1 files changed, 41 insertions, 8 deletions

diff --git a/src/server/games/slots.rs b/src/server/games/slots.rs
index 2ef1b46..1d71c9d 100644
--- a/src/server/games/slots.rs
+++ b/src/server/games/slots.rs
@@ -22,6 +22,13 @@ struct Payout {
     five: u64,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct LineWin {
+    pub line: usize,
+    /// Column-major cell indices of the matched symbols.
+    pub cells: Vec<usize>,
+}
+
 pub struct SlotsGame {
     payouts: HashMap<char, Payout>,
     /// Deterministic grid for tests and demos, in column-major order.
@@ -65,10 +72,11 @@ impl SlotsGame {
             .collect()
     }
 
-    /// Evaluate one spin. Returns the total win and the 1-based winning lines.
-    pub fn calculate_payout(&self, grid: &[char], bet: u64) -> (u64, Vec<usize>) {
+    /// Evaluate one spin. Returns the total win and the winning lines with
+    /// the column-major cells that should be highlighted.
+    pub fn calculate_payout(&self, grid: &[char], bet: u64) -> (u64, Vec<LineWin>) {
         let mut total = 0u64;
-        let mut winning_lines = Vec::new();
+        let mut wins = Vec::new();
 
         for (index, pattern) in PAYLINES.iter().enumerate() {
             let Some(&first) = grid.get(pattern[0]) else {
@@ -99,10 +107,19 @@ impl SlotsGame {
             };
 
             total = total.saturating_add(bet.saturating_mul(multiplier));
-            winning_lines.push(index + 1);
+            let cells = pattern
+                .iter()
+                .enumerate()
+                .take(run)
+                .map(|(col, row)| col * ROWS + row)
+                .collect();
+            wins.push(LineWin {
+                line: index + 1,
+                cells,
+            });
         }
 
-        (total, winning_lines)
+        (total, wins)
     }
 
     /// Exact theoretical return to player for the current paytable.
@@ -213,12 +230,27 @@ impl Game for SlotsGame {
             )));
         }
 
-        let (winnings, winning_lines) = self.calculate_payout(&grid, state.bet_amount);
+        let (winnings, wins) = self.calculate_payout(&grid, state.bet_amount);
         let win_type = classify_win(winnings, state.bet_amount);
-        let win_lines = if winning_lines.is_empty() {
+        let win_lines = if wins.is_empty() {
+            "-".to_string()
+        } else {
+            wins.iter()
+                .map(|win| win.line.to_string())
+                .collect::<Vec<_>>()
+                .join(",")
+        };
+
+        let mut cells: Vec<usize> = wins
+            .iter()
+            .flat_map(|win| win.cells.iter().copied())
+            .collect();
+        cells.sort_unstable();
+        cells.dedup();
+        let win_cells = if cells.is_empty() {
             "-".to_string()
         } else {
-            winning_lines
+            cells
                 .iter()
                 .map(usize::to_string)
                 .collect::<Vec<_>>()
@@ -229,6 +261,7 @@ impl Game for SlotsGame {
         result_data.insert("reels".to_string(), reel_string.clone());
         result_data.insert("win_type".to_string(), win_type.to_string());
         result_data.insert("win_lines".to_string(), win_lines);
+        result_data.insert("win_cells".to_string(), win_cells);
 
         Ok(GameResult {
             session_id: state.session_id.clone(),