/*
    * Copyright 2016 The Lannister 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 net.anyflow.lannister.httphandler.api;
  
  import java.util.stream.Collectors;
  
  import com.fasterxml.jackson.core.JsonProcessingException;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.google.common.base.Strings;
  
  import io.netty.handler.codec.http.HttpResponseStatus;
  import net.anyflow.lannister.http.HttpRequestHandler;
  import net.anyflow.lannister.topic.Topic;
  
  @HttpRequestHandler.Handles(paths = { "api/topics" }, httpMethods = { "GET" })
  public class Topics extends HttpRequestHandler {
  
  	private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(Topics.class);
  
  	@Override
  	public String service() {
  		String filter = Strings.nullToEmpty(httpRequest().parameter("filter"));
  
  		switch (filter) {
  		case "":
  		case "all":
  			return all();
  		case "nosys":
  			return nosys();
  
  		default:
  			return null;
  		}
  	}
  
  	private String all() {
  		try {
  			return new ObjectMapper().writeValueAsString(
  					Topic.NEXUS.keySet().stream().map(key -> Topic.NEXUS.get(key)).collect(Collectors.toList()));
  		}
  		catch (JsonProcessingException e) {
  			logger.error(e.getMessage(), e);
  
  			this.httpResponse().setStatus(HttpResponseStatus.INTERNAL_SERVER_ERROR);
  			return null;
  		}
  	}
  
  	private String nosys() {
  		try {
  			return new ObjectMapper()
  					.writeValueAsString(Topic.NEXUS.keySet().stream().filter(topicName -> !topicName.startsWith("$SYS"))
  							.map(key -> Topic.NEXUS.get(key)).collect(Collectors.toList()));
  		}
  		catch (JsonProcessingException e) {
  			logger.error(e.getMessage(), e);
  			return null;
  		}
  	}
  }