/*-
    * #%L
    * Secured Properties
    * ===============================================================
    * Copyright (C) 2016 - 2019 Brabenetz Harald, Austria
    * ===============================================================
    * 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.
   * #L%
   */
  package net.brabenetz.lib.securedproperties.config;
  
  import net.brabenetz.lib.securedproperties.core.Algorithm;
  import net.brabenetz.lib.securedproperties.core.SupportedAlgorithm;
  import org.apache.commons.lang3.StringUtils;
  
  import java.io.File;
  import java.util.Arrays;
  import java.util.EnumMap;
  import java.util.Map;
  import java.util.function.BiConsumer;
  import java.util.function.Function;
  
  /**
   * Parent helper class to easier implement a custom ConfigInitializer. Only {@link #getValue(ConfigKey)} must be implemented.
   */
  public abstract class AbstractConfigInitializer implements ConfigInitializer {
  
      private static final Map<ConfigKey, BiConsumer<Config, String>> CONFIG_KEY_TO_INIT_FUNCTION_MAPPING = initConfigMappings();
  
      private final Function<ConfigKey, String> keyFactory;
  
      protected AbstractConfigInitializer() {
          this((final ConfigKey key) -> ConfigKey.DEFAULT_PREFIX_KEBAB_CASE + '.' + key.getKebabCase());
      }
  
      protected AbstractConfigInitializer(final Function<ConfigKey, String> keyFactory) {
          this.keyFactory = keyFactory;
      }
  
      /**
       * Small convenience Constructor for concrete implementation which can have an optional config key-prefix.
       */
      protected AbstractConfigInitializer(final String configKeyPrefix,
              final Function<ConfigKey, String> keyFactoryWithoutPrefix,
              final Function<ConfigKey, String> keyFactoryWithPrefix) {
          if (StringUtils.isEmpty(configKeyPrefix)) {
              keyFactory = keyFactoryWithoutPrefix;
          } else {
              keyFactory = keyFactoryWithPrefix;
          }
      }
  
      protected Function<ConfigKey, String> getKeyFactory() {
          return keyFactory;
      }
  
      @Override
      public void init(final Config config) {
          for (final ConfigKey configKey : ConfigKey.values()) {
              final String value = getValue(configKey);
              if (value != null) {
                  CONFIG_KEY_TO_INIT_FUNCTION_MAPPING.get(configKey).accept(config, value);
              }
          }
      }
  
      private static Map<ConfigKey, BiConsumer<Config, String>> initConfigMappings() {
          final Map<ConfigKey, BiConsumer<Config, String>> mapping = new EnumMap<>(ConfigKey.class);
          mapping.put(ConfigKey.SECRET_FILE, AbstractConfigInitializer::initSecretFilePath);
          mapping.put(ConfigKey.SALT_LENGTH, AbstractConfigInitializer::initSaltLength);
          mapping.put(ConfigKey.ALLOWED_ALGORITHM, AbstractConfigInitializer::initAllowedAlgorithm);
          mapping.put(ConfigKey.AUTO_CREATE_SECRET_KEY, AbstractConfigInitializer::initAutoCreateSecretKey);
          return mapping;
  
      }
  
      protected static void initSecretFilePath(final Config config, final String value) {
          config.withSecretFile(new File(value));
      }
  
      protected static void initSaltLength(final Config config, final String value) {
          config.withSaltLength(Integer.parseInt(value));
      }
  
      protected static void initAllowedAlgorithm(final Config config, final String value) {
          config.withAllowedAlgorithm(Arrays.stream(value.split("[, ]+")).map(SupportedAlgorithm::valueOf).toArray(Algorithm[]::new));
      }
  
      protected static void initAutoCreateSecretKey(final Config config, final String value) {
         config.withAutoCreateSecretKey(Boolean.valueOf(value));
     }
 
     /**
      * @param key The {@link ConfigKey} to search the value for.
      * @return the Value as simple string.
      */
     protected abstract String getValue(ConfigKey key);
 }