Refactor the game flow and support splits

Behaves more like a client/server, rather than just taking a decision
function. The CLI logic is more complex now, but the game is more
flexible and and support splits (basically branching the hand off)

Cargo.lock

@@ -52,6 +52,12 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.98"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
+
 [[package]]
 name = "bitflags"
 version = "2.9.1"
@@ -62,10 +68,12 @@ checksum = "1b8e56985ec62d17e9c1001dc89c88ecd7dc08e47eba5ec7c29c7b5eeecde967"
 name = "blackjack"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "clap",
  "console",
  "itertools",
  "rand",
+ "thiserror",
 ]
 
 [[package]]
@@ -275,6 +283,26 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "thiserror"
+version = "2.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "567b8a2dae586314f7be2a752ec7474332959c6460e02bde30d702a66d488708"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "2.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f7cf42b4507d8ea322120659672cf1b9dbb93f8f2d4ecfd6e51350ff5b17a1d"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.18"

Cargo.toml

@@ -4,7 +4,9 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+anyhow = "1.0.98"
 clap = { version = "4.5.40", features = ["derive"] }
 console = "0.16.0"
 itertools = "0.14.0"
 rand = "0.9.1"
+thiserror = "2.0.12"

src/card.rs

@@ -1,7 +1,8 @@
 use std::fmt;
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub enum Suit {
+    Unknown,
     Club,
     Diamond,
     Heart,
@@ -15,12 +16,13 @@ impl fmt::Display for Suit {
             Suit::Diamond => "♦",
             Suit::Heart => "♥",
             Suit::Spade => "♠",
+            Suit::Unknown => "",
         };
         write!(f, "{c}")
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct Card {
     pub suit: Suit,
     pub value: String,
@@ -35,6 +37,27 @@ impl Card {
     }
 }
 
+impl From<(&str, &str)> for Card {
+    fn from(str_card: (&str, &str)) -> Self {
+        let suit = match str_card.0 {
+            "♣" => Suit::Club,
+            "♦" => Suit::Diamond,
+            "♥" => Suit::Heart,
+            "♠" => Suit::Spade,
+            "c" => Suit::Club,
+            "d" => Suit::Diamond,
+            "h" => Suit::Heart,
+            "s" => Suit::Spade,
+            _ => Suit::Unknown,
+        };
+
+        Self {
+            suit,
+            value: str_card.1.to_string(),
+        }
+    }
+}
+
 impl From<&Card> for u8 {
     fn from(card: &Card) -> u8 {
         match card.value.as_ref() {

src/error.rs

@@ -0,0 +1,17 @@
+use crate::game::Phase;
+use crate::hand::Hand;
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum BlackjackError {
+    #[error("Incorrect action for current game phase: {0}")]
+    IncorrectAction(Phase),
+    #[error("Cannot double down with this hand: {0}")]
+    Double(Hand),
+    #[error("Cannot split with this hand: {0}")]
+    Split(Hand),
+    #[error("This turn was already split")]
+    AlreadySplit,
+    #[error("Not enough chips on table to place bet")]
+    InsufficientChips,
+}

src/game.rs

@@ -1,19 +1,36 @@
 use crate::card::{deck_without_jokers, Card};
+use crate::error::BlackjackError;
 use crate::hand::Hand;
 use rand::prelude::*;
-use std::sync::{Arc, RwLock};
+use std::fmt;
 
 #[derive(Debug, PartialEq)]
 pub enum PlayerChoice {
     Hit,
     Stand,
     DoubleDown,
-    // TODO
+    Split,
-    // Split,
     // TODO
     // Surrender,
 }
 
+/// Phase that the game is in. Used in verifying that actions are legal
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum Phase {
+    New,
+    PlayerTurn,
+    DealerTurn,
+    Results,
+    Ended,
+}
+
+impl fmt::Display for Phase {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+#[derive(Debug, PartialEq)]
 pub enum PlayResult {
     Win,             // Player didn't bust, and either has higher value or dealer busted
     Blackjack,       // Player won with a face card and ace
@@ -23,67 +40,75 @@ pub enum PlayResult {
     Bust,            // Player lost because they busted
 }
 
+/// The game state while in the middle, which does not reveal the dealer's full hand
+pub struct MidState {
+    pub shuffled: bool,
+    pub player_hand: Hand,
+    pub dealer_showing: Card,
+    pub count: i16,
+}
+
 /// The state at the end of a round, useful for printing out
+#[derive(Debug)]
 pub struct EndState {
     pub result: PlayResult,
-    pub dealer_cards: Vec<Card>,
+    pub dealer_hand: Hand,
-    pub player_cards: Vec<Card>,
+    pub player_hand: Hand,
-    pub shuffled: bool,
+    pub returns: u32,
 }
 
-impl EndState {
+pub struct Table {
-    fn new(
-        result: PlayResult,
-        dealer_cards: Vec<Card>,
-        player_cards: Vec<Card>,
-        shuffled: bool,
-    ) -> Self {
-        Self {
-            result,
-            dealer_cards,
-            player_cards,
-            shuffled,
-        }
-    }
-}
-
-pub struct Game {
     rng: rand::rngs::ThreadRng,
     shoe: Vec<Card>,
     /// Discard pile. When the shoe runs out, this gets mixed with the shoe and reshuffled.
-    discard: Arc<RwLock<Vec<Card>>>,
+    discard: Vec<Card>,
     /// The current card count, see: https://en.wikipedia.org/wiki/Blackjack#Card_counting
     count: i16,
 
+    player_chips: u32,
+
+    // Mid-game state
+    /// Phase of the current game
+    phase: Phase,
+    dealer_hand: Hand,
+    /// How many player hands need to be resolved
+    pending_turns: u8,
+    /// How many results need to be resolved
+    pending_results: u8,
+
+    // Settings
+    /// If the dealer has a 17 with an Ace, they will hit. Gives advantage to dealer
     hit_on_soft_17: bool,
 
