package de.memtext.db;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * Additional procedures for HSQLDB 
 *  make sure that this class in the classpath.
 * To constantly add it to hsql, go to the directory where your hsqldb.jar is located
 * Call jar -xf hsqlAddOn.jar
 *      jar -uf hsqldb.jar org/hsqldb/Library2.class
 * Delete the directory org.
 * 
 * Open your Database in Database Manager and execute
 * the following commands once:  
 *  GRANT ALL ON CLASS "org.hsqldb.Library2" TO PUBLIC and
 * CREATE ALIAS COPYFROM FOR "org.hsqldb.Library2.copyFrom"
 */
public class Library2 {
    private Library2() {
        super();
    }

    /**
     * Fills regular tables with values from a CSV-file.
     * Similar to Postgres COPY FROM command.
     * 
     * If you want to fill your table TEST with data from test.csv
     * make sure that this class in the classpath and that
     * GRANT ALL ON CLASS "org.hsqldb.Library2" TO PUBLIC and
     * CREATE ALIAS COPYFROM FOR "org.hsqldb.Library2.copyFrom"
     * has been called in your database at some point.
    
     *  * Then execute   
     * COPYFROM("TEST","test.csv",null)
     * 
     * if your not using , but | as a field separator
      COPYFROM("TEST","test.csv","fs=|")
    
     * 
     * @param con - Connection is automatically handed over by HSQL
     * @param table - the name of the table that is to be filled
     * 				  if your table isn't found capital letters may be required
     * @param file - the filename of the CSV-file
     * @param options - you can specify options separated by ; 
     * which are described in the text table documentation e.g.
     * fs=| to use pipe instead of default comma as field separator or
     * or 
     * fs=|;vs=.;lvs=~" varchar separator, longvarchar separator
     * ignore_first=true; ignore first line
     * all_quoted=true or
     * encoding=UTF-8 if you don't have ASCII
     * @throws SQLException
     */
    public static void copyFrom(Connection con, String table, String file, String options) throws SQLException {
        StringBuffer buf = new StringBuffer("create text table TMP_SOURCE_" + table + " (");

        ResultSet rs = con.getMetaData().getColumns(null, null, table, null);
        String colname, coltype;
        boolean tableFound = false;
        while (rs.next()) {
            tableFound = true;
            colname = rs.getObject(4).toString();
            coltype = rs.getObject(6).toString();
            buf.append(colname + " " + coltype + ",");
        }
        rs.close();
        if (!tableFound) throw new IllegalArgumentException("Copy from failed - table " + table + " not found");
        buf.deleteCharAt(buf.lastIndexOf(","));
        buf.append("); SET TABLE TMP_SOURCE_" + table + " SOURCE \"" + file);
        if (options != null) buf.append(";" + options);
        buf.append("\";");
        buf.append("insert into " + table + " select * from TMP_SOURCE_" + table);
        Statement stmt = con.createStatement();
        try {
            stmt.execute(buf.toString());
        } finally {
            stmt.execute("drop table TMP_SOURCE_" + table + " IF EXISTS");
        }
    }
}