// Copyright (C) 2012 The Android Open Source Project
//
// 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.gerrit.httpd.plugins;

import static com.google.common.base.Preconditions.checkState;
import static com.google.gerrit.server.plugins.AutoRegisterUtil.calculateBindAnnotation;

import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.gerrit.extensions.annotations.Export;
import com.google.gerrit.extensions.registration.DynamicSet;
import com.google.gerrit.extensions.webui.JavaScriptPlugin;
import com.google.gerrit.extensions.webui.WebUiPlugin;
import com.google.gerrit.server.plugins.HttpModuleGenerator;
import com.google.gerrit.server.plugins.InvalidPluginException;
import com.google.inject.Module;
import com.google.inject.Scopes;
import com.google.inject.TypeLiteral;
import com.google.inject.servlet.ServletModule;

import java.lang.annotation.Annotation;
import java.util.Map;

import javax.servlet.http.HttpServlet;

class HttpAutoRegisterModuleGenerator extends ServletModule
    implements HttpModuleGenerator {
  private final Map<String, Class<HttpServlet>> serve = Maps.newHashMap();
  private final Multimap<TypeLiteral<?>, Class<?>> listeners = LinkedListMultimap.create();
  private String javascript;

  @Override
  protected void configureServlets() {
    for (Map.Entry<String, Class<HttpServlet>> e : serve.entrySet()) {
      bind(e.getValue()).in(Scopes.SINGLETON);
      serve(e.getKey()).with(e.getValue());
    }
    for (Map.Entry<TypeLiteral<?>, Class<?>> e : listeners.entries()) {
      @SuppressWarnings("unchecked")
      TypeLiteral<Object> type = (TypeLiteral<Object>) e.getKey();

      @SuppressWarnings("unchecked")
      Class<Object> impl = (Class<Object>) e.getValue();

      Annotation n = calculateBindAnnotation(impl);
      bind(type).annotatedWith(n).to(impl);
    }
    if (javascript != null) {
      DynamicSet.bind(binder(), WebUiPlugin.class).toInstance(
          new JavaScriptPlugin(javascript));
    }
  }

  @Override
  public void setPluginName(String name) {
  }

  @SuppressWarnings("unchecked")
  @Override
  public void export(Export export, Class<?> type)
      throws InvalidPluginException {
    if (HttpServlet.class.isAssignableFrom(type)) {
      Class<HttpServlet> old = serve.get(export.value());
      if (old != null) {
        throw new InvalidPluginException(String.format(
            "@Export(\"%s\") has duplicate bindings:\n  %s\n  %s",
            export.value(), old.getName(), type.getName()));
      }
      serve.put(export.value(), (Class<HttpServlet>) type);
    } else {
      throw new InvalidPluginException(String.format(
          "Class %s with @Export(\"%s\") must extend %s",
          type.getName(), export.value(),
          HttpServlet.class.getName()));
    }
  }

  @Override
  public void export(String javascript) {
    checkState(this.javascript == null,
        "Multiple JavaScript plugins detected: %s, %s", this.javascript,
        javascript);
    this.javascript = javascript;
  }

  @Override
  public void listen(TypeLiteral<?> tl, Class<?> clazz) {
    listeners.put(tl, clazz);
  }

  @Override
  public Module create() throws InvalidPluginException {
    return this;
  }
}