/*
    * Copyright 2019-2026 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
    *
    *      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.bremersee.comparator.spring.web;
  
  import static java.util.Objects.isNull;
  
  import java.util.List;
  import org.bremersee.comparator.model.SortOrder;
  import org.springframework.core.MethodParameter;
  import org.springframework.lang.NonNull;
  import org.springframework.lang.Nullable;
  import org.springframework.util.StringUtils;
  import org.springframework.web.reactive.BindingContext;
  import org.springframework.web.reactive.result.method.SyncHandlerMethodArgumentResolver;
  import org.springframework.web.server.ServerWebExchange;
  
  /**
   * The reactive sort order handler method argument resolver.
   *
   * @author Christian Bremer
   */
  public class ReactiveSortOrderHandlerMethodArgumentResolver
      extends SortOrderHandlerMethodArgumentResolverSupport
      implements SyncHandlerMethodArgumentResolver {
  
    /**
     * Instantiates a new reactive sort order handler method argument resolver.
     */
    public ReactiveSortOrderHandlerMethodArgumentResolver() {
      super();
    }
  
    @Override
    public boolean supportsParameter(@NonNull MethodParameter parameter) {
      return SortOrder.class.equals(parameter.getParameterType());
    }
  
    @Nullable
    @Override
    public SortOrder resolveArgumentValue(
        @NonNull MethodParameter parameter,
        @NonNull BindingContext bindingContext,
        @NonNull ServerWebExchange exchange) {
  
      List<String> parameterValues = exchange.getRequest()
          .getQueryParams()
          .get(getParameterName(parameter));
  
      // No parameter
      if (isNull(parameterValues) || parameterValues.isEmpty()) {
        return getDefaultFromAnnotationOrFallback(parameter);
      }
  
      // Single empty parameter, e.g "sort="
      if (parameterValues.size() == 1 && !StringUtils.hasText(parameterValues.get(0))) {
        return getDefaultFromAnnotationOrFallback(parameter);
      }
  
      return parseParameterValues(parameterValues);
    }
  
  }