improvement: add custom bsp as possible build tool (#5791)

metals/src/main/scala/scala/meta/internal/bsp/BspConnector.scala

@@ -7,8 +7,10 @@ import scala.concurrent.Future
 
 import scala.meta.internal.bsp.BspConfigGenerationStatus._
 import scala.meta.internal.builds.BuildServerProvider
+import scala.meta.internal.builds.BuildTool
 import scala.meta.internal.builds.BuildTools
 import scala.meta.internal.builds.SbtBuildTool
+import scala.meta.internal.builds.ScalaCliBuildTool
 import scala.meta.internal.builds.ShellRunner
 import scala.meta.internal.metals.BloopServers
 import scala.meta.internal.metals.BuildServerConnection
@@ -18,6 +20,7 @@ import scala.meta.internal.metals.MetalsEnrichments._
 import scala.meta.internal.metals.StatusBar
 import scala.meta.internal.metals.Tables
 import scala.meta.internal.metals.UserConfiguration
+import scala.meta.internal.metals.scalacli.ScalaCli
 import scala.meta.internal.semver.SemVer
 import scala.meta.io.AbsolutePath
 
@@ -43,13 +46,9 @@ class BspConnector(
    * Resolves the current build servers that either have a bsp entry or if the
    * workspace can support Bloop, it will also resolve Bloop.
    */
-  def resolve(): BspResolvedResult = {
+  def resolve(buildTool: Option[BuildTool]): BspResolvedResult = {
     resolveExplicit().getOrElse {
-      if (
-        buildTools
-          .loadSupported()
-          .exists(_.isBloopDefaultBsp) || buildTools.isBloop
-      )
+      if (buildTool.exists(_.isBloopInstallProvider) || buildTools.isBloop)
         ResolvedBloop
       else bspServers.resolve()
     }
@@ -61,7 +60,10 @@ class BspConnector(
       else
         bspServers
           .findAvailableServers()
-          .find(_.getName == sel)
+          .find(buildServer =>
+            (ScalaCli.names(buildServer.getName()) && ScalaCli.names(sel)) ||
+              buildServer.getName == sel
+          )
           .map(ResolvedBspOne)
     }
   }
@@ -74,19 +76,20 @@ class BspConnector(
    * of the bsp entry has already happened at this point.
    */
   def connect(
-      projectRoot: AbsolutePath,
+      buildTool: Option[BuildTool],
       workspace: AbsolutePath,
       userConfiguration: UserConfiguration,
       shellRunner: ShellRunner,
   )(implicit ec: ExecutionContext): Future[Option[BspSession]] = {
+    val projectRoot = buildTool.map(_.projectRoot).getOrElse(workspace)
     def connect(
         projectRoot: AbsolutePath,
         bspTraceRoot: AbsolutePath,
         addLivenessMonitor: Boolean,
     ): Future[Option[BuildServerConnection]] = {
       def bspStatusOpt = Option.when(addLivenessMonitor)(bspStatus)
       scribe.info("Attempting to connect to the build server...")
-      resolve() match {
+      resolve(buildTool) match {
         case ResolvedNone =>
           scribe.info("No build server found")
           Future.successful(None)
@@ -131,6 +134,7 @@ class BspConnector(
             .map(Some(_))
         case ResolvedBspOne(details) =>
           tables.buildServers.chooseServer(details.getName())
+          optSetBuildTool(details.getName())
           bspServers
             .newServer(projectRoot, bspTraceRoot, details, bspStatusOpt)
             .map(Some(_))
@@ -165,6 +169,7 @@ class BspConnector(
                 )
               )
             _ = tables.buildServers.chooseServer(item.getName())
+            _ = optSetBuildTool(item.getName())
             conn <- bspServers.newServer(
               projectRoot,
               bspTraceRoot,
@@ -180,7 +185,10 @@ class BspConnector(
         possibleBuildServerConn match {
           case None => Future.successful(None)
           case Some(buildServerConn)
-              if buildServerConn.isBloop && buildTools.isSbt =>
+              if buildServerConn.isBloop && buildTool.exists {
+                case _: SbtBuildTool => true
+                case _ => false
+              } =>
             // NOTE: (ckipp01) we special case this here since sbt bsp server
             // doesn't yet support metabuilds. So in the future when that
             // changes, re-work this and move the creation of this out above
@@ -196,6 +204,23 @@ class BspConnector(
     }
   }
 
