The Features That Make Developers Smile: Implementation Magic 🪄 (Part 3/5)

export const UserProfile: React.FC<UserProps> = ({ user, onUpdate }) => { const [editing, setEditing] = useState(false); const handleSave = async (data: UserData) => { // ← I click HERE await updateUser(data); setEditing(false); onUpdate?.(data); }; const validateEmail = (email: string): boolean => { return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email); }; return <div>{/* JSX content */}</div>; }; 

export class CodeAnalysisService { // The regex patterns that saved my sanity ✨ private readonly patterns = { // Classic function declarations functionDeclaration: /^(\s*)(?:export\s+)?(async\s+)?function\s+(\w+)\s*\([^)]*\)\s*[{:]/gm, // Arrow functions (the React staple) arrowFunction: /^(\s*)(?:export\s+)?(?:const|let|var)\s+(\w+)\s*=\s*(async\s+)?\([^)]*\)\s*=>/gm, // Object and class methods  methodDefinition: /^(\s*)(?:(async)\s+)?(\w+)\s*\([^)]*\)\s*[{:]/gm, // React components (starts with capital letter) reactComponent: /^(\s*)(?:export\s+)?(?:const|function)\s+([A-Z]\w+)/gm, // React hooks (starts with 'use') reactHook: /^(\s*)(?:export\s+)?(?:const|let|var)\s+(use[A-Z]\w*)\s*=/gm, }; public async findFunctionAtPosition( document: vscode.TextDocument, position: vscode.Position ): Promise<FunctionInfo | null> { const text = document.getText(); // Find ALL functions in the file const functions = this.findAllFunctions(text, document.languageId); // Here's the magic: find the SMALLEST function containing cursor const containingFunctions = functions.filter(func => this.isPositionInFunction(position, func, document) ); // Return the innermost (smallest) function return this.findInnermostFunction(containingFunctions); } } 

const messyFunction = () => { const config = { nested: { object: { with: { many: { braces: true } } } } }; if (someCondition) { const inner = () => { return { more: { nested: { objects: true } } }; }; } return config; }; // ← Which closing brace belongs to the function?! 

private findFunctionEnd( lines: string[], startIndex: number ): { endLine: number; endColumn: number } { let braceCount = 0; let foundFirstBrace = false; const startLine = lines[startIndex]; const isArrowFunction = startLine?.includes('=>'); // Handle single-expression arrow functions (no braces) if (isArrowFunction && !startLine?.includes('{')) { return { endLine: startIndex + 1, endColumn: startLine?.length || 0 }; } // The brace counting algorithm that took 3 days to perfect 😴 for (let i = startIndex; i < lines.length; i++) { const line = lines[i]; for (let j = 0; j < line.length; j++) { if (line[j] === '{') { braceCount++; foundFirstBrace = true; } else if (line[j] === '}') { braceCount--; // Found the matching closing brace! 🎉 if (foundFirstBrace && braceCount === 0) { return { endLine: i + 1, endColumn: j + 1 }; } } } } // Fallback for malformed code return { endLine: lines.length, endColumn: 0 }; } 

// ✅ Nested functions - finds the right closing brace const outer = () => { const inner = () => "nested"; return inner(); }; // ✅ Async arrow functions - handles async perfectly const fetchUser = async (id: string) => { const response = await fetch(`/api/users/${id}`); return response.json(); }; // ✅ React hooks - detects as React hook, finds correct boundaries const useComplexHook = (initialValue: string) => { const [value, setValue] = useState(initialValue); useEffect(() => { /* magic */ }, [value]); return { value, setValue }; }; 

// Source file: components/UserCard.tsx import React, { useState } from 'react'; import { User } from '../types/User'; import { formatDate } from '../utils/dateUtils'; const validateUser = (user: User): boolean => { return user.email && formatDate(user.createdAt); }; // I want to copy validateUser to... // Target file: components/ProfilePage.tsx  import React from 'react'; // ← React already imported (but differently!) import { Button } from './Button'; // ← Unrelated import // Missing: User, formatDate imports 

