/*
 * 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.xml

import ch.memobase.settings.HeaderMetadata
import java.io.ByteArrayInputStream
import java.io.InputStream
import javax.xml.transform.stream.StreamSource
import net.sf.saxon.s9api.Processor
import net.sf.saxon.s9api.SAXDestination
import net.sf.saxon.s9api.StaticError
import org.memobase.utils.MissingIdentifierException
import org.memobase.utils.XsltException

class XMLTransformer {
    private val processor = Processor(false)

    fun xsltFunction(xsltData: ByteArray): ByteArray {
        return xsltData
    }

    fun applyXSLT(
        key: String,
        headers: HeaderMetadata,
        data: InputStream,
        xsltFile: ByteArray
    ): Pair<String, SAXContentHandler> {
        val contentHandler = SAXContentHandler(key, headers.xmlIdentifierFieldName, headers.xmlRecordTag)
        val errorList = mutableListOf<StaticError>()
        val xsltCompiler = processor.newXsltCompiler()
        xsltCompiler.setErrorList(errorList)
        val source = StreamSource(ByteArrayInputStream(xsltFile))
        val executable = xsltCompiler.compile(source)
        if (errorList.isNotEmpty()) {
            throw XsltException(errorList)
        }
        val transformer = executable.load()
        data.use { stream ->
            transformer.setSource(StreamSource(stream))
            transformer.destination = SAXDestination(contentHandler)
            transformer.transform()
        }
        if (contentHandler.identifier == null || contentHandler.identifier?.isEmpty() == true) {
            throw MissingIdentifierException(key, headers.xmlIdentifierFieldName)
        } else {
            return Pair(contentHandler.identifier!!, contentHandler)
        }
    }
}