }

    
Main entry point with the default input, output and error streams.
Params:
args – The command line arguments/**
     * Main entry point with the default input, output and error streams.
     *
     * @param args The command line arguments
     */
    public static void main(final String[] args) {
        try {
            final int exitCode = main(System.in, System.out, System.err, args);
            if (exitCode != SUCCESS) {
                System.exit(exitCode);
            }
        } catch (final IOException e) {
            System.err.println(e); //bootstrapping, Context.err may not exist
            System.exit(IO_ERROR);
        }
    }

    
Starting point for executing a Shell. Starts a shell with the given arguments and streams and lets it run until exit. 
Params:
in – input stream for Shell
out – output stream for Shell
err – error stream for Shell
args – arguments to Shell
Throws:
IOException – if there's a problem setting up the streams
Returns:
exit code/**
     * Starting point for executing a {@code Shell}. Starts a shell with the
     * given arguments and streams and lets it run until exit.
     *
     * @param in input stream for Shell
     * @param out output stream for Shell
     * @param err error stream for Shell
     * @param args arguments to Shell
     *
     * @return exit code
     *
     * @throws IOException if there's a problem setting up the streams
     */
    public static int main(final InputStream in, final OutputStream out, final OutputStream err, final String[] args) throws IOException {
        return new Shell().run(in, out, err, args);
    }

    
Run method logic.
Params:
in – input stream for Shell
out – output stream for Shell
err – error stream for Shell
args – arguments to Shell
Throws:
IOException – if there's a problem setting up the streams
Returns:
exit code/**
     * Run method logic.
     *
     * @param in input stream for Shell
     * @param out output stream for Shell
     * @param err error stream for Shell
     * @param args arguments to Shell
     *
     * @return exit code
     *
     * @throws IOException if there's a problem setting up the streams
     */
    protected final int run(final InputStream in, final OutputStream out, final OutputStream err, final String[] args) throws IOException {
        final Context context = makeContext(in, out, err, args);
        if (context == null) {
            return COMMANDLINE_ERROR;
        }

        final Global global = context.createGlobal();
        final ScriptEnvironment env = context.getEnv();
        final List<String> files = env.getFiles();
        if (files.isEmpty()) {
            return readEvalPrint(context, global);
        }

        if (env._compile_only) {
            return compileScripts(context, global, files);
        }

        if (env._fx) {
            return runFXScripts(context, global, files);
        }

        return runScripts(context, global, files);
    }

    
Make a new Nashorn Context to compile and/or run JavaScript files.
Params:
in – input stream for Shell
out – output stream for Shell
err – error stream for Shell
args – arguments to Shell
Returns:
null if there are problems with option parsing./**
     * Make a new Nashorn Context to compile and/or run JavaScript files.
     *
     * @param in input stream for Shell
     * @param out output stream for Shell
     * @param err error stream for Shell
     * @param args arguments to Shell
     *
     * @return null if there are problems with option parsing.
     */
    private static Context makeContext(final InputStream in, final OutputStream out, final OutputStream err, final String[] args) {
        final PrintStream pout = out instanceof PrintStream ? (PrintStream) out : new PrintStream(out);
        final PrintStream perr = err instanceof PrintStream ? (PrintStream) err : new PrintStream(err);
        final PrintWriter wout = new PrintWriter(pout, true);
        final PrintWriter werr = new PrintWriter(perr, true);

        // Set up error handler.
        final ErrorManager errors = new ErrorManager(werr);
        // Set up options.
        final Options options = new Options("nashorn", werr);

        // parse options
        if (args != null) {
            try {
                final String[] prepArgs = preprocessArgs(args);
                options.process(prepArgs);
            } catch (final IllegalArgumentException e) {
                werr.println(bundle.getString("shell.usage"));
                options.displayHelp(e);
                return null;
            }
        }

        // detect scripting mode by any source's first character being '#'
        if (!options.getBoolean("scripting")) {
            for (final String fileName : options.getFiles()) {
                final File firstFile = new File(fileName);
                if (firstFile.isFile()) {
                    try (final FileReader fr = new FileReader(firstFile)) {
                        final int firstChar = fr.read();
                        // starts with '#
                        if (firstChar == '#') {
                            options.set("scripting", true);
                            break;
                        }
                    } catch (final IOException e) {
                        // ignore this. File IO errors will be reported later anyway
                    }
                }
            }
        }

        return new Context(options, errors, wout, werr, Thread.currentThread().getContextClassLoader());
    }

