Update Scala Codegen SBT Example (#558)

* Update scala codegen sbt  example to use the latest codegen binaries

Use DAR to generate Scala code, no reason to unzip DALFs.

* Add support for `DA.sdkVersion` system property.

To override the default sdkVersion:
```
> sbt -DDA.sdkVersion=100.12.6 compile
```

* Simplify the way examples run

language-support/scala/codegen-sbt-example/README.md

@@ -1,5 +1,5 @@
 # Mock scala/codegen example (does not send any commands just prints them to STD OUT)
-$ sbt "mock-example/runMain com.digitalasset.example.ExampleMain"
+$ sbt -DDA.sdkVersion=100.12.6 mock-example/run
 
 # Sandbox scala/codegen example (sends commands to sandbox and receives transactions)
-$ sbt "sandbox-example/runMain com.digitalasset.example.ExampleMain ./scala-codegen/target/repository/daml-codegen/Main.dar"
+$ sbt -DDA.sdkVersion=100.12.6 sandbox-example/run

language-support/scala/codegen-sbt-example/build.sbt

@@ -82,7 +82,7 @@ lazy val commonSettings = Seq(
 
 lazy val sandboxDependencies = Seq(
   "com.daml.scala" %% "bindings-akka" % sdkVersion,
-  "com.digitalasset.platform" % "sandbox" % sdkVersion,
+  "com.digitalasset.platform" %% "sandbox" % sdkVersion,
 )
 
 lazy val codeGenDependencies = Seq(
@@ -145,23 +145,15 @@ def generateScalaFrom(
   // directory containing the dar is used as a work directory
   val outDir = darFile.getParentFile
 
-  // Unpack all dalf files in the dar. Note that there may be many ("fat dar"), but at least daml-prim.dalf
-  val dalfFiles = IO.unzip(darFile, outDir, new SimpleFilter(_ endsWith ".dalf"))
-
   // use a FileFunction.cached on the dar
-  val cache = FileFunction.cached(cacheDir, FileInfo.hash) { theDalfs =>
-    val mainDalf = theDalfs
-      .find(_.getName endsWith mainDalfName)
-      .getOrElse(sys.error(s"Main dalf file ($mainDalfName) not found in $theDalfs"))
-    val otherDalfs = theDalfs.filterNot(_ == mainDalf).toList
-
+  val cache = FileFunction.cached(cacheDir, FileInfo.hash) { _ =>
     if (srcManagedDir.exists) // purge output if exists
       IO.delete(srcManagedDir.listFiles)
 
-    CodeGen.generateCode(mainDalf, otherDalfs.map(_.toURI.toURL), packageName, srcManagedDir, Novel)
+    CodeGen.generateCode(List(darFile), packageName, srcManagedDir, Novel)
     (srcManagedDir ** "*.scala").get.toSet
   }
-  cache(dalfFiles)
+  cache(Set(darFile))
 }
 
 // #####################################   end sbt-daml   ##############################

language-support/scala/codegen-sbt-example/project/Versions.scala

@@ -2,10 +2,15 @@
 // SPDX-License-Identifier: Apache-2.0
 
 object Versions {
-  lazy val sdkVersion: String = "100.11.25"
+  val sdkVersion: String = sdkVersionFromSysProps().getOrElse("100.12.6")
+
+  println(s"DA sdkVersion: $sdkVersion")
 
   lazy val detectedOs: String = sys.props("os.name") match {
     case "Mac OS X" => "osx"
     case _ => "linux"
   }
+
+  private def sdkVersionFromSysProps(): Option[String] =
+    sys.props.get("DA.sdkVersion").map(_.toString)
 }

language-support/scala/codegen-sbt-example/sandbox-example/src/main/scala/com/digitalasset/example/ExampleMain.scala

@@ -40,20 +40,16 @@ import scala.concurrent.duration._
 import scala.concurrent.{Await, ExecutionContext, ExecutionContextExecutor, Future}
 
 object ExampleMain extends App {
-  if (args.length == 0)
-    throw new IllegalArgumentException(
-      "Expected at least one DAR or DALF file passed as an argument")
+
+  private val dar = new File("./scala-codegen/target/repository/daml-codegen/Main.dar")
 
   private val ledgerId = "codegen-sbt-example-with-sandbox"
 
   private val port: Int = findOpenPort().fold(e => throw new IllegalStateException(e), identity)
 
-  private def archives(fileNames: List[String]): List[File] =
-    toFiles(args.toList).fold(e => throw new IllegalStateException(e), identity)
-
   private val serverConfig = SandboxConfig.default.copy(
     port = port,
-    damlPackageContainer = DamlPackageContainer(archives(args.toList)),
+    damlPackageContainer = DamlPackageContainer(List(dar)),
     timeProviderType = TimeProviderType.WallClock,
     ledgerIdMode = LedgerIdMode.HardCoded(ledgerId),
   )