Rework and simplify OnTypeFormatting and RangeFormatting classes

I mostly removed a couple of types, which were not adding much and increasing complexity. I also removed the `fn` functions and just inlined everything in the methods, which is overall shorter and simpler to understand.

metals/src/main/scala/scala/meta/internal/metals/MetalsEnrichments.scala

@@ -15,6 +15,7 @@ import java.util.concurrent.CompletionStage
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.TimeoutException
 
+import scala.annotation.tailrec
 import scala.collection.convert.DecorateAsJava
 import scala.collection.convert.DecorateAsScala
 import scala.collection.mutable
@@ -210,6 +211,26 @@ object MetalsEnrichments
     }
   }
 
+  implicit class XtensionList[T](lst: List[T]) {
+    def acceptFirst[R](
+        accept: T => Option[List[R]]
+    ): List[R] = {
+      @tailrec
+      def loop(toCheck: List[T]): List[R] = {
+        toCheck match {
+          case prioritized :: rest =>
+            val contributed = accept(prioritized)
+            contributed match {
+              case Some(edits) => edits
+              case None => loop(rest)
+            }
+          case Nil => Nil
+        }
+      }
+      loop(lst)
+    }
+  }
+
   implicit class XtensionDocumentSymbol(symbol: Seq[l.DocumentSymbol]) {
 
     def toSymbolInformation(uri: String): List[l.SymbolInformation] = {

metals/src/main/scala/scala/meta/internal/metals/MetalsLanguageServer.scala

@@ -56,6 +56,8 @@ import scala.meta.internal.metals.codelenses.WorksheetCodeLens
 import scala.meta.internal.metals.debug.BuildTargetClasses
 import scala.meta.internal.metals.debug.DebugParametersJsonParsers
 import scala.meta.internal.metals.debug.DebugProvider
+import scala.meta.internal.metals.formatting.OnTypeFormattingProvider
+import scala.meta.internal.metals.formatting.RangeFormattingProvider
 import scala.meta.internal.metals.newScalaFile.NewFileProvider
 import scala.meta.internal.mtags._
 import scala.meta.internal.parsing.ClassFinder
@@ -206,9 +208,9 @@ class MetalsLanguageServer(
   private val trees = new Trees(buildTargets, buffers, scalaVersionSelector)
   private val documentSymbolProvider = new DocumentSymbolProvider(trees)
   private val onTypeFormattingProvider =
-    new OnTypeFormattingProvider(buffers, () => userConfig)
+    new OnTypeFormattingProvider(buffers, trees, () => userConfig)
   private val rangeFormattingProvider =
-    new RangeFormattingProvider(buffers)
+    new RangeFormattingProvider(buffers, trees)
   private val classFinder = new ClassFinder(trees)
   private val foldingRangeProvider = new FoldingRangeProvider(trees, buffers)
   // These can't be instantiated until we know the workspace root directory.
@@ -1368,15 +1370,15 @@ class MetalsLanguageServer(
       params: DocumentOnTypeFormattingParams
   ): CompletableFuture[util.List[TextEdit]] =
     CancelTokens { _ =>
-      onTypeFormattingProvider.format(params, trees).asJava
+      onTypeFormattingProvider.format(params).asJava
     }
 
   @JsonRequest("textDocument/rangeFormatting")
   def rangeFormatting(
       params: DocumentRangeFormattingParams
   ): CompletableFuture[util.List[TextEdit]] =
     CancelTokens { _ =>
-      rangeFormattingProvider.format(params, trees).asJava
+      rangeFormattingProvider.format(params).asJava
     }
 
   @JsonRequest("textDocument/prepareRename")

metals/src/main/scala/scala/meta/internal/metals/onTypeRangeFormatters/IndentOnPaste.scala → metals/src/main/scala/scala/meta/internal/metals/formatting/IndentOnPaste.scala

@@ -1,4 +1,4 @@
-package scala.meta.internal.metals.onTypeRangeFormatters
+package scala.meta.internal.metals.formatting
 import scala.util.matching.Regex
 
 import scala.meta.internal.mtags.MtagsEnrichments._
@@ -50,12 +50,11 @@ object IndentOnPaste extends RangeFormatter {
   }
 
   override def contribute(
-      rangeFormatterParams: RangeFormatterParams,
-      tokensParams: TokensParams
+      rangeFormatterParams: RangeFormatterParams
   ): Option[List[TextEdit]] = {
     val formattingOptions = rangeFormatterParams.formattingOptions
-    val startPos = tokensParams.startPos
-    val endPos = tokensParams.endPos
+    val startPos = rangeFormatterParams.startPos
+    val endPos = rangeFormatterParams.endPos
     val splitLines = rangeFormatterParams.splitLines
 
     val insertSpaces = formattingOptions.isInsertSpaces

metals/src/main/scala/scala/meta/internal/metals/onTypeRangeFormatters/MultilineString.scala → metals/src/main/scala/scala/meta/internal/metals/formatting/MultilineString.scala