    
Preprocess the command line arguments passed in by the shell. This method checks, for the first non-option
argument, whether the file denoted by it begins with a shebang line. If so, it is assumed that execution in
shebang mode is intended. The consequence of this is that the identified script file will be treated as the
only script file, and all subsequent arguments will be regarded as arguments to the script.
 This method canonicalizes the command line arguments to the form <options> <script> -- <arguments> if a shebang script is identified. On platforms that pass shebang arguments as single strings, the shebang arguments will be broken down into single arguments; whitespace is used as separator. 
 Shebang mode is entered regardless of whether the script is actually run directly from the shell, or indirectly via the jjs executable. It is the user's / script author's responsibility to ensure that the arguments given on the shebang line do not lead to a malformed argument sequence. In particular, the shebang arguments should not contain any whitespace for purposes other than separating arguments, as the different platforms deal with whitespace in different and incompatible ways. 

Params:
args – the command line arguments as passed into Nashorn.
Implementation Note:
Example:

Shebang line in script.js: #!/path/to/jjs --language=es6
Command line: ./script.js arg2
args array passed to Nashorn: --language=es6,./script.js,arg
Required canonicalized arguments array: --language=es6,./script.js,--,arg2
Returns:
the passed and possibly canonicalized argument list/**
     * Preprocess the command line arguments passed in by the shell. This method checks, for the first non-option
     * argument, whether the file denoted by it begins with a shebang line. If so, it is assumed that execution in
     * shebang mode is intended. The consequence of this is that the identified script file will be treated as the
     * <em>only</em> script file, and all subsequent arguments will be regarded as arguments to the script.
     * <p>
     * This method canonicalizes the command line arguments to the form {@code <options> <script> -- <arguments>} if a
     * shebang script is identified. On platforms that pass shebang arguments as single strings, the shebang arguments
     * will be broken down into single arguments; whitespace is used as separator.
     * <p>
     * Shebang mode is entered regardless of whether the script is actually run directly from the shell, or indirectly
     * via the {@code jjs} executable. It is the user's / script author's responsibility to ensure that the arguments
     * given on the shebang line do not lead to a malformed argument sequence. In particular, the shebang arguments
     * should not contain any whitespace for purposes other than separating arguments, as the different platforms deal
     * with whitespace in different and incompatible ways.
     * <p>
     * @implNote Example:<ul>
     * <li>Shebang line in {@code script.js}: {@code #!/path/to/jjs --language=es6}</li>
     * <li>Command line: {@code ./script.js arg2}</li>
     * <li>{@code args} array passed to Nashorn: {@code --language=es6,./script.js,arg}</li>
     * <li>Required canonicalized arguments array: {@code --language=es6,./script.js,--,arg2}</li>
     * </ul>
     *
     * @param args the command line arguments as passed into Nashorn.
     * @return the passed and possibly canonicalized argument list
     */
    private static String[] preprocessArgs(final String[] args) {
        if (args.length == 0) {
            return args;
        }

        final List<String> processedArgs = new ArrayList<>();
        processedArgs.addAll(Arrays.asList(args));

        // Nashorn supports passing multiple shebang arguments. On platforms that pass anything following the
        // shebang interpreter notice as one argument, the first element of the argument array needs to be special-cased
        // as it might actually contain several arguments. Mac OS X splits shebang arguments, other platforms don't.
        // This special handling is also only necessary if the first argument actually starts with an option.
        if (args[0].startsWith("-") && !System.getProperty("os.name", "generic").startsWith("Mac OS X")) {
            processedArgs.addAll(0, tokenizeString(processedArgs.remove(0)));
        }

