ai-code-battle/engine/match.go

package engine

import (
	"fmt"
	"log"
	"math/rand"
	"sync"
	"time"
)

// MatchRunner orchestrates a match between multiple bots.
type MatchRunner struct {
	config   Config
	bots     []BotInterface
	names    []string
	rng      *rand.Rand
	verbose  bool
	logger   *log.Logger
	timeout  time.Duration // per-turn timeout
}

// MatchOption is a functional option for MatchRunner.
type MatchOption func(*MatchRunner)

// WithVerbose enables verbose logging.
func WithVerbose(v bool) MatchOption {
	return func(mr *MatchRunner) {
		mr.verbose = v
	}
}

// WithLogger sets a custom logger.
func WithLogger(l *log.Logger) MatchOption {
	return func(mr *MatchRunner) {
		mr.logger = l
	}
}

// WithTimeout sets the per-turn timeout.
func WithTimeout(d time.Duration) MatchOption {
	return func(mr *MatchRunner) {
		mr.timeout = d
	}
}

// WithRNG sets the random number generator.
func WithRNG(rng *rand.Rand) MatchOption {
	return func(mr *MatchRunner) {
		mr.rng = rng
	}
}

// NewMatchRunner creates a new match runner.
func NewMatchRunner(config Config, options ...MatchOption) *MatchRunner {
	mr := &MatchRunner{
		config:  config,
		bots:    make([]BotInterface, 0),
		names:   make([]string, 0),
		rng:     rand.New(rand.NewSource(time.Now().UnixNano())),
		verbose: false,
		logger:  log.Default(),
		timeout: 3 * time.Second,
	}

	for _, opt := range options {
		opt(mr)
	}

	return mr
}

// AddBot adds a bot to the match.
func (mr *MatchRunner) AddBot(bot BotInterface, name string) {
	mr.bots = append(mr.bots, bot)
	mr.names = append(mr.names, name)
}

// Run executes the match and returns the result and replay.
func (mr *MatchRunner) Run() (*MatchResult, *Replay, error) {
	if len(mr.bots) < 2 {
		return nil, nil, fmt.Errorf("need at least 2 bots, got %d", len(mr.bots))
	}

	// Initialize game state
	gs := NewGameState(mr.config, mr.rng)

	// Add players
	for range mr.bots {
		gs.AddPlayer()
	}

	// Set up replay writer
	replayWriter := NewReplayWriter(gs.MatchID, mr.config)

	// Record players
	replayPlayers := make([]ReplayPlayer, len(mr.bots))
	for i, name := range mr.names {
		replayPlayers[i] = ReplayPlayer{ID: i, Name: name}
	}
	replayWriter.SetPlayers(replayPlayers)

	// Generate a simple symmetric map for 2 players
	mr.generateMap(gs, len(mr.bots))

	// Record initial map state
	replayWriter.SetMap(gs)

	// Record turn 0 (initial state)
	replayWriter.RecordTurn(gs)

	// Run the match
	var result *MatchResult
	for gs.Turn < mr.config.MaxTurns {
		// Get moves from all bots concurrently
		moves := mr.getMovesFromBots(gs)

		// Submit moves to game state
		gs.ClearTurnState()
		for playerID, playerMoves := range moves {
			for _, move := range playerMoves {
				// Validate bot ownership
				bot := mr.findBotAtPosition(gs, move.Position, playerID)
				if bot != nil && bot.Alive {
					gs.SubmitMove(move.Position, move.Direction)
				}
			}
		}

		// Execute the turn
		result = gs.ExecuteTurn()

		// Record turn state
		replayWriter.RecordTurn(gs)

		if mr.verbose {
			mr.logger.Printf("Turn %d: %d living bots", gs.Turn, gs.GetLivingBotCount())
		}

		if result != nil {
			break
		}
	}

	// Finalize replay
	replayWriter.Finalize(result)

	return result, replayWriter.GetReplay(), nil
}

// getMovesFromBots gets moves from all bots concurrently.
func (mr *MatchRunner) getMovesFromBots(gs *GameState) map[int][]Move {
	moves := make(map[int][]Move)
	var mu sync.Mutex
	var wg sync.WaitGroup

	for playerID, bot := range mr.bots {
		wg.Add(1)
		go func(pid int, b BotInterface) {
			defer wg.Done()

			// Get visible state for this player
			visibleState := gs.GetVisibleState(pid)

			// Get moves with timeout
			moveChan := make(chan []Move, 1)
			errChan := make(chan error, 1)

			go func() {
				m, err := b.GetMoves(visibleState)
				if err != nil {
					errChan <- err
					return
				}
				moveChan <- m
			}()

			select {
			case m := <-moveChan:
				mu.Lock()
				moves[pid] = m
				mu.Unlock()
			case <-errChan:
				// Bot returned error, no moves
				if mr.verbose {
					mr.logger.Printf("Bot %d returned error", pid)
				}
			case <-time.After(mr.timeout):
				// Timeout, no moves
				if mr.verbose {
					mr.logger.Printf("Bot %d timed out", pid)
				}
			}
		}(playerID, bot)
	}

	wg.Wait()
	return moves
}

// findBotAtPosition finds a bot at a position owned by a player.
func (mr *MatchRunner) findBotAtPosition(gs *GameState, pos Position, playerID int) *Bot {
	for _, b := range gs.Bots {
		if b.Alive && b.Position == pos && b.Owner == playerID {
			return b
		}
	}
	return nil
}