export class FileOperations { private async copyCodeToFile( sourceCode: string, targetFile: string, config: ExtensionConfig ): Promise<void> { // Step 1: What imports does the source code need? const sourceImports = this.extractImports(sourceCode); // Step 2: What imports does the target already have? const targetDocument = await vscode.workspace.openTextDocument(targetFile); const targetImports = this.extractImports(targetDocument.getText()); // Step 3: The magic - merge imports intelligently! ✨ const mergedImports = this.intelligentMerge(sourceImports, targetImports, config); // Step 4: Find the perfect spot to insert code const insertionPoint = this.findInsertionPoint(targetDocument.getText(), config); // Step 5: Apply changes atomically (all or nothing) await this.applyChanges(targetDocument, sourceCode, mergedImports, insertionPoint); } } 

private intelligentMerge(sourceImports: string[], targetImports: string[]): string[] { const merged = [...targetImports]; const importMap = new Map<string, Set<string>>(); // Parse existing imports: "from where" → "what's imported" targetImports.forEach(imp => { const parsed = this.parseImportStatement(imp); if (parsed) { if (!importMap.has(parsed.from)) { importMap.set(parsed.from, new Set()); } parsed.imports.forEach(item => importMap.get(parsed.from)!.add(item)); } }); // Process source imports - the magic happens here! ✨ sourceImports.forEach(imp => { const parsed = this.parseImportStatement(imp); if (!parsed) return; if (importMap.has(parsed.from)) { // Same module! Merge the imports const existingImports = importMap.get(parsed.from)!; parsed.imports.forEach(item => existingImports.add(item)); // Replace the old import line with merged version const existingIndex = merged.findIndex(existing => this.parseImportStatement(existing)?.from === parsed.from ); merged[existingIndex] = this.buildImportStatement(parsed.from, Array.from(existingImports)); } else { // New module! Add the import merged.push(imp); importMap.set(parsed.from, new Set(parsed.imports)); } }); return merged; } 

// Before:  import React from 'react'; import { Button } from './Button'; // Source needs: React, useState, User, formatDate // After merge: import React, { useState } from 'react'; // ← Merged! import { Button } from './Button'; // ← Unchanged import { User } from '../types/User'; // ← Added import { formatDate } from '../utils/dateUtils'; // ← Added 

export class FileOperations { private async moveCodeToFile( sourceDocument: vscode.TextDocument, selection: vscode.Selection, targetFile: string, config: ExtensionConfig ): Promise<void> { const selectedCode = sourceDocument.getText(selection); // First, copy to target (handles imports) await this.copyCodeToFile(selectedCode, targetFile, config); // Then, remove from source with cleanup await this.removeCodeWithCleanup(sourceDocument, selection, selectedCode); } private async removeCodeWithCleanup( document: vscode.TextDocument, selection: vscode.Selection, removedCode: string ): Promise<void> { const edit = new vscode.WorkspaceEdit(); // Remove the selected code edit.delete(document.uri, selection); // Analyze remaining code for orphaned imports const remainingContent = this.buildRemainingContent(document, selection); const orphanedImports = this.findOrphanedImports(removedCode, remainingContent); // Remove orphaned imports if (orphanedImports.length > 0) { const importRanges = this.findImportRanges(document, orphanedImports); importRanges.forEach(range => edit.delete(document.uri, range)); } await vscode.workspace.applyEdit(edit); } private findOrphanedImports(removedCode: string, remainingCode: string): string[] { const removedImports = this.codeAnalysisService.extractImports(removedCode, 'typescript'); const usedImports = this.findUsedImports(remainingCode); return removedImports.filter(imp => { const parsed = this.parseImportStatement(imp); return parsed && !parsed.imports.some(item => usedImports.includes(item)); }); } } 

