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/*
 * Jython Database Specification API 2.0
 *
 *
 * Copyright (c) 2001 brian zimmer 
 *
 */
package com.ziclix.python.sql.pipe.db;

import com.ziclix.python.sql.DataHandler;
import com.ziclix.python.sql.PyConnection;
import com.ziclix.python.sql.PyCursor;
import com.ziclix.python.sql.zxJDBC;
import org.python.core.Py;

import java.lang.reflect.Constructor;

/**
 * Abstract class to assist in generating cursors.
 *
 * @author brian zimmer
 */
public abstract class BaseDB {

    /**
     * Field cursor
     */
    protected PyCursor cursor;

    /**
     * Field dataHandler
     */
    protected Class dataHandler;

    /**
     * Field tableName
     */
    protected String tableName;

    /**
     * Field connection
     */
    protected PyConnection connection;

    /**
     * Construct the helper.
     */
    public BaseDB(PyConnection connection, Class dataHandler, String tableName) {

        this.tableName = tableName;
        this.dataHandler = dataHandler;
        this.connection = connection;
        this.cursor = this.cursor();
    }

    /**
     * Create a new constructor and optionally bind a new DataHandler.  The new DataHandler must act as
     * a Decorator, having a single argument constructor of another DataHandler.  The new DataHandler is
     * then expected to delegate all calls to the original while enhancing the functionality in any matter
     * desired.  This allows additional functionality without losing any previous work or requiring any
     * complicated inheritance dependencies.
     */
    protected PyCursor cursor() {

        PyCursor cursor = this.connection.cursor(true);
        DataHandler origDataHandler = cursor.getDataHandler(), newDataHandler = null;

        if ((origDataHandler != null) && (this.dataHandler != null)) {
            Constructor cons = null;

            try {
                Class[] args = new Class[1];

                args[0] = DataHandler.class;
                cons = this.dataHandler.getConstructor(args);
            } catch (Exception e) {
                return cursor;
            }

            if (cons == null) {
                String msg = zxJDBC.getString("invalidCons", new Object[]{this.dataHandler.getName()});

                throw zxJDBC.makeException(msg);
            }

            try {
                Object[] args = new Object[1];

                args[0] = origDataHandler;
                newDataHandler = (DataHandler) cons.newInstance(args);
            } catch (Exception e) {
                return cursor;
            }

            if (newDataHandler != null) {
                cursor.__setattr__("datahandler", Py.java2py(newDataHandler));
            }
        }

        return cursor;
    }
}