Create tasks to generate all previews

There is a task to generate preview images per attachment. It can
either add them (if not present yet) or overwrite them (e.g. some
config has changed).

There is a task that selects all attachments without previews and
submits a task to create it. This is submitted on start automatically
to generate previews for all existing attachments.

modules/common/src/main/scala/docspell/common/AllPreviewsArgs.scala

@@ -0,0 +1,26 @@
+package docspell.common
+
+import io.circe.generic.semiauto._
+import io.circe.{Decoder, Encoder}
+
+/** Arguments for the `AllPreviewsTask` that submits tasks to
+  * generates a preview image for attachments.
+  *
+  * It can replace the current preview image or only generate one, if
+  * it is missing. If no collective is specified, it considers all
+  * attachments.
+  */
+case class AllPreviewsArgs(
+    collective: Option[Ident],
+    storeMode: MakePreviewArgs.StoreMode
+)
+
+object AllPreviewsArgs {
+
+  val taskName = Ident.unsafe("all-previews")
+
+  implicit val jsonEncoder: Encoder[AllPreviewsArgs] =
+    deriveEncoder[AllPreviewsArgs]
+  implicit val jsonDecoder: Decoder[AllPreviewsArgs] =
+    deriveDecoder[AllPreviewsArgs]
+}

modules/common/src/main/scala/docspell/common/DocspellSystem.scala

@@ -2,8 +2,8 @@ package docspell.common
 
 object DocspellSystem {
 
-  val user                 = Ident.unsafe("docspell-system")
-  val taskGroup            = user
-  val migrationTaskTracker = Ident.unsafe("full-text-index-tracker")
-
+  val user                  = Ident.unsafe("docspell-system")
+  val taskGroup             = user
+  val migrationTaskTracker  = Ident.unsafe("full-text-index-tracker")
+  val allPreviewTaskTracker = Ident.unsafe("generate-all-previews")
 }

modules/common/src/main/scala/docspell/common/MakePreviewArgs.scala

@@ -0,0 +1,53 @@
+package docspell.common
+
+import io.circe.generic.semiauto._
+import io.circe.{Decoder, Encoder}
+
+/** Arguments for the `MakePreviewTask` that generates a preview image
+  * for an attachment.
+  *
+  * It can replace the current preview image or only generate one, if
+  * it is missing.
+  */
+case class MakePreviewArgs(
+    attachment: Ident,
+    store: MakePreviewArgs.StoreMode
+)
+
+object MakePreviewArgs {
+
+  val taskName = Ident.unsafe("make-preview")
+
+  sealed trait StoreMode extends Product {
+    final def name: String =
+      productPrefix.toLowerCase()
+  }
+  object StoreMode {
+
+    /** Replace any preview file that may already exist. */
+    case object Replace extends StoreMode
+
+    /** Only create a preview image, if it is missing. */
+    case object WhenMissing extends StoreMode
+
+    def fromString(str: String): Either[String, StoreMode] =
+      Option(str).map(_.trim.toLowerCase()) match {
+        case Some("replace")     => Right(Replace)
+        case Some("whenmissing") => Right(WhenMissing)
+        case _                   => Left(s"Invalid store mode: $str")
+      }
+
+    implicit val jsonEncoder: Encoder[StoreMode] =
+      Encoder.encodeString.contramap(_.name)
+
+    implicit val jsonDecoder: Decoder[StoreMode] =
+      Decoder.decodeString.emap(fromString)
+  }
+
+  implicit val jsonEncoder: Encoder[MakePreviewArgs] =
+    deriveEncoder[MakePreviewArgs]
+
+  implicit val jsonDecoder: Decoder[MakePreviewArgs] =
+    deriveDecoder[MakePreviewArgs]
+
+}

