Merge pull request #34 from drivergroup/synch-refactor

Common code for synchronizers

1 files changed, 52 insertions, 0 deletions

diff --git a/src/main/scala/xyz/driver/pdsuicommon/synchronization/db/SlickDbDiff.scala b/src/main/scala/xyz/driver/pdsuicommon/synchronization/db/SlickDbDiff.scala
new file mode 100644
index 0000000..c226659
--- /dev/null
+++ b/src/main/scala/xyz/driver/pdsuicommon/synchronization/db/SlickDbDiff.scala
@@ -0,0 +1,52 @@
+package xyz.driver.pdsuicommon.synchronization.db
+
+import xyz.driver.pdsuicommon.synchronization.domain.FakeId
+import xyz.driver.pdsuicommon.synchronization.utils.{FakeIdGen, Refiner}
+
+import scala.annotation.tailrec
+import scala.collection.breakOut
+import scala.collection.immutable.SortedSet
+
+object SlickDbDiff {
+
+  /**
+    * Calculates DB-actions to synchronize origEntities with draftEntities.
+    */
+  def calc[DraftT, OrigT](origEntities: Iterable[OrigT], draftEntities: Iterable[DraftT])(
+          implicit draftFakeIdGen: FakeIdGen[DraftT],
+          origFakeIdGen: FakeIdGen[OrigT],
+          refiner: Refiner[DraftT, OrigT]): List[SlickDbAction[OrigT]] = {
+    val origMap: Map[FakeId, OrigT] = origEntities.map(x => origFakeIdGen(x) -> x)(breakOut)
+    val uniqueDraftEntities         = SortedSet.newBuilder[DraftT](Ordering.by[DraftT, FakeId](draftFakeIdGen))
+    uniqueDraftEntities ++= draftEntities
+
+    loop(origMap, uniqueDraftEntities.result(), List.empty)
+  }
+
+  @tailrec private def loop[DraftT, OrigT](origEntitiesMap: Map[FakeId, OrigT],
+                                           draftEntities: Iterable[DraftT],
+                                           actions: List[SlickDbAction[OrigT]])(
+          implicit draftFakeIdGen: FakeIdGen[DraftT],
+          refiner: Refiner[DraftT, OrigT]): List[SlickDbAction[OrigT]] = {
+    draftEntities.headOption match {
+      case None =>
+        // The rest original entities are not a part of draft, so we will delete them
+        val toDelete: List[SlickDbAction[OrigT]] = origEntitiesMap.values.map(x => SlickDbAction.Delete(x))(breakOut)
+        actions ++ toDelete
+
+      case Some(currRaw) =>
+        val rawCore = draftFakeIdGen.getFor(currRaw)
+        val action: Option[SlickDbAction[OrigT]] = origEntitiesMap.get(rawCore) match {
+          // It is a new entity, because it doesn't exist among originals
+          case None => Some(SlickDbAction.Create(refiner.refine(currRaw)))
+          case Some(orig) =>
+            val draft = refiner.refresh(orig, currRaw)
+            if (draft == orig) None
+            else Some(SlickDbAction.Update(draft))
+        }
+
+        loop(origEntitiesMap - rawCore, draftEntities.tail, action.map(_ :: actions).getOrElse(actions))
+    }
+  }
+
+}