JsonConfigurator.java

/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.guice;

import com.fasterxml.jackson.annotation.JacksonInject;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.introspect.AnnotatedField;
import com.fasterxml.jackson.databind.introspect.BeanPropertyDefinition;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Function;
import com.google.common.base.Strings;
import com.google.common.base.Throwables;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.inject.Inject;
import com.google.inject.ProvisionException;
import com.google.inject.spi.Message;
import io.druid.java.util.common.StringUtils;
import io.druid.java.util.common.logger.Logger;

import javax.validation.ConstraintViolation;
import javax.validation.ElementKind;
import javax.validation.Path;
import javax.validation.Validator;
import java.io.IOException;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

/**
 */
public class JsonConfigurator
{
  private static final Logger log = new Logger(JsonConfigurator.class);

  private final ObjectMapper jsonMapper;
  private final Validator validator;

  @Inject
  public JsonConfigurator(
      ObjectMapper jsonMapper,
      Validator validator
  )
  {
    this.jsonMapper = jsonMapper;
    this.validator = validator;
  }

  public <T> T configurate(Properties props, String propertyPrefix, Class<T> clazz) throws ProvisionException
  {
    verifyClazzIsConfigurable(jsonMapper, clazz);

    // Make it end with a period so we only include properties with sub-object thingies.
    final String propertyBase = propertyPrefix.endsWith(".") ? propertyPrefix : propertyPrefix + ".";

    Map<String, Object> jsonMap = Maps.newHashMap();
    for (String prop : props.stringPropertyNames()) {
      if (prop.startsWith(propertyBase)) {
        final String propValue = props.getProperty(prop);
        Object value;
        try {
          // If it's a String Jackson wants it to be quoted, so check if it's not an object or array and quote.
          String modifiedPropValue = propValue;
          if (!(modifiedPropValue.startsWith("[") || modifiedPropValue.startsWith("{"))) {
            modifiedPropValue = jsonMapper.writeValueAsString(propValue);
          }
          value = jsonMapper.readValue(modifiedPropValue, Object.class);
        }
        catch (IOException e) {
          log.info(e, "Unable to parse [%s]=[%s] as a json object, using as is.", prop, propValue);
          value = propValue;
        }
        hieraricalPutValue(propertyPrefix, prop, prop.substring(propertyBase.length()), value, jsonMap);
      }
    }

    final T config;
    try {
      config = jsonMapper.convertValue(jsonMap, clazz);
    }
    catch (IllegalArgumentException e) {
      throw new ProvisionException(
          StringUtils.format("Problem parsing object at prefix[%s]: %s.", propertyPrefix, e.getMessage()), e
      );
    }

    final Set<ConstraintViolation<T>> violations = validator.validate(config);
    if (!violations.isEmpty()) {
      List<String> messages = Lists.newArrayList();

      for (ConstraintViolation<T> violation : violations) {
        StringBuilder path = new StringBuilder();
        try {
          Class<?> beanClazz = violation.getRootBeanClass();
          final Iterator<Path.Node> iter = violation.getPropertyPath().iterator();
          while (iter.hasNext()) {
            Path.Node next = iter.next();
            if (next.getKind() == ElementKind.PROPERTY) {
              final String fieldName = next.getName();
              final Field theField = beanClazz.getDeclaredField(fieldName);

              if (theField.getAnnotation(JacksonInject.class) != null) {
                path = new StringBuilder(StringUtils.format(" -- Injected field[%s] not bound!?", fieldName));
                break;
              }

              JsonProperty annotation = theField.getAnnotation(JsonProperty.class);
              final boolean noAnnotationValue = annotation == null || Strings.isNullOrEmpty(annotation.value());
              final String pathPart = noAnnotationValue ? fieldName : annotation.value();
              if (path.length() == 0) {
                path.append(pathPart);
              } else {
                path.append(".").append(pathPart);
              }
            }
          }
        }
        catch (NoSuchFieldException e) {
          throw Throwables.propagate(e);
        }

        messages.add(StringUtils.format("%s - %s", path.toString(), violation.getMessage()));
      }

      throw new ProvisionException(
          Iterables.transform(
              messages,
              new Function<String, Message>()
              {
                @Override
                public Message apply(String input)
                {
                  return new Message(StringUtils.format("%s%s", propertyBase, input));
                }
              }
          )
      );
    }

    log.info("Loaded class[%s] from props[%s] as [%s]", clazz, propertyBase, config);

    return config;
  }

  private static void hieraricalPutValue(
      String propertyPrefix,
      String originalProperty,
      String property,
      Object value,
      Map<String, Object> targetMap
  )
  {
    int dotIndex = property.indexOf('.');
    // Always put property with name even if it is of form a.b. This will make sure the property is available for classes
    // where JsonProperty names are of the form a.b
    // Note:- this will cause more than required properties to be present in the jsonMap.
    targetMap.put(property, value);
    if (dotIndex < 0) {
      return;
    }
    if (dotIndex == 0) {
      throw new ProvisionException(StringUtils.format("Double dot in property: %s", originalProperty));
    }
    if (dotIndex == property.length() - 1) {
      throw new ProvisionException(StringUtils.format("Dot at the end of property: %s", originalProperty));
    }
    String nestedKey = property.substring(0, dotIndex);
    Object nested = targetMap.computeIfAbsent(nestedKey, k -> new HashMap<String, Object>());
    if (!(nested instanceof Map)) {
      // Clash is possible between properties, which are used to configure different objects: e. g.
      // druid.emitter=parametrized is used to configure Emitter class, and druid.emitter.parametrized.xxx=yyy is used
      // to configure ParametrizedUriEmitterConfig object. So skipping xxx=yyy key-value pair when configuring Emitter
      // doesn't make any difference. That is why we just log this situation, instead of throwing an exception.
      log.info(
          "Skipping %s property: one of it's prefixes is also used as a property key. Prefix: %s",
          originalProperty,
          propertyPrefix
      );
      return;
    }
    Map<String, Object> nestedMap = (Map<String, Object>) nested;
    hieraricalPutValue(propertyPrefix, originalProperty, property.substring(dotIndex + 1), value, nestedMap);
  }

  @VisibleForTesting
  public static <T> void verifyClazzIsConfigurable(ObjectMapper mapper, Class<T> clazz)
  {
    final List<BeanPropertyDefinition> beanDefs = mapper.getSerializationConfig()
                                                        .introspect(mapper.constructType(clazz))
                                                        .findProperties();
    for (BeanPropertyDefinition beanDef : beanDefs) {
      final AnnotatedField field = beanDef.getField();
      if (field == null || !field.hasAnnotation(JsonProperty.class)) {
        throw new ProvisionException(
            StringUtils.format(
                "JsonConfigurator requires Jackson-annotated Config objects to have field annotations. %s doesn't",
                clazz
            )
        );
      }
    }
  }
}