modules/joex/src/main/scala/docspell/joex/JoexAppImpl.scala

@@ -18,6 +18,7 @@ import docspell.joex.learn.LearnClassifierTask
 import docspell.joex.notify._
 import docspell.joex.pdfconv.ConvertAllPdfTask
 import docspell.joex.pdfconv.PdfConvTask
+import docspell.joex.preview._
 import docspell.joex.process.ItemHandler
 import docspell.joex.process.ReProcessItem
 import docspell.joex.scanmailbox._
@@ -68,7 +69,10 @@ final class JoexAppImpl[F[_]: ConcurrentEffect: ContextShift: Timer](
     HouseKeepingTask
       .periodicTask[F](cfg.houseKeeping.schedule)
       .flatMap(pstore.insert) *>
-      MigrationTask.job.flatMap(queue.insertIfNew)
+      MigrationTask.job.flatMap(queue.insertIfNew) *>
+      AllPreviewsTask
+        .job(MakePreviewArgs.StoreMode.WhenMissing, None)
+        .flatMap(queue.insertIfNew)
 }
 
 object JoexAppImpl {
@@ -167,6 +171,20 @@ object JoexAppImpl {
             LearnClassifierTask.onCancel[F]
           )
         )
+        .withTask(
+          JobTask.json(
+            MakePreviewArgs.taskName,
+            MakePreviewTask[F](cfg.convert),
+            MakePreviewTask.onCancel[F]
+          )
+        )
+        .withTask(
+          JobTask.json(
+            AllPreviewsArgs.taskName,
+            AllPreviewsTask[F](queue, joex),
+            AllPreviewsTask.onCancel[F]
+          )
+        )
         .resource
       psch <- PeriodicScheduler.create(
         cfg.periodicScheduler,

modules/joex/src/main/scala/docspell/joex/preview/AllPreviewsTask.scala

@@ -0,0 +1,86 @@
+package docspell.joex.preview
+
+import fs2.{Chunk, Stream}
+import docspell.common._
+import cats.effect._
+import cats.implicits._
+import docspell.store.queue.JobQueue
+import docspell.backend.ops.OJoex
+import docspell.joex.scheduler.Task
+import docspell.joex.scheduler.Context
+import docspell.store.records.RAttachment
+import docspell.store.records.RJob
+
+object AllPreviewsTask {
+
+  type Args = AllPreviewsArgs
+
+  def apply[F[_]: Sync](queue: JobQueue[F], joex: OJoex[F]): Task[F, Args, Unit] =
+    Task { ctx =>
+      for {
+        _ <- ctx.logger.info("Generating previews for attachments")
+        n <- submitConversionJobs(ctx, queue)
+        _ <- ctx.logger.info(s"Submitted $n jobs")
+        _ <- joex.notifyAllNodes
+      } yield ()
+    }
+
+  def onCancel[F[_]: Sync]: Task[F, Args, Unit] =
+    Task.log(_.warn("Cancelling all-previews task"))
+
+  def submitConversionJobs[F[_]: Sync](
+      ctx: Context[F, Args],
+      queue: JobQueue[F]
+  ): F[Int] =
+    ctx.store
+      .transact(RAttachment.findWithoutPreview(ctx.args.collective, 50))
+      .chunks
+      .flatMap(createJobs[F](ctx))
+      .chunks
+      .evalMap(jobs => queue.insertAllIfNew(jobs.toVector).map(_ => jobs.size))
+      .evalTap(n => ctx.logger.debug(s"Submitted $n jobs …"))
+      .compile
+      .foldMonoid
+
+  private def createJobs[F[_]: Sync](
+      ctx: Context[F, Args]
+  )(ras: Chunk[RAttachment]): Stream[F, RJob] = {
+    val collectiveOrSystem = ctx.args.collective.getOrElse(DocspellSystem.taskGroup)
+
+    def mkJob(ra: RAttachment): F[RJob] =
+      for {
+        id  <- Ident.randomId[F]
+        now <- Timestamp.current[F]
+      } yield RJob.newJob(
+        id,
+        MakePreviewArgs.taskName,
+        collectiveOrSystem,
+        MakePreviewArgs(ra.id, ctx.args.storeMode),
+        s"Create preview ${ra.id.id}/${ra.name.getOrElse("-")}",
+        now,
+        collectiveOrSystem,
+        Priority.Low,
+        Some(MakePreviewArgs.taskName / ra.id)
+      )
+
+    val jobs = ras.traverse(mkJob)
+    Stream.evalUnChunk(jobs)
+  }
+
+  def job[F[_]: Sync](storeMode: MakePreviewArgs.StoreMode, cid: Option[Ident]): F[RJob] =
+    for {
+      id  <- Ident.randomId[F]
+      now <- Timestamp.current[F]
+    } yield RJob.newJob(
+      id,
+      AllPreviewsArgs.taskName,
+      cid.getOrElse(DocspellSystem.taskGroup),
+      AllPreviewsArgs(cid, storeMode),
+      "Create preview images",
+      now,
+      DocspellSystem.taskGroup,
+      Priority.Low,
+      Some(DocspellSystem.allPreviewTaskTracker)
+    )
+
+}

