/*
 Copyright (C) 2002-2007 MySQL AB

 This program is free software; you can redistribute it and/or modify
 it under the terms of version 2 of the GNU General Public License as 
 published by the Free Software Foundation.

 There are special exceptions to the terms and conditions of the GPL 
 as it is applied to this software. View the full text of the 
 exception in file EXCEPTIONS-CONNECTOR-J in the directory of this 
 software distribution.

 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.sql.SQLException;
import java.sql.Types;

/**
 * A ResultSetMetaData object can be used to find out about the types and
 * properties of the columns in a ResultSet
 * 
 * @author Mark Matthews
 * @version $Id: ResultSetMetaData.java,v 1.1.2.1 2005/05/13 18:58:38 mmatthews
 *          Exp $
 * 
 * @see java.sql.ResultSetMetaData
 */
public class ResultSetMetaData implements java.sql.ResultSetMetaData {
	private static int clampedGetLength(Field f) {
		long fieldLength = f.getLength();

		if (fieldLength > Integer.MAX_VALUE) {
			fieldLength = Integer.MAX_VALUE;
		}

		return (int) fieldLength;
	}

	/**
	 * Checks if the SQL Type is a Decimal/Number Type
	 * 
	 * @param type
	 *            SQL Type
	 * 
	 * @return ...
	 */
	private static final boolean isDecimalType(int type) {
		switch (type) {
		case Types.BIT:
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.NUMERIC:
		case Types.DECIMAL:
			return true;
		}

		return false;
	}

	Field[] fields;
	boolean useOldAliasBehavior = false;

	/**
	 * Initialise for a result with a tuple set and a field descriptor set
	 * 
	 * @param fields
	 *            the array of field descriptors
	 */
	public ResultSetMetaData(Field[] fields, boolean useOldAliasBehavior) {
		this.fields = fields;
		this.useOldAliasBehavior = useOldAliasBehavior;
	}

	/**
	 * What's a column's table's catalog name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return catalog name, or "" if not applicable
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getCatalogName(int column) throws SQLException {
		Field f = getField(column);

		String database = f.getDatabaseName();

		return (database == null) ? "" : database; //$NON-NLS-1$
	}

	/**
	 * What's the Java character encoding name for the given column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the Java character encoding name for the given column, or null if
	 *         no Java character encoding maps to the MySQL character set for
	 *         the given column.
	 * 
	 * @throws SQLException
	 *             if an invalid column index is given.
	 */
	public String getColumnCharacterEncoding(int column) throws SQLException {
		String mysqlName = getColumnCharacterSet(column);

		String javaName = null;

		if (mysqlName != null) {
			javaName = CharsetMapping.getJavaEncodingForMysqlEncoding(
					mysqlName, null);
		}

		return javaName;
	}

	/**
	 * What's the MySQL character set name for the given column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the MySQL character set name for the given column
	 * 
	 * @throws SQLException
	 *             if an invalid column index is given.
	 */
	public String getColumnCharacterSet(int column) throws SQLException {
		return getField(column).getCharacterSet();
	}

	// --------------------------JDBC 2.0-----------------------------------

	/**
	 * JDBC 2.0
	 * 
	 * <p>
	 * Return the fully qualified name of the Java class whose instances are
	 * manufactured if ResultSet.getObject() is called to retrieve a value from
	 * the column. ResultSet.getObject() may return a subClass of the class
	 * returned by this method.
	 * </p>
	 * 
	 * @param column
	 *            the column number to retrieve information for
	 * 
	 * @return the fully qualified name of the Java class whose instances are
	 *         manufactured if ResultSet.getObject() is called to retrieve a
	 *         value from the column.
	 * 
	 * @throws SQLException
	 *             if an error occurs
	 */
	public String getColumnClassName(int column) throws SQLException {
		Field f = getField(column);

		return getClassNameForJavaType(f.getSQLType(), 
				f.isUnsigned(), 
				f.getMysqlType(), 
				f.isBinary() || f.isBlob(),
				f.isOpaqueBinary()); 
	}

	/**
	 * Whats the number of columns in the ResultSet?
	 * 
	 * @return the number
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getColumnCount() throws SQLException {
		return this.fields.length;
	}

	/**
	 * What is the column's normal maximum width in characters?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the maximum width
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getColumnDisplaySize(int column) throws SQLException {
		Field f = getField(column);

		int lengthInBytes = clampedGetLength(f);

		return lengthInBytes / f.getMaxBytesPerCharacter();
	}

	/**
	 * What is the suggested column title for use in printouts and displays?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the column label
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getColumnLabel(int column) throws SQLException {
		if (this.useOldAliasBehavior) {
			return getColumnName(column);
		}
		
		return getField(column).getColumnLabel();
	}

	/**
	 * What's a column's name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the column name
	 * 
	 * @throws SQLException
	 *             if a databvase access error occurs
	 */
	public String getColumnName(int column) throws SQLException {
		if (this.useOldAliasBehavior) {
			return getField(column).getName();
	}

