/*
 * Copyright 2002-2017 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.springframework.web.reactive.result.method.annotation;

import java.util.Collections;
import java.util.Map;
import java.util.Optional;

import org.springframework.core.MethodParameter;
import org.springframework.core.ReactiveAdapterRegistry;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.reactive.BindingContext;
import org.springframework.web.reactive.HandlerMapping;
import org.springframework.web.reactive.result.method.HandlerMethodArgumentResolverSupport;
import org.springframework.web.reactive.result.method.SyncHandlerMethodArgumentResolver;
import org.springframework.web.server.ServerWebExchange;

/**
 * Resolver for {@link Map} method arguments also annotated with
 * {@link PathVariable @PathVariable} where the annotation does not specify a
 * path variable name. The resulting {@link Map} argument is a coyp of all URI
 * template name-value pairs.
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 * @see PathVariableMethodArgumentResolver
 */
public class PathVariableMapMethodArgumentResolver extends HandlerMethodArgumentResolverSupport
		implements SyncHandlerMethodArgumentResolver {

	public PathVariableMapMethodArgumentResolver(ReactiveAdapterRegistry adapterRegistry) {
		super(adapterRegistry);
	}


	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		return checkAnnotatedParamNoReactiveWrapper(parameter, PathVariable.class, this::allVariables);
	}

	private boolean allVariables(PathVariable pathVariable, Class<?> type) {
		return Map.class.isAssignableFrom(type) && !StringUtils.hasText(pathVariable.value());
	}


	@Override
	public Optional<Object> resolveArgumentValue(MethodParameter methodParameter,
			BindingContext context, ServerWebExchange exchange) {

		String name = HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
		Object value = exchange.getAttribute(name).orElse(Collections.emptyMap());
		return Optional.of(value);
	}

}