content: /*
   * Copyright 2021-2024 Aklivity Inc.
   *
   * Aklivity licenses this file to you 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.aklivity.zilla.runtime.engine.resolver;
  
  import static io.aklivity.zilla.runtime.common.feature.FeatureFilter.filter;
  import static java.util.Collections.unmodifiableMap;
  import static java.util.Objects.requireNonNull;
  import static java.util.ServiceLoader.load;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import io.aklivity.zilla.runtime.engine.Configuration;
  
  public final class Resolver
  {
      private static final Pattern EXPRESSION_PATTERN =
              Pattern.compile("\\$\\{\\{\\s*([^\\s\\}]*)\\.([^\\s\\}]*)\\s*\\}\\}");
  
      private final Map<String, ResolverSpi> resolverSpis;
      private Matcher matcher;
  
      public static Resolver instantiate(
          Configuration config)
      {
          return instantiate(config, filter(load(ResolverFactorySpi.class)));
      }
  
      public String resolve(
          String template)
      {
          return matcher.reset(template)
                  .replaceAll(r -> resolve(r.group(1), r.group(2)));
      }
  
      private String resolve(
          String context,
          String var)
      {
          ResolverSpi resolver = requireNonNull(resolverSpis.get(context), "Unrecognized resolver name: " + context);
          String value = resolver.resolve(var);
          return value != null ? value : "";
      }
  
      private static Resolver instantiate(
          Configuration config,
          Iterable<ResolverFactorySpi> factories)
      {
          Map<String, ResolverSpi> resolversByName = new HashMap<>();
          factories.forEach(f -> resolversByName.put(f.type(), f.create(config)));
          return new Resolver(unmodifiableMap(resolversByName));
      }
  
      private Resolver(
          Map<String, ResolverSpi> resolverSpis)
      {
          this.resolverSpis = resolverSpis;
          this.matcher = EXPRESSION_PATTERN.matcher("");
      }
  
  }
  