Add a TwirlModule to compile Twirl templates (#271)

* initial implementation

* Upgrade to the latest version

* Add tests
* Update the code to comply with the new API
* Use reflection to call TwirlCompiler.compile function

* Run twirllib.test on CI

* Use the Java API as a workaround

* wip

* Cleanup the code (code review)

* Add an example to call the Scala API

* twirl that works with scala API

* Create functions to override the default settings (will be available in the future)

1 files changed, 56 insertions, 0 deletions

diff --git a/twirllib/src/mill/twirllib/TwirlModule.scala b/twirllib/src/mill/twirllib/TwirlModule.scala
new file mode 100644
index 00000000..2df70a1f
--- /dev/null
+++ b/twirllib/src/mill/twirllib/TwirlModule.scala
@@ -0,0 +1,56 @@
+package mill
+package twirllib
+
+import coursier.{Cache, MavenRepository}
+import mill.define.Sources
+import mill.eval.PathRef
+import mill.scalalib.Lib.resolveDependencies
+import mill.scalalib._
+import mill.util.Loose
+
+import scala.io.Codec
+import scala.util.Properties
+
+trait TwirlModule extends mill.Module {
+
+  def twirlVersion: T[String]
+
+  def twirlSources: Sources = T.sources {
+    millSourcePath / 'views
+  }
+
+  def twirlClasspath: T[Loose.Agg[PathRef]] = T {
+    resolveDependencies(
+      Seq(
+        Cache.ivy2Local,
+        MavenRepository("https://repo1.maven.org/maven2")
+      ),
+      Lib.depToDependency(_, "2.12.4"),
+      Seq(
+        ivy"com.typesafe.play::twirl-compiler:${twirlVersion()}",
+        ivy"org.scala-lang.modules::scala-parser-combinators:1.1.0"
+      )
+    )
+  }
+
+  // REMIND currently it's not possible to override these default settings
+  private def twirlAdditionalImports: Seq[String] = Nil
+
+  private def twirlConstructorAnnotations: Seq[String] = Nil
+
+  private def twirlCodec: Codec = Codec(Properties.sourceEncoding)
+
+  private def twirlInclusiveDot: Boolean = false
+
+  def compileTwirl: T[CompilationResult] = T.persistent {
+    TwirlWorkerApi.twirlWorker
+      .compile(
+        twirlClasspath().map(_.path),
+        twirlSources().map(_.path),
+        T.ctx().dest,
+        twirlAdditionalImports,
+        twirlConstructorAnnotations,
+        twirlCodec,
+        twirlInclusiveDot)
+  }
+}