CodeRev

CodeRev is a full-stack coding practice workspace for learning data structures and algorithms, running code, preparing for technical interviews, and competing with friends. It combines a curated problem catalog, visual algorithm walkthroughs, guided feedback, spaced revision, contests, and private battle rooms in one focused developer workspace.

Features

• Curated DSA problem catalog with search, difficulty, topic, and company filters.
• Monaco-based editor with five supported execution languages.
• Sample execution, custom input runs, persisted submissions, and verdict history.
• Guided code review, progressive hints, problem tutoring, recommendations, and weekly progress reports.
• Animated visualizers with synchronized commentary for 75 algorithm scenarios.
• Company preparation banks and system-design interview practice.
• Rated contests, private battle rooms, on-demand formats, and leaderboards.
• Spaced-repetition revision cards created from solved problems and failed attempts.
• Email verification registration, password sign-in, password reset, and optional Google sign-in.
• Admin tools for managing problems, users, and platform statistics.

Tech Stack

• Frontend: Next.js App Router, React, TypeScript, Tailwind CSS, Framer Motion, Recharts, Monaco Editor.
• Backend: Next.js route handlers, Prisma, PostgreSQL, signed HTTP-only sessions.
• Execution: Piston-compatible code execution service.
• Guidance provider: FreeModel-compatible chat completion service with ordered key failover and deterministic fallbacks.
• Deployment: Vercel-compatible Next.js deployment.

Folder Structure

app/                 Pages and route handlers
components/          Reusable interface and feature components
context/             Authentication context
hooks/               Client-side feature hooks
lib/                 Authentication, database, execution, provider, and domain utilities
prisma/              Schema, seed scripts, and canonical problem data
public/               Static visualizer metadata and public assets
scripts/              Verification, data maintenance, and operational scripts

Installation

git clone <repository-url>
cd happy-carson
npm install
cp .env.example .env.local

Fill in the environment values below, then create or update the database:

npx prisma generate
npx prisma db push
npm run dev

The local application runs at http://localhost:3000.

Environment Variables

Variable	Required	Purpose
DATABASE_URL	Yes	PostgreSQL connection string.
PRISMA_CONNECTION_LIMIT	Recommended	Connection limit for serverless database clients.
JWT_SECRET	Yes	Secret used to sign session cookies and verification-code digests.
APP_URL	Production	Canonical application origin used by OAuth redirects.
FREEMODEL_API_KEY	Optional	Primary provider key.
FREEMODEL_API_KEY_2	Optional	First provider backup key.
FREEMODEL_API_KEY_3	Optional	Second provider backup key.
FREEMODEL_BASE_URL	Optional	Provider API base URL.
RESEND_API_KEY	Production	Transactional email delivery key.
RESEND_FROM_EMAIL	Production	Verified sender address for verification emails.
GOOGLE_CLIENT_ID	Optional	Google sign-in client identifier.
GOOGLE_CLIENT_SECRET	Optional	Google sign-in client secret.
GOOGLE_REDIRECT_URI	Optional	Google callback URL.

Email OTP verification uses Resend from server-side route handlers. For production, create a Resend API key, verify your sending domain in Resend, and set RESEND_FROM_EMAIL to that verified sender. Check the configuration with:

npm run verify:email
VERIFY_EMAIL_TO=you@example.com npm run verify:email

Never commit .env, .env.local, provider keys, database credentials, or OAuth secrets. Use platform-managed secrets in deployed environments.

Usage

1. Browse a problem or select a company preparation track.
2. Read the statement, write code in the editor, and run samples or custom input.
3. Submit a solution to record the verdict and update progress.
4. Use walkthroughs, hints, reviews, and the tutor to investigate difficult steps.
5. Revisit generated revision cards and join contests or private rooms for timed practice.

Development

npm run dev
npm run lint
npx tsc --noEmit
npm run build
npm run verify:quality
npm run test:health
npx tsx scripts/test-public-boundaries.ts

npm run verify:quality runs linting, type checking, the production build, dependency auditing, catalog coverage checks, visualizer stress checks, provider boundary checks, resilience checks, and rate-limit checks.

Deployment

See DEPLOYMENT_RUNBOOK.md for Vercel environment configuration, database rollout, health verification, smoke tests, and rollback guidance. Configure all production secrets in the deployment platform before running a migration or exposing the application publicly.

Performance

The application uses database-side counts for dashboard and leaderboard paths, bounded catalog queries, abortable client requests, provider deadlines, ordered provider failover, deterministic fallbacks, and route-level rate limits. A shared rate-limit store and production-sized load test are still recommended before multi-instance public traffic.

Architecture Overview

The browser renders App Router pages and feature components. Client actions call typed route handlers, which validate input, enforce session and rate-limit boundaries, query Prisma, and call execution or guidance providers when needed. Submission outcomes update progress and revision records. Visualizer metadata and problem data are served from bounded catalog queries, while PostgreSQL is the source of truth for users, submissions, contests, rooms, ratings, and revision state.

Contributing

Keep changes focused, preserve existing route contracts, add a regression test for behavior changes, and run npm run verify:quality before opening a pull request. Do not add credentials or generated artifacts to the repository.

License

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