package org.daisy.pipeline.braille.pef.impl;
   
   import java.util.ArrayList;
   import java.util.Collection;
   import java.util.List;
   import java.util.stream.Collectors;
   
   import com.google.common.base.Optional;
   
  import org.daisy.dotify.api.factory.FactoryProperties;
  import org.daisy.dotify.api.table.Table;
  import org.daisy.dotify.api.table.TableProvider;
  
  import org.daisy.pipeline.braille.common.Query;
  import org.daisy.pipeline.braille.common.Query.MutableQuery;
  import static org.daisy.pipeline.braille.common.Query.util.mutableQuery;
  import org.daisy.pipeline.braille.pef.AbstractTableProvider;
  
  import org.osgi.service.component.annotations.Component;
  import org.osgi.service.component.annotations.Reference;
  import org.osgi.service.component.annotations.ReferenceCardinality;
  import org.osgi.service.component.annotations.ReferencePolicy;
  
  // Note that although the name suggests it, this class doesn't use instances
  // of the TableCatalog interface. It uses instances of the more low-level
  // org.daisy.dotify.api.table.TableProvider directly. The name was chosen
  // because it more or less provides the same functionality as a TableCatalog,
  // except that it's based on the query syntax instead of ID's.
  @Component(
  	name = "org.daisy.pipeline.braille.pef.impl.BrailleUtilsTableCatalog",
  	service = { org.daisy.pipeline.braille.pef.TableProvider.class }
  )
  public class BrailleUtilsTableCatalog extends AbstractTableProvider {
  
  	@Override
  	protected Iterable<Table> _get(Query query) {
  		MutableQuery q = mutableQuery(query);
  		if (q.containsKey("id")) {
  			String id = q.removeOnly("id").getValue().get();
  			if (q.isEmpty())
  				return get(id); }
  		return empty;
  	}
  	
  	private Iterable<Table> get(String id) {
  		for (TableProvider p : providers)
  			for (FactoryProperties fp : p.list())
  				if (fp.getIdentifier().equals(id))
  					return Optional.fromNullable(p.newFactory(id)).asSet();
  		return empty;
  	}
  
  	// list all available tables, not only those from the cache (for unit test)
  	Collection<FactoryProperties> listAll() {
  		return providers.stream().flatMap(p -> p.list().stream()).collect(Collectors.toList());
  	}
  
  	private final static Iterable<Table> empty = Optional.<Table>absent().asSet();
  	
  	private final List<TableProvider> providers = new ArrayList<>();
  	
  	@Reference(
  		name = "TableProvider",
  		unbind = "-",
  		service = TableProvider.class,
  		cardinality = ReferenceCardinality.MULTIPLE,
  		policy = ReferencePolicy.STATIC
  	)
  	public void addTableProvider(TableProvider provider) {
  		providers.add(provider);
  	}
  	
  	public void removeTableProvider(TableProvider provider) {
  		providers.remove(provider);
  	}
  }