package com.atlassian.marketplace.client.model;
   
   import java.net.URI;
   
   import com.atlassian.fugue.Either;
   import com.atlassian.fugue.Option;
   import com.atlassian.marketplace.client.api.UriTemplate;
   
   import com.google.common.base.Function;
  import com.google.common.base.Functions;
  import com.google.common.collect.ImmutableMap;
  
  import org.apache.commons.lang.ObjectUtils;
  
  import static com.atlassian.marketplace.client.model.Links.REST_TYPE;
  
  /**
   * A resource/web hyperlink in the HAL-JSON format used by the Marketplace version 2 API.
   * A HAL link can be either a URI or a a {@link UriTemplate}.
   */
  public final class Link
  {
      private final Option<String> type;
      final Either<UriTemplate, URI> templateOrUri;
  
      public Link(Either<UriTemplate, URI> templateOrUri, Option<String> type)
      {
          this.templateOrUri = templateOrUri;
          this.type = type;
      }
  
      public static Link fromUri(URI uri, Option<String> type)
      {
          return new Link(Either.<UriTemplate, URI>right(uri), type);
      }
      
      public static Link fromUriTemplate(UriTemplate ut, Option<String> type)
      {
          return new Link(Either.<UriTemplate, URI>left(ut), type);
      }
      
      /**
       * Returns the link URI (the "href" attribute) if it is a URI; if it is a template,
       * converts it to a URI by removing all variable parameters.
       */
      public URI getUri()
      {
          return templateOrUri.fold(
              new Function<UriTemplate, URI>()
              {
                  public URI apply(UriTemplate t)
                  {
                      return t.resolve(ImmutableMap.<String, String>of());
                  }
              },
              Functions.<URI>identity()
          );
      }
      
      /**
       * Returns the link URI template if it is a template, or {@link Option#none()} if it is a
       * normal URI.
       */
      public Option<UriTemplate> getUriTemplate()
      {
          return templateOrUri.left().toOption();
      }
      
      public Either<UriTemplate, URI> getTemplateOrUri()
      {
          return templateOrUri;
      }
      
      /**
       * Returns the optional "type" attribute, indicating the media type of the linked resource.
       * If this is {@link Option#none()}, assume that the resource contains JSON.
       */
      public Option<String> getType()
      {
          return type;
      }
      
      public boolean matchType(Option<String> desiredType)
      {
          for (String dt: desiredType)
          {
              return type == null ? dt.equals(REST_TYPE) : dt.equals(type); 
          }
          return true;
      }
      
      /**
       * Returns the link URI or link template as a string.
       */
      public String stringValue()
      {
          for (UriTemplate ut: getUriTemplate())
          {
              return ut.getValue();
         }
         return getUri().toASCIIString();
     }
     
     @Override
     public boolean equals(Object other)
     {
         if (other instanceof Link)
         {
             Link o = (Link) other;
             return templateOrUri.equals(o.templateOrUri) &&
                 ObjectUtils.equals(type, o.type);
         }
         return false;
     }
     
     @Override
     public int hashCode()
     {
         return templateOrUri.hashCode() + ((type == null) ? 0 : type.hashCode());
     }
 }