package org.simantics.issues.common;

import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.simantics.db.Issue;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.common.procedure.adapter.TransientCacheListener;
import org.simantics.db.common.request.ResourceRead2;
import org.simantics.db.common.request.ResourceRead3;
import org.simantics.db.common.utils.Functions;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.issues.ontology.IssueResource;
import org.simantics.layer0.Layer0;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class DependencyIssueValidator2 extends ResourceRead3<Boolean> {
    private static final Logger LOGGER = LoggerFactory.getLogger(DependencyIssueValidator2.class);

	public static final boolean DEBUG = false;

	public DependencyIssueValidator2(Resource resource, Resource model, Resource source) {
		super(resource, model, source);
	}

	static class DependencyIssueDescriptions extends ResourceRead2<Set<Issue>> {

		public DependencyIssueDescriptions(Resource source, Resource context0) {
			super(source, context0);
		}
		
		@Override
		public Set<Issue> perform(ReadGraph graph) throws DatabaseException {
			HashSet<Issue> result = new HashSet<Issue>();
			for(Resource issue :  graph.syncRequest(new ManagedIssues(resource))) {
				Issue desc = graph.sync(new StandardIssueDescription(issue));
				if(desc == null) continue;
				if(resource2.equals(desc.getMainContext())) result.add(desc);
			}
			return result;
		}
		
	}
	
	static class Contexts extends ResourceRead2<Set<Issue>> {

		public Contexts(Resource source, Resource resource) {
			super(source, resource);
		}
		
		@Override
		public Set<Issue> perform(ReadGraph graph) throws DatabaseException {
			
			Layer0 L0 = Layer0.getInstance(graph);
			IssueResource IR = IssueResource.getInstance(graph);

			Resource constraint = graph.getSingleObject(resource, IR.Sources_DependencyTracker_HasConstraint);
			Resource function = graph.getSingleObject(constraint, L0.Constraint_Validator);
			try {
				@SuppressWarnings("unchecked")
				Set<Issue> contexts = new HashSet<Issue>((List<Issue>)Functions.exec(graph, function, graph, resource2));
		        if(DEBUG) System.err.println("Validator found: " + contexts.size() + " issues (" + contexts + ")");
		        return contexts;
			} catch (DatabaseException e) {
				LOGGER.error("Reading a constraint validator failed", e);
				return Collections.emptySet();
			}
	        
		}
		
		@Override
		public String toString() {
			return "DependencyIssueValidators2$Contexts[resource=" + resource2 + " source=" + resource + "]";
		}
		
	}

	@Override
	public Boolean perform(ReadGraph graph) throws DatabaseException {
		
		if(DEBUG) System.err.println("Running DependencyValidator for " + NameUtils.getSafeName(graph, resource) + " " +  NameUtils.getSafeName(graph, resource3));

		Set<Issue> existing = graph.syncRequest(new DependencyIssueDescriptions(resource3, resource), TransientCacheListener.<Set<Issue>>instance());

        if(DEBUG) System.err.println("Existing: " + existing.size() + " issues (" + existing + ")");
		
		// Removed resources do not have issues
		if(!graph.hasStatement(resource)) {
	        if(DEBUG) System.err.println("No statements");
			return existing.isEmpty();
		}

        Set<Issue> contexts = graph.syncRequest(new Contexts(resource3, resource), TransientCacheListener.<Set<Issue>>instance());

        if(DEBUG) System.err.println("Current: " + contexts.size() + " issues (" + contexts + ")");
        
		return existing.equals(contexts);

	}

}