        int shebangFilePos = -1; // -1 signifies "none found"
        // identify a shebang file and its position in the arguments array (if any)
        for (int i = 0; i < processedArgs.size(); ++i) {
            final String a = processedArgs.get(i);
            if (!a.startsWith("-")) {
                final Path p = Paths.get(a);
                String l = "";
                try (final BufferedReader r = Files.newBufferedReader(p)) {
                    l = r.readLine();
                } catch (final IOException ioe) {
                    // ignore
                }
                if (l != null && l.startsWith("#!")) {
                    shebangFilePos = i;
                }
                // We're only checking the first non-option argument. If it's not a shebang file, we're in normal
                // execution mode.
                break;
            }
        }
        if (shebangFilePos != -1) {
            // Insert the argument separator after the shebang script file.
            processedArgs.add(shebangFilePos + 1, "--");
        }
        return processedArgs.stream().toArray(String[]::new);
    }

    public static List<String> tokenizeString(final String str) {
        final StreamTokenizer tokenizer = new StreamTokenizer(new StringReader(str));
        tokenizer.resetSyntax();
        tokenizer.wordChars(0, 255);
        tokenizer.whitespaceChars(0, ' ');
        tokenizer.commentChar('#');
        tokenizer.quoteChar('"');
        tokenizer.quoteChar('\'');
        final List<String> tokenList = new ArrayList<>();
        final StringBuilder toAppend = new StringBuilder();
        while (nextToken(tokenizer) != StreamTokenizer.TT_EOF) {
            final String s = tokenizer.sval;
            // The tokenizer understands about honoring quoted strings and recognizes
            // them as one token that possibly contains multiple space-separated words.
            // It does not recognize quoted spaces, though, and will split after the
            // escaping \ character. This is handled here.
            if (s.endsWith("\\")) {
                // omit trailing \, append space instead
                toAppend.append(s.substring(0, s.length() - 1)).append(' ');
            } else {
                tokenList.add(toAppend.append(s).toString());
                toAppend.setLength(0);
            }
        }
        if (toAppend.length() != 0) {
            tokenList.add(toAppend.toString());
        }
        return tokenList;
    }

    private static int nextToken(final StreamTokenizer tokenizer) {
        try {
            return tokenizer.nextToken();
        } catch (final IOException ioe) {
            return StreamTokenizer.TT_EOF;
        }
    }

    
Compiles the given script files in the command line
This is called only when using the --compile-only flag
Params:
context – the nashorn context
global – the global scope
files – the list of script files to compile
Throws:
IOException – when any script file read results in I/O error
Returns:
error code/**
     * Compiles the given script files in the command line
     * This is called only when using the --compile-only flag
     *
     * @param context the nashorn context
     * @param global the global scope
     * @param files the list of script files to compile
     *
     * @return error code
     * @throws IOException when any script file read results in I/O error
     */
    private static int compileScripts(final Context context, final Global global, final List<String> files) throws IOException {
        final Global oldGlobal = Context.getGlobal();
        final boolean globalChanged = (oldGlobal != global);
        final ScriptEnvironment env = context.getEnv();
        try {
            if (globalChanged) {
                Context.setGlobal(global);
            }
            final ErrorManager errors = context.getErrorManager();

            // For each file on the command line.
            for (final String fileName : files) {
                final FunctionNode functionNode = new Parser(env, sourceFor(fileName, new File(fileName)), errors, env._strict, 0, context.getLogger(Parser.class)).parse();

                if (errors.getNumberOfErrors() != 0) {
                    return COMPILATION_ERROR;
                }

                Compiler.forNoInstallerCompilation(
                       context,
                       functionNode.getSource(),
                       env._strict | functionNode.isStrict()).
                       compile(functionNode, CompilationPhases.COMPILE_ALL_NO_INSTALL);

                if (env._print_ast) {
                    context.getErr().println(new ASTWriter(functionNode));
                }

                if (env._print_parse) {
                    context.getErr().println(new PrintVisitor(functionNode));
                }

                if (errors.getNumberOfErrors() != 0) {
                    return COMPILATION_ERROR;
                }
            }
        } finally {
            env.getOut().flush();
            env.getErr().flush();
            if (globalChanged) {
                Context.setGlobal(oldGlobal);
            }
        }

