Add AI difficulty setting

pkg/client/scenes/game.go

@@ -21,6 +21,7 @@ type Game struct {
 	nickname    string
 	whoseTurn   common.Disk
 	multiplayer bool
+	difficulty  int
 }
 
 func (g *Game) Setup(changeScene ChangeScene, sendMessage SendMessage) error {
@@ -30,7 +31,7 @@ func (g *Game) Setup(changeScene ChangeScene, sendMessage SendMessage) error {
 
 	var message interface{}
 	if g.player == 1 {
-		message = common.NewNewGameMessage(g.multiplayer)
+		message = common.NewNewGameMessage(g.multiplayer, g.difficulty)
 	} else {
 		message = common.NewJoinGameMessage()
 	}

pkg/client/scenes/menu.go

@@ -7,7 +7,9 @@ import (
 )
 
 const (
-	buttonSingleplayer = iota
+	buttonNormal = iota
+	buttonEasy
+	buttonHard
 	buttonHostGame
 	buttonJoinGame
 	buttonChangeName
@@ -28,24 +30,32 @@ func (m *Menu) OnTerminalEvent(event termbox.Event) error {
 		case buttonChangeName:
 			m.button = buttonHostGame
 		case buttonHostGame, buttonJoinGame:
-			m.button = buttonSingleplayer
+			m.button = buttonNormal
 		}
 	case dx == 1:
 		switch m.button {
-		case buttonSingleplayer:
+		case buttonEasy, buttonNormal, buttonHard:
 			m.button = buttonHostGame
 		case buttonHostGame, buttonJoinGame:
 			m.button = buttonChangeName
 		}
 	case dy == -1:
 		switch m.button {
+		case buttonNormal:
+			m.button = buttonEasy
+		case buttonHard:
+			m.button = buttonNormal
 		case buttonJoinGame:
 			m.button = buttonHostGame
 		default:
 			m.button = buttonChangeName
 		}
 	case dy == 1:
 		switch m.button {
+		case buttonEasy:
+			m.button = buttonNormal
+		case buttonNormal:
+			m.button = buttonHard
 		case buttonHostGame:
 			m.button = buttonJoinGame
 		case buttonChangeName:
@@ -55,8 +65,12 @@ func (m *Menu) OnTerminalEvent(event termbox.Event) error {
 
 	if event.Key == termbox.KeyEnter {
 		switch m.button {
-		case buttonSingleplayer:
-			return m.ChangeScene(&Game{player: 1, multiplayer: false, nickname: m.nickname})
+		case buttonEasy:
+			return m.ChangeScene(&Game{player: 1, difficulty: 0, nickname: m.nickname})
+		case buttonNormal:
+			return m.ChangeScene(&Game{player: 1, difficulty: 1, nickname: m.nickname})
+		case buttonHard:
+			return m.ChangeScene(&Game{player: 1, difficulty: 2, nickname: m.nickname})
 		case buttonHostGame:
 			return m.ChangeScene(&Game{player: 1, multiplayer: true, nickname: m.nickname})
 		case buttonJoinGame:
@@ -75,18 +89,27 @@ func (m *Menu) Draw() {
 
 	draw(topRight, normal, fmt.Sprintf("Did you know? Your name is %s!", m.nickname))
 
-	buttonColors := [4]color{normal, normal, normal, normal}
+	buttonColors := [6]color{normal, normal, normal, normal, normal, normal}
 	buttonColors[m.button] = inverted
 
 	multiplayerButtonColor := normal
 	multiplayerOffset := offset(centerRight, 1, 3)
 	if m.button == buttonHostGame || m.button == buttonJoinGame {
 		multiplayerButtonColor = inverted
-		draw(offset(multiplayerOffset, 0, 2), buttonColors[buttonHostGame], "[ HOST GAME ]")
-		draw(offset(multiplayerOffset, 0, 4), buttonColors[buttonJoinGame], "[ JOIN GAME ]")
+		draw(offset(multiplayerOffset, 1, 2), buttonColors[buttonHostGame], "[ HOST GAME ]")
+		draw(offset(multiplayerOffset, 1, 4), buttonColors[buttonJoinGame], "[ JOIN GAME ]")
 	}
 
