GitHub Copilot Mastery Part 5: Extending Copilot with Custom Tools

// src/extension.ts
import * as vscode from 'vscode';

export function activate(context: vscode.ExtensionContext) {
    // Register commands that can interact with Copilot
    let disposable = vscode.commands.registerCommand('copilot-custom-tools.generateWithContext', 
        async () => {
            await generateCodeWithCustomContext();
        }
    );

    context.subscriptions.push(disposable);
}

async function generateCodeWithCustomContext() {
    const editor = vscode.window.activeTextEditor;
    if (!editor) return;

    // Get project context
    const projectContext = await analyzeProjectContext();
    
    // Build enhanced prompt with context
    const prompt = buildContextualPrompt(projectContext);
    
    // Request Copilot completion with enhanced context
    const suggestion = await requestCopilotCompletion(prompt, projectContext);
    
    // Insert the suggestion
    await insertSuggestion(editor, suggestion);
}

// src/contextAnalyzer.ts
export class ProjectContextAnalyzer {
    async analyzeProject(): Promise<ProjectContext> {
        const workspaceFolder = vscode.workspace.workspaceFolders?.[0];
        if (!workspaceFolder) throw new Error('No workspace found');

        return {
            framework: await this.detectFramework(workspaceFolder),
            architecture: await this.analyzeArchitecture(workspaceFolder),
            patterns: await this.extractCodePatterns(workspaceFolder),
            dependencies: await this.analyzeDependencies(workspaceFolder),
            standards: await this.loadCodingStandards(workspaceFolder)
        };
    }

    private async detectFramework(workspace: vscode.WorkspaceFolder): Promise<string[]> {
        const packageJsonPath = vscode.Uri.joinPath(workspace.uri, 'package.json');
        
        try {
            const content = await vscode.workspace.fs.readFile(packageJsonPath);
            const packageJson = JSON.parse(content.toString());
            
            const frameworks = [];
            if (packageJson.dependencies?.react) frameworks.push('react');
            if (packageJson.dependencies?.express) frameworks.push('express');
            if (packageJson.dependencies?.['@nestjs/core']) frameworks.push('nestjs');
            if (packageJson.devDependencies?.jest) frameworks.push('jest');
            
            return frameworks;
        } catch {
            return [];
        }
    }

    private async extractCodePatterns(workspace: vscode.WorkspaceFolder): Promise<CodePattern[]> {
        const patterns: CodePattern[] = [];
        
        // Analyze existing code to extract patterns
        const files = await vscode.workspace.findFiles('**/*.{ts,js,tsx,jsx}');
        
        for (const file of files.slice(0, 10)) { // Limit for performance
            const content = await vscode.workspace.fs.readFile(file);
            const text = content.toString();
            
            // Extract function patterns
            const functionPatterns = this.extractFunctionPatterns(text);
            patterns.push(...functionPatterns);
            
            // Extract class patterns
            const classPatterns = this.extractClassPatterns(text);
            patterns.push(...classPatterns);
        }
        
        return patterns;
    }
}

// src/commands/generateComponent.ts
export class ComponentGenerator {
    async generateReactComponent(name: string, type: ComponentType): Promise<void> {
        const context = await this.buildComponentContext(name, type);
        
        const prompt = `
        Generate a React ${type} component named ${name}.
        
        Project Context:
        - Framework: ${context.framework}
        - Styling: ${context.styling}
        - State Management: ${context.stateManagement}
        - Testing: ${context.testing}
        
        Requirements:
        - Follow project conventions: ${context.conventions.join(', ')}
        - Include TypeScript interfaces
        - Add proper error handling
        - Include basic tests
        - Follow accessibility best practices
        `;

        const result = await this.requestCopilotGeneration(prompt, context);
        
        // Create component file
        await this.createComponentFile(name, result.component);
        
        // Create test file
        await this.createTestFile(name, result.tests);
        