@@ -1,4 +1,4 @@
-package scala.meta.internal.metals.onTypeRangeFormatters
+package scala.meta.internal.metals.formatting
 
 import scala.meta.internal.metals.UserConfiguration
 import scala.meta.internal.mtags.MtagsEnrichments._
@@ -134,7 +134,7 @@ case class MultilineString(userConfig: () => UserConfiguration)
 
   private def indent(
       splitLines: Array[String],
-      startPosition: StartPosition,
+      startPosition: meta.Position,
       range: Range
   ): List[TextEdit] = {
     // position.startLine since we want to check current line on rangeFormatting
@@ -184,8 +184,8 @@ case class MultilineString(userConfig: () => UserConfiguration)
   }
 
   private def indentTokensOnTypeFormatting(
-      startPosition: StartPosition,
-      endPosition: EndPosition,
+      startPosition: meta.Position,
+      endPosition: meta.Position,
       tokens: Tokens,
       triggerChar: String,
       splitLines: Array[String],
@@ -220,8 +220,8 @@ case class MultilineString(userConfig: () => UserConfiguration)
   }
 
   def isStringOrInterpolation(
-      startPosition: StartPosition,
-      endPosition: EndPosition,
+      startPosition: meta.Position,
+      endPosition: meta.Position,
       token: Token,
       index: Int,
       text: String,
@@ -350,12 +350,11 @@ case class MultilineString(userConfig: () => UserConfiguration)
   }
 
   override def contribute(
-      onTypeFormatterParams: OnTypeFormatterParams,
-      tokensParams: TokensParams
+      onTypeFormatterParams: OnTypeFormatterParams
   ): Option[List[TextEdit]] = {
-    val tokensOpt = tokensParams.tokens
-    val startPos = tokensParams.startPos
-    val endPos = tokensParams.endPos
+    val tokensOpt = onTypeFormatterParams.tokens
+    val startPos = onTypeFormatterParams.startPos
+    val endPos = onTypeFormatterParams.endPos
     val triggerChar = onTypeFormatterParams.triggerChar
     val splitLines = onTypeFormatterParams.splitLines
     val position = onTypeFormatterParams.position
@@ -386,12 +385,11 @@ case class MultilineString(userConfig: () => UserConfiguration)
   }
 
   override def contribute(
-      rangeFormatterParams: RangeFormatterParams,
-      tokensParams: TokensParams
+      rangeFormatterParams: RangeFormatterParams
   ): Option[List[TextEdit]] = {
-    val tokensOpt = tokensParams.tokens
-    val startPos = tokensParams.startPos
-    val endPos = tokensParams.endPos
+    val tokensOpt = rangeFormatterParams.tokens
+    val startPos = rangeFormatterParams.startPos
+    val endPos = rangeFormatterParams.endPos
     val sourceText = rangeFormatterParams.sourceText
     val range = rangeFormatterParams.range
     val splitLines = rangeFormatterParams.splitLines

metals/src/main/scala/scala/meta/internal/metals/formatting/OnTypeFormattingProvider.scala

@@ -0,0 +1,74 @@
+package scala.meta.internal.metals.formatting
+
+import scala.meta.inputs.Input
+import scala.meta.internal.metals.Buffers
+import scala.meta.internal.metals.MetalsEnrichments._
+import scala.meta.internal.metals.UserConfiguration
+import scala.meta.internal.parsing.Trees
+import scala.meta.tokens.Tokens
+
+import org.eclipse.lsp4j.DocumentOnTypeFormattingParams
+import org.eclipse.lsp4j.Position
+import org.eclipse.lsp4j.Range
+import org.eclipse.lsp4j.TextEdit
+
+class OnTypeFormatter {
+  def contribute(
+      onTypeformatterParams: OnTypeFormatterParams
+  ): Option[List[TextEdit]] = None
+
+}
+
+case class OnTypeFormatterParams(
+    sourceText: String,
+    position: Position,
+    triggerChar: String,
+    startPos: meta.Position,
+    endPos: meta.Position,
+    tokens: Option[Tokens]
+) {
+  lazy val splitLines: Array[String] = sourceText.split("\\r?\\n")
+  val range = new Range(position, position)
+}
+
+class OnTypeFormattingProvider(
+    buffers: Buffers,
+    trees: Trees,
+    userConfig: () => UserConfiguration
+) {
+
+  // The order of which this is important to know which will first return the Edits
+  val formatters: List[OnTypeFormatter] = List(
+    MultilineString(userConfig)
+  )
+
+  def format(
+      params: DocumentOnTypeFormattingParams
+  ): List[TextEdit] = {
+    val uri = params.getTextDocument.getUri.toAbsolutePath
+    val range = new Range(params.getPosition, params.getPosition)
+    val triggerChar = params.getCh
+    val position = params.getPosition
+    buffers
+      .get(uri)
+      .map { sourceText =>
+        val virtualFile = Input.VirtualFile(sourceText.toString(), sourceText)
+        val startPos = range.getStart.toMeta(virtualFile)
+        val endPos = range.getEnd.toMeta(virtualFile)
+        val tokensOpt = trees.tokenized(virtualFile).toOption
+        val onTypeformatterParams =
+          OnTypeFormatterParams(
+            sourceText,
+            position,
+            triggerChar,
+            startPos,
+            endPos,
+            tokensOpt
+          )
+        formatters.acceptFirst(formater =>
+          formater.contribute(onTypeformatterParams)
+        )
+      }
+      .getOrElse(Nil)
+  }
+}