/**

  * HTML via Java(tm) Language Bindings

  * Copyright (C) 2013 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, version 2 of the License.

  *

  * This program 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 for more details. apidesign.org

  * designates this particular file as subject to the

  * "Classpath" exception as provided by apidesign.org

  * in the License file that accompanied this code.

  *

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

  * along with this program. Look for COPYING file in the top folder.

  * If not, see http://wiki.apidesign.org/wiki/GPLwithClassPathException

  */

 package net.java.html;

 import java.util.HashMap;

 import java.util.Map;

 import java.util.ServiceLoader;

 import org.apidesign.html.context.impl.CtxAccssr;

 import org.apidesign.html.context.impl.CtxImpl;

 import org.apidesign.html.context.spi.Contexts;

 /** Represents context where the <code>net.java.html.json.Model</code>

  * and other objects

  * operate in. The context is usually a particular HTML page in a browser.

  * The context is also associated with the actual HTML technology

  * in the HTML page - there is likely to be different context for 

  * <a href="http://knockoutjs.com">knockout.js</a> and different one

  * for <a href="http://angularjs.org">angular</a>.

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  */

 public final class BrwsrCtx {

     private final CtxImpl impl;

     private BrwsrCtx(CtxImpl impl) {

         this.impl = impl;

     }

     static {

         new CtxAccssr() {

             @Override

             protected BrwsrCtx newContext(CtxImpl impl) {

                 return new BrwsrCtx(impl);

             }

             @Override

             protected CtxImpl find(BrwsrCtx context) {

                 return context.impl;

             }

         };

     }

     /** Dummy context without binding to any real browser or technology. 

      * Useful for simple unit testing of behavior of various business logic

      * code.

      */

     public static final BrwsrCtx EMPTY = Contexts.newBuilder().build();

     /** map of known classloaders and their contexts */

     private static final Map<ClassLoader,BrwsrCtx> CTXS = new HashMap<ClassLoader, BrwsrCtx>();

     /** Seeks for the default context that is associated with the requesting

      * class. If no suitable context is found, a warning message is

      * printed and {@link #EMPTY} context is returned.

      * 

      * @param requestor the class that makes the request

      * @return appropriate context for the request

      */

     public static BrwsrCtx findDefault(Class<?> requestor) {

         org.apidesign.html.context.spi.Contexts.Builder cb = Contexts.newBuilder();

         boolean found = false;

         ClassLoader l;

         try {

             l = requestor.getClassLoader();

         } catch (SecurityException ex) {

             l = null;

         }

         synchronized (CTXS) {

             BrwsrCtx c = CTXS.get(l);

             if (c != null) {

                 return c;

             }

         }

         for (org.apidesign.html.context.spi.Contexts.Provider cp : ServiceLoader.load(

             org.apidesign.html.context.spi.Contexts.Provider.class, l

         )) {

             cp.fillContext(cb, requestor);

             found = true;

         }

         try {

             for (org.apidesign.html.context.spi.Contexts.Provider cp : ServiceLoader.load(org.apidesign.html.context.spi.Contexts.Provider.class, org.apidesign.html.context.spi.Contexts.Provider.class.getClassLoader())) {

                 cp.fillContext(cb, requestor);

                 found = true;

             }

         } catch (SecurityException ex) {

             if (!found) {

                 throw ex;

             }

             // if we have some data from regular provides, go on

         }

         if (!found) {

             // XXX: print out a warning

             return EMPTY;

         }

         BrwsrCtx c = cb.build();

         synchronized (CTXS) {

             CTXS.put(l, c);

         }

         return c;

     }

 }