        // Update exports
        await this.updateExports(name);
    }

    private async buildComponentContext(name: string, type: ComponentType): Promise<ComponentContext> {
        const projectAnalyzer = new ProjectContextAnalyzer();
        const projectContext = await projectAnalyzer.analyzeProject();
        
        return {
            name,
            type,
            framework: projectContext.framework,
            styling: this.detectStylingLibrary(projectContext),
            stateManagement: this.detectStateManagement(projectContext),
            testing: this.detectTestingLibrary(projectContext),
            conventions: await this.loadComponentConventions()
        };
    }
}

// src/codeReview.ts
export class CopilotCodeReviewer {
    async reviewChangedFiles(): Promise<ReviewResult[]> {
        const gitExtension = vscode.extensions.getExtension('vscode.git')?.exports;
        const git = gitExtension?.getAPI(1);
        
        if (!git?.repositories[0]) {
            throw new Error('No Git repository found');
        }
        
        const repo = git.repositories[0];
        const changes = await repo.getDiff();
        
        const results: ReviewResult[] = [];
        
        for (const change of changes) {
            const reviewResult = await this.reviewFile(change);
            results.push(reviewResult);
        }
        
        return results;
    }

    private async reviewFile(change: GitChange): Promise<ReviewResult> {
        const prompt = `
        Review this code change for:
        - Security vulnerabilities
        - Performance issues
        - Code quality and maintainability
        - Best practices compliance
        - Potential bugs
        
        Changed Code:
        \`\`\`
        ${change.diff}
        \`\`\`
        
        Context:
        - File: ${change.file}
        - Type: ${change.type}
        - Language: ${change.language}
        `;

        const review = await this.requestCopilotReview(prompt, change);
        
        return {
            file: change.file,
            issues: review.issues,
            suggestions: review.suggestions,
            security: review.security,
            performance: review.performance
        };
    }
}

// src/mcp/server.ts
import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

export class CustomMCPServer {
    private server: Server;

    constructor() {
        this.server = new Server(
            {
                name: 'custom-development-server',
                version: '1.0.0',
                description: 'Custom MCP server for development tools'
            },
            {
                capabilities: {
                    resources: {},
                    tools: {},
                    prompts: {}
                }
            }
        );

        this.setupHandlers();
    }

    private setupHandlers() {
        // Resource handlers for accessing project data
        this.server.setRequestHandler('resources/list', async () => {
            return {
                resources: [
                    {
                        uri: 'project://architecture',
                        name: 'Project Architecture',
                        description: 'Current project architecture and patterns'
                    },
                    {
                        uri: 'project://standards',
                        name: 'Coding Standards',
                        description: 'Project-specific coding standards and conventions'
                    }
                ]
            };
        });

        // Tool handlers for executing actions
        this.server.setRequestHandler('tools/list', async () => {
            return {
                tools: [
                    {
                        name: 'analyze-performance',
                        description: 'Analyze code performance and suggest optimizations',
                        inputSchema: {
                            type: 'object',
                            properties: {
                                code: { type: 'string' },
                                language: { type: 'string' }
                            }
                        }
                    },
                    {
                        name: 'generate-tests',
                        description: 'Generate comprehensive tests for given code',
                        inputSchema: {
                            type: 'object',
                            properties: {
                                code: { type: 'string' },
                                testType: { type: 'string', enum: ['unit', 'integration', 'e2e'] }
                            }
                        }
                    }
                ]
            };
        });
    }

    async start() {
        const transport = new StdioServerTransport();
        await this.server.connect(transport);
    }
}

// src/mcp/databaseServer.ts
export class DatabaseMCPServer extends CustomMCPServer {
    private dbConnection: DatabaseConnection;

    constructor(connectionString: string) {
        super();
        this.dbConnection = new DatabaseConnection(connectionString);
        this.setupDatabaseHandlers();
    }

    private setupDatabaseHandlers() {
        // Provide schema information
        this.server.setRequestHandler('resources/read', async (request) => {
            if (request.params.uri === 'database://schema') {
                const schema = await this.dbConnection.getSchema();
                return {
                    contents: [{
                        uri: 'database://schema',
                        mimeType: 'application/json',
                        text: JSON.stringify(schema, null, 2)
                    }]
                };
            }
        });

