/*
    * Copyright 2018 LINE Corporation
    *
    * LINE Corporation 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:
    *
    *   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 com.linecorp.centraldogma.server.internal.api.converter;
  
  import java.lang.reflect.ParameterizedType;
  
  import javax.annotation.Nullable;
  
  import com.google.common.base.Splitter;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableList.Builder;
  
  import com.linecorp.armeria.common.AggregatedHttpRequest;
  import com.linecorp.armeria.server.ServiceRequestContext;
  import com.linecorp.armeria.server.annotation.RequestConverterFunction;
  import com.linecorp.centraldogma.common.MergeQuery;
  import com.linecorp.centraldogma.common.MergeSource;
  
  import io.netty.handler.codec.http.QueryStringDecoder;
  
  public class MergeQueryRequestConverter implements RequestConverterFunction {
  
      private static final Splitter querySplitter = Splitter.on('&').trimResults().omitEmptyStrings();
  
      @Override
      public MergeQuery<?> convertRequest(
              ServiceRequestContext ctx, AggregatedHttpRequest request, Class<?> expectedResultType,
              @Nullable ParameterizedType expectedParameterizedResultType) throws Exception {
  
          final String queryString = ctx.query();
          if (queryString != null) {
              // Decode queryString manually so that the original order of "path" and "optional_path" is
              // preserved. For example if a user specifies the query as
              // "path=/a.json&optional_path=b.json&path=c.json", the mergeQuery will merge the files
              // in the order of "/a.json", "/b.json" and "/c.json".
              final String decodedString = QueryStringDecoder.decodeComponent(queryString);
              final Iterable<String> queries = querySplitter.split(decodedString);
              final Builder<MergeSource> mergeSourceBuilder = ImmutableList.builder();
              final Builder<String> jsonPathsBuilder = ImmutableList.builder();
              for (String query : queries) {
                  final int index = query.indexOf('=');
                  if (index < 0) {
                      continue;
                  }
                  final String key = query.substring(0, index);
                  final String value = query.substring(index + 1);
                  switch (key) {
                      case "path":
                          mergeSourceBuilder.add(MergeSource.ofRequired(value));
                          break;
                      case "optional_path":
                          mergeSourceBuilder.add(MergeSource.ofOptional(value));
                          break;
                      case "jsonpath":
                          jsonPathsBuilder.add(value);
                          break;
                  }
              }
  
              return MergeQuery.ofJsonPath(mergeSourceBuilder.build(), jsonPathsBuilder.build());
          }
          return RequestConverterFunction.fallthrough();
      }
  }