     /// Returns when hitting blackjack
     blackjack_returns: f32,
 }
 
-impl Game {
+impl Table {
-    pub fn new() -> Self {
+    pub fn new(decks: u8, player_chips: u32) -> Self {
-        Self {
+        let mut table = Self {
             // Game settings
             hit_on_soft_17: false,
             blackjack_returns: 3.0 / 2.0,
 
             // Game state
             rng: rand::rng(),
+            phase: Phase::New,
             shoe: Vec::new(),
-            discard: Arc::new(RwLock::new(Vec::new())),
+            discard: Vec::new(),
+            player_chips,
+            dealer_hand: Hand::new(),
+            pending_turns: 0,
+            pending_results: 0,
             count: 0,
-        }
+        };
-    }
 
-    /// Add some number of decks to the shoe, and shuffle it
+        for _ in 0..decks {
-    pub fn with_decks(mut self, count: u8) -> Self {
+            table.shoe.append(&mut deck_without_jokers())
-        for _ in 0..count {
-            self.shoe.append(&mut deck_without_jokers())
         }
-        self.shoe.shuffle(&mut self.rng);
+        table.shoe.shuffle(&mut table.rng);
 
-        self
+        table
     }
 
     /// Sets the dealer to hit on a soft 17 (one involving an Ace)
@@ -98,138 +123,20 @@ impl Game {
         self
     }
 
-    /// Play one round of Blackjack
+    pub fn player_chips(&self) -> u32 {
-    ///
+        self.player_chips
-    /// Takes a bet and a function, which is what the player will do during their turn. This
+    }
-    /// function must take the player's hand (Vec<Card>) and the card the dealer is showing (Card),
-    /// and returns a choice (hit, stand, etc.).
-    ///
-    /// Returns the winnings of the round
-    pub fn play<F>(
-        &mut self,
-        money_on_table: &mut u32,
-        bet_amount: u32,
-        player_decision: F,
-    ) -> EndState
-    where
-        F: Fn(&Hand, &Card, i16) -> PlayerChoice,
-    {
-        // Shuffle the deck if we've played over 75% of cards
-        let discard_size = self.discard.read().unwrap().len();
-        let mut shuffled = false;
-        if self.shoe.len() < (self.shoe.len() + discard_size) * 1 / 4 {
-            self.shuffle();
-            shuffled = true;
-        }
 
-        let mut bet_amount = bet_amount;
+    /// Reset the shoe - combine shoe and discard and shuffle
-        *money_on_table -= bet_amount;
+    fn shuffle(self: &mut Self) {
-
+        self.shoe.append(&mut self.discard);
-        // Deal cards
+        assert_eq!(self.discard.len(), 0);
-        let mut dealer_hand =
+        self.shoe.shuffle(&mut self.rng);
-            Hand::from([self.deal(), self.deal()].to_vec()).with_discard(self.discard.clone());
+        self.count = 0;
-        let mut player_hand =
-            Hand::from([self.deal(), self.deal()].to_vec()).with_discard(self.discard.clone());
-
-        // If dealer has blackjack, immediately lose. If player has blackjack, they win
-        if dealer_hand.is_blackjack() {
-            return EndState::new(
-                PlayResult::DealerBlackjack,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            );
-        } else if player_hand.is_blackjack() {
-            let returns = bet_amount as f32 * self.blackjack_returns;
-            *money_on_table += returns as u32;
-            return EndState::new(
-                PlayResult::Blackjack,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            );
-        }
-
-        // Player turn
-        loop {
-            let decision = player_decision(&player_hand, &dealer_hand.cards()[0], self.count);
-
-            match decision {
-                PlayerChoice::Stand => break,
-                PlayerChoice::Hit => {
-                    player_hand.push(self.deal());
-                }
-                PlayerChoice::DoubleDown => {
-                    if player_hand.cards().len() >= 3 {
-                        // Can only double-down as first move
-                        // TODO: Provide feedback that this move is invalid
-                        continue;
-                    }
-                    if *money_on_table >= bet_amount {
-                        *money_on_table -= bet_amount;
-                        bet_amount *= 2;
-                    }
-                    player_hand.push(self.deal());
-                    // Player can only take one additional card
-                    break;
-                }
-            }
-
-            // if player busts, immediately lose bet
-            if player_hand.value() > 21 {
-                break;
-            }
-        }
-        if player_hand.value() > 21 {
-            return EndState::new(
-                PlayResult::Bust,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            );
-        }
-
-        // Dealer turn
-        while dealer_hand.value() < 17 {
-            dealer_hand.push(self.deal());
-        }
-
-        if dealer_hand.value() > 21 {
-            *money_on_table += bet_amount * 2;
-            EndState::new(
-                PlayResult::Win,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            )
-        } else if dealer_hand.value() < player_hand.value() {
-            *money_on_table += bet_amount * 2;
-            EndState::new(
-                PlayResult::Win,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            )
-        } else if dealer_hand.value() == player_hand.value() {
-            *money_on_table += bet_amount;
-            EndState::new(
-                PlayResult::Push,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            )
-        } else {
-            EndState::new(
-                PlayResult::Lose,
-                dealer_hand.cards(),
-                player_hand.cards(),
-                shuffled,
-            )
-        }
     }
 
