feat: add /latest endpoint (#1223)

warcholjakub · web-flow · commit b2d3a6be726a · 2025-11-28T11:11:44.000+01:00
Implements a new API endpoint that allows fetching the latest version
of a snippet without knowing its update number. Users can now access
snippets via /{login}/{uuid}/latest to always get the most recent version.
diff --git a/balancer/src/main/scala/org/scastie/balancer/DispatchActor.scala b/balancer/src/main/scala/org/scastie/balancer/DispatchActor.scala
@@ -41,6 +41,7 @@ case class DownloadSnippet(snippetId: SnippetId)
 case class ForkSnippet(snippetId: SnippetId, inputs: InputsWithIpAndUser)
 
 case class FetchSnippet(snippetId: SnippetId)
+case class FetchLatestSnippet(snippetId: SnippetId)
 case class FetchOldSnippet(id: Int)
 case class FetchUserSnippets(user: User)
 
@@ -193,6 +194,10 @@ class DispatchActor(progressActor: ActorRef, statusActor: ActorRef)
       val sender = this.sender()
       logError(container.readSnippet(snippetId).map(sender ! _))
 
+    case FetchLatestSnippet(snippetId) =>
+      val sender = this.sender()
+      logError(container.readLatestSnippet(snippetId).map(sender ! _))
+
     case FetchOldSnippet(id) =>
       val sender = this.sender()
       logError(container.readOldSnippet(id).map(sender ! _))
diff --git a/client/src/main/scala/org/scastie/client/RestApiClient.scala b/client/src/main/scala/org/scastie/client/RestApiClient.scala
@@ -98,6 +98,14 @@ class RestApiClient(serverUrl: Option[String]) extends RestApi {
   def fetch(snippetId: SnippetId): Future[Option[FetchResult]] =
     get[FetchResult]("/snippets/" + snippetId.url)
 
+  def fetchLatest(snippetId: SnippetId): Future[Option[FetchResult]] =
+    snippetId.user match {
+      case Some(SnippetUserPart(login, _)) =>
+        get[FetchResult](s"/snippets/$login/${snippetId.base64UUID}/latest")
+      case None =>
+        fetch(snippetId)
+    }
+
   def fetchOld(id: Int): Future[Option[FetchResult]] =
     get[FetchResult](s"/old-snippets/$id")
 
diff --git a/client/src/main/scala/org/scastie/client/Routing.scala b/client/src/main/scala/org/scastie/client/Routing.scala
@@ -85,6 +85,7 @@ class Routing(defaultServerUrl: String) {
     val anon = snippetId
     val user = alpha / snippetId
     val userUpdate = alpha / snippetId / int
+    val userLatest = alpha / snippetId / "latest"
     val oldId = int
 
     (
@@ -101,6 +102,8 @@ class Routing(defaultServerUrl: String) {
           dynRenderR((page, router) => renderOldSnippetIdPage(page, router))
         | dynamicRouteCT(anon.caseClass[AnonymousResource]) ~>
           dynRenderR((page, router) => renderPage(page, router))
+        | dynamicRouteCT(userLatest.caseClass[UserResourceLatest]) ~>
+          dynRenderR((page, router) => renderPage(page, router))
         | dynamicRouteCT(user.caseClass[UserResource]) ~>
           dynRenderR((page, router) => renderPage(page, router))
         | dynamicRouteCT(userUpdate.caseClass[UserResourceUpdated]) ~>
@@ -151,33 +154,32 @@ class Routing(defaultServerUrl: String) {
   private def renderPage(page: ResourcePage, router: RouterCtl[Page]): VdomElement = {
     val defaultEmbedded = Some(EmbeddedOptions.empty(defaultServerUrl))
 
-    val (embedded, snippetId) = page match {
+    case class PageInfo(embedded: Option[EmbeddedOptions], snippetId: SnippetId)
+
+    val pageInfo = page match {
       case AnonymousResource(uuid) =>
-        val snippetId = SnippetId(uuid, None)
-        (None, snippetId)
+        PageInfo(None, SnippetId(uuid, None))
       case UserResource(login, uuid) =>
-        val snippetId = SnippetId(uuid, Some(SnippetUserPart(login)))
-        (None, snippetId)
+        PageInfo(None, SnippetId(uuid, Some(SnippetUserPart(login))))
+      case UserResourceLatest(login, uuid) =>
+        /* Latest is represented with update -1 */
+        PageInfo(None, SnippetId(uuid, Some(SnippetUserPart(login, -1))))
       case UserResourceUpdated(login, uuid, update) =>
-        val snippetId = SnippetId(uuid, Some(SnippetUserPart(login, update)))
-        (None, snippetId)
+        PageInfo(None, SnippetId(uuid, Some(SnippetUserPart(login, update))))
       case EmbeddedAnonymousResource(uuid) =>
-        val snippetId = SnippetId(uuid, None)
-        (defaultEmbedded, snippetId)
+        PageInfo(defaultEmbedded, SnippetId(uuid, None))
       case EmbeddedUserResource(login, uuid) =>
-        val snippetId = SnippetId(uuid, Some(SnippetUserPart(login)))
-        (defaultEmbedded, snippetId)
+        PageInfo(defaultEmbedded, SnippetId(uuid, Some(SnippetUserPart(login))))
       case EmbeddedUserResourceUpdated(login, uuid, update) =>
-        val snippetId = SnippetId(uuid, Some(SnippetUserPart(login, update)))
-        (defaultEmbedded, snippetId)
+        PageInfo(defaultEmbedded, SnippetId(uuid, Some(SnippetUserPart(login, update))))
     }
 