// generateMap generates a symmetric map for the given number of players.
func (mr *MatchRunner) generateMap(gs *GameState, numPlayers int) {
	// For 2 players: 180° rotational symmetry
	// Place cores at opposite corners
	centerRow := gs.Config.Rows / 2
	centerCol := gs.Config.Cols / 2

	switch numPlayers {
	case 2:
		// Place cores at opposite positions (rotational symmetry through center)
		core0 := Position{Row: centerRow / 2, Col: centerCol / 2}
		core1 := Position{Row: centerRow + centerRow/2, Col: centerCol + centerCol/2}
		gs.AddCore(0, core0)
		gs.AddCore(1, core1)

		// Place bots at cores
		gs.SpawnBot(0, core0)
		gs.SpawnBot(1, core1)

	case 3:
		// 120° rotational symmetry (equilateral triangle)
		// Simplified: place at roughly equal angles
		for i := 0; i < 3; i++ {
			angle := float64(i) * 2.0 * 3.14159 / 3.0
			row := centerRow + int(float64(centerRow/2)*0.8*(1.0+0.5*cos(angle)))
			col := centerCol + int(float64(centerCol/2)*0.8*(1.0+0.5*sin(angle)))
			pos := Position{Row: row, Col: col}
			gs.AddCore(i, pos)
			gs.SpawnBot(i, pos)
		}

	case 4:
		// 90° rotational symmetry (four corners of a square)
		offset := centerRow / 2
		positions := []Position{
			{Row: centerRow - offset, Col: centerCol - offset},
			{Row: centerRow - offset, Col: centerCol + offset},
			{Row: centerRow + offset, Col: centerCol + offset},
			{Row: centerRow + offset, Col: centerCol - offset},
		}
		for i, pos := range positions {
			gs.AddCore(i, pos)
			gs.SpawnBot(i, pos)
		}

	default:
		// Fallback: place cores in a circle
		for i := 0; i < numPlayers; i++ {
			angle := float64(i) * 2.0 * 3.14159 / float64(numPlayers)
			row := centerRow + int(float64(centerRow/2)*0.7*cos(angle))
			col := centerCol + int(float64(centerCol/2)*0.7*sin(angle))
			pos := Position{Row: row, Col: col}
			gs.AddCore(i, pos)
			gs.SpawnBot(i, pos)
		}
	}

	// Place energy nodes symmetrically
	mr.placeEnergyNodes(gs, numPlayers)

	// Place walls symmetrically
	mr.placeWalls(gs, numPlayers)
}

// placeEnergyNodes places energy nodes symmetrically.
func (mr *MatchRunner) placeEnergyNodes(gs *GameState, numPlayers int) {
	centerRow := gs.Config.Rows / 2
	centerCol := gs.Config.Cols / 2

	// Place energy nodes in a ring around the center
	numNodes := mr.config.EnergyInterval * 2 // e.g., 20 nodes for interval 10
	nodesPerSector := numNodes / numPlayers

	for i := 0; i < nodesPerSector; i++ {
		// Generate one position in the first sector
		angle := mr.rng.Float64() * 2.0 * 3.14159 / float64(numPlayers)
		radius := 0.3 + mr.rng.Float64()*0.4 // 30-70% of half-size

		// Mirror for all players
		for p := 0; p < numPlayers; p++ {
			rotAngle := angle + float64(p)*2.0*3.14159/float64(numPlayers)
			r := centerRow + int(float64(centerRow)*radius*cos(rotAngle))
			c := centerCol + int(float64(centerCol)*radius*sin(rotAngle))
			gs.AddEnergyNode(Position{Row: r, Col: c})
		}
	}
}

// placeWalls places walls symmetrically.
func (mr *MatchRunner) placeWalls(gs *GameState, numPlayers int) {
	centerRow := gs.Config.Rows / 2
	centerCol := gs.Config.Cols / 2

	// Calculate target number of walls
	totalTiles := gs.Config.Rows * gs.Config.Cols
	targetWalls := int(float64(totalTiles) * 0.15) // 15% wall density
	wallsPerSector := targetWalls / numPlayers

	for i := 0; i < wallsPerSector; i++ {
		// Generate one position in the first sector
		angle := mr.rng.Float64() * 2.0 * 3.14159 / float64(numPlayers)
		radius := 0.1 + mr.rng.Float64()*0.8 // 10-90% of half-size
		row := centerRow + int(float64(centerRow)*radius*cos(angle))
		col := centerCol + int(float64(centerCol)*radius*sin(angle))

		// Check it's not on a core or energy node
		pos := Position{Row: row, Col: col}
		if mr.isValidWallPosition(gs, pos) {
			// Mirror for all players
			for p := 0; p < numPlayers; p++ {
				rotAngle := angle + float64(p)*2.0*3.14159/float64(numPlayers)
				r := centerRow + int(float64(centerRow)*radius*cos(rotAngle))
				c := centerCol + int(float64(centerCol)*radius*sin(rotAngle))
				mirrorPos := Position{Row: r, Col: c}
				if mr.isValidWallPosition(gs, mirrorPos) {
					gs.Grid.SetPos(mirrorPos, TileWall)
				}
			}
		}
	}
}

// isValidWallPosition checks if a position can have a wall.
func (mr *MatchRunner) isValidWallPosition(gs *GameState, pos Position) bool {
	// Check for core
	for _, c := range gs.Cores {
		if c.Position == pos {
			return false
		}
	}
	// Check for energy node
	for _, en := range gs.Energy {
		if en.Position == pos {
			return false
		}
	}
	return true
}

// cos and sin helpers (avoid importing math for simple cases)
func cos(x float64) float64 {
	// Simple approximation using Taylor series
	return 1 - x*x/2 + x*x*x*x/24 - x*x*x*x*x*x/720
}

func sin(x float64) float64 {
	// Simple approximation using Taylor series
	return x - x*x*x/6 + x*x*x*x*x/120
}