+  /**
+   * Looks for a build tool matching the chosen build server, and sets it as the chosen build server.
+   * Only for `bloop` there will be no matching build tool and the previously chosen one remains.
+   */
+  private def optSetBuildTool(buildServerName: String): Unit =
+    buildTools.loadSupported
+      .find {
+        case _: ScalaCliBuildTool if ScalaCli.names(buildServerName) => true
+        case buildTool: BuildServerProvider
+            if buildTool.buildServerName.contains(buildServerName) =>
+          true
+        case buildTool => buildTool.executableName == buildServerName
+      }
+      .foreach(buildTool =>
+        tables.buildTool.chooseBuildTool(buildTool.executableName)
+      )
+
   private def sbtMetaWorkspaces(root: AbsolutePath): List[AbsolutePath] = {
     def recursive(
         p: AbsolutePath,
@@ -277,7 +302,9 @@ class BspConnector(
       BspConnectionDetails,
     ]] = {
       if (
-        bloopPresent || buildTools.loadSupported().exists(_.isBloopDefaultBsp)
+        bloopPresent || buildTools
+          .loadSupported()
+          .exists(_.isBloopInstallProvider)
       )
         new BspConnectionDetails(
           BloopServers.name,

metals/src/main/scala/scala/meta/internal/bsp/BspServers.scala

@@ -47,6 +47,8 @@ final class BspServers(
     config: MetalsServerConfig,
     userConfig: () => UserConfiguration,
 )(implicit ec: ExecutionContextExecutorService) {
+  private def customProjectRoot =
+    userConfig().getCustomProjectRoot(mainWorkspace)
 
   def resolve(): BspResolvedResult = {
     findAvailableServers() match {
@@ -153,7 +155,7 @@ final class BspServers(
    *  may be a server in the current workspace
    */
   def findAvailableServers(): List[BspConnectionDetails] = {
-    val jsonFiles = findJsonFiles(mainWorkspace)
+    val jsonFiles = findJsonFiles()
     val gson = new Gson()
     for {
       candidate <- jsonFiles
@@ -172,17 +174,16 @@ final class BspServers(
     }
   }
 
-  private def findJsonFiles(
-      projectDirectory: AbsolutePath
-  ): List[AbsolutePath] = {
+  private def findJsonFiles(): List[AbsolutePath] = {
     val buf = List.newBuilder[AbsolutePath]
     def visit(dir: AbsolutePath): Unit =
       dir.list.foreach { p =>
         if (p.extension == "json") {
           buf += p
         }
       }
-    visit(projectDirectory.resolve(".bsp"))
+    visit(mainWorkspace.resolve(".bsp"))
+    customProjectRoot.map(_.resolve(".bsp")).foreach(visit)
     bspGlobalInstallDirectories.foreach(visit)
     buf.result()
   }

metals/src/main/scala/scala/meta/internal/builds/BloopInstall.scala

@@ -37,7 +37,7 @@ final class BloopInstall(
   override def toString: String = s"BloopInstall($workspace)"
 
   def runUnconditionally(
-      buildTool: BuildTool,
+      buildTool: BloopInstallProvider,
       isImportInProcess: AtomicBoolean,
   ): Future[WorkspaceLoadedStatus] = {
     if (isImportInProcess.compareAndSet(false, true)) {
@@ -121,7 +121,7 @@ final class BloopInstall(
   // notifications. This method is synchronized to prevent asking the user
   // twice whether to import the build.
   def runIfApproved(
-      buildTool: BuildTool,
+      buildTool: BloopInstallProvider,
       digest: String,
       isImportInProcess: AtomicBoolean,
   ): Future[WorkspaceLoadedStatus] =

metals/src/main/scala/scala/meta/internal/builds/BloopInstallProvider.scala

@@ -6,10 +6,10 @@ import scala.meta.io.AbsolutePath
 /**
  * Helper trait for build tools that have a Bloop plugin
  */
-trait BloopInstallProvider { this: BuildTool =>
+trait BloopInstallProvider extends BuildTool {
 
   /**
-   * Method used to generate the necesary .bloop files for the
+   * Method used to generate the necessary .bloop files for the
    * build tool.
    */
   def bloopInstall(
@@ -22,4 +22,6 @@ trait BloopInstallProvider { this: BuildTool =>
    * Args necessary for build tool to generate the .bloop files.
    */
   def bloopInstallArgs(workspace: AbsolutePath): List[String]
+
+  override val isBloopInstallProvider = true
 }

metals/src/main/scala/scala/meta/internal/builds/BspOnly.scala

@@ -0,0 +1,25 @@
+package scala.meta.internal.builds
+
+import java.security.MessageDigest
+
+import scala.meta.internal.builds.Digest
+import scala.meta.internal.mtags.MD5
+import scala.meta.io.AbsolutePath
+
+/**
+ * Build tool for custom bsp detected in `.bsp/<name>.json` or `bspGlobalDirectories`
+ */
+case class BspOnly(
+    override val executableName: String,
+    override val projectRoot: AbsolutePath,
+    pathToBspConfig: AbsolutePath,
+) extends BuildTool {
+  override def digest(workspace: AbsolutePath): Option[String] = {
+    val digest = MessageDigest.getInstance("MD5")
+    val isSuccess =
+      Digest.digestJson(pathToBspConfig, digest)
+    if (isSuccess) Some(MD5.bytesToHex(digest.digest()))
+    else None
+  }
+  override val forcesBuildServer = true
+}

metals/src/main/scala/scala/meta/internal/builds/BuildTool.scala

@@ -4,32 +4,12 @@ import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.StandardCopyOption
 