        // Query analysis tool
        this.server.setRequestHandler('tools/call', async (request) => {
            if (request.params.name === 'analyze-query') {
                const { query } = request.params.arguments;
                const analysis = await this.analyzeQuery(query);
                
                return {
                    content: [{
                        type: 'text',
                        text: JSON.stringify(analysis, null, 2)
                    }]
                };
            }
        });
    }

    private async analyzeQuery(query: string): Promise<QueryAnalysis> {
        // Analyze query performance, suggest indexes, etc.
        const plan = await this.dbConnection.explainQuery(query);
        const suggestions = await this.generateOptimizationSuggestions(plan);
        
        return {
            executionPlan: plan,
            performance: this.analyzePerformance(plan),
            suggestions,
            potentialIssues: this.identifyIssues(query, plan)
        };
    }
}

// src/mcp/apiDocsServer.ts
export class APIDocumentationMCPServer extends CustomMCPServer {
    private apiSpecs: Map<string, OpenAPISpec>;

    constructor() {
        super();
        this.apiSpecs = new Map();
        this.setupAPIHandlers();
    }

    async loadAPISpec(name: string, specPath: string) {
        const spec = await this.parseOpenAPISpec(specPath);
        this.apiSpecs.set(name, spec);
    }

    private setupAPIHandlers() {
        this.server.setRequestHandler('tools/call', async (request) => {
            switch (request.params.name) {
                case 'generate-client':
                    return await this.generateAPIClient(request.params.arguments);
                    
                case 'validate-request':
                    return await this.validateAPIRequest(request.params.arguments);
                    
                case 'suggest-endpoint':
                    return await this.suggestEndpoint(request.params.arguments);
            }
        });
    }

    private async generateAPIClient(args: any): Promise<any> {
        const { apiName, language, features } = args;
        const spec = this.apiSpecs.get(apiName);
        
        if (!spec) {
            throw new Error(`API specification '${apiName}' not found`);
        }

        const clientCode = await this.buildClientCode(spec, language, features);
        
        return {
            content: [{
                type: 'text',
                text: clientCode
            }]
        };
    }

    private async buildClientCode(spec: OpenAPISpec, language: string, features: string[]): Promise<string> {
        const generator = new ClientGenerator(spec, language);
        
        let code = generator.generateBaseClient();
        
        if (features.includes('typescript')) {
            code += generator.generateTypeDefinitions();
        }
        
        if (features.includes('validation')) {
            code += generator.generateValidation();
        }
        
        if (features.includes('retry')) {
            code += generator.generateRetryLogic();
        }
        
        return code;
    }
}

// src/cli/copilotCLI.ts
#!/usr/bin/env node
import { Command } from 'commander';
import { CopilotIntegration } from './copilotIntegration';

const program = new Command();
const copilot = new CopilotIntegration();

program
    .name('dev-copilot')
    .description('CLI tool with GitHub Copilot integration')
    .version('1.0.0');

program
    .command('generate <type>')
    .description('Generate code using Copilot')
    .option('-n, --name <name>', 'Name of the component/service/etc')
    .option('-f, --framework <framework>', 'Target framework')
    .option('-t, --template <template>', 'Use specific template')
    .action(async (type, options) => {
        try {
            const result = await copilot.generateCode({
                type,
                name: options.name,
                framework: options.framework,
                template: options.template,
                context: await loadProjectContext()
            });
            
            console.log('Generated code:');
            console.log(result.code);
            
            if (options.save) {
                await saveGeneratedCode(result);
                console.log(`Saved to ${result.filePath}`);
            }
        } catch (error) {
            console.error('Generation failed:', error.message);
            process.exit(1);
        }
    });

