Bloop: Fix output path of submodules

Currently, the output path of a submodule includes the relative path
to its build file, although it should only be relative to the root
project's build path.

Another limitation that these changes address is that the output
folder was not created by Seed such that Bloop might fail to link
the project.

src/main/scala/seed/generation/Bloop.scala

@@ -359,11 +359,13 @@ object Bloop {
   }
 
   def moduleOutputPath(buildPath: Path,
-                       module: Option[Module],
+                       module: Module,
                        defaultName: String): Path =
-    module.flatMap(_.output) match {
-      case Some(p) if p.isAbsolute => p
-      case Some(p) => buildPath.toAbsolutePath.resolve(p).normalize()
+    module.output match {
+      case Some(p) if Paths.get(p).isAbsolute => Paths.get(p)
+      case Some(p) =>
+        val base = buildPath.toAbsolutePath.resolve(p).normalize()
+        if (!p.endsWith("/")) base else base.resolve(defaultName)
       case None => buildPath.toAbsolutePath.resolve(defaultName)
     }
 
@@ -380,12 +382,25 @@ object Bloop {
                  ): Unit = {
     val isCrossBuild = module.targets.toSet.size > 1
 
-    val jsOutputPath = moduleOutputPath(buildPath, module.js, name + ".js")
+    val jsOutputPath = module.js
+      .orElse(if (!module.targets.contains(JavaScript)) None else Some(Module()))
+      .map(js => moduleOutputPath(buildPath, js, name + ".js"))
+
     val nativeOutputPath =
-      moduleOutputPath(buildPath, module.native, name + ".run")
+      module.native
+        .orElse(if (!module.targets.contains(Native)) None else Some(Module()))
+        .map(native => moduleOutputPath(buildPath, native, name + ".run"))
+
+    jsOutputPath.foreach { path =>
+      if (!Files.exists(path.getParent)) Files.createDirectories(path.getParent)
+    }
+
+    nativeOutputPath.foreach { path =>
+      if (!Files.exists(path.getParent)) Files.createDirectories(path.getParent)
+    }
 
     writeJsModule(build, if (!isCrossBuild) name else name + "-js",
-      projectPath, bloopPath, bloopBuildPath, Some(jsOutputPath),
+      projectPath, bloopPath, bloopBuildPath, jsOutputPath,
       module.copy(scalaDeps = collectJsDeps(build, module)),
       collectJsClassPath(bloopBuildPath, build, module),
       module.js, build.project, resolution, compilerResolution,
@@ -402,7 +417,7 @@ object Bloop {
       module.jvm, build.project, resolution, compilerResolution, test = false,
       log)
     writeNativeModule(build, if (!isCrossBuild) name else name + "-native",
-      projectPath, bloopPath, bloopBuildPath, Some(nativeOutputPath),
+      projectPath, bloopPath, bloopBuildPath, nativeOutputPath,
       module.copy(scalaDeps = collectNativeDeps(build, module)),
       collectJvmClassPath(bloopBuildPath, build, module),
       module.native, build.project, resolution, compilerResolution, test = false,

src/main/scala/seed/model/Build.scala

@@ -69,7 +69,10 @@ object Build {
                     moduleDeps: List[String] = List(),
                     mainClass: Option[String] = None,
                     targets: List[Platform] = List(),
-                    output: Option[Path] = None,
+
+                    // If this was a Path, it would include the directory
+                    // relative to the build file.
+                    output: Option[String] = None,
 
                     // JavaScript
                     jsdom: Boolean = false,

src/test/scala/seed/generation/BloopIntegrationSpec.scala

@@ -82,6 +82,24 @@ object BloopIntegrationSpec extends TestSuite[Unit] {
     compileAndRun(buildPath)
   }
 
+  testAsync("Link JavaScript modules with custom target path") { _ =>
+    val BuildConfig.Result(build, projectPath, _) = BuildConfig.load(
+      Paths.get("test/submodule-output-path"), Log.urgent).get
+    val buildPath = tempPath.resolve("submodule-output-path")
+    Files.createDirectory(buildPath)
+    val packageConfig = PackageConfig(tmpfs = false, silent = false,
+      ivyPath = None, cachePath = None)
+    cli.Generate.ui(Config(), projectPath, buildPath, build,
+      Command.Bloop(packageConfig), Log.urgent)
+    TestProcessHelper.runBloop(buildPath)("run", "app", "base", "base2")
+      .map { x =>
+        assertEquals(x.split("\n").count(_ == "hello"), 3)
+        assert(Files.exists(buildPath.resolve("build").resolve("js").resolve("app.js")))
+        assert(Files.exists(buildPath.resolve("build").resolve("js").resolve("base.js")))
+        assert(Files.exists(buildPath.resolve("build").resolve("base2.js")))
+      }
+  }
+
   testAsync("Build project with overridden compiler plug-in version") { _ =>
     val projectPath = Paths.get("test/example-paradise-versions")
     val BuildConfig.Result(build, _, _) =

test/submodule-output-path/build.toml

@@ -0,0 +1,10 @@
+import = ["submodule"]
+
+[project]
+scalaVersion   = "2.13.0"
+scalaJsVersion = "0.6.28"
+
+[module.app.js]
+moduleDeps = ["base"]
+sources    = ["src"]
+output     = "js/app.js"

test/submodule-output-path/src/Main.scala

@@ -0,0 +1 @@
+object Main extends App { println("hello") }

test/submodule-output-path/submodule/build.toml

@@ -0,0 +1,10 @@
+[project]
+scalaVersion   = "2.13.0"
+scalaJsVersion = "0.6.28"
+
+[module.base.js]
+sources = ["src"]
+output  = "js/"
+
+[module.base2.js]
+sources = ["src"]

test/submodule-output-path/submodule/src/Main.scala

@@ -0,0 +1 @@
+object Main extends App { println("hello") }