     Scastie(
       scastieId = UUID.randomUUID(),
       router = Some(router),
-      snippetId = Some(snippetId),
+      snippetId = Some(pageInfo.snippetId),
       oldSnippetId = None,
-      embedded = embedded,
+      embedded = pageInfo.embedded,
       targetType = None,
       tryLibrary = None,
       code = None,
diff --git a/client/src/main/scala/org/scastie/client/RoutingADT.scala b/client/src/main/scala/org/scastie/client/RoutingADT.scala
@@ -43,6 +43,11 @@ case class UserResourceUpdated(
     update: Int
 ) extends ResourcePage
 
+case class UserResourceLatest(
+    login: String,
+    uuid: String
+) extends ResourcePage
+
 case class EmbeddedAnonymousResource(
     uuid: String
 ) extends ResourcePage
diff --git a/client/src/main/scala/org/scastie/client/ScastieBackend.scala b/client/src/main/scala/org/scastie/client/ScastieBackend.scala
@@ -423,6 +423,14 @@ case class ScastieBackend(scastieId: UUID, serverUrl: Option[String], scope: Bac
     )
   }
 
+  def loadLatestSnippet(snippetId: SnippetId): Callback = {
+    loadSnippetBase(
+      restApiClient.fetchLatest(snippetId),
+      afterLoading = _.setSnippetId(snippetId),
+      snippetId = Some(snippetId)
+    )
+  }
+
   private def loadSnippetBase(
       fetchSnippet: => Future[Option[FetchResult]],
       afterLoading: ScastieState => ScastieState = identity,
diff --git a/client/src/main/scala/org/scastie/client/components/Scastie.scala b/client/src/main/scala/org/scastie/client/components/Scastie.scala
@@ -118,7 +118,11 @@ object Scastie {
     val initialState = props.embedded match {
       case None => {
         props.snippetId match {
-          case Some(snippetId) => backend.loadSnippet(snippetId)
+          case Some(snippetId) =>
+            snippetId.user match {
+              case Some(SnippetUserPart(_, -1)) => backend.loadLatestSnippet(snippetId)
+              case _ => backend.loadSnippet(snippetId)
+            }
 
           case None => props.oldSnippetId match {
               case Some(id) => backend.loadOldSnippet(id)
@@ -136,7 +140,11 @@ object Scastie {
       }
       case Some(embededOptions) => {
         val setInputs = (embededOptions.snippetId, embededOptions.inputs) match {
-          case (Some(snippetId), _) => backend.loadSnippet(snippetId)
+          case (Some(snippetId), _) =>
+            snippetId.user match {
+              case Some(SnippetUserPart(_, -1)) => backend.loadLatestSnippet(snippetId)
+              case _ => backend.loadSnippet(snippetId)
+            }
 
           case (_, Some(inputs)) => backend.scope.modState(_.setInputs(inputs))
 
diff --git a/server/src/main/scala/org/scastie/server/RestApiServer.scala b/server/src/main/scala/org/scastie/server/RestApiServer.scala
@@ -81,6 +81,12 @@ class RestApiServer(
       .mapTo[Option[FetchResult]]
   }
 
+  def fetchLatest(snippetId: SnippetId): Future[Option[FetchResult]] = {
+    dispatchActor
+      .ask(FetchLatestSnippet(snippetId))
+      .mapTo[Option[FetchResult]]
+  }
+
   def fetchOld(id: Int): Future[Option[FetchResult]] = {
     dispatchActor
       .ask(FetchOldSnippet(id))
diff --git a/server/src/main/scala/org/scastie/server/routes/ApiRoutes.scala b/server/src/main/scala/org/scastie/server/routes/ApiRoutes.scala
@@ -62,6 +62,9 @@ class ApiRoutes(
           encodeResponseWith(Gzip)(
             get(
               concat(
+                snippetIdLatest("snippets")(
+                  sid => complete(server.fetchLatest(sid))
+                ),
                 snippetIdStart("snippets")(
                   sid => complete(server.fetch(sid))
                 ),
diff --git a/server/src/main/scala/org/scastie/server/routes/package.scala b/server/src/main/scala/org/scastie/server/routes/package.scala
@@ -24,6 +24,11 @@ package object routes {
       matcherStart / _ / matcherEnd
     )(f)
 