		String name = getField(column).getNameNoAliases();
		
		if (name != null && name.length() == 0) {
			return getField(column).getName();
		}
		
		return name;
	}

	/**
	 * What is a column's SQL Type? (java.sql.Type int)
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the java.sql.Type value
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 * 
	 * @see java.sql.Types
	 */
	public int getColumnType(int column) throws SQLException {
		return getField(column).getSQLType();
	}

	/**
	 * Whats is the column's data source specific type name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return the type name
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getColumnTypeName(int column) throws java.sql.SQLException {
		Field field = getField(column);

		int mysqlType = field.getMysqlType();
		int jdbcType = field.getSQLType();

		switch (mysqlType) {
		case MysqlDefs.FIELD_TYPE_BIT:
			return "BIT";
		case MysqlDefs.FIELD_TYPE_DECIMAL:
		case MysqlDefs.FIELD_TYPE_NEW_DECIMAL:
			return field.isUnsigned() ? "DECIMAL UNSIGNED" : "DECIMAL";

		case MysqlDefs.FIELD_TYPE_TINY:
			return field.isUnsigned() ? "TINYINT UNSIGNED" : "TINYINT";

		case MysqlDefs.FIELD_TYPE_SHORT:
			return field.isUnsigned() ? "SMALLINT UNSIGNED" : "SMALLINT";

		case MysqlDefs.FIELD_TYPE_LONG:
			return field.isUnsigned() ? "INT UNSIGNED" : "INT";

		case MysqlDefs.FIELD_TYPE_FLOAT:
			return field.isUnsigned() ? "FLOAT UNSIGNED" : "FLOAT";

		case MysqlDefs.FIELD_TYPE_DOUBLE:
			return field.isUnsigned() ? "DOUBLE UNSIGNED" : "DOUBLE";

		case MysqlDefs.FIELD_TYPE_NULL:
			return "NULL"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_TIMESTAMP:
			return "TIMESTAMP"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_LONGLONG:
			return field.isUnsigned() ? "BIGINT UNSIGNED" : "BIGINT";

		case MysqlDefs.FIELD_TYPE_INT24:
			return field.isUnsigned() ? "MEDIUMINT UNSIGNED" : "MEDIUMINT";

		case MysqlDefs.FIELD_TYPE_DATE:
			return "DATE"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_TIME:
			return "TIME"; //$NON-NLS-1$       

		case MysqlDefs.FIELD_TYPE_DATETIME:
			return "DATETIME"; //$NON-NLS-1$      

		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
			return "TINYBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
			return "MEDIUMBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			return "LONGBLOB"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_BLOB:
			if (getField(column).isBinary()) {
				return "BLOB";//$NON-NLS-1$
			}

			return "TEXT";//$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_VARCHAR:
			return "VARCHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_VAR_STRING:
			if (jdbcType == Types.VARBINARY) {
				return "VARBINARY";
			}
			
			return "VARCHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_STRING:
			if (jdbcType == Types.BINARY) {
				return "BINARY";
			}
			
			return "CHAR"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_ENUM:
			return "ENUM"; //$NON-NLS-1$

		case MysqlDefs.FIELD_TYPE_YEAR:
			return "YEAR"; // $NON_NLS-1$

		case MysqlDefs.FIELD_TYPE_SET:
			return "SET"; //$NON-NLS-1$
			
		case MysqlDefs.FIELD_TYPE_GEOMETRY:
			return "GEOMETRY"; //$NON-NLS-1$
			
		default:
			return "UNKNOWN"; //$NON-NLS-1$
		}
	}

	/**
	 * Returns the field instance for the given column index
	 * 
	 * @param columnIndex
	 *            the column number to retrieve a field instance for
	 * 
	 * @return the field instance for the given column index
	 * 
	 * @throws SQLException
	 *             if an error occurs
	 */
	protected Field getField(int columnIndex) throws SQLException {
		if ((columnIndex < 1) || (columnIndex > this.fields.length)) {
			throw SQLError.createSQLException(Messages.getString("ResultSetMetaData.46"), //$NON-NLS-1$
					SQLError.SQL_STATE_INVALID_COLUMN_NUMBER);
		}

		return this.fields[columnIndex - 1];
	}

	/**
	 * What is a column's number of decimal digits.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the precision
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getPrecision(int column) throws SQLException {
		Field f = getField(column);

