Interfaces: add credentials to public interface

docs/installation.md

@@ -526,6 +526,39 @@ By default, `scalafmt` only formats files that match the
 val scalafmtThatIgnoresProjectSettings = scalafmt.withRespectProjectFilters(false)
 ```
 
+### Alternate repositories and credentials
+
+`scalafmt` uses some default repositories to download the version specified in
+`.scalafmt.conf`; these repositories could be hardcoded or potentially specified
+via the environment variables.
+
+In order to specify explicit repositories as well, one could use
+
+```scala mdoc:silent
+val scalafmtWithRepos = scalafmt.withMavenRepositories(
+  "https://repo-1/snapshots",
+  "https://repo-2/public"
+)
+```
+
+In addition, if some of the default or custom repositories require access credentials,
+they could be specified via
+
+```scala mdoc:silent
+import org.scalafmt.interfaces._
+
+val scalafmtWithCreds = scalafmtWithRepos match {
+  case x: RepositoryCredential.ScalafmtExtension =>
+    x.withRepositoryCredentials(
+      new RepositoryCredential("repo-1", "username", "password")
+    )
+  case x => x
+}
+```
+
+This capability was added to the public interface as an extension method, accessible
+via a separate sub-interface.
+
 ### Clearing resources
 
 Use the `clear()` method to clear up resources of the `scalafmt` instance.

scalafmt-dynamic/src/main/scala/org/scalafmt/dynamic/CoursierDependencyDownloader.scala

@@ -1,14 +1,14 @@
 package org.scalafmt.dynamic
 
 import java.io.OutputStreamWriter
-import java.net.URL
+import java.net.{URI, URL}
 
 import scala.collection.JavaConverters._
 import scala.util.Try
 
 import coursierapi.{Dependency => CoursierDependency, _}
 
-class CoursierDependencyDownloader(
+private class CoursierDependencyDownloader(
     downloadProgressWriter: OutputStreamWriter,
     customRepositories: Seq[Repository]
 ) extends DependencyDownloader {
@@ -38,7 +38,13 @@ object CoursierDependencyDownloader extends DependencyDownloaderFactory {
 
   override def create(properties: ScalafmtProperties): DependencyDownloader = {
     val writer = properties.reporter.downloadOutputStreamWriter()
-    val repositories = properties.repositories.map(MavenRepository.of)
+    val repositories = properties.repositories.map { x =>
+      val host = new URI(x).getHost
+      val repo = MavenRepository.of(x)
+      properties.repositoryCredentials.find(_.host == host).fold(repo) { cred =>
+        repo.withCredentials(Credentials.of(cred.username, cred.password))
+      }
+    }
     new CoursierDependencyDownloader(writer, repositories)
   }
 

scalafmt-dynamic/src/main/scala/org/scalafmt/dynamic/ScalafmtDynamic.scala

@@ -10,6 +10,7 @@ final case class ScalafmtDynamic(
     moduleLoader: ScalafmtModuleLoader,
     configLoader: ScalafmtConfigLoader
 ) extends Scalafmt
+    with RepositoryCredential.ScalafmtExtension
     with ScalafmtSessionFactory {
 
   def this() = this(
@@ -40,6 +41,11 @@ final case class ScalafmtDynamic(
   override def withMavenRepositories(value: String*): Scalafmt =
     copy(properties = properties.withMavenRepositories(value))
 
+  override def withRepositoryCredentials(
+      value: RepositoryCredential*
+  ): Scalafmt =
+    copy(properties = properties.withRepositoryCredentials(value))
+
   override def format(config: Path, file: Path, code: String): String =
     createSession(config).format(file, code)
 

scalafmt-dynamic/src/main/scala/org/scalafmt/dynamic/ScalafmtProperties.scala

@@ -8,6 +8,7 @@ import org.scalafmt.interfaces._
 final case class ScalafmtProperties(
     reporter: ScalafmtReporter = ConsoleScalafmtReporter,
     repositories: Seq[String] = Nil,
+    repositoryCredentials: Seq[RepositoryCredential] = Nil,
     respectExcludeFilters: Boolean = true
 ) {
 
@@ -20,6 +21,11 @@ final case class ScalafmtProperties(
   def withMavenRepositories(value: Seq[String]): ScalafmtProperties =
     copy(repositories = value)
 
+  def withRepositoryCredentials(
+      value: Seq[RepositoryCredential]
+  ): ScalafmtProperties =
+    copy(repositoryCredentials = value)
+
   def reportError(file: Path, error: ScalafmtDynamicError): Unit =
     error match {
       case _: ConfigMissingVersion =>

scalafmt-interfaces/src/main/java/org/scalafmt/interfaces/RepositoryCredential.java

@@ -0,0 +1,18 @@
+package org.scalafmt.interfaces;
+
+public final class RepositoryCredential {
+    public final String host;
+    public final String username;
+    public final String password;
+
+    public RepositoryCredential(String host, String username, String password) {
+        this.host = host;
+        this.username = username;
+        this.password = password;
+    }
+
+    public interface ScalafmtExtension {
+        Scalafmt withRepositoryCredentials(RepositoryCredential... credentials);
+    }
+
+}

scalafmt-interfaces/src/main/java/org/scalafmt/interfaces/Scalafmt.java

@@ -92,6 +92,14 @@ public interface Scalafmt {
      */
     Scalafmt withMavenRepositories(String ... repositories);
 
+    /**
+     * Builder method.
+     *
+     * @param credentials repository credentials to use when resolving
+     * @return an updated interface instance.
+     */
+    Scalafmt withRepositoryCredentials(RepositoryCredential... credentials);
+
     /**
      * Clear internal caches such as classloaded Scalafmt instances.
      */