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Tamagotchi Battle

tamagotchi-battle

Welcome to the exciting world of Tamagotchi Battle! In this fascinating game your faithful companions - Tamagotchi - are ready to fight each other in pursuit of glory and victory. In this game, you will be able to use the tamagotchi that was described in previous article.

To win, you'll have to skillfully manage your Tamagotchi and apply strategy. Take turns making moves, pave your way to success and, of course, rely on luck. In the Tamagotchi Battle Game, your engaging and exciting strategy can take you to the top.

The article explains the programming interface, data structure, basic functions and explains their purpose. It can be used as is or modified to suit your own scenarios. Anyone can easily create their own application and run it on the Vara Network. The source code is available on GitHub.

How to run​

  1. Build a program

Additional details regarding this matter can be located within the README directory of the program.

  1. Upload the program to the Vara Network Testnet

Further details regarding the process of program uploading can be located within the Getting Started section.

  1. Build and run user interface

More information about this can be found in the README directory of the frontend.

Implementation details​

Tamagotchi Battle program description​

The Tamagotchi Battle program contains the following information

tamagotchi-battle/src/lib.rs
struct Battle {
    admins: Vec<ActorId>,
    players: BTreeMap<ActorId, Player>,
    players_ids: Vec<ActorId>,
    current_players: Vec<ActorId>,
    state: BattleState,
    current_winner: ActorId,
    pairs: BTreeMap<PairId, Pair>,
    players_to_pairs: BTreeMap<ActorId, Vec<PairId>>,
    completed_games: u8,
    reservations: BTreeMap<ActorId, ReservationId>,
}
  • admins - administrators, who can start the battle and each new round
  • players - list of player parameters
  • players_ids - the actual tamagotchi id's that are playing
  • current_players - list of all registered tamagotchi
  • state - current battle stage
  • current_winner - winner of the last battle
  • pairs - list of pair parameters
  • players_to_pairs - matching players and their pair_ids
  • completed_games - the number of pairs that finished the battle
  • reservations - reservations id for delayed messages

Player structure looks as follows:

tamagotchi-battle/io/src/lib.rs
pub struct Player {
    pub owner: ActorId,
    pub name: String,
    pub date_of_birth: u64,
    pub tmg_id: TamagotchiId,
    pub defence: u16,
    pub power: u16,
    pub health: u16,
    pub color: String,
    pub victories: u32,
}
  • owner - owner's address
  • name - Tamagotchi name
  • date_of_birth - Tamagotchi's birthday
  • tmg_id - Tamagotchi id
  • defence - level of protection
  • power - level of power
  • health - level of health
  • color - tamagotchi color
  • victories - number of victories

Pair structure looks as follows:

tamagotchi-battle/io/src/lib.rs
pub struct Pair {
    pub owner_ids: Vec<ActorId>,
    pub tmg_ids: Vec<ActorId>,
    pub moves: Vec<Option<Move>>,
    pub rounds: u8,
    pub game_is_over: bool,
    pub winner: ActorId,
    pub move_deadline: u64,
    pub msg_id: MessageId,
}
  • owner_ids - it's a Tamagotchi owner's id
  • tmg_ids - it's a Tamagotchi id
  • moves - history of moves
  • rounds - current round number/number of rounds
  • game_is_over - end-of-game identifier
  • winner - the winner of the battle (in case there is no winner equals to zero address)
  • move_deadline - time limit for making a move
  • msg_id - message id for actions with delayed messages

Action​

The Tamagotchi Battle program offers the following activities:

tamagotchi-battle/io/src/lib.rs
pub enum BattleAction {
    StartRegistration,
    Register {
        tmg_id: TamagotchiId,
    },
    MakeMove {
        pair_id: PairId,
        tmg_move: Move,
    },
    // the following actions are only available to the admin
    StartBattle,
    AddAdmin(ActorId),
    CheckIfMoveMade {
        pair_id: PairId,
        tmg_id: Option<TamagotchiId>,
    },
}
tamagotchi-battle/io/src/lib.rs
pub enum Move {
    Attack,
    Defence,
}

