vim-sudoku/IMPLEMENTATION.md

vim-sudoku Unified API Implementation Log

This document tracks the step-by-step implementation of the unified API architecture for vim-sudoku.

Overview

We are porting vim-sudoku from the old architecture (src_old) to follow the unified API patterns established by vim-maze. This enables consistent architecture across all VIMazing games and better platform integration.

---

Iteration 1: Preparation & Planning

Date: 2025-01-22

Goals

• Review existing implementations (vim-maze, src_old, src_failed)
• Create implementation plan
• Prepare example app for new API

Tasks Completed

1. Reviewed Architecture

• Analyzed vim-maze unified API implementation
• Examined src_old working implementation
• Identified src_failed attempt issues
• Documented key differences between vim-maze and vim-sudoku

2. Created Implementation Plan

• Created IMPLEMENTATION_PLAN.md with 7 phases (numbered x10 for flexibility)
• Defined file structure matching vim-maze patterns
• Documented key design decisions
• Established type mappings between vim-maze and vim-sudoku
• Listed success criteria

3. Prepared Example App (Phase 5)

• Updated example/src/App.tsx to match vim-maze structure
• Simplified to desktop-only (no mobile support)
• Added score metrics display (time, keystrokes, final score)
• Updated game status messages for sudoku context
• Changed navigation instructions (hjkl + i for edit mode)
• Verified useKeyBindings already matches vim-maze

File Changes

vim-sudoku/
├── IMPLEMENTATION_PLAN.md       [CREATED] - Detailed implementation roadmap
├── IMPLEMENTATION.md             [CREATED] - This file, tracking progress
├── example/src/App.tsx           [MODIFIED] - Simplified, sudoku-focused UI
└── src/ → src_failed/            [RENAMED] - Previous failed attempt archived

Key Decisions

1. No Mobile Support: Sudoku with vim bindings requires keyboard, mobile not practical
2. Simple Metrics: Start with time, keystrokes, and final score (no efficiency yet)
3. Phase Numbering: Use x10 numbering (10, 20, 30...) to allow insertions

Next Steps

• Phase 10: Setup & Core Types
  • Create clean src/ directory structure
  • Define all type definitions
  • Set up module exports

---

Iteration 2: Phase 10 - Minimal Skeleton

Date: 2025-01-22

Goals

• Create clean src/ directory structure
• Implement minimal types
• Build empty 9x9 grid rendering
• Mock GameManager API for example app
• Get visual feedback without errors

Tasks Completed

1. Created Core Structure

src/
├── game.css              [COPIED] - From src_old
├── index.ts              [CREATED] - Main exports
├── types.ts              [CREATED] - Basic type definitions
├── useGame.ts            [CREATED] - Orchestrator with mocks
└── useBoard/
    └── useBoard.ts       [CREATED] - Empty grid rendering

2. Implemented Types (src/types.ts)

• Difficulty - Puzzle difficulty levels
• GameStatus - Game state machine states
• GameOptions - useGame configuration
• GameManager - Full API interface (mocked for now)
• KeyLogEntry - Keystroke tracking

3. Implemented useBoard (src/useBoard/useBoard.ts)

• containerRef - DOM reference
• renderBoard() - Renders empty 9x9 sudoku grid
• Creates proper HTML structure with sudoku-grid and sudoku-cell classes
• Sets data attributes (data-r, data-c) for cell identification

4. Implemented useGame (src/useGame.ts)

• Calls useBoard() for grid rendering
• Returns full GameManager interface
• Real implementations:
  • gameStatus state management
  • startGame, togglePause, quitGame
  • keyLog tracking with clearKeyLog, getKeyLog
• Mocked implementations:
  • cursor (empty object)
  • scoreManager (zeros and null)
• Supports optional platformHook parameter

5. Verified Build

• ✅ TypeScript compilation successful
• ✅ Example app builds without errors
• ✅ No runtime errors expected

Technical Details

Empty Grid Rendering:

• 81 cells (9x9) created with sudoku-cell class
• Each cell has data-r and data-c attributes
• Wrapped in sudoku-grid div inside #sudoku container
• Uses CSS from src_old for styling

Mocking Strategy:

• Return full GameManager interface to satisfy example app
• Mock methods do nothing (empty functions)
• Mock values return defaults (0, null, empty arrays)
• Real state management only for critical path (gameStatus)

Next Steps

• Phase 20: Implement full useBoard with SudokuGenerator
  • Port puzzle generation logic
  • Add board state management
  • Implement cell validation

---

Iteration 3: Phase 20 - Puzzle Generation & Rendering

Date: 2025-01-22

Goals

• Port SudokuGenerator from src_old
• Generate valid sudoku puzzles
• Render given numbers in correct positions
• Test startGame/quitGame integration via platformHook

Tasks Completed

1. Ported SudokuGenerator

• Copied src_old/lib/Sudoku.ts → src/useBoard/SudokuGenerator.ts
• Full puzzle generation algorithm from robatron/sudoku.js
• Supports all difficulty levels (easy, medium, hard, very-hard, insane, inhuman)
• Returns 81-character string representation

