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

import java.io.Writer;
import java.sql.Connection;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

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;
import com.mysema.rdfbean.model.STMT;

/**
 * @author tiwe
 * 
 */
public class TupleQueryImpl extends AbstractQueryImpl {

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

    private final Converter converter;

    @Nullable
    private List<String> variables = null;

    @Nullable
    private CloseableIterator<Map<String, NODE>> tuples = null;

    public TupleQueryImpl(Connection connection, Converter converter, int prefetch, String query) {
        super(connection, prefetch, query);
        this.converter = converter;
    }

    @Override
    public boolean getBoolean() {
        throw new UnsupportedOperationException();
    }

    @Override
    public ResultType getResultType() {
        return ResultType.TUPLES;
    }

    @Override
    public CloseableIterator<STMT> getTriples() {
        throw new UnsupportedOperationException();
    }

    @Override
    public CloseableIterator<Map<String, NODE>> getTuples() {
        if (tuples == null) {
            try {
                produceResults();
            } catch (SQLException e) {
                close();
                throw new QueryException(e);
            }
        }
        return tuples;
    }

    @Override
    public List<String> getVariables() {
        if (variables == null) {
            try {
                produceResults();
            } catch (SQLException e) {
                close();
                throw new QueryException(e);
            }
        }
        return variables;
    }

    private void produceResults() throws SQLException {
        try {
            rs = executeQuery(query, true);
            ResultSetMetaData md = rs.getMetaData();
            variables = new ArrayList<String>(md.getColumnCount());
            for (int i = 0; i < md.getColumnCount(); i++) {
                variables.add(md.getColumnName(i + 1));
            }
            tuples = new TupleResultIterator(stmt, rs, query, converter, variables, bindings);
        } catch (SQLException e) {
            logger.error(query);
            throw e;
        }

    }

    @Override
    public void streamTriples(Writer writer, String contentType) {
        throw new UnsupportedOperationException();
    }

}