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World's smallest O/R mapper for Java
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/*******************************************************************************
 * Copyright (c) 2001-2007 The PriDE team and MATHEMA Software GmbH
 * All rights reserved. This toolkit and the accompanying materials 
 * are made available under the terms of the GNU Lesser General Public
 * License (LGPL) which accompanies this distribution, and is available
 * at http://pride.sourceforge.net/LGPL.html
 * 
 * Contributors:
 *     Jan Lessner, MATHEMA Software GmbH - initial API and implementation
 *******************************************************************************/
package pm.pride.util.generator;

/**
 * Meta information about a database table
 *
 * @author Martin Haag
 * @version 1.0
 */

import java.sql.*;
import java.util.*;

public class TableDescription {

	public static final String COLUMN_LIST_START = "(";
	public static final String COLUMN_LIST_END = ")";
	public static final String COLUMN_LIST_SEPARATOR = ",";
	
    protected List columnList;
    protected String tableName;
    protected boolean partial;

	protected List extractColumns(DatabaseMetaData db_meta, String dbType, String tableName, List columnsOfInterest)
			throws SQLException {
		ResultSet rset2 = db_meta.getColumns (null, //con.getCatalog (),
											  null, //"*",
											  tableName, "%");
		List result = new ArrayList<>(0);
		while (rset2.next ()) {
			String columnName = rset2.getString ("COLUMN_NAME");
			int dataType = rset2.getInt ("DATA_TYPE");
			int columnSize = rset2.getInt ("COLUMN_SIZE"); // Timetamp: 11, Date: 7
			int decimalDigits = rset2.getInt ("DECIMAL_DIGITS");
			boolean nullable = rset2.getInt ("NULLABLE")== ResultSetMetaData.columnNoNulls;
			if (columnsOfInterest == null || columnsOfInterest.remove(columnName)) {
				TableColumn tabColumn = new TableColumn(dbType, tableName, columnName,
						dataType, columnSize, decimalDigits, nullable);
				result.add(tabColumn);
			}
		}
		rset2.close ();

		if (columnsOfInterest != null && columnsOfInterest.size() > 0) {
			throw new SQLException("Unknown columns in table " + tableName + ": " + columnsOfInterest);
		}
		return result;
	}

	protected void markKeyColumns(DatabaseMetaData db_meta, String tableName, List columns) throws SQLException {
		ResultSet rset2 = db_meta.getPrimaryKeys(null, //con.getCatalog (),
								                 null, //"*",
								                 tableName);
		while (rset2.next ()) {
			String column_name = rset2.getString ("COLUMN_NAME");
	
			Iterator iter = columns.iterator();
			while(iter.hasNext()) {
			  TableColumn tabColumn = (TableColumn)iter.next();
			  if (tabColumn.columnName.equals(column_name)) {
				  tabColumn.setPrimaryKeyField();
				  break;
			  }
			}
		}
		rset2.close ();
	}

	protected void init(Connection con, String dbType, String tableName) throws SQLException {
		if (tableName.contains(COLUMN_LIST_START)) {
			this.tableName = extractColumnsFromTableName(con, dbType, tableName);
		}
		else {
			this.tableName = extractColumnsFromTableMetadata(con, dbType, tableName, null);
		}
	}
	
    private String extractColumnsFromTableName(Connection con, String dbType, String tableName) throws SQLException {
    	partial = true;
    	String columnNamesString = tableName
    			.replaceFirst(".+\\" + COLUMN_LIST_START, "")
    			.replace(COLUMN_LIST_END, "")
    			.replaceAll("\\s", "");
    	String[] columnNames = columnNamesString.split(COLUMN_LIST_SEPARATOR);
    	List mutableColumnNameList = new ArrayList<>(Arrays.asList(columnNames));
    	String cleanedTableName = tableName.replaceFirst("\\" + COLUMN_LIST_START + ".*\\" + COLUMN_LIST_END, "");
    	return extractColumnsFromTableMetadata(con, dbType, cleanedTableName, mutableColumnNameList);
	}

	protected String extractColumnsFromTableMetadata(Connection con, String dbType, String tableName, List columnsOfInterest) throws SQLException {
		DatabaseMetaData db_meta = con.getMetaData ();
		String[] tbl_types = { "TABLE", "VIEW" };
		ResultSet rset1 = db_meta.getTables (null, //con.getCatalog (),
											 null, //"*",
											 tableName,
											 tbl_types);
		if (rset1.next()) {
			tableName = rset1.getString ("TABLE_NAME"); // Just in case there is something to normalize ;-)
			this.columnList = extractColumns(db_meta, dbType, tableName, columnsOfInterest);
			markKeyColumns(db_meta, tableName, columnList);
		}
		rset1.close ();
		return tableName;
	}

	public TableDescription(Connection con, String dbType, String tableName) throws SQLException {
		init(con, dbType, tableName);
		if (columnList == null) {
			init(con, dbType, tableName.toUpperCase());
			if (columnList == null)
				throw new SQLException("Unknown table " + tableName);
		}
    }

    public boolean hasPrimaryKey() {
        for (TableColumn current: getColumnList()) {
            if (current.isPrimaryKeyField())
                return true;
        }
        return false;
    }
    
    /** Returns an enumerator for the table's columns in form of TableColumns objects */
    public List getColumnList() { return columnList; }

    /** Returns the plain table name */
    public String getTableName() { return tableName; }

    /** Returns the table name with its first letter capitalized */
    public String getTableNameFirstUpper() {
        return tableName.substring(0,1).toUpperCase() + tableName.substring(1);
    }

	public boolean isPartial() {
		return partial;
	}
}