Event​

For each activity, the program responds with the following replies:

tamagotchi-battle/io/src/lib.rs
pub enum BattleEvent {
    RegistrationStarted,
    Registered { tmg_id: TamagotchiId },
    MoveMade,
    GoToWaitingState,
    GameIsOver,
    InfoUpdated,
    NewGame,
    BattleStarted,
    RoundResult((PairId, u16, u16, Option<Move>, Option<Move>)),
    NewRound,
    AdminAdded,
}

Logic​

Before the start of the battle, it is necessary to initiate the registration process, during which the status of the game is checked and the terms of the program are determined.

tamagotchi-battle/src/lib.rs
fn start_registration(&mut self) {
    assert_eq!(
        self.state,
        BattleState::GameIsOver,
        "The previous game must be over"
    );
    self.state = BattleState::Registration;
    self.current_winner = ActorId::zero();
    self.players_ids = Vec::new();
    self.completed_games = 0;
    self.players_to_pairs = BTreeMap::new();
    self.current_players = Vec::new();
    self.pairs = BTreeMap::new();
    msg::reply(BattleEvent::RegistrationStarted, 0)
        .expect("Error in sending a reply `BattleEvent::RegistrationStarted`");
}

After that, registration for players will be available BattleAction::Register { tmg_id: TamagotchiId }, where players must provide the ActorId of their Tamagotchi. The registration function performs a series of checks before including a Tamagotchi in the list of participants. Tamagotchi power and defense are randomly generated during registration.

tamagotchi-battle/src/lib.rs
async fn register(&mut self, tmg_id: &TamagotchiId) {
    assert_eq!(
        self.state,
        BattleState::Registration,
        "The game is not in Registration stage"
    );

    assert!(
        self.players_ids.len() < MAX_PARTICIPANTS as usize,
        "Maximum number of players was reached"
    );

    if self.players_ids.contains(tmg_id) {
        panic!("This tamagotchi is already in game!");
    }
    let (owner, name, date_of_birth) = get_tmg_info(tmg_id).await;

    if owner != msg::source() {
        panic!("It is not your Tamagotchi");
    }
    if !self.players.contains_key(tmg_id) {
        let power = generate_power(*tmg_id);
        let defence = MAX_POWER - power;
    // ...

To start the game, the admin must send the BattleAction::StartBattle, where first checks will be carried out, and then there will be a split into pairs.

tamagotchi-battle/src/lib.rs
fn start_battle(&mut self) {
    assert!(
        self.state == BattleState::Registration || self.state == BattleState::WaitNextRound,
        "The battle can be started from registration stage of after completing a round"
    );

    assert!(
        self.players_ids.len() > 1,
        "At least 2 players must be in the game"
    );

    if !self.admins.contains(&msg::source()) {
        panic!("Only admin can start the battle");
    }

    // Clear the state if the state is `BattleState::WaitNextRound`
    self.pairs = BTreeMap::new();
    self.players_to_pairs = BTreeMap::new();
    self.completed_games = 0;

    self.split_into_pairs();

    self.state = BattleState::GameIsOn;

    msg::reply(BattleEvent::BattleStarted, 0)
        .expect("Error in a reply `BattleEvent::BattleStarted`");
}

Important notice: The split_into_pairs function uses a reserved gas delayed messaging feature msg::send_delayed_from_reservation designed to keep track of whether a player has made a move. If a player does not make a move in the given time, that player will be penalized and will get damage to his health.

tamagotchi-battle/src/lib.rs
fn send_delayed_msg_from_rsv(
    reservation_id: ReservationId,
    pair_id: PairId,
    tmg_id: &ActorId,
) -> MessageId {
    msg::send_delayed_from_reservation(
        reservation_id,
        exec::program_id(),
        BattleAction::CheckIfMoveMade {
            pair_id,
            tmg_id: Some(*tmg_id),
        },
        0,
        TIME_FOR_MOVE + 1,
    )
    .expect("Error in sending a delayed message `BattleAction::CheckIfModeMade`")
}

To make a move, a player needs to send a message BattleAction::MakeMove { pair_id: PairId, tmg_move: Move} that contains the pair id and the move the player wants to make.