		// if (f.getMysqlType() == MysqlDefs.FIELD_TYPE_NEW_DECIMAL) {
		// return f.getLength();
		// }

		if (isDecimalType(f.getSQLType())) {
			if (f.getDecimals() > 0) {
				return clampedGetLength(f) - 1 + f.getPrecisionAdjustFactor();
			}

			return clampedGetLength(f) + f.getPrecisionAdjustFactor();
		}

		switch (f.getMysqlType()) {
		case MysqlDefs.FIELD_TYPE_TINY_BLOB:
		case MysqlDefs.FIELD_TYPE_BLOB:
		case MysqlDefs.FIELD_TYPE_MEDIUM_BLOB:
		case MysqlDefs.FIELD_TYPE_LONG_BLOB:
			return clampedGetLength(f); // this may change in the future
		// for now, the server only
		// returns FIELD_TYPE_BLOB for _all_
		// BLOB types, but varying lengths
		// indicating the _maximum_ size
		// for each BLOB type.
		default:
			return clampedGetLength(f) / f.getMaxBytesPerCharacter();

		}
	}

	/**
	 * What is a column's number of digits to the right of the decimal point?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the scale
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int getScale(int column) throws SQLException {
		Field f = getField(column);

		if (isDecimalType(f.getSQLType())) {
			return f.getDecimals();
		}

		return 0;
	}

	/**
	 * What is a column's table's schema? This relies on us knowing the table
	 * name. The JDBC specification allows us to return "" if this is not
	 * applicable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return the Schema
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getSchemaName(int column) throws SQLException {
		return ""; //$NON-NLS-1$
	}

	/**
	 * Whats a column's table's name?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return column name, or "" if not applicable
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public String getTableName(int column) throws SQLException {
		if (this.useOldAliasBehavior) {
			return getField(column).getTableName();
		}
		
		return getField(column).getTableNameNoAliases();
	}

	/**
	 * Is the column automatically numbered (and thus read-only)
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isAutoIncrement(int column) throws SQLException {
		Field f = getField(column);

		return f.isAutoIncrement();
	}

	/**
	 * Does a column's case matter?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws java.sql.SQLException
	 *             if a database access error occurs
	 */
	public boolean isCaseSensitive(int column) throws java.sql.SQLException {
		Field field = getField(column);

		int sqlType = field.getSQLType();

		switch (sqlType) {
		case Types.BIT:
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		case Types.CHAR:
		case Types.VARCHAR:
		case Types.LONGVARCHAR:

			if (field.isBinary()) {
				return true;
			}

			String collationName = field.getCollation();

			return ((collationName != null) && !collationName.endsWith("_ci"));

		default:
			return true;
		}
	}

	/**
	 * Is the column a cash value?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if its a cash column
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isCurrency(int column) throws SQLException {
		return false;
	}

	/**
	 * Will a write on this column definately succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc..
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isDefinitelyWritable(int column) throws SQLException {
		return isWritable(column);
	}

	/**
	 * Can you put a NULL in this column?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return one of the columnNullable values
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public int isNullable(int column) throws SQLException {
		if (!getField(column).isNotNull()) {
			return java.sql.ResultSetMetaData.columnNullable;
		}

		return java.sql.ResultSetMetaData.columnNoNulls;
	}

	/**
	 * Is the column definitely not writable?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isReadOnly(int column) throws SQLException {
		return getField(column).isReadOnly();
	}

	/**
	 * Can the column be used in a WHERE clause? Basically for this, I split the
	 * functions into two types: recognised types (which are always useable),
	 * and OTHER types (which may or may not be useable). The OTHER types, for
	 * now, I will assume they are useable. We should really query the catalog
	 * to see if they are useable.
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if they can be used in a WHERE clause
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSearchable(int column) throws SQLException {
		return true;
	}

	/**
	 * Is the column a signed number?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2...
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isSigned(int column) throws SQLException {
		Field f = getField(column);
		int sqlType = f.getSQLType();

		switch (sqlType) {
		case Types.TINYINT:
		case Types.SMALLINT:
		case Types.INTEGER:
		case Types.BIGINT:
		case Types.FLOAT:
		case Types.REAL:
		case Types.DOUBLE:
		case Types.NUMERIC:
		case Types.DECIMAL:
			return !f.isUnsigned();

		case Types.DATE:
		case Types.TIME:
		case Types.TIMESTAMP:
			return false;

		default:
			return false;
		}
	}

	/**
	 * Is it possible for a write on the column to succeed?
	 * 
	 * @param column
	 *            the first column is 1, the second is 2, etc.
	 * 
	 * @return true if so
	 * 
	 * @throws SQLException
	 *             if a database access error occurs
	 */
	public boolean isWritable(int column) throws SQLException {
		return !isReadOnly(column);
	}

