feat(intellij): add kotlin language support for collecting declaration.

clients/intellij/build.gradle.kts

@@ -18,7 +18,12 @@ repositories {
 dependencies {
   intellijPlatform {
     intellijIdeaCommunity("2023.1")
-    bundledPlugins(listOf("Git4Idea"))
+    bundledPlugins(
+      listOf(
+        "Git4Idea",
+        "org.jetbrains.kotlin",
+      )
+    )
     pluginVerifier()
     zipSigner()
     instrumentationTools()

clients/intellij/src/main/kotlin/com/tabbyml/intellijtabby/languageSupport/KotlinLanguageSupportProvider.kt

@@ -0,0 +1,68 @@
+package com.tabbyml.intellijtabby.languageSupport
+
+import com.intellij.openapi.application.runReadAction
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import com.tabbyml.intellijtabby.languageSupport.LanguageSupportProvider.*
+import io.ktor.util.*
+import org.eclipse.lsp4j.SemanticTokenTypes
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.forEachDescendantOfType
+
+class KotlinLanguageSupportProvider : LanguageSupportProvider {
+  override fun provideSemanticTokensRange(project: Project, fileRange: FileRange): List<SemanticToken>? {
+    val psiFile = fileRange.file
+    if (psiFile.language.id.toUpperCasePreservingASCIIRules() != "KOTLIN") {
+      return null
+    }
+    return runReadAction {
+      val semanticTokens = mutableListOf<SemanticToken>()
+      psiFile.forEachDescendantOfType<KtReferenceExpression> { element ->
+        if (element.children.isEmpty() && fileRange.range.contains(element.textRange)) {
+          val referenceTarget =
+            element.references.map { it.resolve() }.firstNotNullOfOrNull { it } ?: return@forEachDescendantOfType
+          val type = parseReferenceType(referenceTarget)
+          semanticTokens.add(
+            SemanticToken(
+              text = element.text,
+              range = element.textRange,
+              type = type,
+            )
+          )
+        }
+      }
+      semanticTokens.toList()
+    }
+  }
+
+  override fun provideDeclaration(project: Project, filePosition: FilePosition): List<FileRange>? {
+    val psiFile = filePosition.file
+    if (psiFile.language.id.toUpperCasePreservingASCIIRules() != "KOTLIN") {
+      return null
+    }
+    return runReadAction {
+      val element = psiFile.findElementAt(filePosition.offset)
+      val referenceExpression =
+        element as? KtReferenceExpression ?: element?.parent as? KtReferenceExpression ?: return@runReadAction listOf()
+      val referenceTarget =
+        referenceExpression.references.map { it.resolve() }.firstNotNullOfOrNull { it } ?: return@runReadAction listOf()
+      val file = referenceTarget.containingFile ?: return@runReadAction listOf()
+      val range = referenceTarget.textRange
+      listOf(FileRange(file, range))
+    }
+  }
+
+  private fun parseReferenceType(referenceTarget: PsiElement): String {
+    return when (referenceTarget) {
+      is KtClassOrObject -> SemanticTokenTypes.Class
+      is KtFunction -> SemanticTokenTypes.Function
+      is KtProperty -> SemanticTokenTypes.Property
+      is KtParameter -> SemanticTokenTypes.Parameter
+      is KtVariableDeclaration -> SemanticTokenTypes.Variable
+
+      // 1. Fallback to `Type` for other kotlin element declarations
+      // 2. The reference target may be declared in Java, fallback to `Type` for now
+      else -> SemanticTokenTypes.Type
+    }
+  }
+}

clients/intellij/src/main/resources/META-INF/plugin-kotlin.xml

@@ -0,0 +1,6 @@
+<idea-plugin>
+    <extensions defaultExtensionNs="com.tabbyml.intellij-tabby">
+        <languageSupportProvider
+                implementation="com.tabbyml.intellijtabby.languageSupport.KotlinLanguageSupportProvider"/>
+    </extensions>
+</idea-plugin>

clients/intellij/src/main/resources/META-INF/plugin.xml

@@ -29,7 +29,7 @@
          Read more: https://plugins.jetbrains.com/docs/intellij/plugin-compatibility.html -->
     <depends>com.intellij.modules.platform</depends>
     <depends optional="true" config-file="plugin-Git4Idea.xml">Git4Idea</depends>
-
+    <depends optional="true" config-file="plugin-kotlin.xml">org.jetbrains.kotlin</depends>
 
     <!-- Extension points defined by the plugin.
          Read more: https://plugins.jetbrains.com/docs/intellij/plugin-extension-points.html -->