feat(examples): Implement a two-player Dice Roller game (#2768)

## Description: This PR introduces a basic dice rolling game : **_Dice Roller_** ## Game Rules: > 1. Two players each roll a dice once > 2. Each roll results in a value between 1 and 6 > 3. The player with the highest score will win the game > 4. If both players roll the same value, the game is a draw > 5. No points or stats changes are awarded if you play against yourself ## Purpose: - This package serves to illustrate the application of on-chain randomness using Gno's `p/demo/entropy` and `rand/math` packages. While these packages provide randomness, they are not entirely unpredictable, and their usage in this game is intended to showcase their practical implementation in Gno's realms - Designed with a minimalistic realm to ensure ease of understanding and accessibility for newcomers to Gno realm development ![Screenshot from 2024-09-10 21-56-59](https://github.com/user-attachments/assets/aa3e4c70-2db4-4949-9a50-2e349d51d9a5) You guys can test this game at : https://test4.gno.land/r/g1w6886hdj2tet0seyw6kn8fl92sx06prgd9w9j8/game/v3/diceroller  <details><summary>Contributors' checklist...</summary> - [ ] Added new tests, or not needed, or not feasible - [ ] Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory - [ ] Updated the official documentation or not needed - [ ] No breaking changes were made, or a `BREAKING CHANGE: xxx` message was included in the description - [ ] Added references to related issues and PRs - [ ] Provided any useful hints for running manual tests - [ ] Added new benchmarks to [generated graphs](https://gnoland.github.io/benchmarks), if any. More info [here](https://github.com/gnolang/gno/blob/master/.benchmarks/README.md). </details> --------- Co-authored-by: Leon Hudak <[email protected]> Co-authored-by: Morgan <[email protected]>
gnolang · Oct 2, 2024 · fb85d0c · fb85d0c
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diff --git a/examples/gno.land/r/demo/games/dice_roller/dice_roller.gno b/examples/gno.land/r/demo/games/dice_roller/dice_roller.gno
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+package dice_roller
+
+import (
+	"errors"
+	"math/rand"
+	"sort"
+	"std"
+	"strconv"
+	"strings"
+
+	"gno.land/p/demo/avl"
+	"gno.land/p/demo/entropy"
+	"gno.land/p/demo/seqid"
+	"gno.land/p/demo/ufmt"
+	"gno.land/r/demo/users"
+)
+
+type (
+	// game represents a Dice Roller game between two players
+	game struct {
+		player1, player2 std.Address
+		roll1, roll2     int
+	}
+
+	// player holds the information about each player including their stats
+	player struct {
+		addr                        std.Address
+		wins, losses, draws, points int
+	}
+
+	// leaderBoard is a slice of players, used to sort players by rank
+	leaderBoard []player
+)
+
+const (
+	// Constants to represent game result outcomes
+	ongoing = iota
+	win
+	draw
+	loss
+)
+
+var (
+	games  avl.Tree // AVL tree for storing game states
+	gameId seqid.ID // Sequence ID for games
+
+	players avl.Tree // AVL tree for storing player data
+
+	seed = uint64(entropy.New().Seed())
+	r    = rand.New(rand.NewPCG(seed, 0xdeadbeef))
+)
+
+// rollDice generates a random dice roll between 1 and 6
+func rollDice() int {
+	return r.IntN(6) + 1
+}
+
+// NewGame initializes a new game with the provided opponent's address
+func NewGame(addr std.Address) int {
+	if !addr.IsValid() {
+		panic("invalid opponent's address")
+	}
+
+	games.Set(gameId.Next().String(), &game{
+		player1: std.PrevRealm().Addr(),
+		player2: addr,
+	})
+
+	return int(gameId)
+}
+
+// Play allows a player to roll the dice and updates the game state accordingly
+func Play(idx int) int {
+	g, err := getGame(idx)
+	if err != nil {
+		panic(err)
+	}
+
+	roll := rollDice() // Random the player's dice roll
+
+	// Play the game and update the player's roll
+	if err := g.play(std.PrevRealm().Addr(), roll); err != nil {
+		panic(err)
+	}
+
+	// If both players have rolled, update the results and leaderboard
+	if g.isFinished() {
+		// If the player is playing against themselves, no points are awarded
+		if g.player1 == g.player2 {
+			return roll
+		}
+
+		player1 := getPlayer(g.player1)
+		player2 := getPlayer(g.player2)
+
+		if g.roll1 > g.roll2 {
+			player1.updateStats(win)
+			player2.updateStats(loss)
+		} else if g.roll2 > g.roll1 {
+			player2.updateStats(win)
+			player1.updateStats(loss)
+		} else {
+			player1.updateStats(draw)
+			player2.updateStats(draw)
+		}
+	}
+
+	return roll
+}
+
+// play processes a player's roll and updates their score
+func (g *game) play(player std.Address, roll int) error {
+	if player != g.player1 && player != g.player2 {
+		return errors.New("invalid player")
+	}
+
+	if g.isFinished() {
+		return errors.New("game over")
+	}
+
+	if player == g.player1 && g.roll1 == 0 {
+		g.roll1 = roll
+		return nil
+	}
+
+	if player == g.player2 && g.roll2 == 0 {
+		g.roll2 = roll
+		return nil
+	}
+
+	return errors.New("already played")
+}
+
+// isFinished checks if the game has ended
+func (g *game) isFinished() bool {
+	return g.roll1 != 0 && g.roll2 != 0
+}
+
+// checkResult returns the game status as a formatted string
+func (g *game) status() string {
+	if !g.isFinished() {
+		return resultIcon(ongoing) + " Game still in progress"
+	}
+
+	if g.roll1 > g.roll2 {
+		return resultIcon(win) + " Player1 Wins !"