modules/joex/src/main/scala/docspell/joex/preview/MakePreviewTask.scala

@@ -0,0 +1,57 @@
+package docspell.joex.preview
+
+import cats.implicits._
+import cats.effect._
+import docspell.common._
+import docspell.joex.scheduler.Task
+import docspell.store.records.RAttachmentPreview
+import docspell.joex.scheduler.Context
+import docspell.joex.process.AttachmentPreview
+import docspell.convert.ConvertConfig
+import docspell.extract.pdfbox.PdfboxPreview
+import docspell.store.records.RAttachment
+
+object MakePreviewTask {
+
+  type Args = MakePreviewArgs
+
+  def apply[F[_]: Sync](cfg: ConvertConfig): Task[F, Args, Unit] =
+    Task { ctx =>
+      for {
+        exists  <- previewExists(ctx)
+        preview <- PdfboxPreview(30)
+        _ <-
+          if (exists)
+            ctx.logger.info(
+              s"Preview already exists for attachment ${ctx.args.attachment}. Skipping."
+            )
+          else
+            ctx.logger.info(
+              s"Generating preview image for attachment ${ctx.args.attachment}"
+            ) *> generatePreview(ctx, preview, cfg)
+      } yield ()
+    }
+
+  def onCancel[F[_]: Sync]: Task[F, Args, Unit] =
+    Task.log(_.warn("Cancelling make-preview task"))
+
+  private def generatePreview[F[_]: Sync](
+      ctx: Context[F, Args],
+      preview: PdfboxPreview[F],
+      cfg: ConvertConfig
+  ): F[Unit] =
+    for {
+      ra <- ctx.store.transact(RAttachment.findById(ctx.args.attachment))
+      _ <- ra
+        .map(AttachmentPreview.createPreview(ctx, preview, cfg.chunkSize))
+        .getOrElse(().pure[F])
+    } yield ()
+
+  private def previewExists[F[_]: Sync](ctx: Context[F, Args]): F[Boolean] =
+    if (ctx.args.store == MakePreviewArgs.StoreMode.WhenMissing)
+      ctx.store.transact(
+        RAttachmentPreview.findById(ctx.args.attachment).map(_.isDefined)
+      )
+    else
+      false.pure[F]
+}

modules/joex/src/main/scala/docspell/joex/process/AttachmentPreview.scala

@@ -15,6 +15,7 @@ import docspell.store.records._
 import docspell.store.syntax.MimeTypes._
 
 import bitpeace.{Mimetype, MimetypeHint, RangeDef}
+import docspell.store.queries.QAttachment
 
 /** Goes through all attachments that must be already converted into a
   * pdf. If it is a pdf, the first page is converted into a small
@@ -31,14 +32,14 @@ object AttachmentPreview {
           s"Creating preview images for ${item.attachments.size} files…"
         )
         preview <- PdfboxPreview(24)
-        _       <- item.attachments.traverse(createPreview(ctx, preview, cfg))
+        _       <- item.attachments.traverse(createPreview(ctx, preview, cfg.chunkSize))
       } yield item
     }
 
