Implement posting initial comment

Author: felixmulder

bot/src/dotty/tools/bot/PullRequestService.scala

@@ -3,7 +3,7 @@ package dotty.tools.bot
 import org.http4s.{ Status => _, _ }
 import org.http4s.client.blaze._
 import org.http4s.client.Client
-import org.http4s.headers.Authorization
+import org.http4s.headers.{ Accept, Authorization }
 
 import cats.syntax.applicative._
 import scalaz.concurrent.Task
@@ -47,6 +47,10 @@ trait PullRequestService {
     new Authorization(creds)
   }
 
+  private[this] lazy val previewAcceptHeader =
+    Accept.parse("application/vnd.github.black-cat-preview+json")
+      .getOrElse(throw new Exception("Couldn't initialize accept header"))
+
   private final case class CLASignature(
     user: String,
     signed: Boolean,
@@ -68,14 +72,20 @@ trait PullRequestService {
   def issueCommentsUrl(issueNbr: Int): String =
     s"$githubUrl/repos/lampepfl/dotty/issues/$issueNbr/comments"
 
+  def reviewUrl(issueNbr: Int): String =
+    s"$githubUrl/repos/lampepfl/dotty/pulls/$issueNbr/reviews"
+
   def toUri(url: String): Task[Uri] =
     Uri.fromString(url).fold(Task.fail, Task.now)
 
   def getRequest(endpoint: Uri): Task[Request] =
-    Request(uri = endpoint, method = Method.GET).putHeaders(authHeader).pure[Task]
+    Request(uri = endpoint, method = Method.GET).putHeaders(authHeader)
+      .pure[Task]
 
   def postRequest(endpoint: Uri): Task[Request] =
-    Request(uri = endpoint, method = Method.POST).putHeaders(authHeader).pure[Task]
+    Request(uri = endpoint, method = Method.POST)
+      .putHeaders(authHeader, previewAcceptHeader)
+      .pure[Task]
 
   def shutdownClient(client: Client): Task[Unit] =
     client.shutdownNow().pure[Task]
@@ -191,11 +201,87 @@ trait PullRequestService {
   private def usersFromInvalid(xs: List[CommitStatus]) =
     xs.collect { case Invalid(user, _) => user }
 
-  def sendInitialComment(invalidUsers: List[String]): Task[Unit] = ???
+  def hasBadCommitMessages(commits: List[Commit]): Boolean =
+    commits.exists { cm =>
+      val firstLine = cm.commit.message.takeWhile(_ != '\n').trim.toLowerCase
+      val firstWord = firstLine.takeWhile(x => x != ':' && x != ' ')
+      val containsColon = firstLine.contains(':')
 
-  def checkFreshPR(issue: Issue): Task[Response] = {
+      val wrongTense = firstWord match {
+        case "added" | "fixed" | "removed" | "moved" | "changed" |
+             "finalized" | "re-added"
+        => true
+
+        case "adds" | "fixes" | "removes" | "moves" | "changes" |
+             "finalizes" | "re-adds"
+        => true
+
+        case _
+        => false
+      }
+
+      wrongTense || firstLine.last == '.' || firstLine.length > 100
+    }
 
