docs/crossword-app-plan.md

Crossword Puzzle Webapp - Complete Implementation Plan

Architecture Overview

Frontend (React/Vue/Vanilla JS)

• Topic selection dropdown/buttons
• Generate puzzle button
• Interactive crossword grid display
• Clue lists (across/down)

Backend (Node.js/Python/Go)

• REST API endpoints for puzzle generation
• Crossword algorithm implementation
• Word/clue database management

Database

• Word collections organized by topics
• Clue-answer pairs
• Pre-generated grids (optional caching)

Core Components

1. Topic Management: Categories like "Animals", "Science", "History"
2. Word Selection: Algorithm to pick words from chosen topic
3. Grid Generation: Place words intersecting on a grid
4. Clue Generation: Match words with appropriate clues
5. UI Rendering: Display interactive puzzle with input fields

Key Algorithms Needed

• Grid placement: Find valid intersections between words
• Backtracking: Handle conflicts when placing words
• Difficulty scaling: Adjust grid size and word complexity

Tech Stack Suggestions

• Frontend: React + CSS Grid for puzzle layout
• Backend: Node.js + Express or Python + Flask
• Database: PostgreSQL or MongoDB for word storage
• Deployment: Vercel/Netlify + Railway/Heroku

Frontend Components & UI

Main Page Layout

Header: "Crossword Puzzle Generator"
Topic Selector: Dropdown with categories
Generate Button: "Create Puzzle"
Loading State: Spinner during generation
Puzzle Display: Grid + Clues
Actions: Reset, New Puzzle, Print

Components:

• TopicSelector: Multi-select topics
• PuzzleGrid: Interactive crossword grid
• ClueList: Numbered clues (Across/Down)
• LoadingSpinner: Generation feedback
• PuzzleControls: Reset/New/Difficulty buttons

UI Flow:

1. User selects topic(s)
2. Clicks generate → Loading state
3. Puzzle renders with empty grid
4. User fills in answers
5. Real-time validation feedback

Backend API & Crossword Generation

API Endpoints:

GET /topics - List available topics
POST /generate - Generate puzzle
  Body: { topics: string[], difficulty: 'easy'|'medium'|'hard' }
  Response: { grid: Cell[][], clues: Clue[], metadata: {} }

GET /words/:topic - Get words for topic (admin)
POST /validate - Validate user answers

Core Algorithm:

1. Word Selection: Pick 8-15 words from chosen topics
2. Grid Placement:
   • Start with longest word horizontally
   • Find intersections for perpendicular words
   • Use backtracking for conflicts
3. Grid Optimization: Minimize grid size, maximize word density
4. Clue Matching: Pair each word with appropriate clue

Generation Logic:

class CrosswordGenerator {
  generatePuzzle(topics, difficulty) {
    const words = selectWords(topics, difficulty)
    const grid = createEmptyGrid()
    const placed = placeWords(words, grid)
    return { grid, clues: generateClues(placed) }
  }
}

Data Storage & Word Management

Database Schema:

Topics: id, name, description
Words: id, word, length, difficulty_level, topic_id
Clues: id, word_id, clue_text, difficulty
Generated_Puzzles: id, grid_data, clues_data, created_at (optional caching)

Word Collections by Topic:

• Animals: DOG, ELEPHANT, TIGER, WHALE, BUTTERFLY
• Science: ATOM, GRAVITY, MOLECULE, PHOTON, CHEMISTRY
• Geography: MOUNTAIN, OCEAN, DESERT, CONTINENT, RIVER
• Technology: COMPUTER, INTERNET, ALGORITHM, DATABASE, SOFTWARE

Data Sources:

• Curated word lists with quality clues
• Dictionary APIs for definitions
• Wikipedia API for topic-specific terms
• Manual curation for puzzle quality

Storage Strategy:

• PostgreSQL for structured word/clue data
• JSON columns for flexible puzzle metadata
• Indexing on topic_id and word_length for fast queries
• Caching layer (Redis) for frequent topic combinations

Project Structure

crossword-app/
├── frontend/
│   ├── src/
│   │   ├── components/
│   │   │   ├── TopicSelector.jsx
│   │   │   ├── PuzzleGrid.jsx
│   │   │   ├── ClueList.jsx
│   │   │   └── LoadingSpinner.jsx
│   │   ├── hooks/
│   │   │   └── useCrossword.js
│   │   ├── utils/
│   │   │   └── gridHelpers.js
│   │   ├── styles/
│   │   │   └── puzzle.css
│   │   └── App.jsx
│   ├── package.json
│   └── vite.config.js
├── backend/
│   ├── src/
│   │   ├── controllers/
│   │   │   └── puzzleController.js
│   │   ├── services/
│   │   │   ├── crosswordGenerator.js
│   │   │   └── wordService.js
│   │   ├── models/
│   │   │   ├── Word.js
│   │   │   └── Topic.js
│   │   ├── routes/
│   │   │   └── api.js
│   │   └── app.js
│   ├── data/
│   │   └── word-lists/
│   ├── package.json
│   └── .env
└── database/
    ├── migrations/
    └── seeds/

Tech Stack:

• Frontend: React + Vite, CSS Grid, Axios
• Backend: Node.js + Express, CORS enabled
• Database: PostgreSQL with Prisma ORM
• Development: Nodemon, ESLint, Prettier

Deployment & Hosting Strategy

Development Environment:

• Local PostgreSQL database
• Frontend: npm run dev (Vite dev server)
• Backend: npm run dev (Nodemon)
• Environment variables in .env

Production Deployment:

• Frontend: Vercel or Netlify (static hosting)
• Backend: Railway, Heroku, or DigitalOcean App Platform
• Database: PostgreSQL on Railway/Heroku/AWS RDS
• Domain: Custom domain with HTTPS

CI/CD Pipeline:

• GitHub Actions for automated testing
• Deploy on push to main branch
• Environment-specific configs (dev/staging/prod)

Environment Variables:

DATABASE_URL=postgresql://...
JWT_SECRET=...
CORS_ORIGIN=https://your-frontend-domain.com
PORT=3000

Performance Considerations:

• CDN for static assets
• Database connection pooling
• API rate limiting
• Puzzle result caching (Redis)

Implementation Priority

1. Phase 1: Basic word placement algorithm and simple UI
2. Phase 2: Topic selection and word database
3. Phase 3: Interactive grid with validation
4. Phase 4: Polish UI/UX and deployment
5. Phase 5: Advanced features (difficulty levels, saving puzzles)