/*

 * 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.api.scripting;

import java.util.Arrays;

import java.util.Collections;

import java.util.List;

import java.util.Objects;

import javax.script.ScriptEngine;

import javax.script.ScriptEngineFactory;

import jdk.nashorn.internal.runtime.Context;

import jdk.nashorn.internal.runtime.Version;

/**

 * JSR-223 compliant script engine factory for Nashorn. The engine answers for:

 * <ul>

 * <li>names {@code "nashorn"}, {@code "Nashorn"}, {@code "js"}, {@code "JS"}, {@code "JavaScript"},

 * {@code "javascript"}, {@code "ECMAScript"}, and {@code "ecmascript"};</li>

 * <li>MIME types {@code "application/javascript"}, {@code "application/ecmascript"}, {@code "text/javascript"}, and

 * {@code "text/ecmascript"};</li>

 * <li>as well as for the extension {@code "js"}.</li>

 * </ul>

 * Programs executing in engines created using {@link #getScriptEngine(String[])} will have the passed arguments

 * accessible as a global variable named {@code "arguments"}.

 *

 * @since 1.8u40

 */

public final class NashornScriptEngineFactory implements ScriptEngineFactory {

    @Override

    public String getEngineName() {

        return (String) getParameter(ScriptEngine.ENGINE);

    }

    @Override

    public String getEngineVersion() {

        return (String) getParameter(ScriptEngine.ENGINE_VERSION);

    }

    @Override

    public List<String> getExtensions() {

        return Collections.unmodifiableList(extensions);

    }

    @Override

    public String getLanguageName() {

        return (String) getParameter(ScriptEngine.LANGUAGE);

    }

    @Override

    public String getLanguageVersion() {

        return (String) getParameter(ScriptEngine.LANGUAGE_VERSION);

    }

    @Override

    public String getMethodCallSyntax(final String obj, final String method, final String... args) {

        final StringBuilder sb = new StringBuilder().

            append(Objects.requireNonNull(obj)).append('.').

            append(Objects.requireNonNull(method)).append('(');

        final int len = args.length;

        if (len > 0) {

            sb.append(Objects.requireNonNull(args[0]));

        }

        for (int i = 1; i < len; i++) {

            sb.append(',').append(Objects.requireNonNull(args[i]));

        }

        sb.append(')');

        return sb.toString();

    }

    @Override

    public List<String> getMimeTypes() {

        return Collections.unmodifiableList(mimeTypes);

    }

    @Override

    public List<String> getNames() {

        return Collections.unmodifiableList(names);

    }

    @Override

    public String getOutputStatement(final String toDisplay) {

        return "print(" + toDisplay + ")";

    }

    @Override

    public Object getParameter(final String key) {

        switch (key) {

        case ScriptEngine.NAME:

            return "javascript";

        case ScriptEngine.ENGINE:

            return "Oracle Nashorn";

        case ScriptEngine.ENGINE_VERSION:

            return Version.version();

        case ScriptEngine.LANGUAGE:

            return "ECMAScript";

        case ScriptEngine.LANGUAGE_VERSION:

            return "ECMA - 262 Edition 5.1";

        case "THREADING":

            // The engine implementation is not thread-safe. Can't be

            // used to execute scripts concurrently on multiple threads.

            return null;

        default:

            return null;

        }

    }

    @Override

    public String getProgram(final String... statements) {

        Objects.requireNonNull(statements);

        final StringBuilder sb = new StringBuilder();

        for (final String statement : statements) {

            sb.append(Objects.requireNonNull(statement)).append(';');

        }

        return sb.toString();

    }

    // default options passed to Nashorn script engine

    private static final String[] DEFAULT_OPTIONS = new String[] { "-doe" };

    @Override

    public ScriptEngine getScriptEngine() {

        try {

            return new NashornScriptEngine(this, DEFAULT_OPTIONS, getAppClassLoader(), null);

        } catch (final RuntimeException e) {

            if (Context.DEBUG) {

                e.printStackTrace();

            }

            throw e;

        }

    }

    /**

     * Create a new Script engine initialized with the given class loader.

     *

     * @param appLoader class loader to be used as script "app" class loader.

     * @return newly created script engine.

