/*
 * Copyright 2012 Google Inc.
 *
 * 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.android.apps.iosched.gcm.server;

import com.google.appengine.api.datastore.DatastoreService;
import com.google.appengine.api.datastore.DatastoreServiceFactory;
import com.google.appengine.api.datastore.Entity;
import com.google.appengine.api.datastore.EntityNotFoundException;
import com.google.appengine.api.datastore.Key;
import com.google.appengine.api.datastore.KeyFactory;

import java.util.logging.Logger;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * Context initializer that loads the API key from the App Engine datastore.
 */
public class ApiKeyInitializer implements ServletContextListener {
    private final Logger logger = Logger.getLogger(ApiKeyInitializer.class.getSimpleName());

    // Don't actually hard code your key here; rather, edit the entity in the App Engine console.
    static final String FAKE_API_KEY = "ENTER_KEY_HERE";

    static final String ATTRIBUTE_ACCESS_KEY = "apiKey";

    private static final String ENTITY_KIND = "Settings";
    private static final String ENTITY_KEY = "MyKey";
    private static final String ACCESS_KEY_FIELD = "ApiKey";

    @Override
    public void contextInitialized(ServletContextEvent event) {
        DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
        Key key = KeyFactory.createKey(ENTITY_KIND, ENTITY_KEY);

        Entity entity;
        try {
            entity = datastore.get(key);
        } catch (EntityNotFoundException e) {
            entity = new Entity(key);
            // NOTE: it's not possible to change entities in the local server, so
            // it will be necessary to hardcode the API key below if you are running
            // it locally.
            entity.setProperty(ACCESS_KEY_FIELD, FAKE_API_KEY);
            datastore.put(entity);
            logger.severe("Created fake key. Please go to App Engine admin "
                    + "console, change its value to your API Key (the entity "
                    + "type is '" + ENTITY_KIND + "' and its field to be changed is '"
                    + ACCESS_KEY_FIELD + "'), then restart the server!");
        }
        String accessKey = (String) entity.getProperty(ACCESS_KEY_FIELD);
        event.getServletContext().setAttribute(ATTRIBUTE_ACCESS_KEY, accessKey);
    }

    /**
     * Gets the access key.
     */
    protected String getKey() {
        DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
        Key key = KeyFactory.createKey(ENTITY_KIND, ENTITY_KEY);
        String apiKey = "";
        try {
            Entity entity = datastore.get(key);
            apiKey = (String) entity.getProperty(ACCESS_KEY_FIELD);
        } catch (EntityNotFoundException e) {
            logger.severe("Exception while retrieving the API Key" + e.toString());
        }
        return apiKey;
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
    }
}