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/**
 * Copyright (C) 2010 Mycila ([email protected])
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.inject.servlet;

import com.google.inject.AbstractModule;
import com.google.inject.Provider;
import com.google.inject.Provides;
import com.google.inject.Singleton;

import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.Map;
import java.util.logging.Logger;

import static com.google.inject.servlet.ServletScopes.REQUEST;
import static com.google.inject.servlet.ServletScopes.SESSION;

/**
 * This is a left-factoring of all ServletModules installed in the system.
 * In other words, this module contains the bindings common to all ServletModules,
 * and is bound exactly once per injector.
 *
 * @author [email protected] (Dhanji R. Prasanna)
 */
final class InternalServletModule extends AbstractModule {

    /**
     * Special Provider that tries to obtain an injected servlet context, specific
     * to the current injector, failing which, it falls back to the static singleton
     * instance that is available in the legacy Guice Servlet.
     */
    @Singleton
    static class BackwardsCompatibleServletContextProvider implements Provider {
        private ServletContext injectedServletContext;

        // This setter is called by the GuiceServletContextListener
        void set(ServletContext injectedServletContext) {
            this.injectedServletContext = injectedServletContext;
        }

        public ServletContext get() {
            if (null != injectedServletContext) {
                return injectedServletContext;
            }

            Logger.getLogger(InternalServletModule.class.getName())
                .warning("You are attempting to use a deprecated API (specifically,"
                    + " attempting to @Inject ServletContext inside an eagerly created"
                    + " singleton. While we allow this for backwards compatibility, be"
                    + " warned that this MAY have unexpected behavior if you have more"
                    + " than one injector (with ServletModule) running in the same JVM."
                    + " Please consult the Guice documentation at"
                    + " http://code.google.com/p/google-guice/wiki/Servlets for more"
                    + " information.");
            return GuiceFilter.getServletContext();
        }
    }

    @Override
    protected void configure() {
        bindScope(RequestScoped.class, REQUEST);
        bindScope(SessionScoped.class, SESSION);
        bind(ServletRequest.class).to(HttpServletRequest.class);
        bind(ServletResponse.class).to(HttpServletResponse.class);

        // inject the pipeline into GuiceFilter so it can route requests correctly
        // Unfortunate staticness... =(
        // NOTE(dhanji): This is maintained for legacy purposes.
        requestStaticInjection(GuiceFilter.class);

        bind(ManagedFilterPipeline.class);
        bind(ManagedServletPipeline.class);
        bind(FilterPipeline.class).to(ManagedFilterPipeline.class).asEagerSingleton();

        bind(ServletContext.class).toProvider(BackwardsCompatibleServletContextProvider.class);
    }

    @Provides
    @RequestScoped
    HttpServletRequest provideHttpServletRequest() {
        return GuiceFilter.getRequest();
    }

    @Provides
    @RequestScoped
    HttpServletResponse provideHttpServletResponse() {
        return GuiceFilter.getResponse();
    }

    @Provides
    HttpSession provideHttpSession() {
        return GuiceFilter.getRequest().getSession();
    }

    @SuppressWarnings({"unchecked"})
    @Provides
    @RequestScoped
    @RequestParameters
    Map provideRequestParameters() {
        return GuiceFilter.getRequest().getParameterMap();
    }

    @Override
    public boolean equals(Object o) {
        // Is only ever installed internally, so we don't need to check state.
        return o instanceof InternalServletModule;
    }

    @Override
    public int hashCode() {
        return InternalServletModule.class.hashCode();
    }
}