+  def snippetIdLatest(matcherStart: String)(f: SnippetId => Route): Route =
+    path(matcherStart / Segment / uuidMatcher / "latest" ~ Slash.?) { (user, uuid) =>
+      f(SnippetId(uuid, Some(SnippetUserPart(user, -1))))
+    }
+
   def snippetIdExtension(extension: String)(f: SnippetId => Route): Route =
     snippetIdBase(
       _ ~ extension,
diff --git a/storage/src/main/scala/org/scastie/storage/SnippetsContainer.scala b/storage/src/main/scala/org/scastie/storage/SnippetsContainer.scala
@@ -49,6 +49,7 @@ trait SnippetsContainer {
       snippetId: SnippetId
   ): Future[Option[FetchResultScalaJsSourceMap]]
   def readSnippet(snippetId: SnippetId): Future[Option[FetchResult]]
+  def readLatestSnippet(snippetId: SnippetId): Future[Option[FetchResult]]
   protected def insert(snippetId: SnippetId, inputs: BaseInputs): Future[Unit]
   protected def hideFromUserProfile(snippetId: SnippetId): Future[Unit]
 
diff --git a/storage/src/main/scala/org/scastie/storage/filesystem/FilesystemSnippetsContainer.scala b/storage/src/main/scala/org/scastie/storage/filesystem/FilesystemSnippetsContainer.scala
@@ -4,7 +4,6 @@ import org.scastie.api._
 import org.scastie.storage.OldScastieConverter
 import org.scastie.storage.SnippetsContainer
 import org.scastie.storage.UserLogin
-import io.circe._
 import io.circe.syntax._
 import io.circe.parser._
 
@@ -171,6 +170,35 @@ trait FilesystemSnippetsContainer extends SnippetsContainer with GenericFilesyst
     )
   }
 
+  def readLatestSnippet(snippetId: SnippetId): Future[Option[FetchResult]] = {
+    snippetId.user match {
+      case Some(SnippetUserPart(login, _)) =>
+        Future {
+          findLatestUpdate(login, snippetId.base64UUID).flatMap { latestUpdate =>
+            val latestId = SnippetId(snippetId.base64UUID, Some(SnippetUserPart(login, latestUpdate)))
+            readInputs(latestId).map(inputs =>
+              FetchResult.create(inputs, readOutputs(latestId).getOrElse(Nil))
+            )
+          }
+        }
+      case None =>
+        readSnippet(snippetId)
+    }
+  }
+
+  private def findLatestUpdate(login: String, base64UUID: String): Option[Int] = {
+    val dir = root.resolve(Paths.get(login, base64UUID))
+    if (!Files.isDirectory(dir)) {
+      None
+    } else {
+      import scala.jdk.StreamConverters._
+      Files.list(dir)
+        .toScala(LazyList)
+        .map(_.getFileName.toString.toInt)
+        .maxOption
+    }
+  }
+
   protected def insert(snippetId: SnippetId, inputs: BaseInputs): Future[Unit] =
     Future {
       val adjustedInputs = inputs match {
diff --git a/storage/src/main/scala/org/scastie/storage/inmemory/InMemorySnippetsContainer.scala b/storage/src/main/scala/org/scastie/storage/inmemory/InMemorySnippetsContainer.scala
@@ -65,6 +65,23 @@ trait InMemorySnippetsContainer extends SnippetsContainer {
     snippets.get(snippetId).map(m => FetchResult.create(m.inputs, m.progresses.toList))
   }
 
+  def readLatestSnippet(snippetId: SnippetId): Future[Option[FetchResult]] = Future {
+    snippetId.user match {
+      case Some(SnippetUserPart(login, _)) =>
+        snippets
+          .filter { case (id, _) =>
+            id.base64UUID == snippetId.base64UUID &&
+            id.user.exists(_.login == login)
+          }
+          .toSeq
+          .sortBy { case (id, _) => id.user.map(_.update).getOrElse(0) }
+          .lastOption
+          .map { case (_, storage) => FetchResult.create(storage.inputs, storage.progresses.toList) }
+      case None =>
+        snippets.get(snippetId).map(m => FetchResult.create(m.inputs, m.progresses.toList))
+    }
+  }
+
   def readOldSnippet(id: Int): Future[Option[FetchResult]] = Future(None)
 
   protected def insert(snippetId: SnippetId, inputs: BaseInputs): Future[Unit] = {
diff --git a/storage/src/main/scala/org/scastie/storage/mongodb/MongoDBSnippetsContainer.scala b/storage/src/main/scala/org/scastie/storage/mongodb/MongoDBSnippetsContainer.scala
@@ -107,6 +107,25 @@ trait MongoDBSnippetsContainer extends SnippetsContainer with GenericMongoContai
     readMongoSnippet(snippetId).map(_.map(_.toFetchResult))
   }
 
