KafkaTopology.kt

/*
 * Table Data Import Service
 * Copyright (C) 2020 Memoriav
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package org.memobase

import com.beust.klaxon.JsonObject
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.kotlin.registerKotlinModule
import java.io.StringWriter
import org.apache.kafka.streams.KeyValue
import org.apache.kafka.streams.StreamsBuilder
import org.apache.kafka.streams.Topology
import org.apache.kafka.streams.kstream.KStream
import org.apache.kafka.streams.kstream.Predicate
import org.apache.logging.log4j.LogManager
import org.memobase.helpers.Default
import org.memobase.helpers.JSON
import org.memobase.model.InstitutionSearchDoc
import org.memobase.model.Report
import org.memobase.model.Schema
import org.memobase.model.SearchDoc
import org.memobase.settings.SettingsLoader

class KafkaTopology(private val settings: SettingsLoader) {
    private val log = LogManager.getLogger("SearchDocService")

    private val reportTopic = settings.processReportTopic

    private val searchDocTransform = SearchDocTransform(settings.appSettings.getProperty(KEYS.mediaUrlPropName))
    private val institutionSearchDoc = InstitutionSearchDocBuilder()

    fun build(): Topology {
        val builder = StreamsBuilder()
        val stream = builder.stream<String, String>(settings.inputTopic)
        val branchedStream = stream
            .flatMapValues { value -> JSON.parse(value) }
            .mapValues { value -> JSON.unpack(value) }
            .branch(
                Predicate { _, value -> value.containsKey(JSON.record) },
                Predicate { _, value -> value.containsKey(JSON.institution) },
                Predicate { _, value -> value.containsKey(JSON.recordSet) },
                Predicate { _, _ -> true }
            )

        val recordStream = branchedStream[0]
            .mapValues { readOnlyKey, value ->
                try {
                    Pair(searchDocTransform.transform(value), Report(readOnlyKey, "SUCCESS", "Transformed message into search doc."))
                } catch (ex: InvalidInputException) {
                    Pair(Default.searchDoc, Report(readOnlyKey, "FAILURE", ex.localizedMessage))
                }
            }

        outputStreams(recordStream)

        val institutionStream = branchedStream[1]
            .mapValues { readOnlyKey, value ->
                try {
                    Pair(institutionSearchDoc.transform(value), Report(readOnlyKey, "SUCCESS", "Transformed message into search doc."))
                } catch (ex: InvalidInputException) {
                    Pair(Default.institutionSearchDoc, Report(readOnlyKey, "FAILURE", ex.localizedMessage))
                }
            }

        outputStreams(institutionStream)



        return builder.build()
    }

    private fun outputStreams(stream: KStream<String, Pair<Schema, Report>>) {
        stream
            .map { _, value -> KeyValue(value.second.id, value.second.toJson()) }
            .to(reportTopic)

        stream
            .filterNot { _, value -> value.second.status == "FAILURE" }
            .map { _, value -> KeyValue(value.first.id, value.first) }
            .mapValues { value ->
                val writer = StringWriter()
                ObjectMapper().registerKotlinModule().writeValue(writer, value)
                writer.toString()
            }
            .to(settings.outputTopic)
    }
}