	/**
	 * Returns a string representation of this object
	 * 
	 * @return ...
	 */
	public String toString() {
		StringBuffer toStringBuf = new StringBuffer();
		toStringBuf.append(super.toString());
		toStringBuf.append(" - Field level information: "); //$NON-NLS-1$

		for (int i = 0; i < this.fields.length; i++) {
			toStringBuf.append("\n\t"); //$NON-NLS-1$
			toStringBuf.append(this.fields[i].toString());
		}

		return toStringBuf.toString();
	}
	
	static String getClassNameForJavaType(int javaType, 
			boolean isUnsigned, int mysqlTypeIfKnown, 
			boolean isBinaryOrBlob,
			boolean isOpaqueBinary) {
		switch (javaType) {
		case Types.BIT:
		case Types.BOOLEAN:
			return "java.lang.Boolean"; //$NON-NLS-1$

		case Types.TINYINT:

			if (isUnsigned) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Integer"; //$NON-NLS-1$

		case Types.SMALLINT:

			if (isUnsigned) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Integer"; //$NON-NLS-1$

		case Types.INTEGER:

			if (!isUnsigned || 
					mysqlTypeIfKnown == MysqlDefs.FIELD_TYPE_INT24) {
				return "java.lang.Integer"; //$NON-NLS-1$
			}

			return "java.lang.Long"; //$NON-NLS-1$

		case Types.BIGINT:

			if (!isUnsigned) {
				return "java.lang.Long"; //$NON-NLS-1$
			}

			return "java.math.BigInteger"; //$NON-NLS-1$

		case Types.DECIMAL:
		case Types.NUMERIC:
			return "java.math.BigDecimal"; //$NON-NLS-1$

		case Types.REAL:
			return "java.lang.Float"; //$NON-NLS-1$

		case Types.FLOAT:
		case Types.DOUBLE:
			return "java.lang.Double"; //$NON-NLS-1$

		case Types.CHAR:
		case Types.VARCHAR:
		case Types.LONGVARCHAR:
			if (!isOpaqueBinary) {
				return "java.lang.String"; //$NON-NLS-1$
			}

			return "[B";

		case Types.BINARY:
		case Types.VARBINARY:
		case Types.LONGVARBINARY:

			if (mysqlTypeIfKnown == MysqlDefs.FIELD_TYPE_GEOMETRY) {
				return "[B";
			} else if (isBinaryOrBlob) {
				return "[B";
			} else {
				return "java.lang.String";
			}

		case Types.DATE:
			return "java.sql.Date"; //$NON-NLS-1$

		case Types.TIME:
			return "java.sql.Time"; //$NON-NLS-1$

		case Types.TIMESTAMP:
			return "java.sql.Timestamp"; //$NON-NLS-1$

		default:
			return "java.lang.Object"; //$NON-NLS-1$
		}
	}
	
	/**
     * Returns true if this either implements the interface argument or is directly or indirectly a wrapper
     * for an object that does. Returns false otherwise. If this implements the interface then return true,
     * else if this is a wrapper then return the result of recursively calling <code>isWrapperFor</code> on the wrapped
     * object. If this does not implement the interface and is not a wrapper, return false.
     * This method should be implemented as a low-cost operation compared to <code>unwrap</code> so that
     * callers can use this method to avoid expensive <code>unwrap</code> calls that may fail. If this method
     * returns true then calling <code>unwrap</code> with the same argument should succeed.
     *
     * @param interfaces a Class defining an interface.
     * @return true if this implements the interface or directly or indirectly wraps an object that does.
     * @throws java.sql.SQLException  if an error occurs while determining whether this is a wrapper
     * for an object with the given interface.
     * @since 1.6
     */
	public boolean isWrapperFor(Class iface) throws SQLException {
		// This works for classes that aren't actually wrapping
		// anything
		return iface.isInstance(this);
	}

    /**
     * Returns an object that implements the given interface to allow access to non-standard methods,
     * or standard methods not exposed by the proxy.
     * The result may be either the object found to implement the interface or a proxy for that object.
     * If the receiver implements the interface then that is the object. If the receiver is a wrapper
     * and the wrapped object implements the interface then that is the object. Otherwise the object is
     *  the result of calling <code>unwrap</code> recursively on the wrapped object. If the receiver is not a
     * wrapper and does not implement the interface, then an <code>SQLException</code> is thrown.
     *
     * @param iface A Class defining an interface that the result must implement.
     * @return an object that implements the interface. May be a proxy for the actual implementing object.
     * @throws java.sql.SQLException If no object found that implements the interface 
     * @since 1.6
     */
	public Object unwrap(Class iface) throws java.sql.SQLException {
    	try {
    		// This works for classes that aren't actually wrapping
    		// anything
    		return Util.cast(iface, this);
        } catch (ClassCastException cce) {
            throw SQLError.createSQLException("Unable to unwrap to " + iface.toString(), 
            		SQLError.SQL_STATE_ILLEGAL_ARGUMENT);
        }
    }
}