+	} else if g.roll2 > g.roll1 {
+		return resultIcon(win) + " Player2 Wins !"
+	} else {
+		return resultIcon(draw) + " It's a Draw !"
+	}
+}
+
+// Render provides a summary of the current state of games and leader board
+func Render(path string) string {
+	var sb strings.Builder
+
+	sb.WriteString(`# 🎲 **Dice Roller Game**
+
+Welcome to Dice Roller! Challenge your friends to a simple yet exciting dice rolling game. Roll the dice and see who gets the highest score !
+
+---
+
+## **How to Play**:
+1. **Create a game**: Challenge an opponent using [NewGame](./dice_roller?help&__func=NewGame)
+2. **Roll the dice**: Play your turn by rolling a dice using [Play](./dice_roller?help&__func=Play)
+
+---
+
+## **Scoring Rules**:
+- **Win** 🏆: +3 points
+- **Draw** 🤝: +1 point each
+- **Lose** ❌: No points
+- **Playing against yourself**: No points or stats changes for you
+
+---
+
+## **Recent Games**:
+Below are the results from the most recent games. Up to 10 recent games are displayed
+
+| Game | Player 1 | 🎲 Roll 1 | Player 2 | 🎲 Roll 2 | 🏆 Winner |
+|------|----------|-----------|----------|-----------|-----------|
+`)
+
+	maxGames := 10
+	for n := int(gameId); n > 0 && int(gameId)-n < maxGames; n-- {
+		g, err := getGame(n)
+		if err != nil {
+			continue
+		}
+
+		sb.WriteString(strconv.Itoa(n) + " | " +
+			"<span title=\"" + string(g.player1) + "\">" + shortName(g.player1) + "</span>" + " | " + diceIcon(g.roll1) + " | " +
+			"<span title=\"" + string(g.player2) + "\">" + shortName(g.player2) + "</span>" + " | " + diceIcon(g.roll2) + " | " +
+			g.status() + "\n")
+	}
+
+	sb.WriteString(`
+---
+
+## **Leaderboard**:
+The top players are ranked by performance. Games played against oneself are not counted in the leaderboard
+
+| Rank | Player                | Wins | Losses | Draws | Points |
+|------|-----------------------|------|--------|-------|--------|
+`)
+
+	for i, player := range getLeaderBoard() {
+		sb.WriteString(ufmt.Sprintf("| %s   | <span title=\""+string(player.addr)+"\">**%s**</span> | %d | %d | %d | %d |\n",
+			rankIcon(i+1),
+			shortName(player.addr),
+			player.wins,
+			player.losses,
+			player.draws,
+			player.points,
+		))
+	}
+
+	sb.WriteString("\n---\n**Good luck and have fun !** 🎉")
+	return sb.String()
+}
+
+// shortName returns a shortened name for the given address
+func shortName(addr std.Address) string {
+	user := users.GetUserByAddress(addr)
+	if user != nil {
+		return user.Name
+	}
+	if len(addr) < 10 {
+		return string(addr)
+	}
+	return string(addr)[:10] + "..."
+}
+
+// getGame retrieves the game state by its ID
+func getGame(idx int) (*game, error) {
+	v, ok := games.Get(seqid.ID(idx).String())
+	if !ok {
+		return nil, errors.New("game not found")
+	}
+	return v.(*game), nil
+}
+
+// updateResult updates the player's stats and points based on the game outcome
+func (p *player) updateStats(result int) {
+	switch result {
+	case win:
+		p.wins++
+		p.points += 3
+	case loss:
+		p.losses++
+	case draw:
+		p.draws++
+		p.points++
+	}
+}
+
+// getPlayer retrieves a player or initializes a new one if they don't exist
+func getPlayer(addr std.Address) *player {
+	v, ok := players.Get(addr.String())
+	if !ok {
+		player := &player{
+			addr: addr,
+		}
+		players.Set(addr.String(), player)
+		return player
+	}
+
+	return v.(*player)
+}
+
+// getLeaderBoard generates a leaderboard sorted by points
+func getLeaderBoard() leaderBoard {
+	board := leaderBoard{}
+	players.Iterate("", "", func(key string, value interface{}) bool {
+		player := value.(*player)
+		board = append(board, *player)
+		return false
+	})
+
+	sort.Sort(board)
+
+	return board
+}
+
+// Methods for sorting the leaderboard
+func (r leaderBoard) Len() int {
+	return len(r)
+}
+
+func (r leaderBoard) Less(i, j int) bool {
+	if r[i].points != r[j].points {
+		return r[i].points > r[j].points
+	}
+
+	if r[i].wins != r[j].wins {
+		return r[i].wins > r[j].wins
+	}
+
+	if r[i].draws != r[j].draws {
+		return r[i].draws > r[j].draws
+	}
+
+	return false
+}
+
+func (r leaderBoard) Swap(i, j int) {
+	r[i], r[j] = r[j], r[i]
+}