package org.simantics.db.layer0.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.eclipse.core.runtime.NullProgressMonitor;
import org.simantics.databoard.Bindings;
import org.simantics.databoard.adapter.AdaptException;
import org.simantics.databoard.binding.Binding;
import org.simantics.databoard.binding.mutable.Variant;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.request.ObjectsWithType;
import org.simantics.db.exception.DatabaseException;
import org.simantics.db.layer0.adapter.CopyHandler;
import org.simantics.db.layer0.migration.MigrationState;
import org.simantics.db.layer0.migration.MigrationStateKeys;
import org.simantics.db.layer0.util.SimanticsClipboard.Representation;
import org.simantics.graph.representation.TransferableGraph1;
import org.simantics.layer0.Layer0;

public class ModelDependenciesBean {

	public static final String EXTENSION_KEY = ModelDependenciesBean.class.getSimpleName();

	public static final Binding BINDING = Bindings.getBindingUnchecked(ModelDependenciesBean.class);

	public ModelDependency[] dependencies;

	public ModelDependenciesBean() {
		dependencies = new ModelDependency[0];
	}

	public ModelDependenciesBean(ModelDependency[] dependencies) {
		this.dependencies = dependencies;
	}

	/*
	 * Returns the linked shared ontologies in topological order. 
	 */
	public static List<Resource> collectDependencies(ReadGraph graph, Resource resource) throws DatabaseException {
		LinkedList<Resource> order = new LinkedList<>();
		collectDependencies(graph, resource, order, new HashSet<>());
		return order;
	}

	private static void collectDependencies(ReadGraph graph, Resource resource, LinkedList<Resource> order, Set<Resource> visited) throws DatabaseException {
		Layer0 L0 = Layer0.getInstance(graph);
		for(Resource library : graph.syncRequest(new ObjectsWithType(resource, L0.IsLinkedTo, L0.SharedOntology))) {
			if (order.contains(library)) continue;
			if (visited.contains(library)) throw new DatabaseException("Cyclic dependency detected.");
			visited.add(library);
			collectDependencies(graph, library, order, visited);
			order.addFirst(library);
		}
	}

	private static List<ModelDependency> collectModelDependencies(ReadGraph graph, Resource resource) throws DatabaseException {
		List<Resource> order = collectDependencies(graph, resource);
		Collections.reverse(order);

		List<ModelDependency> modelDependencies = new ArrayList<>(order.size());

		for (Resource library : order) {
			String uri = graph.getPossibleURI(library);
			if(uri == null) continue;
			CopyHandler ch = graph.adapt(library, CopyHandler.class);
			SimanticsClipboardImpl clipboard = new SimanticsClipboardImpl();
			ch.copyToClipboard(graph, clipboard, new NullProgressMonitor());
			for (Set<Representation> object : clipboard.getContents()) {
				TransferableGraph1 tg = ClipboardUtils.accept(graph, object, SimanticsKeys.KEY_TRANSFERABLE_GRAPH);
				if(tg != null) {
					modelDependencies.add(new ModelDependency(uri, tg));
				}
			}
		}
		return modelDependencies;
	}

	public static ModelDependenciesBean create(ReadGraph graph, Resource resource) throws DatabaseException {
		List<ModelDependency> dependencies = collectModelDependencies(graph, resource);
		return new ModelDependenciesBean(dependencies.toArray(new ModelDependency[dependencies.size()]));
	}

	public static ModelDependenciesBean fromMigrationState(MigrationState state) throws DatabaseException, AdaptException {
		Map<String,Variant> extensions = state.getProperty(MigrationStateKeys.TG_EXTENSIONS);
		final Variant variant = extensions.get(ModelDependenciesBean.EXTENSION_KEY);
		return variant != null ? (ModelDependenciesBean) variant.getValue(ModelDependenciesBean.BINDING) : null;
	}

}