/**

 * 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;

    }

}