     /// Deal a single card from the shoe
-    fn deal(self: &mut Self) -> Card {
+    fn deal_card(&mut self) -> Card {
         let card = self.shoe.pop().unwrap();
 
         if u8::from(&card) < 6 {
@@ -241,12 +148,370 @@ impl Game {
         card
     }
 
-    /// Reset the shoe - combine shoe and discard and shuffle
+    /// Deal out a hand and start a game
-    fn shuffle(self: &mut Self) {
+    pub fn deal_hand(&mut self, bet: u32) -> PlayerTurn {
-        let mut discard = self.discard.write().unwrap();
+        self.dealer_hand = Hand::new();
-        self.shoe.append(&mut discard);
+        let mut player = PlayerTurn::new(bet);
-        assert_eq!(discard.len(), 0);
+
-        self.shoe.shuffle(&mut self.rng);
+        // Shuffle the deck if we've played over 75% of cards
-        self.count = 0;
+        let discard_size = self.discard.len();
+        if self.shoe.len() < (self.shoe.len() + discard_size) * 1 / 4 {
+            self.shuffle();
+            player.shuffled = true;
+        }
+
+        // Sanity check to make sure we don't accidentally clone cards into the discard
+        let total_cards = self.shoe.len() + self.discard.len();
+        if total_cards % 52 != 0 {
+            panic!("Wrong number of cards in shoe + discard: {total_cards}");
+        }
+
+        self.player_chips -= bet;
+
+        // Deal cards in a circle, player(s) then dealer
+        for _ in 0..2 {
+            player.hand.push(self.deal_card());
+            let dealer_card = self.deal_card();
+            self.dealer_hand.push(dealer_card);
+        }
+
+        self.phase = Phase::PlayerTurn;
+        self.pending_turns += 1;
+        self.pending_results += 1;
+
+        player
+    }
+
+    /// Returns the card that the dealer is showing
+    pub fn dealer_showing(&self) -> Card {
+        self.dealer_hand.cards()[0].clone()
+    }
+
+    /// Run the dealer's turn and finish the game
+    pub fn dealers_turn(&mut self) -> Result<(), BlackjackError> {
+        if self.phase != Phase::DealerTurn {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+
+        while self.dealer_hand.value() < 17 {
+            let dealer_card = self.deal_card();
+            self.dealer_hand.push(dealer_card);
+        }
+        self.phase = Phase::Results;
+        Ok(())
+    }
+
+    /// Get the results
+    pub fn results(&mut self, turn: PlayerTurn) -> Result<EndState, BlackjackError> {
+        if self.phase != Phase::Results {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+
+        let mut end_state = EndState {
+            result: PlayResult::Lose,
+            dealer_hand: self.dealer_hand.clone(),
+            player_hand: turn.hand.clone(),
+            returns: 0,
+        };
+        if self.dealer_hand.is_blackjack() {
+            end_state.result = PlayResult::DealerBlackjack;
+        } else if turn.hand.is_blackjack() {
+            end_state.result = PlayResult::Blackjack;
+            let bj_winnings = (turn.bet as f32 * self.blackjack_returns) as u32;
+            end_state.returns = turn.bet + bj_winnings;
+        } else if turn.hand.value() > 21 {
+            end_state.result = PlayResult::Bust;
+        } else if self.dealer_hand.value() > 21 {
+            end_state.result = PlayResult::Win;
+            end_state.returns = turn.bet * 2;
+        } else if self.dealer_hand.value() < turn.hand.value() {
+            end_state.result = PlayResult::Win;
+            end_state.returns = turn.bet * 2;
+        } else if self.dealer_hand.value() == turn.hand.value() {
+            end_state.result = PlayResult::Push;
+            end_state.returns = turn.bet;
+        }
+        self.player_chips += end_state.returns;
+        self.pending_results -= 1;
+
+        // Since we're turning the hand in here (taking ownership of the PlayerTurn), we can
+        // discard the cards now
+        self.discard_hand(turn.hand);
+
+        if self.pending_results == 0 {
+            self.phase = Phase::Ended;
+        }
+
+        Ok(end_state)
+    }
+
+    pub fn discard_hand(&mut self, hand: Hand) {
+        self.discard.append(&mut hand.cards());
+    }
+
+    /// End the game and reset table state
+    pub fn end_game(&mut self) -> Result<(), BlackjackError> {
+        if self.phase != Phase::Ended {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+        self.discard.append(&mut self.dealer_hand.cards());
+        self.dealer_hand = Hand::new();
+        self.phase = Phase::New;
+        Ok(())
+    }
+
+    // -- player functions --
+    /// Stand, ending the player's turn
+    pub fn stand(&mut self, turn: &mut PlayerTurn) -> Result<(), BlackjackError> {
+        if self.phase != Phase::PlayerTurn {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+        if turn.stood {
+            return Ok(());
+        }
+        turn.stood = true;
+        self.pending_turns -= 1;
+
+        if self.pending_turns == 0 {
+            self.phase = Phase::DealerTurn;
+        }
+        Ok(())
+    }
+
+    pub fn hit(&mut self, turn: &mut PlayerTurn) -> Result<(), BlackjackError> {
+        if self.phase != Phase::PlayerTurn {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+        turn.hand.push(self.deal_card());
+        Ok(())
+    }
+
+    /// Double the bet and take one additional card, standing afterward
+    pub fn double_down(&mut self, turn: &mut PlayerTurn) -> Result<(), BlackjackError> {
+        if self.phase != Phase::PlayerTurn {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        } else if turn.hand.cards().len() != 2 {
+            return Err(BlackjackError::Double(turn.hand.clone()));
+        } else if self.player_chips < turn.bet {
+            return Err(BlackjackError::InsufficientChips);
+        }
+
+        self.player_chips -= turn.bet;
+        turn.bet *= 2;
+        turn.hand.push(self.deal_card());
+        self.stand(turn)
+    }
+
+    /// Split the hand. Returns a second Round which was split off of this one
