package org.simantics.db.layer0.util;

import java.util.Collection;

import org.simantics.databoard.util.URIStringUtils;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.Statement;
import org.simantics.db.common.request.FunctionalStatementMapOfResource;
import org.simantics.db.common.uri.UnescapedChildMapOfResource;
import org.simantics.db.exception.DatabaseException;
import org.simantics.layer0.Layer0;
import org.simantics.scl.runtime.tuple.Tuple2;

public class ExtendedUris {

    public static Resource resolveAbsoluteUri(ReadGraph graph, String uri) throws DatabaseException {
        if(!uri.startsWith("http:/"))
            throw new IllegalArgumentException("Invalid absolute URI '" + uri + "'.");
        return resolveRelativeUri(graph, graph.getRootLibrary(), uri.substring(6));
    }

    public static Resource resolveRelativeUri(ReadGraph graph, Resource parent, String uri) throws DatabaseException {
        int beginPos = 0;
        while(beginPos < uri.length()) {
            int endPos;
            for(endPos = beginPos+1; endPos < uri.length(); ++endPos) {
                char c = uri.charAt(endPos);
                if(c == '/' || c == '#')
                    break;
            }

            char c = uri.charAt(beginPos);
            if(c == '/') {
                String escapedName = uri.substring(beginPos+1, endPos);
                String name = URIStringUtils.unescape(escapedName);
                parent = graph.syncRequest(new UnescapedChildMapOfResource(parent)).get(name);
                if(parent == null)
                    throw new DatabaseException("Didn't find a child " + name + " for " + uri.substring(0, beginPos));
            }
            else if(c == '#') {
                String escapedName = uri.substring(beginPos+1, endPos);
                String name = URIStringUtils.unescape(escapedName);
                parent = graph.syncRequest(new FunctionalStatementMapOfResource(parent)).get(name);
                if(parent == null)
                    throw new DatabaseException("Didn't find a property " + name);
            }
            else
                throw new IllegalArgumentException("Invalid relative URI '" + uri + "'.");
            beginPos = endPos;
        }
        return parent;
    }
    
    private static boolean initialized = false;
    private static Resource ElementToComponent;
    private static void initialize(ReadGraph graph) throws DatabaseException {
        ElementToComponent = graph.getResource("http://www.simantics.org/Modeling-1.2/ElementToComponent");
        initialized = true;
    }
    
    public static Tuple2 getPrimaryFunctionalReference(ReadGraph graph, Resource r) throws DatabaseException {
        if(!initialized)
            initialize(graph);
        Statement stat = graph.getPossibleStatement(r, ElementToComponent);
        if(stat != null)
            return statementToResult(graph, stat);
        return null;
    }
    
    public static Tuple2 getSecondaryFunctionalReference(ReadGraph graph, Resource r) throws DatabaseException {
        Layer0 L0 = Layer0.getInstance(graph);
        Collection<Statement> statements = graph.getStatements(r, L0.PropertyOf);
        if(statements.size() == 1) 
            for(Statement stat : statements)
                return statementToResult(graph, stat);
        return null;
    }
    
    private static Tuple2 statementToResult(ReadGraph graph, Statement stat) throws DatabaseException {
        return new Tuple2(stat.getObject(), graph.getInverse(stat.getPredicate()));
    }

}