        return SUCCESS;
    }

    
Runs the given JavaScript files in the command line
Params:
context – the nashorn context
global – the global scope
files – the list of script files to run
Throws:
IOException – when any script file read results in I/O error
Returns:
error code/**
     * Runs the given JavaScript files in the command line
     *
     * @param context the nashorn context
     * @param global the global scope
     * @param files the list of script files to run
     *
     * @return error code
     * @throws IOException when any script file read results in I/O error
     */
    private int runScripts(final Context context, final Global global, final List<String> files) throws IOException {
        final Global oldGlobal = Context.getGlobal();
        final boolean globalChanged = (oldGlobal != global);
        try {
            if (globalChanged) {
                Context.setGlobal(global);
            }
            final ErrorManager errors = context.getErrorManager();

            // For each file on the command line.
            for (final String fileName : files) {
                if ("-".equals(fileName)) {
                    final int res = readEvalPrint(context, global);
                    if (res != SUCCESS) {
                        return res;
                    }
                    continue;
                }

                final File file = new File(fileName);
                final ScriptFunction script = context.compileScript(sourceFor(fileName, file), global);
                if (script == null || errors.getNumberOfErrors() != 0) {
                    if (context.getEnv()._parse_only && !errors.hasErrors()) {
                        continue; // No error, continue to consume all files in list
                    }
                    return COMPILATION_ERROR;
                }

                try {
                    apply(script, global);
                } catch (final NashornException e) {
                    errors.error(e.toString());
                    if (context.getEnv()._dump_on_error) {
                        e.printStackTrace(context.getErr());
                    }

                    return RUNTIME_ERROR;
                }
            }
        } finally {
            context.getOut().flush();
            context.getErr().flush();
            if (globalChanged) {
                Context.setGlobal(oldGlobal);
            }
        }

        return SUCCESS;
    }

    
Runs launches "fx:bootstrap.js" with the given JavaScript files provided
as arguments.
Params:
context – the nashorn context
global – the global scope
files – the list of script files to provide
Throws:
IOException – when any script file read results in I/O error
Returns:
error code/**
     * Runs launches "fx:bootstrap.js" with the given JavaScript files provided
     * as arguments.
     *
     * @param context the nashorn context
     * @param global the global scope
     * @param files the list of script files to provide
     *
     * @return error code
     * @throws IOException when any script file read results in I/O error
     */
    private static int runFXScripts(final Context context, final Global global, final List<String> files) throws IOException {
        final Global oldGlobal = Context.getGlobal();
        final boolean globalChanged = (oldGlobal != global);
        try {
            if (globalChanged) {
                Context.setGlobal(global);
            }

            global.addOwnProperty("$GLOBAL", Property.NOT_ENUMERABLE, global);
            global.addOwnProperty("$SCRIPTS", Property.NOT_ENUMERABLE, files);
            context.load(global, "fx:bootstrap.js");
        } catch (final NashornException e) {
            context.getErrorManager().error(e.toString());
            if (context.getEnv()._dump_on_error) {
                e.printStackTrace(context.getErr());
            }

            return RUNTIME_ERROR;
        } finally {
            context.getOut().flush();
            context.getErr().flush();
            if (globalChanged) {
                Context.setGlobal(oldGlobal);
            }
        }

        return SUCCESS;
    }

    
Hook to ScriptFunction "apply". A performance metering shell may
introduce enter/exit timing here.
Params:
target – target function for apply
self – self reference for apply
Returns:
result of the function apply/**
     * Hook to ScriptFunction "apply". A performance metering shell may
     * introduce enter/exit timing here.
     *
     * @param target target function for apply
     * @param self self reference for apply
     *
     * @return result of the function apply
     */
    protected Object apply(final ScriptFunction target, final Object self) {
        return ScriptRuntime.apply(target, self);
    }

