/*	Copyright (c) 2012	Tomislav Gountchev <tomi@gountchev.net>	*/

package jdbcpgbackup;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

public abstract class CachingDBOFactory<T extends DbBackupObject> implements DBOFactory<T> {

	protected final Schema.CachingSchemaFactory schemaFactory;

	protected Map<String,Map<String,T>> map = null;

	protected CachingDBOFactory(Schema.CachingSchemaFactory schemaFactory) {
		this.schemaFactory = schemaFactory;
	}

	@Override
	public Iterable<T> getDbBackupObjects(Connection con, Schema schema) throws SQLException {
		if (map == null) {
			loadMap(con);
		}
		Map<String,T> dbos = map.get(schema.getName());
		if (dbos == null) return Collections.emptyList();
		else return Collections.unmodifiableCollection(dbos.values());
	}

	@Override
	public T getDbBackupObject(Connection con, String name, Schema schema) throws SQLException {
		if (map == null) {
			loadMap(con);
		}
		Map<String,T> dbos = map.get(schema.getName());
		return dbos == null ? null : dbos.get(name);
	}

	protected void loadMap(Connection con) throws SQLException {
		map = new HashMap<String,Map<String,T>>();
		PreparedStatement stmt = null;
		try {
			stmt = getAllStatement(con);
			ZipBackup.debug("loading map in " + CachingDBOFactory.this.getClass());
			ResultSet rs = stmt.executeQuery();
			while (rs.next()) {
				Schema schema = schemaFactory.getFromCurrentBatch(rs.getInt("schema_oid"));
				if (schema == null) continue;
				Map<String,T> dbos = map.get(schema.getName());
				if (dbos == null) {
					dbos = new HashMap<String,T>();
					map.put(schema.getName(), dbos);
				}
				T dbo = newDbBackupObject(con, rs, schema);
				dbos.put(dbo.getName(), dbo);
			}
			rs.close();
		} finally {
			if (stmt != null) stmt.close();
		}
	}

	protected abstract PreparedStatement getAllStatement(Connection con) throws SQLException;

	protected abstract T newDbBackupObject(Connection con, ResultSet rs, Schema schema) throws SQLException;

}