com.expedia.seiso.web.resolver.PEResourceResolver.java Source code

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Here is the source code for com.expedia.seiso.web.resolver.PEResourceResolver.java

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/* 
 * Copyright 2013-2015 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.expedia.seiso.web.resolver;

import java.io.IOException;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import lombok.val;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.MethodParameter;
import org.springframework.data.repository.support.Repositories;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.stereotype.Component;
import org.springframework.util.AntPathMatcher;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;

import com.expedia.seiso.domain.entity.Item;
import com.expedia.seiso.domain.meta.ItemMetaLookup;
import com.expedia.seiso.web.hateoas.PEResource;

/**
 * Reads a resource off the request, binds it to the relevant item metadata, and returns the result.
 * 
 * @author Willie Wheeler
 */
@Component
public class PEResourceResolver implements HandlerMethodArgumentResolver {

    // FIXME DRY up. We're repeating info in com.expedia.seiso.web.converter.
    private static final String ITEM_FORMAT = "/{version}/{repoKey}/{itemKey}";
    private static final String PROPERTY_FORMAT = "/{version}/{repoKey}/{itemKey}/{propKey}";
    private static final String COLLECTION_ELEMENT_FORMAT = "/{version}/{repoKey}/{itemKey}/{propKey}/{propValue}";

    private List<SimplePropertyEntry> simplePropertyEntries;

    @Autowired
    private Repositories repositories;
    @Autowired
    private ItemMetaLookup itemMetaLookup;
    @Autowired
    private ResolverUtils resolverUtils;
    @Autowired
    private List<HttpMessageConverter<?>> messageConverters;

    public PEResourceResolver(List<SimplePropertyEntry> entries) {
        this.simplePropertyEntries = entries;
    }

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return PEResource.class.isAssignableFrom(parameter.getParameterType());
    }

    @Override
    public Object resolveArgument(MethodParameter param, ModelAndViewContainer mavContainer,
            NativeWebRequest nativeWebRequest, WebDataBinderFactory binderFactory) throws Exception {

        val nativeRequest = nativeWebRequest.getNativeRequest(HttpServletRequest.class);
        val path = nativeRequest.getRequestURI();

        Class<?> itemClass = null;
        val matcher = new AntPathMatcher();
        if (matcher.match(ITEM_FORMAT, path)) {
            val variables = matcher.extractUriTemplateVariables(ITEM_FORMAT, path);
            itemClass = itemMetaLookup.getItemClass(variables.get("repoKey"));
        } else if (matcher.match(PROPERTY_FORMAT, path)) {
            val variables = matcher.extractUriTemplateVariables(PROPERTY_FORMAT, path);
            val repoKey = variables.get("repoKey");
            val propKey = variables.get("propKey");
            itemClass = findPropertyClass(repoKey, propKey);
        } else if (matcher.match(COLLECTION_ELEMENT_FORMAT, path)) {
            val variables = matcher.extractUriTemplateVariables(COLLECTION_ELEMENT_FORMAT, path);
            val repoKey = variables.get("repoKey");
            val propKey = variables.get("propKey");
            itemClass = findPropertyClass(repoKey, propKey);
        } else {
            throw new RuntimeException("No resolver for requestUri=" + path);
        }

        val pEntity = repositories.getPersistentEntity(itemClass);
        val item = toItem(itemClass, nativeRequest);
        return new PEResource(pEntity, item);

    }

    private Class<?> findPropertyClass(String repoKey, String propKey) {
        for (val entry : simplePropertyEntries) {
            if (entry.getRepoKey().equals(repoKey) && entry.getPropKey().equals(propKey)) {
                return entry.getPropClass();
            }
        }
        throw new RuntimeException("No simple property entry for repoKey=" + repoKey + ", propKey=" + propKey);
    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    private Item toItem(Class<?> itemClass, HttpServletRequest request) throws IOException {
        val wrappedRequest = resolverUtils.wrapRequest(request);
        val contentType = wrappedRequest.getHeaders().getContentType();

        for (HttpMessageConverter messageConverter : messageConverters) {

            // This is how we process application/json separately from application/hal+json.
            if (messageConverter.canRead(itemClass, contentType)) {
                return (Item) messageConverter.read(itemClass, wrappedRequest);
            }
        }

        throw new RuntimeException(
                "No converter for itemClass=" + itemClass.getName() + ", contentType=" + contentType.getType());
    }
}