Implement BSP buildTarget/resources command

main/src/main/scala/sbt/Keys.scala

@@ -405,6 +405,8 @@ object Keys {
   val bspBuildTarget = taskKey[BuildTarget]("Description of the BSP build targets").withRank(DTask)
   val bspBuildTargetSources = inputKey[Unit]("").withRank(DTask)
   val bspBuildTargetSourcesItem = taskKey[SourcesItem]("").withRank(DTask)
+  val bspBuildTargetResources = inputKey[Unit]("").withRank(DTask)
+  val bspBuildTargetResourcesItem = taskKey[ResourcesItem]("").withRank(DTask)
   val bspBuildTargetDependencySources = inputKey[Unit]("").withRank(DTask)
   val bspBuildTargetDependencySourcesItem = taskKey[DependencySourcesItem]("").withRank(DTask)
   val bspBuildTargetCompile = inputKey[Unit]("").withRank(DTask)

main/src/main/scala/sbt/internal/server/BuildServerProtocol.scala

@@ -117,6 +117,19 @@ object BuildServerProtocol {
       }
     }.evaluated,
     bspBuildTargetSources / aggregate := false,
+    bspBuildTargetResources := Def.inputTaskDyn {
+      val s = state.value
+      val workspace = bspWorkspace.value
+      val targets = spaceDelimited().parsed.map(uri => BuildTargetIdentifier(URI.create(uri)))
+      val filter = ScopeFilter.in(targets.map(workspace))
+      // run the worker task concurrently
+      Def.task {
+        val items = bspBuildTargetResourcesItem.all(filter).value
+        val result = ResourcesResult(items.toVector)
+        s.respondEvent(result)
+      }
+    }.evaluated,
+    bspBuildTargetResources / aggregate := false,
     bspBuildTargetDependencySources := Def.inputTaskDyn {
       val s = state.value
       val workspace = bspWorkspace.value
@@ -201,6 +214,18 @@ object BuildServerProtocol {
         })
       SourcesItem(id, items)
     },
+    bspBuildTargetResourcesItem := {
+      val id = bspTargetIdentifier.value
+      // Trigger resource generation
+      val _ = managedResources.value
+      val uris = resourceDirectories.value.toVector
+        .map { resourceDirectory =>
+          // Add any missing ending slash to the URI to explicitly mark it as a directory
+          // See https://github.com/build-server-protocol/build-server-protocol/issues/181 for more information
+          URI.create(s"${resourceDirectory.toURI.toString.replaceAll("([^/])$", "$1/")}")
+        }
+      ResourcesItem(id, uris)
+    },
     bspBuildTargetDependencySourcesItem := dependencySourcesItemTask.value,
     bspBuildTargetCompileItem := bspCompileTask.value,
     bspBuildTargetRun := bspRunTask.evaluated,
@@ -319,6 +344,12 @@ object BuildServerProtocol {
             val targets = param.targets.map(_.uri).mkString(" ")
             val command = Keys.bspScalaMainClasses.key
             val _ = callback.appendExec(s"$command $targets", Some(r.id))
+
+          case r if r.method == "buildTarget/resources" =>
+            val param = Converter.fromJson[ResourcesParams](json(r)).get
+            val targets = param.targets.map(_.uri).mkString(" ")
+            val command = Keys.bspBuildTargetResources.key
+            val _ = callback.appendExec(s"$command $targets", Some(r.id))
         },
         onResponse = PartialFunction.empty,
         onNotification = {

server-test/src/test/scala/testpkg/BuildServerTest.scala

@@ -200,6 +200,19 @@ object BuildServerTest extends AbstractServerTest {
     })
   }
 
+  test("buildTarget/resources") { _ =>
+    val x = s"${svr.baseDirectory.getAbsoluteFile.toURI}#util/Compile"
+    svr.sendJsonRpc(
+      s"""{ "jsonrpc": "2.0", "id": "23", "method": "buildTarget/resources", "params": {
+         |  "targets": [{ "uri": "$x" }]
+         |} }""".stripMargin
+    )
+    assert(processing("buildTarget/resources"))
+    assert(svr.waitForString(10.seconds) { s =>
+      (s contains """"id":"23"""") && (s contains "util/src/main/resources/")
+    })
+  }
+
   private def initializeRequest(): Unit = {
     svr.sendJsonRpc(
       """{ "jsonrpc": "2.0", "id": "10", "method": "build/initialize",