/*
    * 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.basepom.mojo.dvc;
  
  import static com.google.common.base.Preconditions.checkNotNull;
  import static com.google.common.base.Preconditions.checkState;
  
  import org.basepom.mojo.dvc.model.ResolverDefinition;
  import org.basepom.mojo.dvc.strategy.Strategy;
  import org.basepom.mojo.dvc.strategy.StrategyProvider;
  
  import java.util.Arrays;
  import java.util.Map;
  import java.util.concurrent.ExecutionException;
  
  import com.google.common.cache.Cache;
  import com.google.common.cache.CacheBuilder;
  import com.google.common.collect.ImmutableMap;
  
  public final class StrategyCache {
  
      /**
       * name of an artifact to  version resolution strategy.
       */
      private final Cache<QualifiedName, Strategy> resolverCache = CacheBuilder.newBuilder().concurrencyLevel(10).build();
  
      private final ImmutableMap<QualifiedNameMatcher, Strategy> resolverPatterns;
      private final Strategy defaultStrategy;
  
      StrategyCache(final StrategyProvider strategyProvider, final ResolverDefinition[] resolvers, final String defaultStrategyName) {
          checkNotNull(strategyProvider, "strategyProvider is null");
          checkNotNull(resolvers, "resolvers is null");
          checkNotNull(defaultStrategyName, "defaultStrategyName is null");
  
          this.defaultStrategy = strategyProvider.forName(defaultStrategyName);
          checkState(defaultStrategy != null, "Could not locate default version strategy '%s'", defaultStrategyName);
  
          final ImmutableMap.Builder<QualifiedNameMatcher, Strategy> builder = ImmutableMap.builder();
          Arrays.stream(resolvers).forEach(r -> {
              final Strategy strategy = strategyProvider.forName(r.getStrategy());
              checkState(strategy != null, "Could not locate version strategy %s! Check for typos!", r.getStrategy());
              r.getIncludes().forEach(include -> builder.put(include, strategy));
          });
          this.resolverPatterns = builder.build();
      }
  
      public Strategy forQualifiedName(final QualifiedName name) {
          checkNotNull(name, "name is null");
          try {
              return resolverCache.get(name, () -> {
                  for (final Map.Entry<QualifiedNameMatcher, Strategy> entry : resolverPatterns.entrySet()) {
                      if (entry.getKey().matches(name)) {
                          return entry.getValue();
                      }
                  }
                  return defaultStrategy;
              });
          } catch (ExecutionException e) {
              // ignore, never happens.
              return defaultStrategy;
          }
      }
  }