/*
 * Copyright (c) 2010 Mysema Ltd.
 * All rights reserved.
 *
 */
package com.mysema.rdfbean.virtuoso;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

import javax.annotation.Nullable;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.mysema.commons.lang.CloseableIterator;
import com.mysema.query.QueryException;
import com.mysema.rdfbean.model.NODE;

/**
 * @author tiwe
 * 
 */
public class TupleResultIterator implements CloseableIterator<Map<String, NODE>> {

    private static final Logger logger = LoggerFactory.getLogger(TupleResultIterator.class);

    private final Statement stmt;

    private final ResultSet rs;

    private final String query;

    private final Converter converter;

    private final Map<String, NODE> bindings;

    private final List<String> variables;

    private final boolean wildcard;

    @Nullable
    private Boolean next;

    public TupleResultIterator(Statement stmt,
            ResultSet rs,
            String query,
            Converter converter,
            List<String> variables,
            Map<String, NODE> bindings) {
        this.stmt = stmt;
        this.rs = rs;
        this.query = query;
        this.converter = converter;
        this.variables = variables;
        this.bindings = bindings;
        this.wildcard = query.toLowerCase().startsWith("sparql\n select *")
                || query.toLowerCase().startsWith("sparql\n select distinct *");
    }

    @Override
    public void close() {
        AbstractQueryImpl.close(stmt, rs);
    }

    @Override
    public boolean hasNext() {
        if (next == null) {
            try {
                next = rs.next();
            } catch (SQLException e) {
                close();
                logger.warn("Caught exception for query " + query, e);
                throw new QueryException(e);
            }
        }
        return next;
    }

    @Override
    public Map<String, NODE> next() {
        if (hasNext()) {
            try {
                next = null;
                Map<String, NODE> tuples = new HashMap<String, NODE>();
                if (wildcard) {
                    tuples.putAll(bindings);
                }
                for (String variable : variables) {
                    if (bindings.containsKey(variable)) {
                        tuples.put(variable, bindings.get(variable));
                    } else {
                        Object obj = rs.getObject(variable);
                        if (obj != null) {
                            tuples.put(variable, converter.toNODE(obj));
                        }
                    }
                }
                return tuples;
            } catch (SQLException e) {
                close();
                logger.warn("Caught exception for query " + query, e);
                throw new QueryException(e);
            }
        } else {
            throw new NoSuchElementException();
        }
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }

}