+    pub fn split(&mut self, turn: &mut PlayerTurn) -> Result<PlayerTurn, BlackjackError> {
+        if self.phase != Phase::PlayerTurn {
+            return Err(BlackjackError::IncorrectAction(self.phase));
+        }
+        // Make sure the user isn't trying to split again, and that the hand is valid to split
+        if turn.was_split {
+            return Err(BlackjackError::AlreadySplit);
+        } else if !turn.hand.is_pair() {
+            return Err(BlackjackError::Split(turn.hand.clone()));
+        } else if self.player_chips < turn.bet {
+            return Err(BlackjackError::InsufficientChips);
+        }
+
+        self.player_chips -= turn.bet;
+
+        let mut other_hand = turn.hand.split();
+        turn.hand.push(self.deal_card());
+        other_hand.push(self.deal_card());
+
+        self.pending_turns += 1;
+        self.pending_results += 1;
+
+        turn.was_split = true;
+        Ok(PlayerTurn {
+            hand: other_hand,
+            bet: turn.bet,
+            shuffled: turn.shuffled,
+            stood: false,
+            was_split: true,
+        })
+    }
+}
+
+/// Represents one round (or hand) of Blackjack. Becomes duplicated on a split.
+pub struct PlayerTurn {
+    hand: Hand,
+    pub bet: u32,
+    pub stood: bool,
+    pub was_split: bool,
+
+    /// Indicates if the deck was shuffled when dealing cards for this turn
+    pub shuffled: bool,
+}
+
+impl PlayerTurn {
+    pub fn new(bet: u32) -> Self {
+        Self {
+            hand: Hand::new(),
+            bet,
+            shuffled: false,
+            stood: false,
+            was_split: false,
+        }
+    }
+
+    /// Returns a read-only copy of the player's hand
+    pub fn player_hand(&self) -> Hand {
+        Hand::from(self.hand.cards())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Set up a game with the specified hands
+    fn setup_hands(
+        bet: u32,
+        dealer_cards: Vec<(&str, &str)>,
+        player_cards: Vec<(&str, &str)>,
+    ) -> (Table, PlayerTurn) {
+        let mut table = Table::new(6, bet);
+        table.pending_turns = 1;
+        table.pending_results = 1;
+        table.dealer_hand = Hand::from(dealer_cards);
+        table.phase = Phase::PlayerTurn;
+
+        let mut turn = PlayerTurn::new(10);
+        turn.hand = Hand::from(player_cards);
+
+        (table, turn)
+    }
+
+    /// Play a game with the specified hands
+    fn play_hands(
+        bet: u32,
+        dealer_cards: Vec<(&str, &str)>,
+        player_cards: Vec<(&str, &str)>,
+    ) -> anyhow::Result<EndState> {
+        let (mut table, mut turn) = setup_hands(bet, dealer_cards, player_cards);
+        table.stand(&mut turn)?;
+        table.dealers_turn()?;
+
+        Ok(table.results(turn)?)
+    }
+
+    #[test]
+    fn player_lose() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "9"), ("♣", "10")]),
+            Vec::from([("♣", "5"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::Lose);
+        assert_eq!(result.returns, 0);
+    }
+
+    #[test]
+    fn player_win() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "5"), ("♣", "10")]),
+            Vec::from([("♣", "9"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::Win);
+        assert_eq!(result.returns, 20);
+    }
+
+    #[test]
+    fn tie() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "9"), ("♣", "10")]),
+            Vec::from([("♣", "9"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::Push);
+        assert_eq!(result.returns, 10);
+    }
+
+    #[test]
+    fn player_blackjack() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "5"), ("♣", "10")]),
+            Vec::from([("♣", "A"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::Blackjack);
+        assert_eq!(result.returns, 10 + 15);
+    }
+
+    #[test]
+    fn player_blackjack_dealer_21() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "5"), ("♣", "10"), ("♣", "6")]),
+            Vec::from([("♣", "A"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::Blackjack);
+        assert_eq!(result.returns, 10 + 15);
+    }
+
+    #[test]
+    fn dealer_blackjack() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "A"), ("♣", "10")]),
+            Vec::from([("♣", "9"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::DealerBlackjack);
+        assert_eq!(result.returns, 0);
+    }
+
+    #[test]
+    fn both_blackjack() {
+        let result = play_hands(
+            10,
+            Vec::from([("♣", "A"), ("♣", "10")]),
+            Vec::from([("♣", "A"), ("♣", "10")]),
+        )
+        .unwrap();
+        assert_eq!(result.result, PlayResult::DealerBlackjack);
+        assert_eq!(result.returns, 0);
+    }
+
+    #[test]
+    /// A shuffle should leave us with the same number of cards
+    fn shuffle_same_cards() {
+        let mut table = Table::new(6, 0);
+
+        // Initial state sanity check
+        let discard_size = table.discard.len();
+        let pre = table.shoe.len() + discard_size;
+        println!("Pre shuffle: {}, {}", table.shoe.len(), discard_size);
+
+        table.shuffle();
+
+        let discard_size = table.discard.len();
+        let post = table.shoe.len() + table.discard.len();
+        println!("Post shuffle: {}, {}", table.shoe.len(), discard_size);
+        assert_eq!(pre, post);
+
+        // Deal out some cards and discard them, then shuffle to make sure we're good
+        let hand1 = Hand::from([table.deal_card(), table.deal_card()].to_vec());
+        let hand2 = Hand::from([table.deal_card(), table.deal_card()].to_vec());
+        table.discard_hand(hand1);
+        table.discard_hand(hand2);
+        assert_eq!(table.discard.len(), 4);
+
+        table.shuffle();
+
+        let discard_size = table.discard.len();
+        let post = table.shoe.len() + table.discard.len();
+        println!("Post shuffle: {}, {}", table.shoe.len(), discard_size);
+        assert_eq!(pre, post);
     }
 }

src/hand.rs

@@ -1,32 +1,20 @@
 use crate::card::Card;
 use itertools::Itertools;
 use std::fmt;
-use std::sync::{Arc, RwLock};
 
