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/*
 * Copyright 2013-2017 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 com.blazebit.persistence.spring.data.webflux.impl;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.core.MethodParameter;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.web.PageableDefault;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.reactive.BindingContext;
import org.springframework.web.reactive.result.method.HandlerMethodArgumentResolver;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Optional;
import java.util.Set;

/**
 * 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}.
 *
 * NOTE: This was adapted from the original implementation to support the reactive model.
 * 
 * @since 1.6
 * @author Oliver Gierke
 * @author Nick Williams
 * @author Mark Paluch
 * @author Christoph Strobl
 */
public class PageableHandlerMethodArgumentResolver implements HandlerMethodArgumentResolver {

	private static final SortHandlerMethodArgumentResolver DEFAULT_SORT_RESOLVER = new SortHandlerMethodArgumentResolver();
	private static final String INVALID_DEFAULT_PAGE_SIZE = "Invalid default page size configured for method %s! Must not be less than one!";

	private static final String DEFAULT_PAGE_PARAMETER = "page";
	private static final String DEFAULT_SIZE_PARAMETER = "size";
	private static final String DEFAULT_PREFIX = "";
	private static final String DEFAULT_QUALIFIER_DELIMITER = "_";
	private static final int DEFAULT_MAX_PAGE_SIZE = 2000;
	static final Pageable DEFAULT_PAGE_REQUEST = new PageRequest(0, 20);

	private Pageable fallbackPageable = DEFAULT_PAGE_REQUEST;
	private SortArgumentResolver sortResolver;
	private String pageParameterName = DEFAULT_PAGE_PARAMETER;
	private String sizeParameterName = DEFAULT_SIZE_PARAMETER;
	private String prefix = DEFAULT_PREFIX;
	private String qualifierDelimiter = DEFAULT_QUALIFIER_DELIMITER;
	private int maxPageSize = DEFAULT_MAX_PAGE_SIZE;
	private boolean oneIndexedParameters = false;

	/**
	 * 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 {@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 {@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;
	}

	/**
	 * Configures the {@link Pageable} to be used as fallback in case no {@link PageableDefault} or
	 * {@link PageableDefault} (the latter only supported in legacy mode) can be found at the method parameter to be
	 * resolved.
	 * 