program
    .command('review [files...]')
    .description('Review code with Copilot')
    .option('--fix', 'Automatically apply suggested fixes')
    .action(async (files, options) => {
        const filesToReview = files.length ? files : await getChangedFiles();
        
        for (const file of filesToReview) {
            console.log(`Reviewing ${file}...`);
            
            const review = await copilot.reviewCode({
                file,
                content: await readFile(file),
                context: await loadFileContext(file)
            });
            
            displayReview(review);
            
            if (options.fix && review.fixes.length > 0) {
                await applyFixes(file, review.fixes);
                console.log(`Applied ${review.fixes.length} fixes to ${file}`);
            }
        }
    });

program.parse();

// src/buildPlugins/webpackCopilotPlugin.ts
export class WebpackCopilotPlugin {
    private copilot: CopilotIntegration;
    private options: PluginOptions;

    constructor(options: PluginOptions = {}) {
        this.options = options;
        this.copilot = new CopilotIntegration();
    }

    apply(compiler: any) {
        compiler.hooks.beforeCompile.tapAsync('CopilotPlugin', async (params: any, callback: any) => {
            if (this.options.generateMissingTypes) {
                await this.generateMissingTypeDefinitions(compiler.context);
            }
            callback();
        });

        compiler.hooks.compilation.tap('CopilotPlugin', (compilation: any) => {
            compilation.hooks.buildModule.tap('CopilotPlugin', async (module: any) => {
                if (this.shouldAnalyzeModule(module)) {
                    const analysis = await this.copilot.analyzeModule({
                        path: module.resource,
                        content: module._source?.source()
                    });
                    
                    if (analysis.suggestions.length > 0) {
                        this.emitSuggestions(compilation, module, analysis.suggestions);
                    }
                }
            });
        });
    }

    private async generateMissingTypeDefinitions(context: string) {
        const jsFiles = await glob('**/*.js', { cwd: context });
        
        for (const jsFile of jsFiles) {
            const tsFile = jsFile.replace('.js', '.d.ts');
            const tsPath = path.join(context, tsFile);
            
            if (!fs.existsSync(tsPath)) {
                const jsContent = fs.readFileSync(path.join(context, jsFile), 'utf-8');
                
                const typeDefinitions = await this.copilot.generateTypeDefinitions({
                    code: jsContent,
                    filename: jsFile,
                    context: await this.loadProjectContext(context)
                });
                
                fs.writeFileSync(tsPath, typeDefinitions);
                console.log(`Generated type definitions for ${jsFile}`);
            }
        }
    }
}

// src/cicd/copilotCI.ts
export class CopilotCIIntegration {
    private copilot: CopilotIntegration;
    private config: CIConfig;

    constructor(config: CIConfig) {
        this.config = config;
        this.copilot = new CopilotIntegration();
    }

    async runPreCommitAnalysis(): Promise<AnalysisResult> {
        const changedFiles = await this.getChangedFiles();
        const results: AnalysisResult[] = [];

        for (const file of changedFiles) {
            const content = await this.readFile(file);
            
            const analysis = await this.copilot.analyzeCode({
                file,
                content,
                checks: this.config.checks,
                context: await this.loadProjectContext()
            });

            results.push({
                file,
                issues: analysis.issues,
                suggestions: analysis.suggestions,
                security: analysis.security,
                performance: analysis.performance
            });
        }

        return this.consolidateResults(results);
    }

    async generatePullRequestReview(prNumber: number): Promise<PRReview> {
        const pr = await this.getPullRequestDetails(prNumber);
        const diff = await this.getPullRequestDiff(prNumber);

        const review = await this.copilot.reviewPullRequest({
            title: pr.title,
            description: pr.description,
            diff,
            context: await this.loadProjectContext()
        });

        return {
            summary: review.summary,
            comments: review.comments.map(comment => ({
                file: comment.file,
                line: comment.line,
                message: comment.message,
                severity: comment.severity
            })),
            approval: review.recommendation === 'approve'
        };
    }

