# AI Code Battle - Implementation Progress

## Current Phase: Phase 1 - Core Engine

**Status: ✅ COMPLETE**

### Completed

- [x] Go module initialization (`github.com/aicodebattle/acb`)
- [x] Project structure (`engine/`, `cmd/acb-local/`, `cmd/acb-mapgen/`)
- [x] Core types (`engine/types.go`)
  - Position, Tile, Direction, Bot, Core, EnergyNode, Player
  - Config with default values
  - MatchResult, VisibleState (fog-filtered state)
- [x] Grid implementation (`engine/grid.go`)
  - Toroidal wrapping
  - Distance calculations (squared for performance)
  - Visibility computation
  - Wall/obstacle handling
- [x] Game state (`engine/game.go`)
  - State management for bots, cores, energy, players
  - Bot spawning and killing
  - Fog of war filtering
- [x] Turn execution (`engine/turn.go`)
  - Movement phase with collision detection
  - Focus-fire combat resolution
  - Core capture mechanics
  - Energy collection (contested resources)
  - Bot spawning at active cores
  - Energy node ticking
  - Win condition checking (elimination, draw, dominance, turns)
- [x] Replay writer (`engine/replay.go`)
  - Full replay JSON format
  - Turn-by-turn state recording
- [x] Match runner (`engine/match.go`)
  - Concurrent bot communication
  - Per-turn timeout
  - Symmetric map generation
- [x] Local bot interface (`engine/bot_local.go`)
  - RandomBot, IdleBot implementations
- [x] CLI runner (`cmd/acb-local/main.go`)
  - Configurable parameters (seed, size, turns)
  - Replay output
- [x] Map generator (`cmd/acb-mapgen/main.go`)
  - Rotational symmetry (2/3/4/6 players)
  - Configurable density
- [x] Unit tests for core engine
  - Grid operations, wrapping, distances
  - Combat resolution (1v1, 2v1, formations)
  - Core capture
  - Energy collection
  - Spawning
  - Win conditions
- [x] Map generator connectivity validation (`cmd/acb-mapgen/connectivity.go`)
  - BFS-based connectivity check
  - Retry mechanism for connected map generation
- [x] Determinism tests (`engine/determinism_test.go`)
  - Same seed produces identical replays
  - Turn execution is deterministic
  - Grid operations are deterministic
  - Combat resolution is deterministic
  - Replay serialization round-trip
  - Full 500-turn match validation

### Exit Criteria Progress

| Criterion | Status |
|-----------|--------|
| Can run a complete 500-turn match locally | ✅ Works |
| Produce a valid replay file | ✅ Works |
| Comprehensive unit tests | ✅ 32 tests passing |

## Next Phase: Phase 2 - HTTP Protocol & Strategy Bots

**Status: Ready to start**

## File Structure

```
ai-code-battle/
├── go.mod
├── engine/
│   ├── types.go        # Core data types
│   ├── grid.go         # Toroidal grid implementation
│   ├── game.go         # Game state management
│   ├── turn.go         # Turn execution phases
│   ├── replay.go       # Replay recording
│   ├── match.go        # Match runner
│   ├── bot_local.go    # Local bot interface
│   ├── grid_test.go    # Grid tests
│   └── turn_test.go    # Turn execution tests
├── cmd/
│   ├── acb-local/      # CLI match runner
│   │   └── main.go
│   └── acb-mapgen/     # Map generator
│       └── main.go
└── docs/
    └── plan/
        └── plan.md     # Full implementation plan
```

## Key Design Decisions

1. **Position-based moves**: Bots are identified by their current position in the move protocol (not bot IDs), which works better with fog of war.

2. **Squared distances**: Using squared distances throughout (Distance2, Radius2) avoids expensive square root operations.

3. **Simultaneous resolution**: Combat deaths are computed first, then applied, ensuring true simultaneous resolution.

4. **Symmetric map generation**: Maps are generated by creating one sector and rotating for all players.

## Running Tests

```bash
go test ./engine/... -v
```

## Building CLI Tools

```bash
go build ./cmd/acb-local
go build ./cmd/acb-mapgen
```

## Example Usage

```bash
# Run a match
./acb-local -seed 42 -max-turns 100 -output replay.json -verbose

# Generate a map
./acb-mapgen -players 2 -rows 60 -cols 60 -output map.json
```