Allow to change position of attachments

modules/store/src/main/scala/docspell/store/impl/Column.scala

@@ -72,12 +72,18 @@ case class Column(name: String, ns: String = "", alias: String = "") {
   def isGt[A: Put](a: A): Fragment =
     f ++ fr"> $a"
 
+  def isGte[A: Put](a: A): Fragment =
+    f ++ fr">= $a"
+
   def isGt(c: Column): Fragment =
     f ++ fr">" ++ c.f
 
   def isLt[A: Put](a: A): Fragment =
     f ++ fr"< $a"
 
+  def isLte[A: Put](a: A): Fragment =
+    f ++ fr"<= $a"
+
   def isLt(c: Column): Fragment =
     f ++ fr"<" ++ c.f
 
@@ -103,4 +109,10 @@ case class Column(name: String, ns: String = "", alias: String = "") {
 
   def max: Fragment =
     fr"MAX(" ++ f ++ fr")"
+
+  def increment[A: Put](a: A): Fragment =
+    f ++ fr"=" ++ f ++ fr"+ $a"
+
+  def decrement[A: Put](a: A): Fragment =
+    f ++ fr"=" ++ f ++ fr"- $a"
 }

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

@@ -1,8 +1,9 @@
 package docspell.store.queries
 
 import bitpeace.FileMeta
-import cats.implicits._
 import cats.effect.Sync
+import cats.data.OptionT
+import cats.implicits._
 import fs2.Stream
 import doobie._
 import doobie.implicits._
@@ -16,6 +17,44 @@ import org.log4s._
 object QItem {
   private[this] val logger = getLogger
 
+  def moveAttachmentBefore(
+      itemId: Ident,
+      source: Ident,
+      target: Ident
+  ): ConnectionIO[Int] = {
+
+    // rs < rt
+    def moveBack(rs: RAttachment, rt: RAttachment): ConnectionIO[Int] =
+      for {
+        n <- RAttachment.decPositions(itemId, rs.position, rt.position)
+        k <- RAttachment.updatePosition(rs.id, rt.position)
+      } yield n + k
+
+    // rs > rt
+    def moveForward(rs: RAttachment, rt: RAttachment): ConnectionIO[Int] =
+      for {
+        n <- RAttachment.incPositions(itemId, rt.position, rs.position)
+        k <- RAttachment.updatePosition(rs.id, rt.position)
+      } yield n + k
+
+    (for {
+      _ <- OptionT.liftF(
+        if (source == target)
+          Sync[ConnectionIO].raiseError(new Exception("Attachments are the same!"))
+        else ().pure[ConnectionIO]
+      )
+      rs <- OptionT(RAttachment.findById(source)).filter(_.itemId == itemId)
+      rt <- OptionT(RAttachment.findById(target)).filter(_.itemId == itemId)
+      n <- OptionT.liftF(
+        if (rs.position == rt.position || rs.position + 1 == rt.position)
+          0.pure[ConnectionIO]
+        else if (rs.position < rt.position) moveBack(rs, rt)
+        else moveForward(rs, rt)
+      )
+    } yield n).getOrElse(0)
+
+  }
+
   case class ItemData(
       item: RItem,
       corrOrg: Option[ROrganization],

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

@@ -38,6 +38,20 @@ object RAttachment {
       fr"${v.id},${v.itemId},${v.fileId.id},${v.position},${v.created},${v.name}"
     ).update.run
 
+  def decPositions(iId: Ident, lowerBound: Int, upperBound: Int): ConnectionIO[Int] =
+    updateRow(
+      table,
+      and(itemId.is(iId), position.isGte(lowerBound), position.isLte(upperBound)),
+      position.decrement(1)
+    ).update.run
+
+  def incPositions(iId: Ident, lowerBound: Int, upperBound: Int): ConnectionIO[Int] =
+    updateRow(
+      table,
+      and(itemId.is(iId), position.isGte(lowerBound), position.isLte(upperBound)),
+      position.increment(1)
+    ).update.run
+
   def nextPosition(id: Ident): ConnectionIO[Int] =
     for {
       max <- selectSimple(position.max, table, itemId.is(id)).query[Option[Int]].unique