content: /*
   * Copyright (C) 2020 ActiveJ LLC.
   *
   * 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 io.activej.config.converter;
  
  import io.activej.common.function.FunctionEx;
  import io.activej.config.Config;
  import org.jetbrains.annotations.Nullable;
  
  import java.util.function.Function;
  
  import static io.activej.common.Checks.checkNotNull;
  
  public abstract class SimpleConfigConverter<T> implements ConfigConverter<T> {
  	@Override
  	public final T get(Config config) {
  		return fromString(checkNotNull(config.getValue()));
  	}
  
  	@Override
  	public final @Nullable T get(Config config, @Nullable T defaultValue) {
  		String value = config.getValue(defaultValue == null ? "" : toString(defaultValue));
  		return value == null || value.trim().isEmpty() ? defaultValue : fromString(value);
  	}
  
  	protected abstract T fromString(String string);
  
  	protected abstract String toString(T value);
  
  	public static <T> SimpleConfigConverter<T> of(FunctionEx<String, T> fromStringFn, Function<T, String> toStringFn) {
  		return new SimpleConfigConverter<>() {
  			@Override
  			protected T fromString(String string) {
  				try {
  					return fromStringFn.apply(string);
  				} catch (Exception e) {
  					throw new IllegalArgumentException(e);
  				}
  			}
  
  			@Override
  			protected String toString(T value) {
  				return toStringFn.apply(value);
  			}
  		};
  	}
  }
  