/*
   Copyright (C) 2002 MySQL AB

      This program is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published by
      the Free Software Foundation; either version 2 of the License, or
      (at your option) any later version.

      This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.

      You should have received a copy of the GNU General Public License
      along with this program; if not, write to the Free Software
      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */
package com.mysql.jdbc;

import java.io.UnsupportedEncodingException;


/**
 * Field is a class used to describe fields in a
 * ResultSet
 *
 * @author Mark Matthews
 * @version $Id: Field.java,v 1.15.2.6 2004/02/06 00:54:16 mmatthew Exp $
 */
public class Field {
    //~ Static fields/initializers ---------------------------------------------

    private static final int AUTO_INCREMENT_FLAG = 512;
    private static final int NO_CHARSET_INFO = -1;

    //~ Instance fields --------------------------------------------------------

    private Connection connection = null;
    private String charsetName = null;
    private String databaseName = null;
    private String defaultValue = null;
    private String fullName = null;
    private String fullNameWithDatabase = null;
    private String fullOriginalName = null;
    private String fullOriginalNameWithDatabase = null;
    private String name; // The Field name
    private String originalColumnName = null;
    private String originalTableName = null;
    private String tableName; // The Name of the Table
    private byte[] buffer;
    private int charsetIndex = 0;
    private int colDecimals;
    private int databaseNameLength = -1;

    // database name info
    private int databaseNameStart = -1;
    private int defaultValueLength = -1;

    // default value info - from COM_LIST_FIELDS execution
    private int defaultValueStart = -1;
    private int length; // Internal length of the field;
    private int mysqlType = -1; // the MySQL type
    private int nameLength;
    private int nameStart;
    private int originalColumnNameLength = -1;

    // column name info (before aliasing)
    private int originalColumnNameStart = -1;
    private int originalTableNameLength = -1;

    // table name info (before aliasing)
    private int originalTableNameStart = -1;
    private int precisionAdjustFactor = 0;
    private int sqlType = -1; // the java.sql.Type
    private int tableNameLength;
    private int tableNameStart;
    private short colFlag;

    //~ Constructors -----------------------------------------------------------

    /**
    * Constructor used by DatabaseMetaData methods.
    */
    Field(String tableName, String columnName, int jdbcType, int length) {
        this.tableName = tableName;
        this.name = columnName;
        this.length = length;
        sqlType = jdbcType;
        colFlag = 0;
        colDecimals = 0;
    }

    /**
     * Constructor used when communicating with pre 4.1 servers
     */
    Field(Connection conn, byte[] buffer, int nameStart, int nameLength,
        int tableNameStart, int tableNameLength, int length, int mysqlType,
        short colFlag, int colDecimals) {
        this(conn, buffer, -1, -1, tableNameStart, tableNameLength, -1, -1,
            nameStart, nameLength, -1, -1, length, mysqlType, colFlag,
            colDecimals, -1, -1, NO_CHARSET_INFO);
    }

    /**
     * Constructor used when communicating with 4.1 and newer
     * servers
     */
    Field(Connection conn, byte[] buffer, int databaseNameStart,
        int databaseNameLength, int tableNameStart, int tableNameLength,
        int originalTableNameStart, int originalTableNameLength, int nameStart,
        int nameLength, int originalColumnNameStart,
        int originalColumnNameLength, int length, int mysqlType, short colFlag,
        int colDecimals, int defaultValueStart, int defaultValueLength,
        int charsetIndex) {
        this.connection = conn;
        this.buffer = buffer;
        this.nameStart = nameStart;
        this.nameLength = nameLength;
        this.tableNameStart = tableNameStart;
        this.tableNameLength = tableNameLength;
        this.length = length;
        this.colFlag = colFlag;
        this.colDecimals = colDecimals;
        this.mysqlType = mysqlType;

        // 4.1 field info...
        this.databaseNameStart = databaseNameStart;
        this.databaseNameLength = databaseNameLength;

        this.originalTableNameStart = originalTableNameStart;
        this.originalTableNameLength = originalTableNameLength;

        this.originalColumnNameStart = originalColumnNameStart;
        this.originalColumnNameLength = originalColumnNameLength;

        this.defaultValueStart = defaultValueStart;
        this.defaultValueLength = defaultValueLength;

        // Map MySqlTypes to java.sql Types
        sqlType = MysqlDefs.mysqlToJavaType(mysqlType);

        // If we're not running 4.1 or newer, use the connection's
        // charset
        if (charsetIndex != NO_CHARSET_INFO) {
            this.charsetIndex = charsetIndex;
			this.charsetName = CharsetMapping.INDEX_TO_CHARSET[this.charsetIndex];
            
            // Punt
            if (this.charsetName == null) {
				this.charsetName = this.connection.getEncoding();
            }  
        } else {
            this.charsetName = this.connection.getEncoding();
        }

        boolean isBinary = isBinary();

        //
        // Handle TEXT type (special case), Fix proposed by Peter McKeown
        //
        if ((sqlType == java.sql.Types.LONGVARBINARY) && !isBinary) {
            sqlType = java.sql.Types.LONGVARCHAR;
        } else if ((sqlType == java.sql.Types.VARBINARY) && !isBinary) {
            sqlType = java.sql.Types.VARCHAR;
        }

        //
        // Handle odd values for 'M' for floating point/decimal numbers
        //
        if (!isUnsigned()) {
            switch (this.mysqlType) {
            case MysqlDefs.FIELD_TYPE_DECIMAL:
                this.precisionAdjustFactor = -1;

                break;

            case MysqlDefs.FIELD_TYPE_DOUBLE:
            case MysqlDefs.FIELD_TYPE_FLOAT:
                this.precisionAdjustFactor = 1;

                break;
            }
        } else {
            switch (this.mysqlType) {
            case MysqlDefs.FIELD_TYPE_DOUBLE:
            case MysqlDefs.FIELD_TYPE_FLOAT:
                this.precisionAdjustFactor = 1;

                break;
            }
        }
    }

    //~ Methods ----------------------------------------------------------------

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isAutoIncrement() {
        return ((colFlag & AUTO_INCREMENT_FLAG) > 0);
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isBinary() {
        return ((colFlag & 128) > 0);
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public boolean isBlob() {
        return ((colFlag & 16) > 0);
    }

    /**
     * Returns the character set (if known) for this
     * field.
     *
     * @return the character set
     */
    public String getCharacterSet() {
        return this.charsetName;
    }

    /**
     * DOCUMENT ME!
     *
     * @param conn DOCUMENT ME!
     */
    public void setConnection(Connection conn) {
        this.connection = conn;
        
		this.charsetName = this.connection.getEncoding();
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public String getDatabaseName() {
        if ((this.databaseName == null) && (this.databaseNameStart != -1)
                && (this.databaseNameLength != -1)) {
            this.databaseName = getStringFromBytes(this.databaseNameStart,
                    this.databaseNameLength);
        }

        return this.databaseName;
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public String getFullName() {
        if (fullName == null) {
            StringBuffer fullNameBuf = new StringBuffer(getTableName().length()
                    + 1 + getName().length());
            fullNameBuf.append(tableName);

            // much faster to append a char than a String
            fullNameBuf.append('.');