/*
    *    Copyright 2009-2023 the original author or authors.
    *
    *    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
    *
    *       https://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.mybatis.guice.datasource.helper;
  
  import static com.google.inject.name.Names.named;
  
  import com.google.inject.Injector;
  import com.google.inject.Key;
  
  import jakarta.inject.Inject;
  import jakarta.inject.Provider;
  
  final class KeyResolver implements Provider<String> {
  
    private final Key<String> key;
  
    private final String defaultValue;
  
    private final String toString;
  
    @Inject
    private Injector injector;
  
    public KeyResolver(final String key, final String defaultValue) {
      this.key = Key.get(String.class, named(key));
      this.defaultValue = defaultValue;
      toString = "${" + key + "}";
    }
  
    public void setInjector(Injector injector) {
      this.injector = injector;
    }
  
    /**
     * {@inheritDoc}
     */
    @Override
    public String get() {
      try {
        return injector.getInstance(key);
      } catch (Throwable e) {
        if (defaultValue != null) {
          return defaultValue;
        }
        return toString;
      }
    }
  
    @Override
    public String toString() {
      return toString;
    }
  
  }