* If you set this to {@literal Optional#empty()}, be aware that you controller methods will get {@literal null} * handed into them in case no {@link Pageable} data can be found in the request. Note, that doing so will require you * supply bot the page and the size parameter with the requests as there will be no default for any of the * parameters available. * * @param fallbackPageable the {@link Pageable} to be used as general fallback. */ public void setFallbackPageable(Pageable fallbackPageable) { Assert.notNull(fallbackPageable, "Fallback Pageable must not be null!"); this.fallbackPageable = fallbackPageable; } /** * Returns whether the given {@link Pageable} is the fallback one. * * @param pageable can be {@literal null}. * @since 1.9 * @return */ public boolean isFallbackPageable(Pageable pageable) { return fallbackPageable == null ? false : fallbackPageable.equals(pageable); } /** * Configures the maximum page size to be accepted. This allows to put an upper boundary of the page size to prevent * potential attacks trying to issue an {@link OutOfMemoryError}. Defaults to {@link #DEFAULT_MAX_PAGE_SIZE}. * * @param maxPageSize the maxPageSize to set */ public void setMaxPageSize(int maxPageSize) { this.maxPageSize = maxPageSize; } /** * Retrieves the maximum page size to be accepted. This allows to put an upper boundary of the page size to prevent * potential attacks trying to issue an {@link OutOfMemoryError}. Defaults to {@link #DEFAULT_MAX_PAGE_SIZE}. * * @return the maximum page size allowed. */ protected int getMaxPageSize() { return this.maxPageSize; } /** * Configures the parameter name to be used to find the page number in the request. Defaults to {@code page}. * * @param pageParameterName the parameter name to be used, must not be {@literal null} or empty. */ public void setPageParameterName(String pageParameterName) { Assert.hasText(pageParameterName, "Page parameter name must not be null or empty!"); this.pageParameterName = pageParameterName; } /** * Retrieves the parameter name to be used to find the page number in the request. Defaults to {@code page}. * * @return the parameter name to be used, never {@literal null} or empty. */ protected String getPageParameterName() { return this.pageParameterName; } /** * Configures the parameter name to be used to find the page size in the request. Defaults to {@code size}. * * @param sizeParameterName the parameter name to be used, must not be {@literal null} or empty. */ public void setSizeParameterName(String sizeParameterName) { Assert.hasText(sizeParameterName, "Size parameter name must not be null or empty!"); this.sizeParameterName = sizeParameterName; } /** * Retrieves the parameter name to be used to find the page size in the request. Defaults to {@code size}. * * @return the parameter name to be used, never {@literal null} or empty. */ protected String getSizeParameterName() { return this.sizeParameterName; } /** * Configures a general prefix to be prepended to the page number and page size parameters. Useful to namespace the * property names used in case they are clashing with ones used by your application. By default, no prefix is used. * * @param prefix the prefix to be used or {@literal null} to reset to the default. */ public void setPrefix(String prefix) { this.prefix = prefix == null ? DEFAULT_PREFIX : prefix; } /** * The delimiter to be used between the qualifier and the actual page number and size properties. Defaults to * {@code _}. So a qualifier of {@code foo} will result in a page number parameter of {@code foo_page}. * * @param qualifierDelimiter the delimiter to be used or {@literal null} to reset to the default. */ public void setQualifierDelimiter(String qualifierDelimiter) { this.qualifierDelimiter = qualifierDelimiter == null ? DEFAULT_QUALIFIER_DELIMITER : qualifierDelimiter; } /** * Configures whether to expose and assume 1-based page number indexes in the request parameters. Defaults to * {@literal false}, meaning a page number of 0 in the request equals the first page. If this is set to * {@literal true}, a page number of 1 in the request will be considered the first page. * * @param oneIndexedParameters the oneIndexedParameters to set */ public void setOneIndexedParameters(boolean oneIndexedParameters) { this.oneIndexedParameters = oneIndexedParameters; } /** * Indicates whether to expose and assume 1-based page number indexes in the request parameters. Defaults to * {@literal false}, meaning a page number of 0 in the request equals the first page. If this is set to * {@literal true}, a page number of 1 in the request will be considered the first page. * * @return whether to assume 1-based page number indexes in the request parameters. */ protected boolean isOneIndexedParameters() { return this.oneIndexedParameters; } /* * (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()); } @Override public Mono resolveArgument(MethodParameter methodParameter, BindingContext bindingContext, ServerWebExchange serverWebExchange) { assertPageableUniqueness(methodParameter); Optional defaultOrFallback = getDefaultFromAnnotationOrFallback(methodParameter).toOptional(); String pageString = serverWebExchange.getRequest().getQueryParams().getFirst(getParameterNameToUse(pageParameterName, methodParameter)); String pageSizeString = serverWebExchange.getRequest().getQueryParams().getFirst(getParameterNameToUse(sizeParameterName, methodParameter)); Optional page = parseAndApplyBoundaries(pageString, Integer.MAX_VALUE, true); Optional pageSize = parseAndApplyBoundaries(pageSizeString, maxPageSize, false); if (!