+#[derive(Clone, Debug)]
 pub struct Hand {
     cards: Vec<Card>,
-    discard: Option<Arc<RwLock<Vec<Card>>>>,
 }
 
 impl Hand {
     pub fn new() -> Self {
-        Self {
+        Self { cards: Vec::new() }
-            cards: Vec::new(),
-            discard: None,
-        }
-    }
-
-    pub fn with_discard(mut self, discard: Arc<RwLock<Vec<Card>>>) -> Self {
-        self.discard = Some(discard);
-        self
     }
 
     /// Returns the value of the hand. If there are any aces, this is the highest value without
     /// busting.
     pub fn value(&self) -> u8 {
-        // TODO: Return the highest value without busting? And maybe let the player function
-        // determine if they have an ace and want to hit instead.
-        // Basic Strategy actually says what to do in the case of an ace
         let mut num_aces = 0;
         let mut sum = 0;
 
@@ -80,7 +68,12 @@ impl Hand {
         false
     }
 
-    /// Returns a copy of the cards in the hand
+    /// Returns true if the hand has a pair (can be split)
+    pub fn is_pair(&self) -> bool {
+        self.cards.len() == 2 && u8::from(&self.cards[0]) == u8::from(&self.cards[1])
+    }
+
+    /// Returns a read-only copy of the cards in the hand
     pub fn cards(&self) -> Vec<Card> {
         self.cards.clone()
     }
@@ -89,13 +82,25 @@ impl Hand {
     pub fn push(&mut self, card: Card) {
         self.cards.push(card)
     }
+
+    /// Split the hand into two
+    pub fn split(&mut self) -> Hand {
+        let other_cards: Vec<Card> = Vec::from(self.cards.pop().as_slice());
+
+        Hand { cards: other_cards }
+    }
 }
 
 impl From<Vec<Card>> for Hand {
     fn from(cards: Vec<Card>) -> Self {
+        Self { cards }
+    }
+}
+
+impl From<Vec<(&str, &str)>> for Hand {
+    fn from(str_cards: Vec<(&str, &str)>) -> Self {
         Self {
-            cards,
+            cards: str_cards.into_iter().map(|c| (c).into()).collect(),
-            discard: None,
         }
     }
 }
@@ -112,18 +117,6 @@ impl fmt::Display for Hand {
     }
 }
 
-impl Drop for Hand {
-    fn drop(&mut self) {
-        match &mut self.discard {
-            Some(x) => {
-                let mut discard = x.write().unwrap();
-                discard.append(&mut self.cards)
-            }
-            None => {}
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -154,26 +147,4 @@ mod tests {
         h.cards.push(Card::new(Suit::Club, "A"));
         assert_eq!(h.value(), 16);
     }
-
-    #[test]
-    /// If we give the hand a discard pile, then it should throw its cards in there when it gets
-    /// dropped
-    fn discard_pile() {
-        let discard = Arc::new(RwLock::new(Vec::new()));
-
-        {
-            let hand =
-                Hand::from([Card::new(Suit::Heart, "1"), Card::new(Suit::Heart, "2")].to_vec())
-                    .with_discard(discard.clone());
-
-            assert_eq!(hand.value(), 3);
-
-            // Hand still in scope, so discard pile is empty
-            assert_eq!(discard.read().unwrap().len(), 0);
-        }
-
-        let d = discard.read().unwrap();
-        // Hand went out of scope and got discarded
-        assert_eq!(d.len(), 2);
-    }
 }

src/lib.rs

@@ -1,3 +1,4 @@
 pub mod card;
+pub mod error;
 pub mod game;
 pub mod hand;

src/main.rs

@@ -1,5 +1,5 @@
 use blackjack::card::Card;
-use blackjack::game::{Game, PlayResult, PlayerChoice};
+use blackjack::game::{EndState, PlayResult, PlayerChoice, PlayerTurn, Table};
 use blackjack::hand::Hand;
 use clap::{Parser, ValueEnum};
 use console::Term;
@@ -7,12 +7,11 @@ use std::env;
 use std::fs;
 use std::io;
 use std::io::prelude::*;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
-fn main() {
+fn main() -> anyhow::Result<()> {
     // TODO: Use anyhow for error handling, get rid of unwraps
     let args = Args::parse();
-    println!("{:?}", args);
     match args.mode {
         Mode::Interactive => interactive_play(),
         Mode::OldMan => old_man(),
@@ -32,16 +31,15 @@ struct Args {
     mode: Mode,
 }
 
-fn interactive_play() {
+fn interactive_play() -> anyhow::Result<()> {
     // TODO: Make a way to reset bank
-    //
     let term = Term::stdout();
-    let mut bank: u32 = match load_bank() {
+    let mut bank: u32 = match load_bank()? {
         Some(b) => b,
         None => 1_000,
     };
 
-    let mut game = Game::new().with_decks(6).with_hit_on_soft_17();
+    let mut table = Table::new(6, bank).with_hit_on_soft_17();
     let mut last_bet: Option<u32> = None;
 
     loop {
@@ -51,11 +49,12 @@ fn interactive_play() {
         let mut bet: u32;
         loop {
             if last_bet.is_some() {
-                print!("Your bet [{}]? ", last_bet.unwrap());
+                let last_bet = last_bet.unwrap();
+                print!("Your bet [{}]? ", last_bet);
                 io::stdout().flush().unwrap();
-                let input = term.read_line().unwrap();
+                let input = term.read_line()?;
                 if input == "" {
-                    bet = last_bet.unwrap();
+                    bet = last_bet;
                 } else {
                     match input.parse() {
                         Ok(b) => bet = b,
@@ -64,8 +63,8 @@ fn interactive_play() {
                 }
             } else {
                 print!("Your bet? ");
-                io::stdout().flush().unwrap();
+                io::stdout().flush()?;
-                match term.read_line().unwrap().parse() {
+                match term.read_line()?.parse() {
                     Ok(b) => bet = b,
                     Err(_) => continue,
                 }
@@ -80,118 +79,274 @@ fn interactive_play() {
         last_bet = Some(bet);
         println!();
 
