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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.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.inject.AbstractModule;
import com.google.inject.Key;
import com.google.inject.internal.UniqueAnnotations;

import javax.servlet.http.HttpServlet;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Builds the guice module that binds configured servlets, with their
 * wrapper ServletDefinitions. Is part of the binding EDSL. Very similar to
 * {@link FiltersModuleBuilder}.
 *
 * @author Dhanji R. Prasanna ([email protected])
 */
class ServletsModuleBuilder extends AbstractModule {
    private final List servletDefinitions = Lists.newArrayList();
    private final List servletInstanceEntries = Lists.newArrayList();

    //invoked on injector config
    @Override
    protected void configure() {
        // Create bindings for servlet instances
        for (ServletInstanceBindingEntry entry : servletInstanceEntries) {
            bind(entry.key).toInstance(entry.servlet);
        }

        // Ensure that servlets are not bound twice to the same pattern.
        Set servletUris = Sets.newHashSet();
        for (ServletDefinition servletDefinition : servletDefinitions) {
            if (servletUris.contains(servletDefinition.getPattern())) {
                addError("More than one servlet was mapped to the same URI pattern: "
                    + servletDefinition.getPattern());
            } else {
                bind(Key.get(ServletDefinition.class, UniqueAnnotations.create())).toProvider(servletDefinition);
                servletUris.add(servletDefinition.getPattern());
            }
        }
    }

    //the first level of the EDSL--
    public ServletModule.ServletKeyBindingBuilder serve(List urlPatterns) {
        return new ServletKeyBindingBuilderImpl(urlPatterns, UriPatternType.SERVLET);
    }

    public ServletModule.ServletKeyBindingBuilder serveRegex(List regexes) {
        return new ServletKeyBindingBuilderImpl(regexes, UriPatternType.REGEX);
    }

    private static class ServletInstanceBindingEntry {
        final Key key;
        final HttpServlet servlet;

        ServletInstanceBindingEntry(Key key, HttpServlet servlet) {
            this.key = key;
            this.servlet = servlet;
        }
    }

    //non-static inner class so it can access state of enclosing module class
    class ServletKeyBindingBuilderImpl implements ServletModule.ServletKeyBindingBuilder {
        private final List uriPatterns;
        private final UriPatternType uriPatternType;

        private ServletKeyBindingBuilderImpl(List uriPatterns, UriPatternType uriPatternType) {
            this.uriPatterns = uriPatterns;
            this.uriPatternType = uriPatternType;
        }

        public void with(Class servletKey) {
            with(Key.get(servletKey));
        }

        public void with(Key servletKey) {
            with(servletKey, new HashMap());
        }

        public void with(HttpServlet servlet) {
            with(servlet, new HashMap());
        }

        public void with(Class servletKey,
                         Map initParams) {
            with(Key.get(servletKey), initParams);
        }

        public void with(Key servletKey,
                         Map initParams) {
            with(servletKey, initParams, null);
        }

        private void with(Key servletKey,
                          Map initParams,
                          HttpServlet servletInstance) {
            for (String pattern : uriPatterns) {
                servletDefinitions.add(
                    new ServletDefinition(pattern, servletKey, UriPatternType.get(uriPatternType, pattern),
                        initParams, servletInstance));
            }
        }

        public void with(HttpServlet servlet,
                         Map initParams) {
            Key servletKey = Key.get(HttpServlet.class, UniqueAnnotations.create());
            servletInstanceEntries.add(new ServletInstanceBindingEntry(servletKey, servlet));
            with(servletKey, initParams, servlet);
        }
    }
}