(page.isPresent() && pageSize.isPresent()) && !defaultOrFallback.isPresent()) { return Mono.just(Pageable.unpaged()); } int p = page .orElseGet(() -> defaultOrFallback.map(Pageable::getPageNumber).orElseThrow(IllegalStateException::new)); int ps = pageSize .orElseGet(() -> defaultOrFallback.map(Pageable::getPageSize).orElseThrow(IllegalStateException::new)); // Limit lower bound ps = ps < 1 ? defaultOrFallback.map(Pageable::getPageSize).orElseThrow(IllegalStateException::new) : ps; // Limit upper bound ps = ps > maxPageSize ? maxPageSize : ps; final int size = ps; @SuppressWarnings("unchecked") Mono sort = (Mono) (Mono) sortResolver.resolveArgument(methodParameter, bindingContext, serverWebExchange); return sort.map(s -> Mono.just(PageRequest.of(p, size, s.isSorted() ? s : defaultOrFallback.map(Pageable::getSort).orElseGet(Sort::unsorted)))); } /** * Returns the name of the request parameter to find the {@link Pageable} information in. Inspects the given * {@link MethodParameter} for {@link Qualifier} present and prefixes the given source parameter name with it. * * @param source the basic parameter name. * @param parameter the {@link MethodParameter} potentially qualified. * @return the name of the request parameter. */ protected String getParameterNameToUse(String source, @Nullable MethodParameter parameter) { StringBuilder builder = new StringBuilder(prefix); Qualifier qualifier = parameter == null ? null : parameter.getParameterAnnotation(Qualifier.class); if (qualifier != null) { builder.append(qualifier.value()); builder.append(qualifierDelimiter); } return builder.append(source).toString(); } private Pageable getDefaultFromAnnotationOrFallback(MethodParameter methodParameter) { PageableDefault defaults = methodParameter.getParameterAnnotation(PageableDefault.class); if (defaults != null) { return getDefaultPageRequestFrom(methodParameter, defaults); } return fallbackPageable; } private static Pageable getDefaultPageRequestFrom(MethodParameter parameter, PageableDefault defaults) { Integer defaultPageNumber = defaults.page(); Integer defaultPageSize = getSpecificPropertyOrDefaultFromValue(defaults, "size"); if (defaultPageSize < 1) { Method annotatedMethod = parameter.getMethod(); throw new IllegalStateException(String.format(INVALID_DEFAULT_PAGE_SIZE, annotatedMethod)); } if (defaults.sort().length == 0) { return PageRequest.of(defaultPageNumber, defaultPageSize); } return PageRequest.of(defaultPageNumber, defaultPageSize, defaults.direction(), defaults.sort()); } /** * Tries to parse the given {@link String} into an integer and applies the given boundaries. Will return 0 if the * {@link String} cannot be parsed. * * @param parameter the parameter value. * @param upper the upper bound to be applied. * @param shiftIndex whether to shift the index if {@link #oneIndexedParameters} is set to true. * @return */ private Optional parseAndApplyBoundaries(@Nullable String parameter, int upper, boolean shiftIndex) { if (!StringUtils.hasText(parameter)) { return Optional.empty(); } try { int parsed = Integer.parseInt(parameter) - (oneIndexedParameters && shiftIndex ? 1 : 0); return Optional.of(parsed < 0 ? 0 : parsed > upper ? upper : parsed); } catch (NumberFormatException e) { return Optional.of(0); } } /** * Asserts uniqueness of all {@link Pageable} parameters of the method of the given {@link MethodParameter}. * * @param parameter must not be {@literal null}. */ private static void assertPageableUniqueness(MethodParameter parameter) { Method method = parameter.getMethod(); if (method == null) { throw new IllegalArgumentException(String.format("Method parameter %s is not backed by a method.", parameter)); } if (containsMoreThanOnePageableParameter(method)) { Annotation[][] annotations = method.getParameterAnnotations(); assertQualifiersFor(method.getParameterTypes(), annotations); } } /** * Returns whether the given {@link Method} has more than one {@link Pageable} parameter. * * @param method must not be {@literal null}. * @return */ private static boolean containsMoreThanOnePageableParameter(Method method) { boolean pageableFound = false; for (Class type : method.getParameterTypes()) { if (pageableFound && type.equals(Pageable.class)) { return true; } if (type.equals(Pageable.class)) { pageableFound = true; } } return false; } /** * Returns the value of the given specific property of the given annotation. If the value of that property is the * properties default, we fall back to the value of the {@code value} attribute. * * @param annotation must not be {@literal null}. * @param property must not be {@literal null} or empty. * @return */ @SuppressWarnings("unchecked") private static T getSpecificPropertyOrDefaultFromValue(Annotation annotation, String property) { Object propertyDefaultValue = AnnotationUtils.getDefaultValue(annotation, property); Object propertyValue = AnnotationUtils.getValue(annotation, property); Object result = ObjectUtils.nullSafeEquals(propertyDefaultValue, propertyValue) // ? AnnotationUtils.getValue(annotation) // : propertyValue; if (result == null) { throw new IllegalStateException("Exepected to be able to look up an annotation property value but failed!"); } return (T) result; } /** * Asserts that every {@link Pageable} parameter of the given parameters carries an {@link Qualifier} annotation to * distinguish them from each other. * * @param parameterTypes must not be {@literal null}. * @param annotations must not be {@literal null}. */ private static void assertQualifiersFor(Class[] parameterTypes, Annotation[][] annotations) { Set values = new HashSet<>(); for (int i = 0; i < annotations.length; i++) { if (Pageable.class.equals(parameterTypes[i])) { Qualifier qualifier = findAnnotation(annotations[i]); if (null == qualifier) { throw new IllegalStateException( "Ambiguous Pageable arguments in handler method. If you use multiple parameters of type Pageable you need to qualify them with @Qualifier"); } if (values.contains(qualifier.value())) { throw new IllegalStateException("Values of the user Qualifiers must be unique!"); } values.add(qualifier.value()); } } } /** * Returns a {@link Qualifier} annotation from the given array of {@link Annotation}s. Returns {@literal null} if the * array does not contain a {@link Qualifier} annotation. * * @param annotations must not be {@literal null}. * @return */ @Nullable private static Qualifier findAnnotation(Annotation[] annotations) { for (Annotation annotation : annotations) { if (annotation instanceof Qualifier) { return (Qualifier) annotation; } } return null; } }