-        let result = game.play(&mut bank, bet, interactive_decision);
+        let mut turn = table.deal_hand(bet);
-        let dealer_hand = Hand::from(result.dealer_cards);
+        if turn.shuffled {
-        let player_hand = Hand::from(result.player_cards);
+            println!("Deck was shuffled");
-
-        term.clear_screen().unwrap();
-        println!("Dealer's hand: {} = {}", dealer_hand, dealer_hand.value());
-        println!("Your hand: {} = {}", player_hand, player_hand.value());
-
-        match result.result {
-            PlayResult::Win => println!("You won!"),
-            PlayResult::Blackjack => println!("Blackjack!"),
-            PlayResult::Lose => println!("You lost"),
-            PlayResult::Push => println!("Push"),
-            PlayResult::DealerBlackjack => println!("Dealer got blackjack"),
-            PlayResult::Bust => println!("You busted"),
-        }
-        if result.shuffled {
-            println!("Deck was shuffled at beginning of round");
         }
 
-        save_bank(bank);
+        let split_turn = interactive_play_turn(&mut turn, &mut table)?;
+        if split_turn.is_none() {
+            table.dealers_turn()?;
+            let result = table.results(turn)?;
+            term.clear_screen()?;
+            print_result(&result);
+        } else {
+            let mut split_turn = split_turn.unwrap();
+            interactive_play_turn(&mut split_turn, &mut table)?;
+            table.dealers_turn()?;
+            let result = table.results(turn)?;
+            let split_result = table.results(split_turn)?;
+
+            term.clear_screen()?;
+            print_result(&result);
+            println!();
+            print_result(&split_result);
+        }
+
+        table.end_game()?;
+        bank = table.player_chips();
+        save_bank(bank)?;
 
         if bank == 0 {
             println!("You're out of money.");
-            return;
+            break;
         }
     }
+
+    Ok(())
 }
 
-fn interactive_decision(hand: &Hand, dealer_showing: &Card, _count: i16) -> PlayerChoice {
+/// Play a turn. Returns another turn if this one was split
+fn interactive_play_turn(
+    turn: &mut PlayerTurn,
+    table: &mut Table,
+) -> anyhow::Result<Option<PlayerTurn>> {
+    let mut initial_play = true && !turn.was_split;
+    let mut other_turn = None;
+
     let term = Term::stdout();
-    term.clear_screen().unwrap();
-
-    println!("Dealer showing: {dealer_showing}");
-    println!("Your hand: {hand}");
-    println!();
-
-    if hand.value() == 21 {
-        println!("You have 21, standing.");
-        return PlayerChoice::Stand;
-    }
-
-    let choice: PlayerChoice;
-    let can_dd = hand.cards().len() == 2;
     loop {
+        term.clear_screen()?;
+        let hand = turn.player_hand();
+
+        println!("Your bet: ${}", turn.bet);
+        println!("Dealer showing: {}", table.dealer_showing());
+        println!("Your hand: {hand}");
+        println!();
+
+        if hand.value() == 21 {
+            println!("You have 21, standing.");
+            table.stand(turn)?;
+            break;
+        } else if hand.value() > 21 {
+            println!("You busted");
+            table.stand(turn)?;
+            break;
+        }
+
         let mut msg = String::from("(h)it, (s)tand");
-        if can_dd {
+        if initial_play {
             msg += ", (d)ouble-down";
+            if hand.is_pair() {
+                msg += ", s(p)lit";
+            }
         }
         msg += "? ";
-        io::stdout().write_all(msg.as_bytes()).unwrap();
+        io::stdout().write_all(msg.as_bytes())?;
-        io::stdout().flush().unwrap();
+        io::stdout().flush()?;
-        choice = match term.read_char().unwrap() {
+
-            'h' => PlayerChoice::Hit,
+        let mut stop = false;
-            's' => PlayerChoice::Stand,
+        match term.read_char()? {
-            'd' if can_dd => PlayerChoice::DoubleDown,
+            'h' => {
-            _ => continue,
+                table.hit(turn)?;
+                initial_play = false;
+            }
+            's' => {
+                table.stand(turn)?;
+                stop = true;
+                initial_play = false;
+            }
+            'd' if initial_play => {
+                table.double_down(turn)?;
+                stop = true;
+                initial_play = false;
+            }
+            'p' if initial_play && turn.player_hand().is_pair() => {
+                other_turn = Some(table.split(turn)?);
+                initial_play = false;
+            }
+            _ => {}
         };
-        println!("\n");
+        if stop {
-        break;
+            break;
+        }
     }
-    choice
+
+    Ok(other_turn)
 }
 
