package com.atlassian.plugin.webresource;
   
   import com.atlassian.util.concurrent.LazyReference;
   import com.google.common.base.Function;
   import com.google.common.base.Supplier;
   import com.google.common.base.Suppliers;
   import com.google.common.cache.CacheBuilder;
   import com.google.common.cache.CacheLoader;
   
  import static com.google.common.base.Preconditions.checkNotNull;
  
  /**
   * The set of identifying information for a resource.
   */
  interface ResourceKey
  {
      /** @return the complete key of the module containing the resource. */
      String key();
      /** @return the name of the resource, including the file type suffix. */
      String name();
      /** @return the file type suffix. */
      String suffix();
  
      /**
       * A ResourceKey, for when we know ahead of time what all the properties are.
       */
      class Strict implements ResourceKey
      {
          final String key;
          final String name;
          final String suffix;
  
          Strict(String key, String name, String suffix)
          {
              this.key = checkNotNull(key);
              this.name = checkNotNull(name);
              this.suffix = checkNotNull(suffix);
          }
  
          public String key()
          {
              return key;
          }
  
          public String name()
          {
              return name;
          }
  
          public String suffix()
          {
              return suffix;
          }
          @Override
          public boolean equals(Object o)
          {
              if (!(o instanceof ResourceKey))
                  return false;
              return Equality.equal(this, (ResourceKey) o);
          }
  
          @Override
          public int hashCode()
          {
  
              return Equality.hash(this);
          }
      }
  
      /**
       * A resource key, for when one or more of the properties are derived.
       */
      class Lazy implements ResourceKey
      {
          final Supplier<String> key;
          final Supplier<String> name;
          final Supplier<String> suffix;
  
          Lazy(Supplier<String> key, Supplier<String> name, Supplier<String> suffix)
          {
              this.key = checkNotNull(key);
              this.name = checkNotNull(name);
              this.suffix = checkNotNull(suffix);
          }
  
          public String key()
          {
              return key.get();
          }
  
          public String name()
          {
              return name.get();
          }
  
          public String suffix()
          {
              return suffix.get();
          }
 
         @Override
         public boolean equals(Object o)
         {
             if (!(o instanceof ResourceKey))
                 return false;
             return Equality.equal(this, (ResourceKey) o);
         }
 
         @Override
         public int hashCode()
         {
             return Equality.hash(this);
         }
     }
 
     /**
      * Builds ResourceKeys.
      */
     class Builder
     {
         /**
          * Builds a lazy key that will create the resourceName when it is actually required
          */
         static ResourceKey lazy(final String completeKey, final Supplier<String> suffix)
         {
             return new ResourceKey.Lazy(
                 Suppliers.ofInstance(completeKey),
                 new LazyReference<String>()
                 {
                     @Override
                     protected String create()
                     {
                         return completeKey + "." + suffix.get();
                     }
                 },
                 suffix
             );
         }
 
         static final String DEFAULT_RESOURCE_NAME_PREFIX = "batch";
 
         static final Function<String, ResourceKey> BATCH_RESOURCE_KEY_CACHE = CacheBuilder.newBuilder().build(
             CacheLoader.from(new Function<String, ResourceKey>()
             {
                 @Override
                 public ResourceKey apply(String suffix)
                 {
                     return new ResourceKey.Strict(DEFAULT_RESOURCE_NAME_PREFIX, DEFAULT_RESOURCE_NAME_PREFIX + "." + suffix, suffix);
                 }
             }));
 
         /**
          * Builds a lazy key that will have a resourceName of "batch.[suffix]".
          * @param suffix
          * @return
          */
         static ResourceKey batch(String suffix)
         {
             // PERF: cache these because we would otherwise create hundreds of them, and they're always the same.
             return BATCH_RESOURCE_KEY_CACHE.apply(suffix);
         }
     }
 
     /**
      * Equals and hashcode for any ResourceKey.
      */
     class Equality
     {
         static boolean equal(ResourceKey left, ResourceKey right)
         {
             if (!left.key().equals(right.key()))
             {
                 return false;
             }
             if (!left.name().equals(right.name()))
             {
                 return false;
             }
             return left.suffix().equals(right.suffix());
         }
 
         public static int hash(ResourceKey resource)
         {
             int result = resource.key().hashCode();
             result = 31 * result + resource.name().hashCode();
             result = 31 * result + resource.suffix().hashCode();
             return result;
         }
     }
 }