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/*
 * SPDX-License-Identifier: Apache-2.0
 * Copyright (c) The original authors
 *
 * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */
package io.streamthoughts.jikkou.kafka.transform;

import static io.streamthoughts.jikkou.core.models.CoreAnnotations.JIKKOU_IO_TRANSFORM_PREFIX;

import io.streamthoughts.jikkou.core.ReconciliationContext;
import io.streamthoughts.jikkou.core.annotation.Priority;
import io.streamthoughts.jikkou.core.annotation.SupportedResource;
import io.streamthoughts.jikkou.core.config.ConfigProperty;
import io.streamthoughts.jikkou.core.exceptions.ConfigException;
import io.streamthoughts.jikkou.core.extension.ExtensionContext;
import io.streamthoughts.jikkou.core.models.HasItems;
import io.streamthoughts.jikkou.core.models.HasMetadata;
import io.streamthoughts.jikkou.core.models.HasPriority;
import io.streamthoughts.jikkou.core.transform.Transformation;
import io.streamthoughts.jikkou.kafka.models.V1KafkaTopic;
import io.streamthoughts.jikkou.kafka.models.V1KafkaTopicSpec;
import java.util.Optional;
import org.jetbrains.annotations.NotNull;

/**
 * This transformation can be used to enforce a maximum number of partitions for a kafka topic.
 */
@Priority(HasPriority.HIGHEST_PRECEDENCE)
@SupportedResource(type = V1KafkaTopic.class)
public class KafkaTopicMaxNumPartitionsTransformation implements Transformation {

    public static final String JIKKOU_IO_KAFKA_MAX_NUM_PARTITION = JIKKOU_IO_TRANSFORM_PREFIX + "/kafka-max-num-partition";

    public static final ConfigProperty MAX_NUM_PARTITIONS_CONFIG = ConfigProperty
            .ofInt("maxNumPartitions");

    private Integer maxNumPartitions;

    /**
     * {@inheritDoc}
     **/
    @Override
    public void init(@NotNull ExtensionContext context) {
        maxNumPartitions = MAX_NUM_PARTITIONS_CONFIG.getOptional(context.appConfiguration())
                .orElseThrow(() -> new ConfigException(
                        String.format("The '%s' configuration property is required for transformation class: %s",
                                MAX_NUM_PARTITIONS_CONFIG.key(),
                                KafkaTopicMaxNumPartitionsTransformation.class.getName()
                        )
                ));
    }

    /**
     * {@inheritDoc}
     **/
    @Override
    public @NotNull Optional transform(@NotNull V1KafkaTopic resource,
                                                     @NotNull HasItems resources,
                                                     @NotNull ReconciliationContext context) {
        V1KafkaTopicSpec spec = resource.getSpec();
        Integer partitions = spec.getPartitions();
        if (partitions != null && partitions > maxNumPartitions) {
            V1KafkaTopicSpec newSpec = spec.withPartitions(maxNumPartitions);
            resource = HasMetadata.addMetadataAnnotation(resource, JIKKOU_IO_KAFKA_MAX_NUM_PARTITION, maxNumPartitions);
            return Optional.of(resource.withSpec(newSpec));
        }
        return Optional.of(resource);
    }
}