/*
 * Copyright 2012-2014 Institut National des Sciences Appliquées de Lyon (INSA-Lyon)
 *
 * 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 org.gololang.microbenchmarks.filtermapreduce;

import java.util.*;

public class JavaCopyingFilterMapReduce {

  public static interface Predicate {
    boolean apply(Object object);
  }

  public static interface Function {
    Object apply(Object a);
  }

  public static interface BiFunction {
    Object apply(Object a, Object b);
  }

  public static Collection<Object> newWithSameType(Collection<?> collection) {
    if (collection instanceof RandomAccess) {
      return new ArrayList<>();
    } else if (collection instanceof List) {
      return new LinkedList<>();
    } else if (collection instanceof Set) {
      return new HashSet<>();
    } else {
      throw new RuntimeException("Not a supported collection: " + collection.getClass());
    }
  }

  public static Collection<?> filter(Collection<?> collection, Predicate predicate) {
    Collection<Object> result = newWithSameType(collection);
    for (Object obj : collection) {
      if (predicate.apply(obj)) {
        result.add(obj);
      }
    }
    return result;
  }

  public static Collection<?> map(Collection<?> collection, Function fun) {
    Collection<Object> result = newWithSameType(collection);
    for (Object obj : collection) {
      result.add(fun.apply(obj));
    }
    return result;
  }

  public static Object reduce(Collection<?> collection, Object initialValue, BiFunction reducer) {
    Object result = initialValue;
    for (Object obj : collection) {
      result = reducer.apply(result, obj);
    }
    return result;
  }
}
