package com.atlassian.plugins.rest.common.expand.parameter;
   
   import com.atlassian.plugins.rest.common.expand.Expandable;
   import com.google.common.base.Preconditions;
   import com.google.common.collect.ImmutableList;
   import com.google.common.collect.Lists;
   
   import java.util.Collection;
   import java.util.LinkedList;
  
  class ChainingExpandParameter implements ExpandParameter {
      private final Collection<ExpandParameter> expandParameters;
  
      ChainingExpandParameter(ExpandParameter... expandParameters) {
          this(Lists.newArrayList(expandParameters));
      }
  
      ChainingExpandParameter(Iterable<ExpandParameter> expandParameters) {
          this.expandParameters = ImmutableList.copyOf(Preconditions.checkNotNull(expandParameters));
      }
  
      public boolean shouldExpand(Expandable expandable) {
          for (ExpandParameter expandParameter : expandParameters) {
              if (expandParameter.shouldExpand(expandable)) {
                  return true;
              }
          }
          return false;
      }
  
      public Indexes getIndexes(Expandable expandable) {
          // we do not merge indexes,
          // so if we find an IndexParser.ALL that's what we return
          // if we find only one non-empty, that's what we return
          // else we throw an exception
  
          Indexes indexes = null;
          for (ExpandParameter expandParameter : expandParameters) {
              final Indexes i = expandParameter.getIndexes(expandable);
              if (i.equals(IndexParser.ALL)) {
                  return IndexParser.ALL;
              }
              if (!i.equals(IndexParser.EMPTY)) {
                  if (indexes == null) {
                      indexes = i;
                  } else {
                      throw new IndexException("Cannot merge multiple indexed expand parameters.");
                  }
              }
          }
          return indexes != null ? indexes : IndexParser.EMPTY;
      }
  
      public ExpandParameter getExpandParameter(Expandable expandable) {
          final Collection<ExpandParameter> newExpandParameters = new LinkedList<ExpandParameter>();
          for (ExpandParameter expandParameter : expandParameters) {
              newExpandParameters.add(expandParameter.getExpandParameter(expandable));
          }
          return new ChainingExpandParameter(newExpandParameters);
      }
  
      public boolean isEmpty() {
          for (ExpandParameter expandParameter : expandParameters) {
              if (!expandParameter.isEmpty()) {
                  return false;
              }
          }
          return true;
      }
  }