    async generateReleaseNotes(from: string, to: string): Promise<ReleaseNotes> {
        const commits = await this.getCommitsBetween(from, to);
        const changes = await this.analyzeChanges(commits);

        const releaseNotes = await this.copilot.generateReleaseNotes({
            version: to,
            commits,
            changes,
            context: await this.loadProjectContext()
        });

        return {
            version: to,
            date: new Date().toISOString(),
            summary: releaseNotes.summary,
            features: releaseNotes.features,
            bugfixes: releaseNotes.bugfixes,
            breaking: releaseNotes.breaking,
            migration: releaseNotes.migration
        };
    }
}

// src/workflows/codeGeneration.ts
export class CodeGenerationWorkflow {
    private copilot: CopilotIntegration;
    private templates: TemplateManager;

    constructor() {
        this.copilot = new CopilotIntegration();
        this.templates = new TemplateManager();
    }

    async generateFeature(spec: FeatureSpec): Promise<GeneratedFeature> {
        // Step 1: Analyze requirements
        const analysis = await this.copilot.analyzeRequirements({
            description: spec.description,
            requirements: spec.requirements,
            constraints: spec.constraints
        });

        // Step 2: Generate architecture
        const architecture = await this.copilot.designArchitecture({
            analysis,
            patterns: await this.loadArchitecturePatterns(),
            constraints: spec.technicalConstraints
        });

        // Step 3: Generate code components
        const components = await Promise.all(
            architecture.components.map(component => 
                this.generateComponent(component, architecture)
            )
        );

        // Step 4: Generate tests
        const tests = await this.generateTests(components, spec);

        // Step 5: Generate documentation
        const documentation = await this.generateDocumentation(
            components, 
            tests, 
            architecture
        );

        return {
            architecture,
            components,
            tests,
            documentation,
            deploymentConfig: await this.generateDeploymentConfig(architecture)
        };
    }

    private async generateComponent(
        component: ComponentSpec, 
        architecture: Architecture
    ): Promise<GeneratedComponent> {
        const prompt = this.buildComponentPrompt(component, architecture);
        
        const code = await this.copilot.generateCode({
            prompt,
            template: await this.templates.getTemplate(component.type),
            context: {
                architecture,
                dependencies: component.dependencies,
                patterns: await this.loadComponentPatterns(component.type)
            }
        });

        return {
            name: component.name,
            type: component.type,
            code: code.implementation,
            interfaces: code.interfaces,
            exports: code.exports,
            dependencies: component.dependencies
        };
    }
}

// src/workflows/refactoring.ts
export class RefactoringWorkflow {
    private copilot: CopilotIntegration;
    private analyzer: CodeAnalyzer;

    constructor() {
        this.copilot = new CopilotIntegration();
        this.analyzer = new CodeAnalyzer();
    }

    async refactorCodebase(target: RefactoringTarget): Promise<RefactoringResult> {
        // Step 1: Analyze current codebase
        const analysis = await this.analyzer.analyzeCodebase(target.path);
        
        // Step 2: Identify refactoring opportunities
        const opportunities = await this.copilot.identifyRefactoringOpportunities({
            analysis,
            goals: target.goals,
            constraints: target.constraints
        });

        // Step 3: Plan refactoring steps
        const plan = await this.copilot.planRefactoring({
            opportunities,
            impact: analysis.impact,
            dependencies: analysis.dependencies
        });

        // Step 4: Execute refactoring in safe steps
        const results = await this.executeRefactoringPlan(plan);

        return {
            plan,
            results,
            summary: await this.generateRefactoringSummary(results),
            rollback: await this.createRollbackPlan(results)
        };
    }

    private async executeRefactoringPlan(plan: RefactoringPlan): Promise<RefactoringStepResult[]> {
        const results: RefactoringStepResult[] = [];

        for (const step of plan.steps) {
            try {
                // Create backup
                const backup = await this.createBackup(step.affectedFiles);