export class FileSaveService { public async saveAllFiles(config: ExtensionConfig): Promise<SaveAllResult> { const result: SaveAllResult = { totalFiles: 0, savedFiles: 0, failedFiles: [], skippedFiles: [], success: true }; // Get all dirty (unsaved) documents const dirtyDocuments = vscode.workspace.textDocuments.filter(doc => doc.isDirty); result.totalFiles = dirtyDocuments.length; if (dirtyDocuments.length === 0) { vscode.window.showInformationMessage('No files need saving'); return result; } // Show progress with cancellation support return vscode.window.withProgress({ location: vscode.ProgressLocation.Notification, title: 'Saving files...', cancellable: true }, async (progress, token) => { const increment = 100 / dirtyDocuments.length; for (const [index, document] of dirtyDocuments.entries()) { // Check for cancellation if (token.isCancellationRequested) { break; } // Update progress progress.report({ increment, message: `Saving ${path.basename(document.fileName)} (${index + 1}/${dirtyDocuments.length})` }); try { // Handle read-only files if (this.isReadOnly(document) && config.saveAll.skipReadOnly) { result.skippedFiles.push(document.fileName); continue; } // Attempt to save const saved = await document.save(); if (saved) { result.savedFiles++; } else { result.failedFiles.push(document.fileName); result.success = false; } } catch (error) { this.logger.error(`Failed to save ${document.fileName}`, error); result.failedFiles.push(document.fileName); result.success = false; } } // Show completion notification if (config.saveAll.showNotification) { this.showCompletionNotification(result); } return result; }); } private isReadOnly(document: vscode.TextDocument): boolean { // Check various read-only indicators return document.isUntitled || document.uri.scheme === 'untitled' || document.uri.scheme === 'git' || document.uri.scheme === 'output'; } private showCompletionNotification(result: SaveAllResult): void { if (result.success && result.failedFiles.length === 0) { vscode.window.showInformationMessage( `Successfully saved ${result.savedFiles} file(s)${ result.skippedFiles.length > 0 ? ` (${result.skippedFiles.length} skipped)` : '' }` ); } else { const message = `Saved ${result.savedFiles}/${result.totalFiles} files`; const action = result.failedFiles.length > 0 ? 'Show Details' : undefined; vscode.window.showWarningMessage(message, action).then(selection => { if (selection === 'Show Details') { this.showFailureDetails(result); } }); } } } 

export class ContextMenuManager { private async registerCommands(): Promise<void> { // Copy Function Command this.disposables.push( vscode.commands.registerCommand('additionalContextMenus.copyFunction', async () => { const editor = vscode.window.activeTextEditor; if (!editor) return; const functionInfo = await this.codeAnalysisService.findFunctionAtPosition( editor.document, editor.selection.active ); if (functionInfo) { const functionText = functionInfo.fullText; await vscode.env.clipboard.writeText(functionText); vscode.window.showInformationMessage(`Copied function: ${functionInfo.name}`); } else { vscode.window.showWarningMessage('No function found at cursor position'); } }) ); // Copy to Existing File Command this.disposables.push( vscode.commands.registerCommand('additionalContextMenus.copyCodeToFile', async () => { await this.handleCopyToFile(); }) ); // Move to Existing File Command  this.disposables.push( vscode.commands.registerCommand('additionalContextMenus.moveCodeToFile', async () => { await this.handleMoveToFile(); }) ); // Save All Command this.disposables.push( vscode.commands.registerCommand('additionalContextMenus.saveAll', async () => { const config = this.configService.getConfiguration(); const result = await this.fileSaveService.saveAllFiles(config); this.logger.info('Save All completed', result); }) ); } } 

private async handleCopyToFile(): Promise<void> { const editor = vscode.window.activeTextEditor; if (!editor?.selection || editor.selection.isEmpty) { vscode.window.showWarningMessage('Please select code to copy'); return; } const sourceExtension = path.extname(editor.document.fileName); const compatibleFiles = await this.fileDiscoveryService.getCompatibleFiles(sourceExtension); if (compatibleFiles.length === 0) { vscode.window.showWarningMessage('No compatible files found in workspace'); return; } const targetFile = await this.fileDiscoveryService.showFileSelector(compatibleFiles); if (!targetFile) return; const selectedCode = editor.document.getText(editor.selection); const config = this.configService.getConfiguration(); await this.copyCodeToFile(selectedCode, targetFile, config); } 

// This breaks most parsers, but we handle it gracefully const broken = function( { // Missing closing parenthesis, but we can still find function boundaries return "somehow works"; }; 

const complex = () => { const inner1 = () => { const inner2 = () => { const inner3 = () => "deep nesting"; return inner3(); }; return inner2(); }; return inner1(); }; // ← We find the correct closing brace 

// We handle all of these in one file: import React from 'react'; import { useState, useEffect } from 'react'; import * as utils from '../utils'; import type { User } from '../types';