    
Parse potentially partial code and keep track of the start of last expression.
This 'partial' parsing support is meant to be used for code-completion.
Params:
context – the nashorn context
code – code that is to be parsed
Returns:
the start index of the last expression parsed in the (incomplete) code./**
     * Parse potentially partial code and keep track of the start of last expression.
     * This 'partial' parsing support is meant to be used for code-completion.
     *
     * @param context the nashorn context
     * @param code code that is to be parsed
     * @return the start index of the last expression parsed in the (incomplete) code.
     */
    @Override
    public final int getLastExpressionStart(final Context context, final String code) {
        final int[] exprStart = { -1 };

        final Parser p = new Parser(context.getEnv(), sourceFor("<partial_code>", code),new Context.ThrowErrorManager()) {
            @Override
            protected Expression expression() {
                exprStart[0] = this.start;
                return super.expression();
            }

            @Override
            protected Expression assignmentExpression(final boolean noIn) {
                exprStart[0] = this.start;
                return super.assignmentExpression(noIn);
            }
        };

        try {
            p.parse();
        } catch (final Exception ignored) {
            // throw any parser exception, but we are partial parsing anyway
        }

        return exprStart[0];
    }


    
read-eval-print loop for Nashorn shell.
Params:
context – the nashorn context
global –  global scope object to use
Returns:
return code/**
     * read-eval-print loop for Nashorn shell.
     *
     * @param context the nashorn context
     * @param global  global scope object to use
     * @return return code
     */
    protected int readEvalPrint(final Context context, final Global global) {
        final String prompt = bundle.getString("shell.prompt");
        final BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        final PrintWriter err = context.getErr();
        final Global oldGlobal = Context.getGlobal();
        final boolean globalChanged = (oldGlobal != global);
        final ScriptEnvironment env = context.getEnv();

        try {
            if (globalChanged) {
                Context.setGlobal(global);
            }

            global.addShellBuiltins();

            while (true) {
                err.print(prompt);
                err.flush();

                String source = "";
                try {
                    source = in.readLine();
                } catch (final IOException ioe) {
                    err.println(ioe.toString());
                }

                if (source == null) {
                    break;
                }

                if (source.isEmpty()) {
                    continue;
                }

                try {
                    final Object res = context.eval(global, source, global, "<shell>");
                    if (res != ScriptRuntime.UNDEFINED) {
                        err.println(toString(res, global));
                    }
                } catch (final Exception e) {
                    err.println(e);
                    if (env._dump_on_error) {
                        e.printStackTrace(err);
                    }
                }
            }
        } finally {
            if (globalChanged) {
                Context.setGlobal(oldGlobal);
            }
        }

        return SUCCESS;
    }

    
Converts result to a printable string. The reason we don't use JSType.toString(Object) or ScriptRuntime.safeToString(Object) is that we want to be able to render Symbol values even if they occur within an Array, and therefore have to implement our own Array to String conversion. 
Params:
result – the result
global – the global object
Returns:
the string representation/**
     * Converts {@code result} to a printable string. The reason we don't use {@link JSType#toString(Object)}
     * or {@link ScriptRuntime#safeToString(Object)} is that we want to be able to render Symbol values
     * even if they occur within an Array, and therefore have to implement our own Array to String
     * conversion.
     *
     * @param result the result
     * @param global the global object
     * @return the string representation
     */
    protected static String toString(final Object result, final Global global) {
        if (result instanceof Symbol) {
            // Normal implicit conversion of symbol to string would throw TypeError
            return result.toString();
        }

        if (result instanceof NativeSymbol) {
            return JSType.toPrimitive(result).toString();
        }

        if (isArrayWithDefaultToString(result, global)) {
            // This should yield the same string as Array.prototype.toString but
            // will not throw if the array contents include symbols.
            final StringBuilder sb = new StringBuilder();
            final Iterator<Object> iter = ArrayLikeIterator.arrayLikeIterator(result, true);

            while (iter.hasNext()) {
                final Object obj = iter.next();

                if (obj != null && obj != ScriptRuntime.UNDEFINED) {
                    sb.append(toString(obj, global));
                }

                if (iter.hasNext()) {
                    sb.append(',');
                }
            }

            return sb.toString();
        }

        return JSType.toString(result);
    }

    private static boolean isArrayWithDefaultToString(final Object result, final Global global) {
        if (result instanceof ScriptObject) {
            final ScriptObject sobj = (ScriptObject) result;
            return sobj.isArray() && sobj.get("toString") == global.getArrayPrototype().get("toString");
        }
        return false;
    }
}