/*
 * Copyright 2013-2020 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
 *
 *      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 org.springframework.data.web;

import org.springframework.core.MethodParameter;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.lang.Nullable;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.ModelAndViewContainer;

Extracts paging information from web requests and thus allows injecting Pageable instances into controller methods. Request properties to be parsed can be configured. Default configuration uses request parameters beginning with DEFAULT_PAGE_PARAMETERDEFAULT_QUALIFIER_DELIMITER. 
Author:
Oliver Gierke, Nick Williams, Mark Paluch, Christoph Strobl
Since:
1.6/**
 * Extracts paging information from web requests and thus allows injecting {@link Pageable} instances into controller
 * methods. Request properties to be parsed can be configured. Default configuration uses request parameters beginning
 * with {@link #DEFAULT_PAGE_PARAMETER}{@link #DEFAULT_QUALIFIER_DELIMITER}.
 *
 * @since 1.6
 * @author Oliver Gierke
 * @author Nick Williams
 * @author Mark Paluch
 * @author Christoph Strobl
 */
public class PageableHandlerMethodArgumentResolver extends PageableHandlerMethodArgumentResolverSupport
		implements PageableArgumentResolver {

	private static final SortHandlerMethodArgumentResolver DEFAULT_SORT_RESOLVER = new SortHandlerMethodArgumentResolver();
	private SortArgumentResolver sortResolver;

	
Constructs an instance of this resolved with a default SortHandlerMethodArgumentResolver. /**
	 * Constructs an instance of this resolved with a default {@link SortHandlerMethodArgumentResolver}.
	 */
	public PageableHandlerMethodArgumentResolver() {
		this((SortArgumentResolver) null);
	}

	
Constructs an instance of this resolver with the specified SortHandlerMethodArgumentResolver. 
Params:
sortResolver – the sort resolver to use/**
	 * Constructs an instance of this resolver with the specified {@link SortHandlerMethodArgumentResolver}.
	 *
	 * @param sortResolver the sort resolver to use
	 */
	public PageableHandlerMethodArgumentResolver(SortHandlerMethodArgumentResolver sortResolver) {
		this((SortArgumentResolver) sortResolver);
	}

	
Constructs an instance of this resolver with the specified SortArgumentResolver. 
Params:
sortResolver – the sort resolver to use
Since:
1.13/**
	 * Constructs an instance of this resolver with the specified {@link SortArgumentResolver}.
	 *
	 * @param sortResolver the sort resolver to use
	 * @since 1.13
	 */
	public PageableHandlerMethodArgumentResolver(@Nullable SortArgumentResolver sortResolver) {
		this.sortResolver = sortResolver == null ? DEFAULT_SORT_RESOLVER : sortResolver;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.web.method.support.HandlerMethodArgumentResolver#supportsParameter(org.springframework.core.MethodParameter)
	 */
	@Override
	public boolean supportsParameter(MethodParameter parameter) {
		return Pageable.class.equals(parameter.getParameterType());
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.web.method.support.HandlerMethodArgumentResolver#resolveArgument(org.springframework.core.MethodParameter, org.springframework.web.method.support.ModelAndViewContainer, org.springframework.web.context.request.NativeWebRequest, org.springframework.web.bind.support.WebDataBinderFactory)
	 */
	@Override
	public Pageable resolveArgument(MethodParameter methodParameter, @Nullable ModelAndViewContainer mavContainer,
			NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) {

		String page = webRequest.getParameter(getParameterNameToUse(getPageParameterName(), methodParameter));
		String pageSize = webRequest.getParameter(getParameterNameToUse(getSizeParameterName(), methodParameter));

		Sort sort = sortResolver.resolveArgument(methodParameter, mavContainer, webRequest, binderFactory);
		Pageable pageable = getPageable(methodParameter, page, pageSize);

		if (sort.isSorted()) {
			return PageRequest.of(pageable.getPageNumber(), pageable.getPageSize(), sort);
		}

		return pageable;
	}
}