+  def readLatestSnippet(snippetId: SnippetId): Future[Option[FetchResult]] = {
+    snippetId.user match {
+      case Some(SnippetUserPart(login, _)) =>
+        val query = and(
+          equal("snippetId.base64UUID", snippetId.base64UUID),
+          equal("snippetId.user.login", login)
+        )
+
+        snippets
+          .find(query)
+          .sort(Sorts.descending("snippetId.user.update"))
+          .first()
+          .headOption()
+          .map(_.flatMap(fromBson[MongoSnippet]).map(_.toFetchResult))
+      case None =>
+        readSnippet(snippetId)
+    }
+  }
+
   def listSnippets(user: UserLogin): Future[List[SnippetSummary]] = {
     val userSnippets = and(
       equal("snippetId.user.login", user.login),
diff --git a/storage/src/test/scala/org/scastie/storage/ContainerTest.scala b/storage/src/test/scala/org/scastie/storage/ContainerTest.scala
@@ -246,5 +246,58 @@ class ContainerTest extends AnyFunSuite with BeforeAndAfterAll with OptionValues
       val removeUser = testContainer.deleteUser(UserLogin(username)).await
       assert(removeUser == true)
     }
+
+    test(s"[$typeName] readLatestSnippet returns latest version") {
+      val user = UserLogin("github-user-latest" + Random.nextInt())
+
+      val inputs1 = inputType.copyBaseInput(code = "version 1")
+      val snippetId1 = testContainer.save(inputs1, Some(user)).await
+
+      val inputs2 = inputType.copyBaseInput(code = "version 2")
+      val snippetId2 = testContainer.update(snippetId1, inputs2).await.get
+
+      val inputs3 = inputType.copyBaseInput(code = "version 3")
+      val snippetId3 = testContainer.update(snippetId2, inputs3).await.get
+
+      val latest = testContainer.readLatestSnippet(snippetId1).await.value
+
+      assert(latest.inputs.code == "version 3", "should return latest version")
+      assert(snippetId3.user.get.update == 2, "latest should be update 2")
+    }
+
+    test(s"[$typeName] readLatestSnippet with base snippet ID") {
+      val user = UserLogin("github-user-latest-base" + Random.nextInt())
+
+      val inputs1 = inputType.copyBaseInput(code = "first")
+      val snippetId1 = testContainer.save(inputs1, Some(user)).await
+
+      val inputs2 = inputType.copyBaseInput(code = "second")
+      val snippetId2 = testContainer.update(snippetId1, inputs2).await.get
+
+      val latestFromFirst = testContainer.readLatestSnippet(snippetId1).await.value
+      val latestFromSecond = testContainer.readLatestSnippet(snippetId2).await.value
+
+      assert(latestFromFirst.inputs.code == "second")
+      assert(latestFromSecond.inputs.code == "second")
+    }
+
+    test(s"[$typeName] readLatestSnippet with anonymous user") {
+      val inputs = inputType.copyBaseInput(code = "anonymous snippet")
+      val snippetId = testContainer.save(inputs, None).await
+
+      val latest = testContainer.readLatestSnippet(snippetId).await.value
+
+      assert(latest.inputs.code == "anonymous snippet")
+      assert(snippetId.user.isEmpty)
+    }
+
+    test(s"[$typeName] readLatestSnippet with non-existent snippet") {
+      val user = UserLogin("github-user-nonexistent" + Random.nextInt())
+      val nonExistentId = SnippetId("nonexistent", Some(SnippetUserPart(user.login, 0)))
+
+      val result = testContainer.readLatestSnippet(nonExistentId).await
+
+      assert(result.isEmpty, "should return None for non-existent snippet")
+    }
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -423,6 +423,14 @@ case class ScastieBackend(scastieId: UUID, serverUrl: Option[String], scope: Bac`
`423`	`423`	`)`
`424`	`424`	`}`
`425`	`425`
	`426`	`+ def loadLatestSnippet(snippetId: SnippetId): Callback = {`
	`427`	`+ loadSnippetBase(`
	`428`	`+ restApiClient.fetchLatest(snippetId),`
	`429`	`+ afterLoading = _.setSnippetId(snippetId),`
	`430`	`+ snippetId = Some(snippetId)`
	`431`	`+ )`
	`432`	`+ }`
	`433`	`+`
`426`	`434`	`private def loadSnippetBase(`
`427`	`435`	`fetchSnippet: => Future[Option[FetchResult]],`
`428`	`436`	`afterLoading: ScastieState => ScastieState = identity,`