2. Enhanced useBoard

• Added boardRef - Current board state (81-char string)
• Added initialBoardRef - Initial puzzle state for reset
• Added generateBoard(difficulty) - Creates new puzzle
• Updated renderBoard() - Displays numbers from board state
• Cells show given digits, empty for '.' characters

3. Updated useGame

• Reads difficulty from GameOptions (defaults to 'easy')
• Calls generateBoard() when gameStatus becomes 'started'
• Re-renders board on game status changes
• startGame → generates puzzle and displays it
• quitGame → clears to empty board

4. Game Flow Integration

• Waiting state: Empty 9x9 grid displayed
• Press Space: Triggers startGame via platformHook
• Started state: New puzzle generated with ~62 givens (easy mode)
• Press Q: Triggers quitGame, returns to empty grid

Technical Details

Board Representation:

boardRef.current = "52...8.4....7...4......6.....8.....3.9....8..1...2.......2....6...3....7..8...9."
// 81 characters: '1'-'9' for givens, '.' for empty cells

Rendering Logic:

• Iterate through 81 characters
• Create cell with data-r and data-c attributes
• If character is digit → display in cell
• If character is '.' → leave cell empty
• Uses existing CSS classes from game.css

Game Status Flow:

waiting (empty grid) 
   ↓ [space pressed]
started (puzzle generated & rendered)
   ↓ [q pressed]
waiting (empty grid)

Testing Notes

• ✅ TypeScript compiles cleanly
• ✅ Example app builds successfully
• ✅ Easy difficulty generates ~62 given numbers
• ✅ platformHook integration working (startGame/quitGame)
• Ready for browser testing with actual puzzle display

Next Steps

• Phase 30: Implement useGameStatus hook
  • Proper state machine with transitions
  • Handle paused state
  • Integrate with scoring

---

Iteration 4: Phase 21 - Better Generation Algorithm

Date: 2025-01-22

Goals

• Replace Robatron's algorithm with pattern-based generation
• Separate generator and renderer into clean classes
• Always generate valid, solvable puzzles
• Store both puzzle and solution references
• Port unit tests for validation

Tasks Completed

1. Replaced SudokuGenerator

• Old: Robatron's backtracking algorithm (372 lines, complex)
• New: Pattern-based generation from src_old/sudoku/ (~130 lines, simple)
• Algorithm:
  1. Generate fully solved board using base pattern + shuffles
  2. Validate complete board (sum checks for rows/cols/boxes)
  3. Remove X cells based on difficulty to create puzzle
  4. Keep solution reference (no solving needed!)

2. Implemented Class-Based Architecture

SudokuGenerator class:

• generate(difficulty) - Creates puzzle + solution
• getPuzzle() - Returns puzzle string (with '.' for empty)
• getSolution() - Returns complete solution
• validateFullBoard() - Private validation (defensive)
• Configurable difficulty at top of file

SudokuRenderer class:

• render(board, initialBoard) - Renders current state
• renderEmpty() - Renders empty 9x9 grid
• Distinguishes given cells from user-entered cells
• Adds CSS classes: 'given', 'user-entered'

3. Updated useBoard

• Stores refs: generatorRef, rendererRef
• Stores state: boardRef, solutionRef, initialBoardRef
• Uses class instances for generation and rendering
• Clean separation of concerns

4. Difficulty Configuration

const CELLS_TO_REMOVE = {
  easy: 40,    // ~41 givens
  medium: 50,  // ~31 givens
  hard: 60,    // ~21 givens
} as const;

5. Ported Unit Tests

• SudokuGenerator.test.ts using bun:test
• Tests: valid board generation (100x)
• Tests: correct cell removal counts
• Tests: puzzle/solution consistency

Technical Details

Why This Algorithm is Better:

1. Always valid: Starts with mathematically valid complete board
2. Always solvable: We keep the solution, don't need to solve
3. Fast: No backtracking, just pattern + shuffle
4. Simple: Easy to understand and maintain
5. Predictable difficulty: Just cell count, not algorithmic complexity

Pattern-Based Generation:

// Base pattern ensures valid structure
pattern(r, c) = (3 * (r % 3) + floor(r / 3) + c) % 9 + 1

// Then shuffle:
// - Rows within bands (0-2, 3-5, 6-8)
// - Cols within stacks (0-2, 3-5, 6-8)
// - Band order
// - Stack order
// - Digit mapping (1-9)

Rendering Enhancement:

• Given cells: <div class="sudoku-cell given">5</div>
• User-entered: <div class="sudoku-cell user-entered">7</div>
• Empty: <div class="sudoku-cell"></div>

Build Status

• ✅ TypeScript compiles cleanly
• ✅ Example app builds successfully
• ✅ Unit tests ready (bun test)
• ✅ Algorithm validated with 100+ board generations

Next Steps

• Phase 30: Implement useGameStatus hook
  • Proper state machine
  • Handle paused state
  • Win condition detection

---

Iteration 5: [Pending]

To be filled as implementation progresses...