-	draw(offset(centerLeft, -1, 3), buttonColors[buttonSingleplayer], "[ SINGLEPLAYER ]")
+	singleplayerButtonColor := normal
+	singleplayerOffset := offset(centerLeft, -1, 3)
+	if m.button == buttonEasy || m.button == buttonNormal || m.button == buttonHard {
+		singleplayerButtonColor = inverted
+		draw(offset(singleplayerOffset, -4, 2), buttonColors[buttonEasy], "[ EASY ]")
+		draw(offset(singleplayerOffset, -3, 4), buttonColors[buttonNormal], "[ NORMAL ]")
+		draw(offset(singleplayerOffset, -4, 6), buttonColors[buttonHard], "[ HARD ]")
+	}
+
+	draw(offset(centerLeft, -1, 3), singleplayerButtonColor, "[ SINGLEPLAYER ]")
 	draw(multiplayerOffset, multiplayerButtonColor, "[ MULTIPLAYER ]")
 	draw(offset(topRight, 0, 2), buttonColors[buttonChangeName], "[ CHANGE NAME ]")
 }

pkg/common/messages.go

@@ -86,12 +86,14 @@ func NewUpdateBoardMessage(board Board, player Disk) UpdateBoardMessage {
 type NewGameMessage struct {
 	Action      string `json:"action"`
 	Multiplayer bool   `json:"multiplayer"`
+	Difficulty  int    `json:"difficulty"`
 }
 
-func NewNewGameMessage(multiplayer bool) NewGameMessage {
+func NewNewGameMessage(multiplayer bool, difficulty int) NewGameMessage {
 	return NewGameMessage{
 		Action:      NewGameAction,
 		Multiplayer: multiplayer,
+		Difficulty:  difficulty,
 	}
 }
 

pkg/server/ai.go

@@ -9,16 +9,26 @@ import (
 )
 
 // doAIPlayerMove takes a turn as the AI player.
-func doAIPlayerMove(ctx context.Context, board common.Board, player common.Disk) common.Board {
+func doAIPlayerMove(ctx context.Context, board common.Board, player common.Disk, difficulty int) common.Board {
 	aiState := &aiGameState{
 		board:  board,
 		player: player,
 	}
 
-	ctx2, cancel := context.WithTimeout(ctx, time.Second)
+	ctx2, cancel := context.WithTimeout(ctx, time.Second*2)
 	defer cancel()
 
-	move := minimaxWithIterativeDeepening(ctx2, aiState, 64)
+	var depth int
+	switch difficulty {
+	default:
+		depth = 1
+	case 1:
+		depth = 5
+	case 2:
+		depth = common.BoardSize * common.BoardSize // No limit
+	}
+
+	move := minimaxWithIterativeDeepening(ctx2, aiState, depth)
 	return aiState.moves[move]
 }
 

pkg/server/db.go

@@ -25,13 +25,15 @@ type gameState struct {
 	board       common.Board
 	player      common.Disk
 	multiplayer bool
+	difficulty  int
 }
 
 type gameItem struct {
 	ID          string `json:"id"`
 	Board       []byte `json:"board"`
 	Player      int    `json:"player"`
 	Multiplayer bool   `json:"multiplayer"`
+	Difficulty  int    `json:"difficulty"`
 }
 
 func getAllConnectionIDs(ctx context.Context) ([]string, error) {
@@ -108,6 +110,7 @@ func loadGame(ctx context.Context) (gameState, error) {
 		board:       board,
 		player:      common.Disk(gameItem.Player),
 		multiplayer: gameItem.Multiplayer,
+		difficulty:  gameItem.Difficulty,
 	}, err
 }
 
@@ -124,6 +127,7 @@ func saveGame(ctx context.Context, game gameState) error {
 		Board:       b,
 		Player:      int(game.player),
 		Multiplayer: game.multiplayer,
+		Difficulty:  game.difficulty,
 	}
 
 	item, err := dynamodbattribute.MarshalMap(gameItem)

pkg/server/handler.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"time"
 
 	"github.com/aws/aws-lambda-go/events"
 
@@ -84,7 +85,13 @@ func handlePlaceDisk(ctx context.Context, req events.APIGatewayWebsocketProxyReq
 	for !game.multiplayer && game.player == 2 && common.HasMoves(game.board, 2) {
 		log.Println("Taking AI turn")
 
-		game.board = doAIPlayerMove(ctx, game.board, game.player)
+		turnStartedAt := time.Now()
+		game.board = doAIPlayerMove(ctx, game.board, game.player, game.difficulty)
+
+		// Pad the turn time in case the AI was very quick, so the player doesn't stress or know
+		// they're losing.
+		time.Sleep(time.Second - time.Since(turnStartedAt))
+
 		if common.HasMoves(game.board, game.player%2+1) {
 			game.player = game.player%2 + 1
 		}
@@ -116,6 +123,7 @@ func handleNewGame(ctx context.Context, req events.APIGatewayWebsocketProxyReque
 		board:       board,
 		player:      1,
 		multiplayer: message.Multiplayer,
+		difficulty:  message.Difficulty,
 	}
 
 	if err := saveGame(ctx, game); err != nil {