XMLTransformer.kt 2.81 KB
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/*
 * xml-data-transform
 * 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 net.sf.saxon.s9api.Processor
import net.sf.saxon.s9api.SAXDestination
import net.sf.saxon.s9api.StaticError
import net.sf.saxon.s9api.XsltExecutable
import org.apache.kafka.streams.KeyValue
import org.apache.logging.log4j.LogManager
import java.io.File
import java.io.FileInputStream
import java.io.InputStream
import java.util.Properties
import javax.xml.transform.stream.StreamSource

class XMLTransformer(appSettings: Properties) {
    private val log = LogManager.getLogger("XMLTransformer")

    private val xlstFilePath = appSettings.getProperty("xsltFilePath")
    private val identifierFieldName = appSettings.getProperty("identifierFieldName")
    private val recordTag = appSettings.getProperty("recordTag")

    init {
        if (identifierFieldName == "placeholderValue") {
            log.error("Requires a value for identifier field name, but found default value.")
        }
    }

    private val processor = Processor(false)
    private val xslt = compileXslt()
    private val transformer = xslt.load()

    private fun compileXslt(): XsltExecutable {
        val errorList = mutableListOf<StaticError>()
        val xsltCompiler = processor.newXsltCompiler()
        xsltCompiler.setErrorList(errorList)
        val source = StreamSource(FileInputStream(File(xlstFilePath)))
        val executable = xsltCompiler.compile(source)
        if (errorList.isEmpty()) {
            return executable
        } else {
            throw Exception(errorList.joinToString())
        }
    }

    fun applyXSLT(key: String, data: InputStream): KeyValue<String, SAXContentHandler> {
        val contentHandler = SAXContentHandler(key, identifierFieldName, recordTag)
        data.use {
            transformer.setSource(StreamSource(it))
            transformer.destination = SAXDestination(contentHandler)
            transformer.transform()
        }
        if (contentHandler.identifier.isEmpty()) {
            throw Exception("No valid identifier found in record $key in field $identifierFieldName.")
        } else {
            return KeyValue(contentHandler.identifier, contentHandler)
        }
    }
}