BinaryResourceMetadata.scala

/*
 * Media Converter
 * Extracts media files from Fedora repository
 * 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 ch.memobase.models

import ch.memobase.RecordUtils
import ujson.Value

import scala.collection.mutable.ArrayBuffer
import scala.util.Try


/**
 * Essential information on a binary file residing in Fedora
 *
 * @param id        Identifier of the binary file
 * @param filePath  File path (URL) to resource
 * @param mimeType  MIME type
 * @param resource  Type of instantiation
 * @param eventType Action to be performed on the copy of the file
 */
case class BinaryResourceMetadata(id: String,
                                  filePath: String,
                                  mimeType: MimeType,
                                  resource: MemobaseResource,
                                  eventType: Event) {
}

object BinaryResourceMetadata extends RecordUtils {

  /**
   * Builds a `BinaryResourceMetadata` object from a JSON-LD object pulled from Kafka topic
   *
   * @param msg             Pulled Kafka message
   * @param externalBaseUrl Base URL of resource used outside of Fedora
   * @return
   */
  def build(msg: String, externalBaseUrl: String): List[Try[BinaryResourceMetadata]] = {
    val jsonldGraph = getJsonldGraph(msg)
    extractBinaryResourceMetadata(jsonldGraph, externalBaseUrl)
  }

  //noinspection ScalaStyle
  private def extractBinaryResourceMetadata(jsonldGraph: ArrayBuffer[Value], baseUrl: String): List[Try[BinaryResourceMetadata]] =
    jsonldGraph.value
      .withFilter {
        v => isDigitalObject(v.obj) || isPreviewImage(v.obj)
      }
      .map { v => {
        val id = v.obj.getOrElse("@id", Value("<unknown id>")).str
        Try(
          v.obj match {
            case v if isLocalRecord(v, baseUrl) && isProcessableMimeType(v) =>
              getEventType(jsonldGraph) match {
                case Some(UnknownEvent(e)) => throw new UnknownEventType(s"Event type `$e` for $id not known")
                case Some(eventType) =>
                  val instantiation = MemobaseResource(v("type").str)
                  BinaryResourceMetadata(
                    v("@id").str.substring(s"$baseUrl/digital/".length - 1),
                    v("locator").str,
                    if (instantiation == Thumbnail) {
                      JpegFile
                    } else {
                      Conversions.getMediaFileType(v("hasMimeType").str).get
                    },
                    instantiation,
                    eventType)
                case None => throw new NoEventType(id)
              }
            case v if isLocalRecord(v, baseUrl) =>
              val resource = MemobaseResource(v("type").str)
              throw new UnmanageableMediaFileType(s"Media file type for $id unknown", resource)
            case v =>
              val resource = MemobaseResource(v("type").str)
              throw new NoLocalBinary(id, resource)
          }
        )

      }
      }.toList
}