/*
 * 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.client.impl.schema;

import static com.google.common.base.Preconditions.checkState;
import java.util.Optional;
import lombok.Setter;
import org.apache.pulsar.client.api.Schema;
import org.apache.pulsar.client.api.schema.KeyValueSchema;
import org.apache.pulsar.common.schema.KeyValueEncodingType;
import org.apache.pulsar.common.schema.SchemaInfo;
import org.apache.pulsar.common.schema.SchemaType;

/**
 * Auto detect schema.
 */
public class AutoProduceBytesSchema<T> implements Schema<byte[]> {

    @Setter
    private volatile boolean requireSchemaValidation = true;
    private volatile Schema<T> schema;
    private final boolean userProvidedSchema;

    public AutoProduceBytesSchema() {
        this.userProvidedSchema = false;
    }

    public AutoProduceBytesSchema(Schema<T> schema) {
        this.schema = schema;
        this.userProvidedSchema = true;
        SchemaInfo schemaInfo = schema.getSchemaInfo();
        this.requireSchemaValidation = schemaInfo != null
                                       && schemaInfo.getType() != SchemaType.BYTES
                                       && schemaInfo.getType() != SchemaType.NONE;
    }

    private AutoProduceBytesSchema(AutoProduceBytesSchema<T> other) {
        this.schema = other.schema != null ? other.schema.clone() : null;
        this.userProvidedSchema = other.userProvidedSchema;
        this.requireSchemaValidation = other.requireSchemaValidation;
    }

    public void setSchema(Schema<T> schema) {
        this.schema = schema;
        this.requireSchemaValidation = schema.getSchemaInfo() != null
            && SchemaType.BYTES != schema.getSchemaInfo().getType()
            && SchemaType.NONE != schema.getSchemaInfo().getType();
    }

    private void ensureSchemaInitialized() {
        checkState(schemaInitialized(), "Schema is not initialized before used");
    }

    public boolean schemaInitialized() {
        return schema != null;
    }

    public boolean hasUserProvidedSchema() {
        return userProvidedSchema;
    }

    @Override
    public void validate(byte[] message) {
        ensureSchemaInitialized();

        schema.validate(message);
    }

    @Override
    public byte[] encode(byte[] message) {
        ensureSchemaInitialized();

        if (requireSchemaValidation) {
            // verify if the message can be decoded by the underlying schema
            Schema<T> localSchema = schema;
            if (localSchema instanceof KeyValueSchema && ((KeyValueSchema) localSchema).getKeyValueEncodingType()
                    .equals(KeyValueEncodingType.SEPARATED)) {
                ((KeyValueSchema) localSchema).getValueSchema().validate(message);
            } else {
                localSchema.validate(message);
            }
        }

        return message;
    }

    @Override
    public byte[] decode(byte[] bytes, byte[] schemaVersion) {
        ensureSchemaInitialized();

        if (requireSchemaValidation) {
            // verify the message can be detected by the underlying schema
            schema.decode(bytes, schemaVersion);
        }

        return bytes;
    }

    @Override
    public SchemaInfo getSchemaInfo() {
        ensureSchemaInitialized();

        return schema.getSchemaInfo();
    }

    @Override
    public Optional<Object> getNativeSchema() {
        return Optional
                .ofNullable(schema)
                .map(s->s.getNativeSchema())
                .orElse(Optional.empty());
    }

    @Override
    public Schema<byte[]> clone() {
        return new AutoProduceBytesSchema<>(this);
    }
}