-fn basic_strategy(hand: &Hand, dealer_showing: &Card, _count: i16) -> PlayerChoice {
+fn print_result(result: &EndState) {
+    println!(
+        "Dealer's hand: {} = {}",
+        result.dealer_hand,
+        result.dealer_hand.value()
+    );
+    println!(
+        "Your hand: {} = {}",
+        result.player_hand,
+        result.player_hand.value()
+    );
+
+    match result.result {
+        PlayResult::Win => println!("You won!"),
+        PlayResult::Blackjack => println!("Blackjack!"),
+        PlayResult::Lose => println!("You lost"),
+        PlayResult::Push => println!("Push"),
+        PlayResult::DealerBlackjack => println!("Dealer got blackjack"),
+        PlayResult::Bust => println!("You busted"),
+    }
+    println!("You got: ${}", result.returns);
+}
+
+// TODO: Make this use a lookup table, this if logic is gnarly
+fn basic_strategy(
+    hand: &Hand,
+    dealer_showing: &Card,
+    can_split: bool,
+    can_dd: bool,
+) -> PlayerChoice {
     // Source: https://en.wikipedia.org/wiki/Blackjack#Basic_strategy
     let dv = u8::from(dealer_showing);
-    let can_dd = hand.cards().len() == 2;
+
-    if hand.has_ace() && hand.cards().len() == 2 {
+    if hand.is_pair() && can_split {
+        // Got a pair, maybe should split
+        // We check can_split right at the get-go, because if we can't we just follow the Hard
+        // Total table.
+        let aces = hand.cards()[0].value == String::from("A");
+        match hand.value() {
+            12 if aces => PlayerChoice::Split,
+            20 => PlayerChoice::Stand,
+            18 => match dv {
+                2..=6 => PlayerChoice::Split,
+                7 => PlayerChoice::Stand,
+                _ => PlayerChoice::Split,
+            },
+            16 => PlayerChoice::Split,
+            14 => match dv {
+                2..=7 => PlayerChoice::Split,
+                _ => PlayerChoice::Hit,
+            },
+            12 => match dv {
+                2..=6 => PlayerChoice::Split,
+                _ => PlayerChoice::Hit,
+            },
+            10 => match dv {
+                2..=9 if can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
+            },
+            8 => match dv {
+                5..=6 => PlayerChoice::Split,
+                _ => PlayerChoice::Hit,
+            },
+            4..=6 => match dv {
+                2..=7 => PlayerChoice::Split,
+                _ => PlayerChoice::Hit,
+            },
+            _ => PlayerChoice::Stand,
+        }
+    } else if hand.has_ace() && hand.cards().len() == 2 {
         // Ace and some other card
         match hand.value() {
-            v if v >= 19 => PlayerChoice::Stand,
+            20 => PlayerChoice::Stand,
-            v if v == 18 && (7..=8).contains(&dv) => PlayerChoice::Stand,
+            19 if dv == 6 && can_dd => PlayerChoice::DoubleDown,
-            v if v == 18 && dv < 7 && can_dd => PlayerChoice::DoubleDown,
+            19 => PlayerChoice::Stand,
-            v if v == 18 && dv < 7 => PlayerChoice::Stand,
+            18 => match dv {
-            v if v == 17 && (3..=6).contains(&dv) && can_dd => PlayerChoice::DoubleDown,
+                2..=6 if can_dd => PlayerChoice::DoubleDown,
-            v if v == 17 && (3..=6).contains(&dv) => PlayerChoice::Hit,
+                9..=11 => PlayerChoice::Hit,
-            v if (15..=16).contains(&v) && (4..=6).contains(&dv) && can_dd => {
+                _ => PlayerChoice::Stand,
-                PlayerChoice::DoubleDown
+            },
-            }
+            17 => match dv {
-            v if (15..=16).contains(&v) && (4..=6).contains(&dv) => PlayerChoice::Hit,
+                3..=6 if can_dd => PlayerChoice::DoubleDown,
-            v if (13..=14).contains(&v) && (5..=6).contains(&dv) && can_dd => {
+                _ => PlayerChoice::Hit,
-                PlayerChoice::DoubleDown
+            },
-            }
+            15..=16 => match dv {
-            v if (13..=14).contains(&v) && (5..=6).contains(&dv) => PlayerChoice::Hit,
+                4..=6 if can_dd => PlayerChoice::DoubleDown,
-            v if v == 12 && dv == 6 && can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
-            v if v == 12 && dv == 6 => PlayerChoice::Hit,
+            },
+            13..=14 => match dv {
+                5..=6 if can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
+            },
+            12 if dv == 6 && can_dd => PlayerChoice::DoubleDown,
             _ => PlayerChoice::Hit,
         }
     } else {
         match hand.value() {
-            v if v >= 17 => PlayerChoice::Stand,
+            17..=21 => PlayerChoice::Stand,
-            v if v > 12 && dv < 7 => PlayerChoice::Stand,
+            13..=16 if dv >= 7 => PlayerChoice::Hit,
-            v if v == 12 && (4..=6).contains(&dv) => PlayerChoice::Stand,
+            13..=16 => PlayerChoice::Stand,
-            v if v == 11 && can_dd => PlayerChoice::DoubleDown,
+            12 => match dv {
-            v if v == 11 => PlayerChoice::Hit,
+                4..=6 => PlayerChoice::Stand,
-            v if v == 10 && dv < 10 && can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
-            v if v == 10 && dv < 10 => PlayerChoice::Hit,
+            },
-            v if v == 9 && (3..=6).contains(&dv) && can_dd => PlayerChoice::DoubleDown,
+            11 if can_dd => PlayerChoice::DoubleDown,
-            v if v == 9 && (3..=6).contains(&dv) => PlayerChoice::Hit,
+            11 => PlayerChoice::Hit,
-            _ => PlayerChoice::Hit,
+            10 => match dv {
+                2..=9 if can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
+            },
+            9 => match dv {
+                3..=6 if can_dd => PlayerChoice::DoubleDown,
+                _ => PlayerChoice::Hit,
+            },
+            _ => PlayerChoice::Stand,
         }
     }
 }
 
