/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.pulsar.broker.service.schema.validator;

import static java.nio.charset.StandardCharsets.UTF_8;

import org.apache.pulsar.broker.service.schema.exceptions.InvalidSchemaDataException;
import org.apache.pulsar.common.protocol.schema.SchemaData;

/**
 * Validate if the string schema is in expected form.
 */
class StringSchemaDataValidator implements SchemaDataValidator {

    public static final StringSchemaDataValidator of() {
        return INSTANCE;
    }

    private static final StringSchemaDataValidator INSTANCE = new StringSchemaDataValidator();

    private static final String PY_NONE_SCHEMA_INFO = "null";

    private StringSchemaDataValidator() {}

    @Override
    public void validate(SchemaData schemaData) throws InvalidSchemaDataException {
        byte[] data = schemaData.getData();
        if (null != data && data.length > 0) {
            // python send 'null' string as schema data
            String schemaDataStr = new String(data, UTF_8);
            if (!PY_NONE_SCHEMA_INFO.equals(schemaDataStr)) {
                throw new InvalidSchemaDataException("Invalid schema definition data for string schema : '"
                    + schemaDataStr + "'");
            }
        }
    }
}
