/*

 * 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.script.javascript;

import com.sun.script.util.*;

import javax.script.*;

import sun.org.mozilla.javascript.internal.*;

import java.lang.reflect.Method;

import java.io.*;

import java.util.*;

/**

 * Implementation of <code>ScriptEngine</code> using the Mozilla Rhino

 * interpreter.

 *

 * @author Mike Grogan

 * @author A. Sundararajan

 * @since 1.6

 */

public final class RhinoScriptEngine extends AbstractScriptEngine

        implements  Invocable, Compilable {

    private static final boolean DEBUG = false;

    /* Scope where standard JavaScript objects and our

     * extensions to it are stored. Note that these are not

     * user defined engine level global variables. These are

     * variables have to be there on all compliant ECMAScript

     * scopes. We put these standard objects in this top level.

     */

    private RhinoTopLevel topLevel;

    /* map used to store indexed properties in engine scope

     * refer to comment on 'indexedProps' in ExternalScriptable.java.

     */

    private Map<Object, Object> indexedProps;

    private ScriptEngineFactory factory;

    private InterfaceImplementor implementor;

    private static final int languageVersion = getLanguageVersion();

    private static final int optimizationLevel = getOptimizationLevel();

    static {

        ContextFactory.initGlobal(new ContextFactory() {

            protected Context makeContext() {

                Context cx = super.makeContext();

                cx.setLanguageVersion(languageVersion);

                cx.setOptimizationLevel(optimizationLevel);

                cx.setClassShutter(RhinoClassShutter.getInstance());

                cx.setWrapFactory(RhinoWrapFactory.getInstance());

                return cx;

            }

        });

    }

    private static final String RHINO_JS_VERSION = "rhino.js.version";

    private static int getLanguageVersion() {

        int version;

        String tmp = java.security.AccessController.doPrivileged(

            new sun.security.action.GetPropertyAction(RHINO_JS_VERSION));

        if (tmp != null) {

            version = Integer.parseInt((String)tmp);

        } else {

            version = Context.VERSION_1_8;

        }

        return version;

    }

    private static final String RHINO_OPT_LEVEL = "rhino.opt.level";

    private static int getOptimizationLevel() {

        int optLevel = -1;

        // disable optimizer under security manager, for now.

        if (System.getSecurityManager() == null) {

            optLevel = Integer.getInteger(RHINO_OPT_LEVEL, -1);

        }

        return optLevel;

    }

    /**

     * Creates a new instance of RhinoScriptEngine

     */

    public RhinoScriptEngine() {

        Context cx = enterContext();

        try {

            topLevel = new RhinoTopLevel(cx, this);

        } finally {

            cx.exit();

        }

        indexedProps = new HashMap<Object, Object>();

        //construct object used to implement getInterface

        implementor = new InterfaceImplementor(this) {

                protected boolean isImplemented(Object thiz, Class<?> iface) {

                    Context cx = enterContext();

                    try {

                        if (thiz != null && !(thiz instanceof Scriptable)) {

                            thiz = cx.toObject(thiz, topLevel);

                        }

                        Scriptable engineScope = getRuntimeScope(context);

                        Scriptable localScope = (thiz != null)? (Scriptable) thiz :

                                                    engineScope;

                        for (Method method : iface.getMethods()) {

                            // ignore methods of java.lang.Object class

                            if (method.getDeclaringClass() == Object.class) {

                                continue;

                            }

                            Object obj = ScriptableObject.getProperty(localScope, method.getName());

                            if (! (obj instanceof Function)) {

                                return false;

                            }

                        }

                        return true;

                    } finally {

                        cx.exit();

                    }

                }

                protected Object convertResult(Method method, Object res)

                                            throws ScriptException {

                    Class desiredType = method.getReturnType();

                    if (desiredType == Void.TYPE) {

                        return null;

                    } else {

                        return Context.jsToJava(res, desiredType);

                    }

                }

            };

    }

    public Object eval(Reader reader, ScriptContext ctxt)

    throws ScriptException {

        Object ret;

        Context cx = enterContext();

        try {

            Scriptable scope = getRuntimeScope(ctxt);

            String filename = (String) get(ScriptEngine.FILENAME);

            filename = filename == null ? "<Unknown source>" : filename;

            ret = cx.evaluateReader(scope, reader, filename , 1,  null);

        } catch (RhinoException re) {

            if (DEBUG) re.printStackTrace();

            int line = (line = re.lineNumber()) == 0 ? -1 : line;

            String msg;

            if (re instanceof JavaScriptException) {

                msg = String.valueOf(((JavaScriptException)re).getValue());

            } else {

                msg = re.toString();

            }

            ScriptException se = new ScriptException(msg, re.sourceName(), line);

            se.initCause(re);

            throw se;

        } catch (IOException ee) {

            throw new ScriptException(ee);

        } finally {

            cx.exit();

        }

        return unwrapReturnValue(ret);

    }

    public Object eval(String script, ScriptContext ctxt) throws ScriptException {

        if (script == null) {

            throw new NullPointerException("null script");

        }

        return eval(new StringReader(script) , ctxt);

    }

    public ScriptEngineFactory getFactory() {

        if (factory != null) {

            return factory;

        } else {

            return new RhinoScriptEngineFactory();

        }

    }

    public Bindings createBindings() {

        return new SimpleBindings();

