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/*
 * Copyright (c) 2016 Uber Technologies, Inc. ([email protected])
 *
 * 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.uber.hoodie.common.util;

import com.google.common.reflect.ClassPath;
import com.google.common.reflect.ClassPath.ClassInfo;
import com.uber.hoodie.common.model.HoodieRecordPayload;
import com.uber.hoodie.exception.HoodieException;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Stream;

public class ReflectionUtils {

  private static Map> clazzCache = new HashMap<>();

  private static Class getClass(String clazzName) {
    if (!clazzCache.containsKey(clazzName)) {
      try {
        Class clazz = Class.forName(clazzName);
        clazzCache.put(clazzName, clazz);
      } catch (ClassNotFoundException e) {
        throw new HoodieException("Unable to load class", e);
      }
    }
    return clazzCache.get(clazzName);
  }

  public static  T loadClass(String fqcn) {
    try {
      return (T) getClass(fqcn).newInstance();
    } catch (InstantiationException | IllegalAccessException e) {
      throw new HoodieException("Could not load class " + fqcn, e);
    }
  }

  /**
   * Instantiate a given class with a generic record payload
   */
  public static  T loadPayload(String recordPayloadClass,
      Object[] payloadArgs,
      Class... constructorArgTypes) {
    try {
      return (T) getClass(recordPayloadClass).getConstructor(constructorArgTypes)
          .newInstance(payloadArgs);
    } catch (InstantiationException | IllegalAccessException
        | InvocationTargetException | NoSuchMethodException e) {
      throw new HoodieException("Unable to instantiate payload class ", e);
    }
  }

  /**
   * Creates an instnace of the given class. Use this version when dealing with interface types as constructor args.
   */
  public static Object loadClass(String clazz, Class[] constructorArgTypes, Object... constructorArgs) {
    try {
      return getClass(clazz).getConstructor(constructorArgTypes).newInstance(constructorArgs);
    } catch (InstantiationException | IllegalAccessException
        | InvocationTargetException | NoSuchMethodException e) {
      throw new HoodieException("Unable to instantiate class ", e);
    }
  }

  /**
   * Creates an instance of the given class. Constructor arg types are inferred.
   */
  public static Object loadClass(String clazz, Object... constructorArgs) {
    Class[] constructorArgTypes = Arrays.stream(constructorArgs)
        .map(Object::getClass).toArray(Class[]::new);
    return loadClass(clazz, constructorArgTypes, constructorArgs);
  }

  /**
   * Return stream of top level class names in the same class path as passed-in class
   * @param clazz
   */
  public static Stream getTopLevelClassesInClasspath(Class clazz) {
    try {
      ClassPath classPath = ClassPath.from(clazz.getClassLoader());
      return classPath.getTopLevelClasses().stream().map(ClassInfo::getName);
    } catch (IOException e) {
      throw new RuntimeException("Got exception while dumping top level classes", e);
    }
  }
}