                // Apply refactoring
                const refactoredCode = await this.copilot.refactorCode({
                    step,
                    context: await this.loadStepContext(step)
                });

                // Validate refactoring
                const validation = await this.validateRefactoring(refactoredCode, step);

                if (validation.isValid) {
                    await this.applyRefactoring(refactoredCode);
                    results.push({
                        step,
                        success: true,
                        changes: refactoredCode.changes,
                        backup
                    });
                } else {
                    await this.restoreBackup(backup);
                    results.push({
                        step,
                        success: false,
                        error: validation.errors,
                        backup
                    });
                }
            } catch (error) {
                results.push({
                    step,
                    success: false,
                    error: error.message
                });
            }
        }

        return results;
    }
}

// tests/copilot.integration.test.ts
describe('Copilot Integration', () => {
    let copilot: CopilotIntegration;

    beforeEach(() => {
        copilot = new CopilotIntegration({
            apiKey: process.env.COPILOT_TEST_KEY,
            model: 'gpt-4',
            timeout: 30000
        });
    });

    describe('Code Generation', () => {
        it('should generate React component with correct structure', async () => {
            const result = await copilot.generateCode({
                type: 'react-component',
                name: 'UserProfile',
                requirements: [
                    'Display user information',
                    'Include edit functionality',
                    'Handle loading states'
                ]
            });

            expect(result.code).toContain('function UserProfile');
            expect(result.code).toContain('useState');
            expect(result.code).toContain('interface UserProfileProps');
            expect(result.tests).toBeDefined();
        });

        it('should respect custom instructions', async () => {
            const result = await copilot.generateCode({
                type: 'api-endpoint',
                name: 'createUser',
                customInstructions: [
                    'Use Zod for validation',
                    'Include rate limiting',
                    'Add comprehensive logging'
                ]
            });

            expect(result.code).toMatch(/z\.(object|string|number)/);
            expect(result.code).toContain('rateLimiter');
            expect(result.code).toContain('logger.');
        });
    });

    describe('Code Review', () => {
        it('should identify security issues', async () => {
            const vulnerableCode = `
                app.get('/user/:id', (req, res) => {
                    const query = \`SELECT * FROM users WHERE id = \${req.params.id}\`;
                    db.query(query, (err, results) => {
                        res.json(results[0]);
                    });
                });
            `;

            const review = await copilot.reviewCode({
                code: vulnerableCode,
                checks: ['security', 'performance', 'style']
            });

            expect(review.issues).toHaveLength(1);
            expect(review.issues[0].type).toBe('security');
            expect(review.issues[0].description).toContain('SQL injection');
        });
    });
});

// src/monitoring/copilotMetrics.ts
export class CopilotMetrics {
    private metrics: Map<string, Metric> = new Map();

    trackRequest(operation: string, duration: number, success: boolean) {
        const key = `copilot.${operation}`;
        
        if (!this.metrics.has(key)) {
            this.metrics.set(key, {
                count: 0,
                totalDuration: 0,
                successes: 0,
                failures: 0,
                avgDuration: 0
            });
        }

        const metric = this.metrics.get(key)!;
        metric.count++;
        metric.totalDuration += duration;
        
        if (success) {
            metric.successes++;
        } else {
            metric.failures++;
        }
        
        metric.avgDuration = metric.totalDuration / metric.count;
    }

    getEfficiencyReport(): EfficiencyReport {
        const operations = Array.from(this.metrics.entries());
        
        return {
            totalRequests: operations.reduce((sum, [_, metric]) => sum + metric.count, 0),
            averageResponseTime: this.calculateOverallAverageResponseTime(),
            successRate: this.calculateOverallSuccessRate(),
            mostUsedOperations: this.getMostUsedOperations(),
            slowestOperations: this.getSlowestOperations(),
            recommendations: this.generateOptimizationRecommendations()
        };
    }
}