+  def sendInitialComment(issueNbr: Int, invalidUsers: List[String], commits: List[Commit], client: Client): Task[ReviewResponse] = {
+
+    val cla = if (invalidUsers.nonEmpty) {
+      s"""|## CLA ##
+          |In order for us to be able to accept your contribution, all users
+          |must sign the Scala CLA.
+          |
+          |Users:
+          |${ invalidUsers.map("@" + _).mkString("- ", "\n- ", "") }
+          |
+          |Could you folks please sign the CLA? :pray:
+          |
+          |Please do this here: https://www.lightbend.com/contribute/cla/scala
+          |""".stripMargin
+    } else "All contributors have signed the CLA, thank you! :heart:"
+
+    val commitRules = if (hasBadCommitMessages(commits)) {
+      """|## Commit Messages ##
+         |We want to keep history, but for that to actually be useful we have
+         |some rules on how to format our commit messages ([relevant xkcd](https://xkcd.com/1296/)).
+         |
+         |Please stick to these guidelines for commit messages:
+         |
+         |> 1. Separate subject from body with a blank line
+         |> 1. When fixing an issue, start your commit message with `Fix #<ISSUE-NBR>: `
+         |> 1. Limit the subject line to 80 characters
+         |> 1. Capitalize the subject line
+         |> 1. Do not end the subject line with a period
+         |> 1. Use the imperative mood in the subject line ("Added" instead of "Add")
+         |> 1. Wrap the body at 80 characters
+         |> 1. Use the body to explain what and why vs. how
+         |>
+         |> adapted from https://chris.beams.io/posts/git-commit""".stripMargin
+    } else ""
+
+    val body =
+      s"""|Hello, and thank you for opening this PR! :tada:
+          |
+          |If you haven't already, please request a review from one of our
+          |collaborators (have no fear, we don't bite)!
+          |
+          |$cla
+          |
+          |$commitRules
+          |
+          |Have an awesome day! :sunny:""".stripMargin
+
+    val review = Review.comment(body)
+
+    for {
+      endpoint <- toUri(reviewUrl(issueNbr))
+      req      <- postRequest(endpoint).withBody(review.asJson)
+      res      <- client.expect(req)(jsonOf[ReviewResponse])
+    } yield res
+  }
+
+  def checkFreshPR(issue: Issue): Task[Response] = {
     val httpClient = PooledHttp1Client()
+
     for {
       commits  <- getCommits(issue.number, httpClient)
       statuses <- checkCLA(commits, httpClient)
@@ -215,7 +301,7 @@ trait PullRequestService {
       }
 
       // Send positive comment:
-      _    <- sendInitialComment(invalidUsers)
+      _    <- sendInitialComment(issue.number, invalidUsers, commits, httpClient)
       _    <- shutdownClient(httpClient)
       resp <- Ok("Fresh PR checked")
     } yield resp

bot/src/dotty/tools/bot/model/Github.scala

@@ -2,21 +2,15 @@ package dotty.tools.bot
 package model
 
 object Github {
-  case class PullRequest(
-    url: String,
-    id: Long,
-    commits_url: String
-  )
-
   case class Issue(
     action: String, // "opened", "reopened", "closed", "synchronize"
     number: Int,
     pull_request: Option[PullRequest]
   )
 
-  case class CommitInfo(
-    message: String
-  )
+  case class PullRequest(url: String, id: Long, commits_url: String)
+
+  case class CommitInfo(message: String)
 
   case class Commit(
     sha: String,
@@ -36,14 +30,20 @@ object Github {
     context: String = "CLA"
   )
 
-  // TODO: Can we get a `Commit` from `StatusResponse`? 
-  case class StatusResponse(
-    url: String,
-    id: Long,
-    state: String
-  ) {
+  case class StatusResponse(url: String, id: Long, state: String) {
     def sha: String = url.split('/').last
   }
 
   case class Comment(user: Author)
+
+  /** A PR review */
+  case class Review (body: String, event: String)
+
+  object Review {
+    def approve(body: String) = Review(body, "APPROVE")
+    def requestChanges(body: String) = Review(body, "REQUEST_CHANGES")
+    def comment(body: String) = Review(body, "COMMENT")
+  }
+
+  case class ReviewResponse(body: String, state: String, id: Long)
 }

bot/test/PRServiceTests.scala

@@ -121,4 +121,17 @@ class PRServiceTests extends PullRequestService {
 
     assert(rechecked.forall(cs => cs.isValid), s"Should have set all statuses to valid, but got: $rechecked")
   }
+
+  @Test def canPostReview = {
+    val invalidUsers = "felixmulder" :: "smarter" :: Nil
+    val commit = Commit("", Author(Some("smarter")), Author(Some("smarter")), CommitInfo("Added stuff"))
+    val res = withClient(sendInitialComment(2281, invalidUsers, commit :: Nil, _))
+
+    assert(
+      res.body.contains("We want to keep history") &&
+      res.body.contains("Could you folks please sign the CLA?") &&
+      res.body.contains("Have an awesome day!"),
+      s"Body of review was not as expected:\n${res.body}"
+    )
+  }
 }