package org.simantics.district.selection.ui;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.simantics.Simantics;
import org.simantics.browsing.ui.common.AdaptableHintContext;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.request.ResourceRead;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.QueryIndexUtils;
import org.simantics.db.layer0.SelectionHints;
import org.simantics.db.layer0.request.ActiveModels;
import org.simantics.db.layer0.variable.Variable;
import org.simantics.db.request.Read;
import org.simantics.district.selection.ElementSelectionResource;
import org.simantics.district.selection.ElementSelector;
import org.simantics.layer0.Layer0;
import org.simantics.ui.selection.AnyResource;
import org.simantics.ui.selection.AnyVariable;
import org.simantics.ui.selection.WorkbenchSelectionContentType;

public class ElementSelectionTools {

	public static final class SelectionElement extends AdaptableHintContext {
		public SelectionElement(Key[] keys) {
			super(keys);
		}

		@SuppressWarnings("unchecked")
		public <T> T getContent(WorkbenchSelectionContentType<T> contentType) {
			Resource element = getHint(SelectionHints.KEY_MAIN);
			if (contentType instanceof AnyResource) {
				return (T)element;
			}
			else if (contentType instanceof AnyVariable) {
				AnyVariable type = (AnyVariable) contentType;
				try {
					return (T) type.processor.syncRequest(new ResourceRead<Variable>(element) {
						public Variable perform(ReadGraph graph) throws DatabaseException {
							return ElementSelector.getVariableForElement(graph, resource);
						}
					});
				} catch (DatabaseException e) {
					return null;
				}
			}
			
			return null;
		}
	}

	public static final class SelectionsRequest implements Read<Collection<ElementSelector>> {
		@Override
		public Collection<ElementSelector> perform(ReadGraph graph) throws DatabaseException {
			Layer0 L0 = Layer0.getInstance(graph);
			ElementSelectionResource ES = ElementSelectionResource.getInstance(graph);
			
			Resource model = ActiveModels.getPossibleActiveModel(graph, Simantics.getProjectResource());
			if (model == null) {
				return Collections.emptyList();
			}
			
			List<Resource> libs = QueryIndexUtils.searchByType(graph, model, ES.SelectionLibrary);
			if (libs.isEmpty())
				return Collections.emptyList();
			
			Resource lib = libs.get(0);
			
			List<ElementSelector> result = new ArrayList<>();
			for (Resource selection : graph.getObjects(lib, L0.ConsistsOf)) {
				if (!graph.isInstanceOf(selection, ES.Selection))
					continue;
				
				result.add(ElementSelector.getSelector(graph, selection));
			}
			
			return result;
		}
	}

}