-import scala.concurrent.Future
-
 import scala.meta.io.AbsolutePath
 
 trait BuildTool {
 
-  /**
-   * Export the build to Bloop
-   *
-   * This operation should be roughly equivalent to running `sbt bloopInstall`
-   * and should work for both updating an existing Bloop build or creating a new
-   * Bloop build.
-   */
-  def bloopInstall(
-      workspace: AbsolutePath,
-      systemProcess: List[String] => Future[WorkspaceLoadedStatus],
-  ): Future[WorkspaceLoadedStatus]
-
   def digest(workspace: AbsolutePath): Option[String]
 
-  def version: String
-
-  def minimumVersion: String
-
-  def recommendedVersion: String
-
   protected lazy val tempDir: Path = {
     val dir = Files.createTempDirectory("metals")
     dir.toFile.deleteOnExit()
@@ -40,15 +20,16 @@ trait BuildTool {
 
   def executableName: String
 
-  def isBloopDefaultBsp = true
-
   def projectRoot: AbsolutePath
 
+  val forcesBuildServer = false
+
+  val isBloopInstallProvider = false
+
 }
 
 object BuildTool {
 
-  case class Found(buildTool: BuildTool, digest: String)
   def copyFromResource(
       tempDir: Path,
       filePath: String,
@@ -62,4 +43,16 @@ object BuildTool {
     outFile
   }
 
+  trait Verified
+  case class IncompatibleVersion(buildTool: VersionRecommendation)
+      extends Verified {
+    def message: String = s"Unsupported $buildTool version ${buildTool.version}"
+  }
+  case class NoChecksum(buildTool: BuildTool, root: AbsolutePath)
+      extends Verified {
+    def message: String =
+      s"Could not calculate checksum for ${buildTool.executableName} in $root"
+  }
+  case class Found(buildTool: BuildTool, digest: String) extends Verified
+
 }

metals/src/main/scala/scala/meta/internal/builds/BuildTools.scala

@@ -9,6 +9,7 @@ import scala.meta.internal.io.PathIO
 import scala.meta.internal.metals.BloopServers
 import scala.meta.internal.metals.MetalsEnrichments._
 import scala.meta.internal.metals.UserConfiguration
+import scala.meta.internal.metals.scalacli.ScalaCli
 import scala.meta.io.AbsolutePath
 
 import ujson.ParsingFailedException
@@ -54,6 +55,7 @@ final class BuildTools(
   def isBloop: Boolean = bloopProject.isDefined
   def isBsp: Boolean = {
     hasJsonFile(workspace.resolve(".bsp")) ||
+    customProjectRoot.exists(root => hasJsonFile(root.resolve(".bsp"))) ||
     bspGlobalDirectories.exists(hasJsonFile)
   }
   private def hasJsonFile(dir: AbsolutePath): Boolean = {
@@ -121,16 +123,34 @@ final class BuildTools(
   )
   def isBazel: Boolean = bazelProject.isDefined
 
-  private def customProjectRoot =
-    userConfig().customProjectRoot
-      .map(relativePath => workspace.resolve(relativePath.trim()))
-      .filter { projectRoot =>
-        val exists = projectRoot.exists
-        if (!exists) {
-          scribe.error(s"custom project root $projectRoot does not exist")
+  private def customBsps: List[BspOnly] = {
+    val bspFolders =
+      (workspace :: customProjectRoot.toList).distinct
+        .map(_.resolve(".bsp")) ++ bspGlobalDirectories
+    val root = customProjectRoot.getOrElse(workspace)
+    for {
+      bspFolder <- bspFolders
+      if (bspFolder.exists && bspFolder.isDirectory)
+      buildTool <- bspFolder.toFile
+        .listFiles()
+        .collect {
+          case file
+              if file.isFile() && file.getName().endsWith(".json") &&
+                !knownBsps(file.getName().stripSuffix(".json")) =>
+            BspOnly(
+              file.getName().stripSuffix(".json"),
+              root,
+              AbsolutePath(file.toPath()),
+            )
         }
-        exists
-      }
+        .toList
+    } yield buildTool
+  }
+
+  private def knownBsps =
+    Set(SbtBuildTool.name, MillBuildTool.name) ++ ScalaCli.names
+
+  private def customProjectRoot = userConfig().getCustomProjectRoot(workspace)
 
   private def searchForBuildTool(
       isProjectRoot: AbsolutePath => Boolean
@@ -187,6 +207,7 @@ final class BuildTools(
     mavenProject.foreach(buf += MavenBuildTool(userConfig, _))
     millProject.foreach(buf += MillBuildTool(userConfig, _))
     scalaCliProject.foreach(buf += ScalaCliBuildTool(workspace, _, userConfig))
+    buf.addAll(customBsps)
 
     buf.result()
   }
@@ -208,6 +229,11 @@ final class BuildTools(
       Some(MavenBuildTool.name)
     else if (isMill && MillBuildTool.isMillRelatedPath(path))
       Some(MillBuildTool.name)
+    else if (
+      path.isFile && path.filename.endsWith(".json") &&
+      path.parent.filename == ".bsp"
+    )
+      Some(path.filename.stripSuffix(".json"))
     else None
   }
 
@@ -221,6 +247,7 @@ final class BuildTools(
     val before = lastDetectedBuildTools.getAndUpdate(_ + buildTool)
     !before.contains(buildTool)
   }
+
 }
 
 object BuildTools {