     * @throws SecurityException

     *         if the security manager's {@code checkPermission}

     *         denies {@code RuntimePermission("nashorn.setConfig")}

     */

    public ScriptEngine getScriptEngine(final ClassLoader appLoader) {

        return newEngine(DEFAULT_OPTIONS, appLoader, null);

    }

    /**

     * Create a new Script engine initialized with the given class filter.

     *

     * @param classFilter class filter to use.

     * @return newly created script engine.

     * @throws NullPointerException if {@code classFilter} is {@code null}

     * @throws SecurityException

     *         if the security manager's {@code checkPermission}

     *         denies {@code RuntimePermission("nashorn.setConfig")}

     */

    public ScriptEngine getScriptEngine(final ClassFilter classFilter) {

        return newEngine(DEFAULT_OPTIONS, getAppClassLoader(), Objects.requireNonNull(classFilter));

    }

    /**

     * Create a new Script engine initialized with the given arguments.

     *

     * @param args arguments array passed to script engine.

     * @return newly created script engine.

     * @throws NullPointerException if {@code args} is {@code null}

     * @throws SecurityException

     *         if the security manager's {@code checkPermission}

     *         denies {@code RuntimePermission("nashorn.setConfig")}

     */

    public ScriptEngine getScriptEngine(final String... args) {

        return newEngine(Objects.requireNonNull(args), getAppClassLoader(), null);

    }

    /**

     * Create a new Script engine initialized with the given arguments and the given class loader.

     *

     * @param args arguments array passed to script engine.

     * @param appLoader class loader to be used as script "app" class loader.

     * @return newly created script engine.

     * @throws NullPointerException if {@code args} is {@code null}

     * @throws SecurityException

     *         if the security manager's {@code checkPermission}

     *         denies {@code RuntimePermission("nashorn.setConfig")}

     */

    public ScriptEngine getScriptEngine(final String[] args, final ClassLoader appLoader) {

        return newEngine(Objects.requireNonNull(args), appLoader, null);

    }

    /**

     * Create a new Script engine initialized with the given arguments, class loader and class filter.

     *

     * @param args arguments array passed to script engine.

     * @param appLoader class loader to be used as script "app" class loader.

     * @param classFilter class filter to use.

     * @return newly created script engine.

     * @throws NullPointerException if {@code args} or {@code classFilter} is {@code null}

     * @throws SecurityException

     *         if the security manager's {@code checkPermission}

     *         denies {@code RuntimePermission("nashorn.setConfig")}

     */

    public ScriptEngine getScriptEngine(final String[] args, final ClassLoader appLoader, final ClassFilter classFilter) {

        return newEngine(Objects.requireNonNull(args), appLoader, Objects.requireNonNull(classFilter));

    }

    private ScriptEngine newEngine(final String[] args, final ClassLoader appLoader, final ClassFilter classFilter) {

        checkConfigPermission();

        try {

            return new NashornScriptEngine(this, args, appLoader, classFilter);

        } catch (final RuntimeException e) {

            if (Context.DEBUG) {

                e.printStackTrace();

            }

            throw e;

        }

    }

    // -- Internals only below this point

    private static void checkConfigPermission() {

        final SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(new RuntimePermission(Context.NASHORN_SET_CONFIG));

        }

    }

    private static final List<String> names;

    private static final List<String> mimeTypes;

    private static final List<String> extensions;

    static {

        names = immutableList(

                    "nashorn", "Nashorn",

                    "js", "JS",

                    "JavaScript", "javascript",

                    "ECMAScript", "ecmascript"

                );

        mimeTypes = immutableList(

                        "application/javascript",

                        "application/ecmascript",

                        "text/javascript",

                        "text/ecmascript"

                    );

        extensions = immutableList("js");

    }

    private static List<String> immutableList(final String... elements) {

        return Collections.unmodifiableList(Arrays.asList(elements));

    }

    private static ClassLoader getAppClassLoader() {

        // Revisit: script engine implementation needs the capability to

        // find the class loader of the context in which the script engine

        // is running so that classes will be found and loaded properly

        final ClassLoader ccl = Thread.currentThread().getContextClassLoader();

        return (ccl == null)? NashornScriptEngineFactory.class.getClassLoader() : ccl;

    }

}