/**
    *
    * Copyright (C) 2011 Cloud Conscious, LLC. <info@cloudconscious.com>
    *
    * ====================================================================
    * 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.jclouds.blobstore.functions;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkNotNull;
  import static com.google.common.base.Preconditions.checkState;
  import static org.jclouds.blobstore.reference.BlobStoreConstants.PROPERTY_USER_METADATA_PREFIX;
  import static org.jclouds.blobstore.util.BlobStoreUtils.getNameFor;
  
  import java.net.URI;
  import java.util.Map.Entry;
  
  import javax.inject.Inject;
  import javax.inject.Named;
  import javax.inject.Provider;
  import javax.ws.rs.core.HttpHeaders;
  
  import org.jclouds.blobstore.domain.MutableBlobMetadata;
  import org.jclouds.date.DateService;
  import org.jclouds.http.HttpException;
  import org.jclouds.http.HttpRequest;
  import org.jclouds.http.HttpResponse;
  import org.jclouds.http.HttpUtils;
  import org.jclouds.rest.InvocationContext;
  import org.jclouds.rest.internal.GeneratedHttpRequest;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.base.Function;
  
  /**
   * @author Adrian Cole
   */
  public class ParseSystemAndUserMetadataFromHeaders implements Function<HttpResponse, MutableBlobMetadata>,
           InvocationContext<ParseSystemAndUserMetadataFromHeaders> {
     private final String metadataPrefix;
     private final DateService dateParser;
     private final Provider<MutableBlobMetadata> metadataFactory;
  
     private String name;
     private URI endpoint;
  
     @Inject
     public ParseSystemAndUserMetadataFromHeaders(Provider<MutableBlobMetadata> metadataFactory, DateService dateParser,
              @Named(PROPERTY_USER_METADATA_PREFIX) String metadataPrefix) {
        this.metadataFactory = checkNotNull(metadataFactory, "metadataFactory");
        this.dateParser = checkNotNull(dateParser, "dateParser");
        this.metadataPrefix = checkNotNull(metadataPrefix, "metadataPrefix");
     }
  
     public MutableBlobMetadata apply(HttpResponse from) {
        checkNotNull(from, "request");
        checkState(name != null, "name must be initialized by now");
  
        MutableBlobMetadata to = metadataFactory.get();
        to.setName(name);
        to.setUri(endpoint);
        if (from.getPayload() != null)
           HttpUtils.copy(from.getPayload().getContentMetadata(), to.getContentMetadata());
        addETagTo(from, to);
        parseLastModifiedOrThrowException(from, to);
        addUserMetadataTo(from, to);
        return to;
     }
  
     @VisibleForTesting
     void addUserMetadataTo(HttpResponse from, MutableBlobMetadata metadata) {
        for (Entry<String, String> header : from.getHeaders().entries()) {
           if (header.getKey() != null && header.getKey().startsWith(metadataPrefix))
              metadata.getUserMetadata().put((header.getKey().substring(metadataPrefix.length())).toLowerCase(),
                       header.getValue());
        }
     }
  
     @VisibleForTesting
     void parseLastModifiedOrThrowException(HttpResponse from, MutableBlobMetadata metadata) throws HttpException {
        String lastModified = from.getFirstHeaderOrNull(HttpHeaders.LAST_MODIFIED);
        if (lastModified == null) {
           // scaleup-storage uses the wrong case for the last modified header
           if ((lastModified = from.getFirstHeaderOrNull("Last-modified")) == null)
              throw new HttpException(HttpHeaders.LAST_MODIFIED + " header not present in response: " + from);
        }
  
       // Walrus
       if (lastModified.startsWith("20")) {
          metadata.setLastModified(dateParser.iso8601DateParse(lastModified.replace("+0000", "Z")));
       } else {
          metadata.setLastModified(dateParser.rfc822DateParse(lastModified));
       }
 
       if (metadata.getLastModified() == null)
          throw new HttpException("could not parse: " + HttpHeaders.LAST_MODIFIED + ": " + lastModified);
    }
 
    protected void addETagTo(HttpResponse from, MutableBlobMetadata metadata) {
       String eTag = from.getFirstHeaderOrNull(HttpHeaders.ETAG);
       if (metadata.getETag() == null && eTag != null) {
          metadata.setETag(eTag);
       }
    }
 
    public ParseSystemAndUserMetadataFromHeaders setContext(HttpRequest request) {
       this.endpoint = request.getEndpoint();
       checkArgument(request instanceof GeneratedHttpRequest<?>, "note this handler requires a GeneratedHttpRequest");
       return setName(getNameFor(GeneratedHttpRequest.class.cast(request)));
    }
 
    public ParseSystemAndUserMetadataFromHeaders setName(String name) {
       this.name = checkNotNull(name, "name");
       return this;
    }
 }