feat(completion): improve file reference provider with project file index #101

The completion provider for file references has been enhanced to use the project file index, which allows for more accurate and efficient completion suggestions. This change ensures that only relevant files within the project are considered, improving the user experience.

Author: phodal

exts/devin-lang/src/main/kotlin/cc/unitmesh/devti/language/completion/FileReferenceLanguageProvider.kt

@@ -1,10 +1,13 @@
 package cc.unitmesh.devti.language.completion
 
-import com.intellij.codeInsight.completion.*
+import com.intellij.codeInsight.completion.CompletionParameters
+import com.intellij.codeInsight.completion.CompletionProvider
+import com.intellij.codeInsight.completion.CompletionResultSet
 import com.intellij.codeInsight.lookup.LookupElementBuilder
 import com.intellij.ide.presentation.VirtualFilePresentation
 import com.intellij.openapi.fileEditor.impl.EditorHistoryManager
 import com.intellij.openapi.project.guessProjectDir
+import com.intellij.openapi.roots.ProjectFileIndex
 import com.intellij.util.ProcessingContext
 import java.io.File
 
@@ -33,5 +36,22 @@ class FileReferenceLanguageProvider : CompletionProvider<CompletionParameters>()
 
             result.addElement(element)
         }
+
+        val projectFileIndex = ProjectFileIndex.getInstance(project)
+        projectFileIndex.iterateContent {
+            val removePrefix = it.path.removePrefix(basePath)
+            val relativePath: String = removePrefix.removePrefix(File.separator)
+
+            val element = LookupElementBuilder.create(relativePath)
+                .withIcon(VirtualFilePresentation.getIcon(it))
+                .withInsertHandler { context, _ ->
+                    context.editor.caretModel.moveCaretRelatively(
+                        1, 0, false, false, false
+                    )
+                }
+
+            result.addElement(element)
+            true
+        }
     }
 }