1 files changed, 120 insertions, 0 deletions
diff --git a/bot/src/dotty/tools/bot/PullRequestService.scala b/bot/src/dotty/tools/bot/PullRequestService.scala
new file mode 100644
index 000000000..8b568b134
--- /dev/null
+++ b/bot/src/dotty/tools/bot/PullRequestService.scala
@@ -0,0 +1,120 @@
+package dotty.tools.bot
+
+import org.http4s._
+import org.http4s.client.blaze._
+import org.http4s.client.Client
+
+import scalaz.concurrent.Task
+
+import io.circe._
+import io.circe.generic.auto._
+import io.circe.syntax._
+import org.http4s.circe._
+import org.http4s.dsl._
+
+import github4s.Github
+import github4s.jvm.Implicits._
+import github4s.free.domain.{ Commit, Issue }
+
+trait PullRequestService {
+
+  val prService = HttpService {
+    case request @ POST -> Root =>
+      request.as(jsonOf[Issue]).flatMap(checkPullRequest)
+  }
+
+  private case class CLASignature(
+    user: String,
+    signed: Boolean,
+    version: String,
+    currentVersion: String
+  )
+
+  private case class Status(
+    state: String,
+    target_url: String,
+    description: String,
+    context: String = "continuous-integration/CLA"
+  )
+
+  def claUrl(userName: String): String =
+   s"https://www.lightbend.com/contribute/cla/scala/check/$userName"
+
+  def commitsUrl(prNumber: Int): String =
+    s"https://api.github.com/repos/lampepfl/dotty/pulls/$prNumber/commits"
+
+  def toUri(url: String): Task[Uri] =
+    Uri.fromString(url).fold(Task.fail, Task.now)
+
+  def getRequest(endpoint: Uri): Task[Request] = Task.now {
+    Request(uri = endpoint, method = Method.GET)
+  }
+
+  def postRequest(endpoint: Uri): Task[Request] = Task.now {
+    Request(uri = endpoint, method = Method.POST)
+  }
+
+  def shutdownClient(client: Client): Task[Unit] = Task.now {
+    client.shutdownNow()
+  }
+
+  def users(xs: List[Commit]): Task[Set[String]] = Task.now {
+    xs.map(_.login).flatten.toSet
+  }
+
+  sealed trait CommitStatus {
+    def commit: Commit
+    def isValid: Boolean
+  }
+  final case class Valid(commit: Commit) extends CommitStatus { def isValid = true }
+  final case class Invalid(commit: Commit) extends CommitStatus { def isValid = false }
+
+  /** Partitions invalid and valid commits */
+  def checkCLA(xs: List[Commit], httpClient: Client): Task[List[CommitStatus]] = {
+    def checkUser(commit: Commit): Task[CommitStatus] = for {
+      endpoint <- toUri(claUrl(commit.login.get))
+      claReq   <- getRequest(endpoint)
+      claRes   <- httpClient.expect(claReq)(jsonOf[CLASignature])
+      res = if (claRes.signed) Valid(commit) else Invalid(commit)
+    } yield res
+
+    Task.gatherUnordered(xs.filter(_.login.isDefined).map(checkUser))
+  }
+
+  def sendStatuses(xs: List[CommitStatus], httpClient: Client): Task[Unit] = {
+    def setStatus(cm: CommitStatus): Task[Unit] = for {
+      endpoint <- toUri(cm.commit.url.replaceAll("git\\/commits", "statuses"))
+
+      target = claUrl(cm.commit.login.getOrElse("<invalid-user>"))
+      state = if (cm.isValid) "success" else "failure"
+      desc =
+        if (cm.isValid) "User signed CLA"
+        else "User needs to sign cla: https://www.lightbend.com/contribute/cla/scala"
+
+      statusReq <- postRequest(endpoint).map(_.withBody(Status(state, target, desc).asJson))
+      statusRes <- httpClient.expect(statusReq)(jsonOf[String])
+      print     <- Task.now(println(statusRes))
+    } yield print
+
+    Task.gatherUnordered(xs.map(setStatus)).map(_ => ())
+  }
+
+  def checkPullRequest(issue: Issue): Task[Response] = {
+    val httpClient = PooledHttp1Client()
+
+    for {
+      // First get all the commits from the PR
+      endpoint   <- toUri(commitsUrl(issue.number))
+      commitsReq <- getRequest(endpoint)
+      commitsRes <- httpClient.expect(commitsReq)(jsonOf[List[Commit]])
+
+      // Then get check the CLA of each commit
+      statuses   <- checkCLA(commitsRes, httpClient)
+
+      // Send statuses to Github and exit
+      _          <- sendStatuses(statuses, httpClient)
+      _          <- shutdownClient(httpClient)
+      resp       <- Ok("All statuses checked")
+    } yield resp
+  }
+}