package com.ximple.io.dgn7;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Iterator;

import org.apache.log4j.Logger;

import oracle.jdbc.OracleConnection;
import oracle.sql.BLOB;

/**
 * Dgn7OracleReader
 * User: Ulysses
 * Date: 2007/10/24
 * Time: 下午 01:01:08
 */
public class Dgn7OracleReader implements Iterator<Element>
{
    private final static Logger logger = Logger.getLogger(Dgn7OracleReader.class);

    private String _sql;
    private String _fieldName;
    private Connection _connection;
    private ResultSet _resultSet;
    private static final int FETCHSIZE = 20;
    private Element _element;

    public Dgn7OracleReader(String sql, String fieldName, OracleConnection connection)
    {
        this._sql = sql;
        this._fieldName = fieldName;
        this._connection = connection;
    }

    public String getSql()
    {
        return _sql;
    }

    public void setSql(String sql)
    {
        this._sql = sql;
    }

    public String getFieldName()
    {
        return _fieldName;
    }

    public void setFieldName(String fieldName)
    {
        this._fieldName = fieldName;
    }

    public boolean hasNext()
    {
        if (_resultSet == null)
        {
            try
            {
                initializeReader();
            } catch (SQLException e)
            {
                throw new RuntimeException("initialize oralce error.", e);
            } catch (Dgn7fileException e)
            {
                throw new RuntimeException("initialize oralce error.", e);
            }
        }
        if (_element == null)
        {
            return false;
        }
        return true;
    }

    public Element next()
    {
        Element result = _element;

        try
        {
            fetchElement();
        } catch (SQLException e)
        {
            throw new RuntimeException("Error:" + e.getMessage(), e);
        } catch (Dgn7fileException e)
        {
            throw new RuntimeException("Error:" + e.getMessage(), e);
        }

        return result;
    }

    public void remove()
    {
        throw new RuntimeException("Not Support this method.");
    }

    private boolean initializeReader() throws SQLException, Dgn7fileException
    {
        if (_resultSet != null) return true;
        Statement stmtSrc = _connection.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);

        stmtSrc.setFetchSize(FETCHSIZE);
        _resultSet = stmtSrc.executeQuery(_sql);

        fetchElement();

        return true;
    }

    private boolean fetchElement() throws SQLException, Dgn7fileException
    {
        if (_resultSet.next())
        {
            byte[] raw = null;
            Object value = _resultSet.getObject(this._fieldName);

            if (value instanceof BLOB)
            {
                BLOB blob = (BLOB) value;

                try
                {
                    raw = getBytesFromBLOB(blob);
                } catch (IOException e)
                {
                    throw new SQLException("IOError", e);
                }
                blob.close();
            } else if (value instanceof byte[])
            {
                raw = (byte[]) value;
            }
            if (raw == null)
            {
                _element = null;
                return false;
            }

            ByteBuffer buffer = ByteBuffer.wrap(raw);
            buffer.order(ByteOrder.LITTLE_ENDIAN);
            short signature = buffer.getShort();

            // byte type = (byte) (buffer.get() & 0x7f);
            byte type = (byte) ((signature >>> 8) & 0x007f);

            // silly Bentley say contentLength is in 2-byte words
            // and ByteByffer uses bytes.
            // track the record location
            int elementLength = (buffer.getShort() * 2) + 4;
            ElementType recordType = ElementType.forID(type);
            IElementHandler handler = recordType.getElementHandler();
            _element = (Element) handler.read(buffer, signature, elementLength);
            if (recordType.isComplexElement() && (elementLength < raw.length))
            {
                int offset = elementLength;
                while (offset < (raw.length - 4))
                {
                    buffer.position(offset);
                    signature = buffer.getShort();
                    type = (byte) ((signature >>> 8) & 0x007f);
                    elementLength = (buffer.getShort() * 2) + 4;
                    if (raw.length < (offset + elementLength))
                    {
                        System.out.println("Length not match:" + offset +":"+ buffer.position() +":"+buffer.limit());
                        break;
                    }
                    recordType = ElementType.forID(type);
                    handler = recordType.getElementHandler();
                    if (handler != null)
                    {
                        Element subElement = (Element) handler.read(buffer, signature, elementLength);
                        ((ComplexElement) _element).add(subElement);
                        offset += elementLength;
                    } else
                    {
                        byte[] remain = new byte[buffer.remaining()];
                        System.arraycopy(raw, offset, remain, 0, buffer.remaining());
                        for (int i = 0; i < remain.length; i++)
                        {
                            if (remain[i] != 0)
                            {
                                logger.info("fetch element has some error. index=" + (offset + i) + ":value=" + remain[i]);
                                System.out.println("fetch element has some error. index=" + (offset + i) + ":value=" + remain[i]);
                            }
                        }
                        break;
                    }
                }
            }

        } else
        {
            _element = null;
            return false;
        }
        return true;
    }

    protected static byte[] getBytesFromBLOB(BLOB blob) throws SQLException, IOException
    {
        byte[] raw = null;

        // BLOB        blob        = (BLOB) rs.getBlob(1);
        int optimalSize = blob.getChunkSize();
        byte[] chunk = new byte[optimalSize];
        InputStream is = blob.getBinaryStream(0);
        ByteBuffer buffer = null;    // ByteBuffer.allocate(optimalSize);
        int len = 0;

        try
        {
            while ((len = (is.read(chunk))) != -1)
            {
                if (buffer != null)
                {
                    buffer.limit(buffer.limit() + len);
                } else
                {
                    buffer = ByteBuffer.allocate(len);
                }

                buffer.put(chunk);
            }

            is.close();
            buffer.position(0);
            raw = buffer.array();
        } catch (IOException e)
        {
            e.printStackTrace();
            throw e;
        }

        return raw;
    }
}