/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 sample;

import java.io.IOException;
import java.net.URL;
import java.util.Date;
import java.util.Stack;

import org.oasisopen.sca.annotation.EagerInit;
import org.oasisopen.sca.annotation.Init;
import org.oasisopen.sca.annotation.Reference;
import org.oasisopen.sca.annotation.Scope;
import org.oasisopen.sca.annotation.Service;

import com.google.appengine.api.datastore.DatastoreService;
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 com.google.appengine.api.datastore.Transaction;
import com.google.appengine.api.memcache.Expiration;
import com.google.appengine.api.memcache.MemcacheService;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.appengine.api.urlfetch.URLFetchService;
import com.google.appengine.api.users.User;
import com.google.appengine.api.users.UserService;

@EagerInit
@Scope("COMPOSITE")
@Service(HelloworldService.class)
public class HelloworldServiceImpl implements HelloworldService {
    @Reference
    protected UserService userService;

    @Reference
    protected URLFetchService fetchService;

    @Reference
    protected MemcacheService memcacheService;

    @Reference
    protected DatastoreService datastoreService;

    public String sayHello(String name) {
        User user = userService.getCurrentUser();
        String id = (user == null) ? "" : user.getUserId();

        Stack<String> stack = cacheHistory(name);

        Long count = countInStore();

        String content = fetch();
        return "[" + id
            + "] Hello "
            + name
            + "<hr><h2>Content from Tuscany Web Site via URLFetch</h2><p>"
            + content
            + "<p>"
            + toHTML(stack)
            + "</p><b>Counter from DataStore: "
            + count
            + "</b><p>";
    }

    private String fetch() {
        String content = "";
        try {
            HTTPResponse response = fetchService.fetch(new URL("http://tuscany.apache.org"));
            content = new String(response.getContent(), 0, 1024);
            content = content.replace("<", "&lt;");
            content = content.replace(">", "&gt;");
            content = content.replace("\"", "&quot;");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return content;
    }

    private Long countInStore() {
        Transaction tx = datastoreService.beginTransaction();
        Entity entity = null;
        Key key = KeyFactory.createKey("HitCounter", "counter");
        try {
            entity = datastoreService.get(tx, key);
        } catch (EntityNotFoundException e1) {
            entity = new Entity(key);
            entity.setProperty("counter", new Long(0));
        }

        Long count = (Long)entity.getProperty("counter");
        count = new Long(count.longValue() + 1);
        entity.setProperty("counter", count);

        datastoreService.put(tx, entity);
        tx.commit();
        return count;
    }

    private Stack<String> cacheHistory(String name) {
        Stack<String> stack = (Stack<String>)memcacheService.get("history");
        if (stack == null) {
            stack = new Stack<String>();
        }
        stack.push(new Date().toString() + ": " + name);
        memcacheService.put("history", stack, Expiration.byDeltaSeconds(60));
        return stack;
    }

    private String toHTML(Stack<String> stack) {
        StringBuffer html = new StringBuffer("<h2>History from Memcache (expired in 1 minute)</h2><hr><ul>");
        for (String item : stack) {
            html.append("<li>").append(item).append("</li>");
        }
        html.append("</ul><hr>");
        return html.toString();
    }

    @Init
    public void init() {
        System.out.println("Starting...");
    }

}