package org.aksw.jena_sparql_api.core;

import java.io.Closeable;
import java.io.IOException;

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

import org.apache.jena.query.QuerySolution;
import org.apache.jena.query.ResultSet;
import org.apache.jena.sparql.engine.binding.Binding;


/**
 * @author Claus Stadler
 *         <p/>
 *         Date: 7/23/11
 *         Time: 10:54 PM
 *
 * Unlike JCDB, Jena does not provide the close method on the ResultSet, but on the object that
 * created the result set. Therefore:
 *
 *
 */
public class ResultSetClose
        extends ResultSetDecorator
        implements Closeable
{
    private static final Logger logger = LoggerFactory.getLogger(ResultSetClose.class);

    private boolean isClosed = false;
    private boolean closeOnException = true;


    public ResultSetClose(ResultSet decoratee, boolean skipCheckClose) {
        super(decoratee);

        if(!skipCheckClose) {
            checkClose();
        }
    }


    public ResultSetClose(ResultSet decoratee, boolean isClosed, boolean skipCheckClose) {
        super(decoratee);
        this.isClosed = isClosed;

        if(!skipCheckClose) {
            checkClose();
        }
    }

    public ResultSetClose(ResultSet decoratee, boolean isClosed, boolean closeOnException, boolean skipCheckClose) {
        super(decoratee);
        this.isClosed = isClosed;
        this.closeOnException = closeOnException;

        if(!skipCheckClose) {
            checkClose();
        }
    }


    /*
    public ResultSetClose(ResultSet decoratee, IClosable closable) {
        super(decoratee);
        //this.closable = closable;
        checkClose();
    }
    */


    protected boolean checkClose() {
        if(!isClosed) {
            boolean hasNext;

            // If an exception occurs, still try to close first
            Exception tmp = null;
            try {
                hasNext = decoratee.hasNext();
            } catch(Exception e) {
                hasNext = false;
                tmp = e;
            }

            if(!hasNext) {
                try {
                    isClosed = true ;
                    close();
                }
                catch(Exception e) {
                    logger.error("Error closing an object supposedly underlying a Jena ResultSet", e);
                }
            }

            if(tmp != null) {
                throw new RuntimeException(tmp);
            }
        }
        return isClosed;
    }

    @Override
    public boolean hasNext() {
        return !checkClose();
    }

    @Override
    public void remove() {
        decoratee.remove();
        checkClose();
    }


    @Override
    public QuerySolution nextSolution() {
        try {
            QuerySolution result = decoratee.nextSolution();
            checkClose();
            return result;
        } catch(Exception e) {
            if(closeOnException) {
                try {
                    close();
                } catch(Exception f) {
                    throw new RuntimeException(f);
                }
            }
            throw new RuntimeException(e);
        }
    }

    @Override
    public Binding nextBinding() {
        try {
            Binding result = decoratee.nextBinding();
            checkClose();
            return result;
        } catch(Exception e) {
            if(closeOnException) {
                try {
                    close();
                } catch(Exception f) {
                    throw new RuntimeException(f);
                }
            }
            throw new RuntimeException(e);
        }
    }

    @Override
    public void close() throws IOException {
        if(!isClosed) {
            if(decoratee instanceof Closeable) {
                Closeable closeable = (Closeable)decoratee;
                closeable.close();
                isClosed = true;
            }
        }
    }
}