tamagotchi-battle/src/lib.rs
fn make_move(&mut self, pair_id: PairId, tmg_move: Move) {
    assert_eq!(
        self.state,
        BattleState::GameIsOn,
        "The game is not in `GameIsOn` state"
    );

    let pair = self.pairs.get(&pair_id).expect("Pair does not exist");
    assert!(!pair.game_is_over, "The game for this pair is over");

    let current_turn = pair.moves.len();
    let owner = pair.owner_ids[current_turn];
    assert_eq!(
        owner,
        msg::source(),
        "It is not your turn or not your game!"
    );

    // ...

    let game_is_over = self.make_move_internal(pair_id, Some(tmg_move));

    if !game_is_over {
        let msg_id = send_delayed_msg_with_gas(pair_id);
        self.pairs
            .entry(pair_id)
            .and_modify(|pair| pair.msg_id = msg_id);
    }

    reply_move_made();
}

After the move is repeated, the delayed messages are used for the same purpose, but in this case, a different type of delayed message is used msg::send_with_gas_delayed, where the gas is applied separately.

tamagotchi-battle/src/lib.rs
fn send_delayed_msg_with_gas(pair_id: PairId) -> MessageId {
    msg::send_with_gas_delayed(
        exec::program_id(),
        BattleAction::CheckIfMoveMade {
            pair_id,
            tmg_id: None,
        },
        GAS_AMOUNT,
        0,
        TIME_FOR_MOVE + 1,
    )
    .expect("Error in sending a delayed message `BattleAction::CheckIfModeMade`")
}

After the battle and determination of the winner, the game status is switched to BattleState::WaitNextRound, where the winners will fight each other to determine the strongest.

Important details​

  1. If after a certain number of rounds (MAX_STEPS_IN_ROUND), it was not possible to determine the winner, then the one with more health wins.
tamagotchi-battle/src/lib.rs
if pair.rounds == MAX_STEPS_IN_ROUND && winner.is_none() {
    winner = if players[0].health >= players[1].health {
        players[1].health = 0;
        Some(0)
    } else {
        players[0].health = 0;
        Some(1)
    };
}
  1. After each round, it re-generates the power and defense of the Tamagotchi.
tamagotchi-battle/src/lib.rs
players[0].power = generate_power(pair.tmg_ids[0]);
players[0].defence = MAX_POWER - players[0].power;
players[1].power = generate_power(pair.tmg_ids[1]);
players[1].defence = MAX_POWER - players[1].power;
  1. When a player makes an attack, and the other player doesn't respond, the damage accumulates for both the attacker's strike and the opponent's penalty.
tamagotchi-battle/src/lib.rs
[Some(Move::Attack), None] => {
    let player_0_power = players[0].power / 6;
    // penalty for skipping the move
    let penalty = generate_damage();
    health_loss_1 = players[1].health.saturating_sub(
        players[1]
            .health
            .saturating_sub(player_0_power)
            .saturating_sub(penalty),
    );
    players[1].health = players[1]
        .health
        .saturating_sub(player_0_power)
        .saturating_sub(penalty);
    if players[1].health == 0 {
        winner = Some(0);
    }
    (winner, health_loss_0, health_loss_1)
}

Program metadata and state​

Metadata interface description:

tamagotchi-battle/io/src/lib.rs
pub struct BattleMetadata;

impl Metadata for BattleMetadata {
    type Init = ();
    type Handle = InOut<BattleAction, BattleEvent>;
    type Others = ();
    type Reply = ();
    type Signal = ();
    type State = Out<Battle>;
}

To display the program state information, the state() function is used:

tamagotchi-battle/src/lib.rs
#[no_mangle]
extern fn state() {
    let battle = unsafe { BATTLE.take().expect("Unexpected error in taking state") };
    msg::reply(battle, 0).expect("Failed to share state");
}

Source code​

The source code of this example of Tamagotchi Battle program and the example of an implementation of its testing is available on gear-foundation/dapp/contracts/tamagotchi-battle.

See also an example of the smart program testing implementation based on gtest: gear-foundation/dapps/tamagotchi-battle/tests.

For more details about testing programs written on Vara, refer to the Program Testing article.