FIR: Add collecting top-level scopes of the file

It will be useful in the completion when we need to dicide if we
need to import FQN or not

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirBodyResolveTransformer.kt

@@ -49,6 +49,8 @@ open class FirBodyResolveTransformer(
     override fun transformFile(file: FirFile, data: ResolutionMode): CompositeTransformResult<FirFile> {
         checkSessionConsistency(file)
         return context.withFile(file, components) {
+            onBeforeFileContentResolution(file)
+
             file.replaceResolvePhase(transformerPhase)
             @Suppress("UNCHECKED_CAST")
             transformDeclarationContent(file, data) as CompositeTransformResult<FirFile>
@@ -73,6 +75,8 @@ open class FirBodyResolveTransformer(
         return data.expectedTypeRef.compose()
     }
 
+    open fun onBeforeFileContentResolution(file: FirFile) {}
+
     open fun onBeforeStatementResolution(statement: FirStatement) {}
 
     open fun onBeforeDeclarationContentResolve(declaration: FirDeclaration) {}

idea/idea-frontend-api/src/org/jetbrains/kotlin/idea/frontend/api/components/KtScopeProvider.kt

@@ -50,6 +50,9 @@ interface KtScopeProviderMixIn : KtAnalysisSessionMixIn {
 
     fun KtFile.getScopeContextForPosition(positionInFakeFile: KtElement): KtScopeContext =
         analysisSession.scopeProvider.getScopeContextForPosition(this, positionInFakeFile)
+
+    fun KtFile.getScopeContextForFile(): KtScopeContext =
+        analysisSession.scopeProvider.getScopeContextForPosition(this, this)
 }
 
 data class KtScopeContext(val scopes: KtCompositeScope, val implicitReceiversTypes: List<KtType>)

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/element/builder/FirTowerDataContextCollector.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.idea.fir.low.level.api.element.builder
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.fir.ThreadSafeMutableState
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.psi
 import org.jetbrains.kotlin.fir.resolve.FirTowerDataContext
@@ -17,6 +18,11 @@ import org.jetbrains.kotlin.psi.*
 class FirTowerDataContextCollector {
     private val state: MutableMap<KtElement, FirTowerDataContext> = hashMapOf()
 
+    fun addFileContext(file: FirFile, context: FirTowerDataContext) {
+        val ktFile = file.psi as? KtFile ?: return
+        state[ktFile] = context
+    }
+
     fun addStatementContext(statement: FirStatement, context: FirTowerDataContext) {
         val closestStatementInBlock = statement.psi?.closestBlockLevelOrInitializerExpression() ?: return
         state[closestStatementInBlock] = context

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/trasformers/FirDesignatedBodyResolveTransformerForIDE.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.idea.fir.low.level.api.trasformers
 
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
 import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.resolve.ResolutionMode
@@ -44,6 +45,10 @@ internal class FirDesignatedBodyResolveTransformerForIDE(
             super.transformDeclarationContent(declaration, data)
         }
 
+    override fun onBeforeFileContentResolution(file: FirFile) {
+        towerDataContextCollector?.addFileContext(file, context.towerDataContext)
+    }
+
     override fun onBeforeDeclarationContentResolve(declaration: FirDeclaration) {
         towerDataContextCollector?.addDeclarationContext(declaration, context.towerDataContext)
     }