/*
    * #%L
    * wcm.io
    * %%
    * Copyright (C) 2017 wcm.io
    * %%
    * 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.
   * #L%
   */
  package io.wcm.handler.url.impl;
  
  import java.lang.annotation.Annotation;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.lang3.StringUtils;
  import org.apache.sling.api.SlingHttpServletRequest;
  import org.apache.sling.api.adapter.Adaptable;
  import org.apache.sling.api.adapter.AdapterFactory;
  import org.apache.sling.api.resource.Resource;
  import org.apache.sling.caconfig.ConfigurationBuilder;
  import org.apache.sling.caconfig.resource.ConfigurationResourceResolver;
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  
  import com.github.benmanes.caffeine.cache.Cache;
  import com.github.benmanes.caffeine.cache.Caffeine;
  
  import io.wcm.handler.url.SiteConfig;
  import io.wcm.handler.url.spi.UrlHandlerConfig;
  import io.wcm.sling.commons.caservice.ContextAwareServiceResolver;
  
  /**
   * Adapts resources or requests to {@link UrlHandlerConfig} and {@link SiteConfig}.
   */
  @Component(service = AdapterFactory.class,
      property = {
          AdapterFactory.ADAPTABLE_CLASSES + "=org.apache.sling.api.resource.Resource",
          AdapterFactory.ADAPTABLE_CLASSES + "=org.apache.sling.api.SlingHttpServletRequest",
          AdapterFactory.ADAPTER_CLASSES + "=io.wcm.handler.url.spi.UrlHandlerConfig",
          AdapterFactory.ADAPTER_CLASSES + "=io.wcm.handler.url.SiteConfig"
      })
  public class UrlHandlerAdapterFactory implements AdapterFactory {
  
    @Reference
    private ContextAwareServiceResolver serviceResolver;
    @Reference
    private ConfigurationResourceResolver configurationResourceResolver;
  
    // cache resolving of site root level per resource path
    private final Cache<String, SiteConfig> siteConfigCache = Caffeine.newBuilder()
        .expireAfterWrite(5, TimeUnit.SECONDS)
        .maximumSize(10000)
        .build();
  
    @SuppressWarnings({ "unchecked", "null" })
    @Override
    public <AdapterType> AdapterType getAdapter(Object adaptable, Class<AdapterType> type) {
      if (type == UrlHandlerConfig.class) {
        return (AdapterType)serviceResolver.resolve(UrlHandlerConfig.class, (Adaptable)adaptable);
      }
      if (type == SiteConfig.class) {
        return (AdapterType)getSiteConfigForSiteRoot(getContextResource(adaptable));
      }
      return null;
    }
  
    private Resource getContextResource(Object adaptable) {
      if (adaptable instanceof Resource) {
        return (Resource)adaptable;
      }
      else if (adaptable instanceof SlingHttpServletRequest) {
        return ((SlingHttpServletRequest)adaptable).getResource();
      }
      return null;
    }
  
    private SiteConfig getSiteConfigForSiteRoot(Resource contextResource) {
      if (contextResource == null) {
        return null;
      }
      String contextRootPath = configurationResourceResolver.getContextPath(contextResource);
  
      // site root cannot be detected? then get SiteConfig directly from resource without any caching
      if (StringUtils.isBlank(contextRootPath)) {
        return getSiteConfigForResource(contextResource);
      }
  
      // get site config for site root resource and cache the result (for a short time)
      return siteConfigCache.get(contextRootPath, path -> {
       Resource siteRootResource = contextResource.getResourceResolver().getResource(contextRootPath);
       return getSiteConfigForResourceCacheable(siteRootResource);
     });
   }
 
   /**
    * Converts the SiteConfig instance to a newly created instance, because the original implementation
    * implements lazy property reading and is connected to the original resource resolver implementation.
    * @param contextResource Context resource
    * @return Cacheable site configuration
    */
   private SiteConfig getSiteConfigForResourceCacheable(Resource contextResource) {
     final SiteConfig siteConfig = getSiteConfigForResource(contextResource);
     return new SiteConfig() {
       @Override
       public Class<? extends Annotation> annotationType() {
         return SiteConfig.class;
       }
       @Override
       public String siteUrl() {
         return siteConfig.siteUrl();
       }
       @Override
       public String siteUrlSecure() {
         return siteConfig.siteUrlSecure();
       }
       @Override
       public String siteUrlAuthor() {
         return siteConfig.siteUrlAuthor();
       }
 
     };
   }
 
   @SuppressWarnings("java:S112") // allow runtime exception
   private SiteConfig getSiteConfigForResource(Resource contextResource) {
     ConfigurationBuilder configurationBuilder = contextResource.adaptTo(ConfigurationBuilder.class);
     if (configurationBuilder == null) {
       throw new RuntimeException("No configuration builder.");
     }
     return configurationBuilder.as(SiteConfig.class);
   }
 
 }