package org.bremersee.apiclient.webflux.contract.spring;
   
   import static java.util.Objects.nonNull;
   
   import java.lang.reflect.Method;
   import java.util.Optional;
   import java.util.function.Function;
   import org.bremersee.apiclient.webflux.Invocation;
   import org.bremersee.apiclient.webflux.InvocationParameter;
  import org.springframework.core.ResolvableType;
  import org.springframework.http.MediaType;
  import org.springframework.util.MultiValueMap;
  import org.springframework.web.reactive.function.BodyInserters;
  import org.springframework.web.reactive.function.client.WebClient.RequestBodyUriSpec;
  import org.springframework.web.reactive.function.client.WebClient.RequestHeadersUriSpec;
  
  /**
   * The form data inserter.
   *
   * @author Christian Bremer
   */
  public class FormDataInserter extends SingleBodyInserter<MultiValueMap<String, ?>> {
  
    private Function<Invocation, Optional<MediaType>> contentTypeResolver = new ContentTypeResolver();
  
    /**
     * With content type resolver.
     *
     * @param contentTypeResolver the content type resolver
     * @return the form data inserter
     */
    public FormDataInserter withContentTypeResolver(
        Function<Invocation, Optional<MediaType>> contentTypeResolver) {
  
      if (nonNull(contentTypeResolver)) {
        this.contentTypeResolver = contentTypeResolver;
      }
      return this;
    }
  
    @Override
    public boolean canInsert(Invocation invocation) {
      return isFormData(invocation) && super.canInsert(invocation);
    }
  
    /**
     * Is form data.
     *
     * @param invocation the invocation
     * @return the boolean
     */
    protected boolean isFormData(Invocation invocation) {
      return contentTypeResolver.apply(invocation)
          .filter(contentType -> contentType.isCompatibleWith(MediaType.APPLICATION_FORM_URLENCODED))
          .isPresent();
    }
  
    @Override
    protected MultiValueMap<String, ?> mapBody(InvocationParameter invocationParameter) {
      //noinspection unchecked
      return (MultiValueMap<String, ?>) invocationParameter.getValue();
    }
  
    @Override
    protected boolean isPossibleBodyValue(InvocationParameter invocationParameter) {
      return invocationParameter.getValue() instanceof MultiValueMap && isString(invocationParameter);
    }
  
    private boolean isString(InvocationParameter invocationParameter) {
      Method method = invocationParameter.getMethod();
      int index = invocationParameter.getIndex();
      return Optional.of(ResolvableType.forMethodParameter(method, index))
          .filter(resolvableType -> resolvableType.getGenerics().length >= 2)
          .map(resolvableType -> resolvableType.resolveGeneric(0))
          .filter(String.class::isAssignableFrom)
          .isPresent();
    }
  
    @Override
    protected RequestHeadersUriSpec<?> insert(
        MultiValueMap<String, ?> body,
        RequestBodyUriSpec requestBodyUriSpec) {
  
      //noinspection rawtypes,unchecked
      return (RequestHeadersUriSpec) requestBodyUriSpec
          .body(BodyInserters.fromFormData((MultiValueMap<String, String>) body));
    }
  
  }