    }

    //Invocable methods

    public Object invokeFunction(String name, Object... args)

    throws ScriptException, NoSuchMethodException {

        return invoke(null, name, args);

    }

    public Object invokeMethod(Object thiz, String name, Object... args)

    throws ScriptException, NoSuchMethodException {

        if (thiz == null) {

            throw new IllegalArgumentException("script object can not be null");

        }

        return invoke(thiz, name, args);

    }

    private Object invoke(Object thiz, String name, Object... args)

    throws ScriptException, NoSuchMethodException {

        Context cx = enterContext();

        try {

            if (name == null) {

                throw new NullPointerException("method name is null");

            }

            if (thiz != null && !(thiz instanceof Scriptable)) {

                thiz = cx.toObject(thiz, topLevel);

            }

            Scriptable engineScope = getRuntimeScope(context);

            Scriptable localScope = (thiz != null)? (Scriptable) thiz :

                                                    engineScope;

            Object obj = ScriptableObject.getProperty(localScope, name);

            if (! (obj instanceof Function)) {

                throw new NoSuchMethodException("no such method: " + name);

            }

            Function func = (Function) obj;

            Scriptable scope = func.getParentScope();

            if (scope == null) {

                scope = engineScope;

            }

            Object result = func.call(cx, scope, localScope,

                                      wrapArguments(args));

            return unwrapReturnValue(result);

        } catch (RhinoException re) {

            if (DEBUG) re.printStackTrace();

            int line = (line = re.lineNumber()) == 0 ? -1 : line;

            ScriptException se = new ScriptException(re.toString(), re.sourceName(), line);

            se.initCause(re);

            throw se;

        } finally {

            cx.exit();

        }

    }

    public <T> T getInterface(Class<T> clasz) {

        try {

            return implementor.getInterface(null, clasz);

        } catch (ScriptException e) {

            return null;

        }

    }

    public <T> T getInterface(Object thiz, Class<T> clasz) {

        if (thiz == null) {

            throw new IllegalArgumentException("script object can not be null");

        }

        try {

            return implementor.getInterface(thiz, clasz);

        } catch (ScriptException e) {

            return null;

        }

    }

    private static final String printSource =

            "function print(str, newline) {                \n" +

            "    if (typeof(str) == 'undefined') {         \n" +

            "        str = 'undefined';                    \n" +

            "    } else if (str == null) {                 \n" +

            "        str = 'null';                         \n" +

            "    }                                         \n" +

            "    var out = context.getWriter();            \n" +

            "    if (!(out instanceof java.io.PrintWriter))\n" +

            "        out = new java.io.PrintWriter(out);   \n" +

            "    out.print(String(str));                   \n" +

            "    if (newline) out.print('\\n');            \n" +

            "    out.flush();                              \n" +

            "}\n" +

            "function println(str) {                       \n" +

            "    print(str, true);                         \n" +

            "}";

    Scriptable getRuntimeScope(ScriptContext ctxt) {

        if (ctxt == null) {

            throw new NullPointerException("null script context");

        }

        // we create a scope for the given ScriptContext

        Scriptable newScope = new ExternalScriptable(ctxt, indexedProps);

        // Set the prototype of newScope to be 'topLevel' so that

        // JavaScript standard objects are visible from the scope.

        newScope.setPrototype(topLevel);

        // define "context" variable in the new scope

        newScope.put("context", newScope, ctxt);

        // define "print", "println" functions in the new scope

        Context cx = enterContext();

        try {

            cx.evaluateString(newScope, printSource, "print", 1, null);

        } finally {

            cx.exit();

        }

        return newScope;

    }

    //Compilable methods

    public CompiledScript compile(String script) throws ScriptException {

        return compile(new StringReader(script));

    }

    public CompiledScript compile(java.io.Reader script) throws ScriptException {

        CompiledScript ret = null;

        Context cx = enterContext();

        try {

            String fileName = (String) get(ScriptEngine.FILENAME);

            if (fileName == null) {

                fileName = "<Unknown Source>";

            }

            Scriptable scope = getRuntimeScope(context);

            Script scr = cx.compileReader(scope, script, fileName, 1, null);

            ret = new RhinoCompiledScript(this, scr);

        } catch (Exception e) {

            if (DEBUG) e.printStackTrace();

            throw new ScriptException(e);

        } finally {

            cx.exit();

        }

        return ret;

    }

    //package-private helpers

    static Context enterContext() {

        // call this always so that initializer of this class runs

        // and initializes custom wrap factory and class shutter.

        return Context.enter();

    }

    void setEngineFactory(ScriptEngineFactory fac) {

        factory = fac;

    }

    Object[] wrapArguments(Object[] args) {

        if (args == null) {

            return Context.emptyArgs;

        }

        Object[] res = new Object[args.length];

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

            res[i] = Context.javaToJS(args[i], topLevel);

        }

        return res;

    }

    Object unwrapReturnValue(Object result) {

        if (result instanceof Wrapper) {

            result = ( (Wrapper) result).unwrap();

        }

        return result instanceof Undefined ? null : result;

    }

    /*

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

        if (args.length == 0) {

            System.out.println("No file specified");

            return;

        }

        InputStreamReader r = new InputStreamReader(new FileInputStream(args[0]));

        ScriptEngine engine = new RhinoScriptEngine();

        engine.put("x", "y");

        engine.put(ScriptEngine.FILENAME, args[0]);

        engine.eval(r);

        System.out.println(engine.get("x"));

    }

    */

}