/*
 * Copyright 2012 LinkedIn, 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.linkedin.parseq.example.common;

import java.io.IOException;
import java.util.Map;
import java.util.Random;

import com.linkedin.parseq.Task;
import com.linkedin.parseq.trace.TraceUtil;


/**
 * @author Chris Pettitt (cpettitt@linkedin.com)
 */
public class ExampleUtil {
  private static final Random RANDOM = new Random();
  private static final int DEFAULT_LATENCY_MEAN = 100;
  private static final int DEFAULT_LATENCY_STDDEV = 50;
  private static final int LATENCY_MIN = 10;

  private ExampleUtil() {
  }

  public static <K, RES> Task<RES> callService(final String name, final MockService<RES> service,
      final MockRequest<RES> request, K key) {
    if (service instanceof BatchableMockService) {
      BatchableMockService<RES> batchableService = (BatchableMockService<RES>)service;
      return batchableService.task(name, new MockRequestWithKey<K, RES>(key, request));
    } else {
      return Task.async(name, () -> service.call(request));
    }
  }

  public static <T> Task<T> fetch(String name, final MockService<T> service, final int id, final Map<Integer, T> map) {
    final long mean = DEFAULT_LATENCY_MEAN;
    final long stddev = DEFAULT_LATENCY_STDDEV;
    final long latency = Math.max(LATENCY_MIN, (int) (RANDOM.nextGaussian() * stddev + mean));
    final MockRequest<T> request = (map.containsKey(id)) ? new SimpleMockRequest<T>(latency, map.get(id))
        : new ErrorMockRequest<T>(latency, new Exception("404"));
    return callService("fetch" + name + "[id=" + id + "]", service, request, id);
  }

  public static Task<String> fetchUrl(final MockService<String> httpClient, final String url) {
    final long mean = DEFAULT_LATENCY_MEAN;
    final long stddev = DEFAULT_LATENCY_STDDEV;
    final long latency = Math.max(LATENCY_MIN, (int) (RANDOM.nextGaussian() * stddev + mean));
    return callService("fetch[url=" + url + "]", httpClient,
        new SimpleMockRequest<String>(latency, "HTTP response for " + url), url);
  }

  public static Task<String> fetchUrl(final MockService<String> httpClient, final String url, final long latency) {
    return callService("fetch[url=" + url + "]", httpClient,
        new SimpleMockRequest<String>(latency, "HTTP response for " + url), url);
  }

  public static Task<String> fetch404Url(final MockService<String> httpClient, final String url) {
    final long mean = DEFAULT_LATENCY_MEAN;
    final long stddev = DEFAULT_LATENCY_STDDEV;
    final long latency = Math.max(LATENCY_MIN, (int) (RANDOM.nextGaussian() * stddev + mean));
    return callService("fetch[url=" + url + "]", httpClient,
        new ErrorMockRequest<String>(latency, new Exception(url + ": 404")), url);
  }

  public static void printTracingResults(final Task<?> task) {
    System.out.println();
    System.out.println();
    System.out.println("JSON Trace:");

    try {
      System.out.println(TraceUtil.getJsonTrace(task));
    } catch (IOException e) {
      System.err.println("Failed to encode JSON");
    }
    System.out.println();
  }
}