/*
 * GNU LESSER GENERAL PUBLIC LICENSE Copyright (C) 2006 The Lobo Project
 * 
 * This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 * 
 * Contact info: xamjadmin@users.sourceforge.net
 */
package org.cobra_grendel.html.js;

import java.util.logging.Level;
import java.util.logging.Logger;

import org.cobra_grendel.html.UserAgentContext;
import org.cobra_grendel.html.domimpl.NodeImpl;
import org.cobra_grendel.js.JavaScript;
import org.mozilla.javascript.Context;
import org.mozilla.javascript.Function;
import org.mozilla.javascript.Scriptable;
import org.mozilla.javascript.ScriptableObject;
import org.w3c.dom.Document;

public class Executor
{
    /**
     * A document <code>UserData</code> key used to map Javascript scope in the HTML document.
     */
    public static final String SCOPE_KEY = "cobra.js.scope";

    private static final Logger logger = Logger.getLogger(Executor.class.getName());

    /**
     * This method should be invoked instead of <code>Context.enter</code>.
     * 
     * @param codeSource
     * @param ucontext
     */
    public static Context createContext(final java.net.URL codeSource, final UserAgentContext ucontext)
    {
        Context prev = Context.getCurrentContext();
        Context ctx = Context.enter();
        ctx.setOptimizationLevel(ucontext.getScriptingOptimizationLevel());
        if (prev == null)
        {
            // If there was a previous context, this one must be nested.
            // We still need to create a context because of exit() but
            // we cannot set a new security controller.
            ctx.setSecurityController(new SecurityControllerImpl(codeSource, ucontext.getSecurityPolicy()));
        }
        return ctx;
    }

    public static boolean executeFunction(final NodeImpl element, final Function f, final Event event)
    {
        return Executor.executeFunction(element, element, f, event);
    }

    public static boolean executeFunction(final NodeImpl element, final Object thisObject, final Function f, final Event event)
    {
        Document doc = element.getOwnerDocument();
        if (doc == null)
        {
            throw new IllegalStateException("Element does not belong to a document.");
        }
        Context ctx = createContext(element.getDocumentURL(), element.getUserAgentContext());
        try
        {
            Scriptable scope = (Scriptable) doc.getUserData(Executor.SCOPE_KEY);
            if (scope == null)
            {
                throw new IllegalStateException("Scriptable (scope) instance was expected to be keyed as UserData to document using " + Executor.SCOPE_KEY);
            }
            JavaScript js = JavaScript.getInstance();
            Scriptable thisScope = (Scriptable) js.getJavascriptObject(thisObject, scope);
            try
            {
                Scriptable eventScriptable = (Scriptable) js.getJavascriptObject(event, thisScope);
                ScriptableObject.defineProperty(thisScope, "event", eventScriptable, ScriptableObject.READONLY);
                Object result = f.call(ctx, thisScope, thisScope, new Object[0]);
                if (!(result instanceof Boolean))
                {
                    return true;
                }
                return ((Boolean) result).booleanValue();
            }
            catch (Exception thrown)
            {
                logger.log(Level.WARNING, "executeFunction(): There was an error in Javascript code.", thrown);
                return true;
            }
        }
        finally
        {
            Context.exit();
        }
    }

    public static boolean executeFunction(final Scriptable thisScope, final Function f, final java.net.URL codeSource, final UserAgentContext ucontext)
    {
        Context ctx = createContext(codeSource, ucontext);
        try
        {
            try
            {
                Object result = f.call(ctx, thisScope, thisScope, new Object[0]);
                if (!(result instanceof Boolean))
                {
                    return true;
                }
                return ((Boolean) result).booleanValue();
            }
            catch (Exception err)
            {
                logger.log(Level.WARNING, "executeFunction(): Unable to execute Javascript function " + f.getClassName() + ".", err);
                return true;
            }
        }
        finally
        {
            Context.exit();
        }
    }
}