package org.postgresql.util;

import java.sql.*;

/**
 * Converts to and from the postgresql bytea datatype used by the backend.
 *
 * $Id: Encoding.java,v 1.1 2001/07/21 18:52:11 momjian Exp $
 */

public class PGbytea {

        /**
         * Converts a PG bytea string (i.e. the text representation
         * of the bytea data type) into a java byte[]
         */
        public static byte[] toBytes(String s) throws SQLException {
          if(s==null)
            return null;
          int slength = s.length();
          byte[] buf = new byte[slength];
          int bufpos = 0;
          int thebyte;
          char nextchar;
          char secondchar;
          for (int i = 0; i < slength; i++) {
            nextchar = s.charAt(i);
            if (nextchar == '\\') {
              secondchar = s.charAt(++i);
              if (secondchar == '\\') {
                //escaped \
                buf[bufpos++] = (byte)'\\';
              } else {
                thebyte = (secondchar-48)*64 + (s.charAt(++i)-48)*8 + (s.charAt(++i)-48);
                if (thebyte > 127)
                  thebyte -= 256;
                buf[bufpos++] = (byte)thebyte;
              }
            } else {
              buf[bufpos++] = (byte)nextchar;
            }
          }
          byte[] l_return = new byte[bufpos];
          System.arraycopy(buf,0,l_return,0,bufpos);
          return l_return;
        }

        /**
         * Converts a java byte[] into a PG bytea string (i.e. the text
         * representation of the bytea data type)
         */
        public static String toPGString(byte[] p_buf) throws SQLException
        {
          if(p_buf==null)
            return null;
          StringBuffer l_strbuf = new StringBuffer();
          for (int i = 0; i < p_buf.length; i++) {
            int l_int = (int)p_buf[i];
            if (l_int < 0) {
              l_int = 256 + l_int;
            }
            //we escape the same non-printable characters as the backend
            //we must escape all 8bit characters otherwise when convering
            //from java unicode to the db character set we may end up with
            //question marks if the character set is SQL_ASCII
            if (l_int < 040 || l_int > 0176) {
              //escape charcter with the form \000, but need two \\ because of
              //the parser
              l_strbuf.append("\\");
              l_strbuf.append((char)(((l_int >> 6) & 0x3)+48));
              l_strbuf.append((char)(((l_int >> 3) & 0x7)+48));
              l_strbuf.append((char)((l_int & 0x07)+48));
            } else if (p_buf[i] == (byte)'\\') {
              //escape the backslash character as \\, but need four \\\\ because
              //of the parser
              l_strbuf.append("\\\\");
            } else {
              //other characters are left alone
              l_strbuf.append((char)p_buf[i]);
            }
          }
          return l_strbuf.toString();
        }


}