   def createPreview[F[_]: Sync](
       ctx: Context[F, _],
       preview: PdfboxPreview[F],
-      cfg: ConvertConfig
+      chunkSize: Int
   )(
       ra: RAttachment
   ): F[Option[RAttachmentPreview]] =
@@ -46,7 +47,7 @@ object AttachmentPreview {
       case MimeType.PdfMatch(_) =>
         preview.previewPNG(loadFile(ctx)(ra)).flatMap {
           case Some(out) =>
-            createRecord(ctx, out, ra, cfg.chunkSize).map(_.some)
+            createRecord(ctx, out, ra, chunkSize).map(_.some)
           case None =>
             (None: Option[RAttachmentPreview]).pure[F]
         }
@@ -55,7 +56,7 @@ object AttachmentPreview {
         (None: Option[RAttachmentPreview]).pure[F]
     }
 
-  def createRecord[F[_]: Sync](
+  private def createRecord[F[_]: Sync](
       ctx: Context[F, _],
       png: Stream[F, Byte],
       ra: RAttachment,
@@ -75,6 +76,7 @@ object AttachmentPreview {
         .lastOrError
       now <- Timestamp.current[F]
       rp = RAttachmentPreview(ra.id, Ident.unsafe(fileMeta.id), name.map(_.fullName), now)
+      _ <- QAttachment.deletePreview(ctx.store)(ra.id)
       _ <- ctx.store.transact(RAttachmentPreview.insert(rp))
     } yield rp
   }

modules/store/src/main/scala/docspell/store/queries/QAttachment.scala

@@ -17,6 +17,22 @@ import doobie.implicits._
 object QAttachment {
   private[this] val logger = org.log4s.getLogger
 
+  def deletePreview[F[_]: Sync](store: Store[F])(attachId: Ident): F[Int] = {
+    val findPreview =
+      for {
+        rp <- RAttachmentPreview.findById(attachId)
+      } yield rp.toSeq
+
+    Stream
+      .evalSeq(store.transact(findPreview))
+      .map(_.fileId.id)
+      .flatMap(store.bitpeace.delete)
+      .map(flag => if (flag) 1 else 0)
+      .evalMap(_ => store.transact(RAttachmentPreview.delete(attachId)))
+      .compile
+      .foldMonoid
+  }
+
   /** Deletes an attachment, its related source and meta data records.
     * It will only delete an related archive file, if this is the last
     * attachment in that archive.

modules/store/src/main/scala/docspell/store/records/RAttachment.scala

@@ -231,6 +231,38 @@ object RAttachment {
   def findItemId(attachId: Ident): ConnectionIO[Option[Ident]] =
     selectSimple(Seq(itemId), table, id.is(attachId)).query[Ident].option
 
+  def findWithoutPreview(
+      coll: Option[Ident],
+      chunkSize: Int
+  ): Stream[ConnectionIO, RAttachment] = {
+    val aId   = Columns.id.prefix("a")
+    val aItem = Columns.itemId.prefix("a")
+    val pId   = RAttachmentPreview.Columns.id.prefix("p")
+    val iId   = RItem.Columns.id.prefix("i")
+    val iColl = RItem.Columns.cid.prefix("i")
+
+    val cols = all.map(_.prefix("a"))
+    val baseJoin =
+      table ++ fr"a LEFT OUTER JOIN" ++
+        RAttachmentPreview.table ++ fr"p ON" ++ pId.is(aId)
+
+    val baseCond =
+      Seq(pId.isNull)
+
+    coll match {
+      case Some(cid) =>
+        val join = baseJoin ++ fr"INNER JOIN" ++ RItem.table ++ fr"i ON" ++ iId.is(aItem)
+        val cond = and(baseCond ++ Seq(iColl.is(cid)))
+        selectSimple(cols, join, cond)
+          .query[RAttachment]
+          .streamWithChunkSize(chunkSize)
+      case None =>
+        selectSimple(cols, baseJoin, and(baseCond))
+          .query[RAttachment]
+          .streamWithChunkSize(chunkSize)
+    }
+  }
+
   def findNonConvertedPdf(
       coll: Option[Ident],
       chunkSize: Int