+fn basic_strategy_play_turn(
+    turn: &mut PlayerTurn,
+    table: &mut Table,
+) -> anyhow::Result<Option<PlayerTurn>> {
+    let mut other_turn: Option<PlayerTurn> = None;
+    loop {
+        // Enough chips to split or double down?
+        let enough_chips = turn.bet <= table.player_chips();
+
+        let can_split = !turn.was_split && enough_chips && turn.player_hand().is_pair();
+        let can_dd = enough_chips && turn.player_hand().cards().len() == 2;
+
+        match basic_strategy(
+            &turn.player_hand(),
+            &table.dealer_showing(),
+            can_split,
+            can_dd,
+        ) {
+            PlayerChoice::Hit => table.hit(turn)?,
+            PlayerChoice::Stand => {
+                table.stand(turn)?;
+                break;
+            }
+            PlayerChoice::DoubleDown => {
+                table.double_down(turn)?;
+                break;
+            }
+            PlayerChoice::Split => {
+                other_turn = Some(table.split(turn)?);
+            }
+        }
+    }
+
+    Ok(other_turn)
+}
+
 /// An cab driver to the LAS airport was a former dealer and told me about this retired guy who
 /// would come play Blackjack every day at 7am like clockwork. He'd bring $400 to the table, play
 /// basic strategy, and would walk away once he was $100 up. He made about $3000/mo off of this, in
 /// addition to points/comps which he would use to eat brunch for free.
 ///
 /// Does this actually work, or was the driver full of it?
-fn old_man() {
+fn old_man() -> anyhow::Result<()> {
     const START: u32 = 100_000;
     const PER_DAY: u32 = 400;
     const MIN_BET: u32 = 15;
@@ -199,7 +354,7 @@ fn old_man() {
     // Walk away when we're up by this much
     const MAX_WIN: u32 = 100;
     // Walk away when we're down by this much
-    const MAX_LOSS: u32 = 100;
+    const MAX_LOSS: u32 = MAX_WIN;
     // Run sim for this many days
     const DAYS: u16 = 30;
 
@@ -208,53 +363,76 @@ fn old_man() {
     println!("Starting with bank: ${bank}");
     // Let's simulate this for 30 days
     for day in 1..=DAYS {
-        let mut in_hand: u32 = PER_DAY;
+        bank -= PER_DAY;
-        bank -= in_hand;
 
-        let mut game = Game::new().with_decks(6).with_hit_on_soft_17();
+        let mut table = Table::new(6, PER_DAY).with_hit_on_soft_17();
         let mut rounds = 0;
-        while in_hand > MIN_BET && in_hand < (PER_DAY + MAX_WIN) && in_hand > (PER_DAY - MAX_LOSS) {
+        while table.player_chips() > MIN_BET
-            let bet = MIN_BET;
+            && table.player_chips() < (PER_DAY + MAX_WIN)
-            game.play(&mut in_hand, bet, basic_strategy);
+            && table.player_chips() > (PER_DAY - MAX_LOSS)
+        {
+            let mut turn = table.deal_hand(MIN_BET);
+            let split_turn = basic_strategy_play_turn(&mut turn, &mut table)?;
+            if split_turn.is_none() {
+                table.dealers_turn()?;
+                table.results(turn)?;
+                // No need to handle result since we take chips off table at end of day
+            } else {
+                let mut split_turn = split_turn.unwrap();
+                basic_strategy_play_turn(&mut split_turn, &mut table)?;
+                table.dealers_turn()?;
+                // No need to handle result since we take chips off table at end of day
+                table.results(turn)?;
+                table.results(split_turn)?;
+            }
+
+            table.end_game()?;
             rounds += 1;
         }
-        println!("Day {day}, after {rounds} rounds, in-hand: ${in_hand}");
+        bank += table.player_chips();
-        bank += in_hand;
+        println!(
+            "Day {day}, after {rounds} rounds, returns: ${}, bank: ${}",
+            table.player_chips() as i32 - PER_DAY as i32,
+            bank,
+        );
     }
 
     let pl: i64 = bank as i64 - START as i64;
     println!("Ending with: ${bank}");
     println!("Profit/Loss: ${pl}");
+
+    Ok(())
 }
 
 fn data_dir() -> PathBuf {
     env::home_dir().unwrap().join(".local/share/blackjack")
 }
 
-fn save_bank(bank: u32) {
+fn save_bank(bank: u32) -> anyhow::Result<()> {
-    ensure_data_dir();
+    ensure_data_dir()?;
     let bank_path = data_dir().join("bank.txt");
-    fs::write(bank_path, bank.to_string()).unwrap();
+    Ok(fs::write(bank_path, bank.to_string())?)
 }
 
-fn load_bank() -> Option<u32> {
+fn load_bank() -> anyhow::Result<Option<u32>> {
     let bank_path = data_dir().join("bank.txt");
-    if fs::exists(&bank_path).unwrap() {
+    if fs::exists(&bank_path)? {
-        let bank = fs::read_to_string(&bank_path).unwrap().parse().unwrap();
+        let bank = fs::read_to_string(&bank_path)?.parse()?;
         if bank > 0 {
-            Some(bank)
+            Ok(Some(bank))
         } else {
-            None
+            Ok(None)
         }
     } else {
-        None
+        Ok(None)
     }
 }
 
-fn ensure_data_dir() {
+fn ensure_data_dir() -> anyhow::Result<()> {
-    if !fs::exists(data_dir()).unwrap() {
+    if !fs::exists(data_dir())? {
-        fs::create_dir_all(data_dir()).unwrap();
+        fs::create_dir_all(data_dir())?;
     }
+    Ok(())
 }
 
 #[cfg(test)]
@@ -276,7 +454,8 @@ mod tests {
                     .to_vec()
                 ),
                 &Card::new(Suit::Heart, "J"),
-                0,
+                true,
+                true,
             ),
             PlayerChoice::Stand,
         )