v1.2.0: show the symbol paytable on the slots board

4 files changed, 45 insertions, 26 deletions

diff --git a/src/client/games/slots.rs b/src/client/games/slots.rs
index c367fcb..7e59919 100644
--- a/src/client/games/slots.rs
+++ b/src/client/games/slots.rs
@@ -1,10 +1,8 @@
 use super::traits::{Game, GamePhase, GameState};
+use crate::slots::{paytable_line, REELS, ROWS};
 
 /// Height of the game board. It must never depend on the spin result.
 pub const SLOT_BOARD_LINES: usize = 9;
-pub const LINES: usize = 5;
-pub const REELS: usize = 5;
-pub const ROWS: usize = 3;
 
 pub struct SlotsGame;
 
@@ -106,13 +104,13 @@ impl Game for SlotsGame {
         let grid = self.render_grid(&reels, &winning);
 
         format!(
-            "=== SLOTS ===\r\nBet: {} PLN   Lines: {}   Balance: {} PLN\r\n{}\r\n{}\r\n{}\r\n\r\n{}\r\n{}\r\n[+/-] Bet   [SPACE] Spin   [Q] Quit",
+            "=== SLOTS ===\r\nBet: {} PLN   Balance: {} PLN\r\n{}\r\n{}\r\n{}\r\n{}\r\n{}\r\n{}\r\n[+/-] Bet   [SPACE] Spin   [Q] Quit",
             state.bet_amount,
-            LINES,
             balance,
             grid[0],
             grid[1],
             grid[2],
+            paytable_line(),
             self.render_status(state),
             self.render_win_lines(state)
         )
diff --git a/src/lib.rs b/src/lib.rs
index e700173..a261ab0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,4 +8,5 @@
 pub mod client;
 pub mod protocol;
 pub mod server;
+pub mod slots;
 pub mod tofu;
diff --git a/src/server/games/slots.rs b/src/server/games/slots.rs
index 1d71c9d..e9f58b1 100644
--- a/src/server/games/slots.rs
+++ b/src/server/games/slots.rs
@@ -1,19 +1,9 @@
 use super::traits::{Game, GameError, GamePhase, GameResult, GameState};
+use crate::slots::PAYTABLE;
 use rand::Rng;
 use std::collections::HashMap;
 
-pub const REELS: usize = 5;
-pub const ROWS: usize = 3;
-pub const SYMBOLS: [char; 6] = ['C', 'L', 'O', 'G', 'D', 'S'];
-
-/// Five paylines, each entry is the row used on reel 0..4.
-pub const PAYLINES: [[usize; REELS]; 5] = [
-    [0, 0, 0, 0, 0], // line 1: top
-    [1, 1, 1, 1, 1], // line 2: middle
-    [2, 2, 2, 2, 2], // line 3: bottom
-    [0, 1, 2, 1, 0], // line 4: V
-    [2, 1, 0, 1, 2], // line 5: inverted V
-];
+pub use crate::slots::{PAYLINES, REELS, ROWS, SYMBOLS};
 
 #[derive(Clone, Copy)]
 struct Payout {
@@ -37,15 +27,12 @@ pub struct SlotsGame {
 
 impl SlotsGame {
     pub fn new() -> Self {
-        let mut payouts = HashMap::new();
-
-        // RTP = 425/432 = 0.9838 (1.62% house edge) with five paylines.
-        payouts.insert('C', Payout { three: 2, four: 5, five: 15 });
-        payouts.insert('L', Payout { three: 3, four: 7, five: 20 });
-        payouts.insert('O', Payout { three: 3, four: 8, five: 25 });
-        payouts.insert('G', Payout { three: 4, four: 12, five: 40 });
-        payouts.insert('D', Payout { three: 6, four: 18, five: 70 });
-        payouts.insert('S', Payout { three: 9, four: 30, five: 150 });
+        let payouts = PAYTABLE
+            .iter()
+            .map(|&(symbol, three, four, five)| {
+                (symbol, Payout { three, four, five })
+            })
+            .collect();
 
         Self {
             payouts,
diff --git a/src/slots.rs b/src/slots.rs
new file mode 100644
index 0000000..561c449
--- /dev/null
+++ b/src/slots.rs
@@ -0,0 +1,33 @@
+//! Shared slots rules used by both the server engine and the client board.
+
+pub const REELS: usize = 5;
+pub const ROWS: usize = 3;
+pub const SYMBOLS: [char; 6] = ['C', 'L', 'O', 'G', 'D', 'S'];
+
+/// Five paylines, each entry is the row used on reel 0..4.
+pub const PAYLINES: [[usize; REELS]; 5] = [
+    [0, 0, 0, 0, 0], // line 1: top
+    [1, 1, 1, 1, 1], // line 2: middle
+    [2, 2, 2, 2, 2], // line 3: bottom
+    [0, 1, 2, 1, 0], // line 4: V
+    [2, 1, 0, 1, 2], // line 5: inverted V
+];
+
+/// (symbol, 3-of-a-kind, 4-of-a-kind, 5-of-a-kind) multipliers of total bet.
+pub const PAYTABLE: [(char, u64, u64, u64); 6] = [
+    ('C', 2, 5, 15),
+    ('L', 3, 7, 20),
+    ('O', 3, 8, 25),
+    ('G', 4, 12, 40),
+    ('D', 6, 18, 70),
+    ('S', 9, 30, 150),
+];
+
+/// One-line paytable rendered under the reels.
+pub fn paytable_line() -> String {
+    let entries: Vec<String> = PAYTABLE
+        .iter()
+        .map(|(symbol, three, four, five)| format!("{symbol} {three}/{four}/{five}"))
+        .collect();
+    format!("Pays 3/4/5 x bet: {}", entries.join(" "))
+}