package com.luxoft;

import java.io.*;
import java.sql.*;
import java.util.logging.Logger;

import static java.lang.System.out;

public class ClobLoader {

    static int calcChars(Reader r) throws SQLException, IOException {
        int cnt = 0;
        while (-1 != r.read()) cnt++;
        r.close();
        return cnt;
    }

    static Logger logger = Logger.getLogger("ClobLoader");

    public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException {
        if (args.length==0){
            out.printf("Usage:\n\n");
            out.printf("  $ java -jar ClobLoader-x.x.x.jar jdbc-connection-string select-blob-exprnnession file-name [encoding]\n\n");
            out.printf(" Examples:\n");
            out.printf("  Update the existing CLOB from textfile with utf-8 encoding:\n");
            out.printf("  $ java -jar ClobLoader-x.x.x.jar \\ \n");
            out.printf("              \"jdbc:oracle:thin:scott/tiger@127.0.0.1:1521/XE\" \\ \n");
            out.printf("              \"UPDATE mytable SET clobField=? WHERE id=12345\" \\ \n");
            out.printf("              readme.txt \\ \n");
            out.printf("              utf-8 \n\n");
            out.printf("  Insert a new CLOB:\n");
            out.printf("  $ java -jar ClobLoader-x.x.x.jar \\ \n");
            out.printf("              \"jdbc:oracle:thin:scott/tiger@127.0.0.1:1521/XE\" \\ \n");
            out.printf("              \"INSERT INTO test VALUES (test_seq.nextval,?)\" \\ \n");
            out.printf("              readme2.txt \\ \n");
            out.printf("              windows-1251\n\n");
            out.printf(" To force quickstart you can add -XX:+UseSerialGC option\n\n");
            return;
        }
        String encoding = "windows-1251";
        if (args.length>=4){
            logger.info("Default encoding has been changed into '"+encoding+"'");
            encoding = args[3];
        }
        logger.info("Begin");
        Class.forName("oracle.jdbc.OracleDriver");
        logger.info("Get connection...");
        Connection conn = DriverManager.getConnection(args[0]);
        conn.setAutoCommit(false);
        String sql = args[1];
        String fileName = args[2];
        logger.info("Estimate size in chars...");
        // TODO: Redundant step. Should be refactored without double-reading of InputStream
        Reader reader = new InputStreamReader(new FileInputStream(fileName), encoding);
        int length = calcChars(reader);
        logger.info("Prepare statement '"+sql+"'");
        PreparedStatement pStmt = conn.prepareStatement(sql);
        logger.info("Bind variables...");
        reader = new InputStreamReader(new FileInputStream(fileName), encoding);
        pStmt.setCharacterStream(1, reader, length);
        logger.info("Exec update...");
        pStmt.executeUpdate();
        pStmt.close();
        logger.info("Commit");
        conn.commit();
        logger.info("Close connection");
        conn.close();
        logger.info("End");
    }
}