package com.randomnoun.common.db;
   
   /* (c) 2013 randomnoun. All Rights Reserved. This work is licensed under a
    * BSD Simplified License. (http://www.randomnoun.com/bsd-simplified.html)
    */
   
   import java.util.HashMap;
   
   import javax.sql.DataSource;
  
  import org.springframework.jdbc.core.JdbcTemplate;
  
  import com.randomnoun.common.db.to.SchemaTO;
  import com.randomnoun.common.db.to.TableColumnTO;
  import com.randomnoun.common.db.to.TableTO;
  
  /** Container class for database metadata.
   * 
   * <p>Rewrite of DatabaseTO to be marginally more structured
   * 
   * <p>Contains methods for populating metadata from the data dictionaries of
   * Oracle and MySQL, for the purposes of whatever it is that I'm doing at the time.
   *
   *  
   *  NB: does not set default values for oracle
   *  
   */
  public abstract class DatabaseReader {
  
  	protected com.randomnoun.common.db.to.DatabaseTO db;
      
  	// only required for online DB metadata
  	public DataSource ds;
  	public JdbcTemplate jt;
  	
  	/* these aren't used yet
  	public static class SourceTypeTO {
  		public SchemaTO schema;
  		public List packages;
  		public List packageBodies;
  		public List procedures;
  		public List functions;
  		public List triggers;
  	}
  	
  	public static class UserTypeTO {
  		public SchemaTO schema;
  		public List arrayTypes;
  		public List objectTypes;
  		public List tableTypes;
  		public List xmlSchema;
  	}
  	
  	public static class SecurityTO {
  		public SchemaTO schema;
  		public List users;
  		public List roles;
  		public List profiles;
  	}
  	
  	public static class StorageTO {
  		public SchemaTO schema;
  		public Map<String, TableTO> tablespaces;
  		public List datafiles;
  		public List rollbackSegments;
  		public List redoLogGroups;
  		public List archiveLogs;
  	}
  	
  	public static class DistributedTO {
  		public SchemaTO schema;
  		public List inDoubtTransactions;
  		public List databaseLinks;
  		public List streams;
  		public List advancedQueues;
  		public List advancedReplication;
  	}
  	*/
  	
  	/** Database metadata container. Will load reference data on demand */
  	// @TODO look up correct Reader instance and use that 
  	public DatabaseReader(DataSource dataSource /*, DatabaseType dbType*/) {
  		this.ds = dataSource;
  		this.jt = new JdbcTemplate(dataSource);
  		this.db = new com.randomnoun.common.db.to.DatabaseTO();
  		db.setDatabaseType(null);
  		db.setSchemaMap(new HashMap<String, SchemaTO>());
  	}
  	
  	
  	// this only works for MYSQL. so that's odd.
  	public SchemaTO getSchema(String schemaName) {
  		
  		// default schema name
  		if (schemaName==null) {
  			switch (db.getDatabaseType()) {
  				case ORACLE:
  					throw new UnsupportedOperationException("Not supported for this database type");
  				
 				case MYSQL:
 					schemaName = (String) jt.queryForObject("SELECT DATABASE();", java.lang.String.class);
 					break;
 			
 				case SQLSERVER:
 					throw new UnsupportedOperationException("Not supported for this database type");
 					
 				default:
 					throw new IllegalStateException("Unknown database type " + db.getDatabaseType());
 			}
 		}
 		
 		SchemaTO schema = db.getSchemaMap().get(db.upper(schemaName));
 		if (schema == null) {
 			schema = readSchema(db.upper(schemaName));
 			db.getSchemaMap().put(db.upper(schemaName), schema); 
 		}
 		return schema;
 	}
 	
 	abstract public SchemaTO readSchema(String schemaName);  // SchemaTO schema
 	
 	
 	// @TODO pass in current schema/table for context resolution
 	public TableColumnTO getColumn(com.randomnoun.common.db.to.DatabaseTO db, String identifier) {
 		String schemaName = null;
 		String tableName = null;
 		String columnName = null;
 		String[] bits = identifier.split("\\.");
 		if (bits.length > 3) { throw new IllegalArgumentException("Too many components in column identifier '" + identifier + "'"); }
 		if (bits.length < 1) { throw new IllegalArgumentException("Too few components in column identifier '" + identifier + "'"); }
 		if (bits.length > 2) { schemaName = bits[bits.length - 3]; }
 		if (bits.length > 1) { tableName = bits[bits.length - 2]; }
 		columnName = bits[bits.length - 1];
 		SchemaTO schema = db.getSchemaMap().get(schemaName); 
 		TableTO table = schema.getTable(tableName);
 		return table.getTableColumn(columnName);
 	}
 	
 }