From 0f3c580176ee50795908bf16b4abf9f6faa0565c Mon Sep 17 00:00:00 2001
From: Kjetil Orbekk <kj@orbekk.com>
Date: Fri, 23 Dec 2022 21:29:46 -0500
Subject: Fix winning trick implementation

---
 protocol/src/bridge_engine.rs | 52 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 9 deletions(-)

diff --git a/protocol/src/bridge_engine.rs b/protocol/src/bridge_engine.rs
index 70dcda4..fb4efa7 100644
--- a/protocol/src/bridge_engine.rs
+++ b/protocol/src/bridge_engine.rs
@@ -92,9 +92,28 @@ pub struct Trick {
 }
 
 impl Trick {
-    pub fn winner(&self) -> Player {
-        error!("XXX: Returning incorrect result for winner");
-        self.leader
+    pub fn suit(&self) -> Option<Suit> {
+        self.cards_played.iter().next().map(|&Card(suit, _)| suit)
+    }
+
+    // TODO: This should be moved somewhere we can guarantee that cards are non-empty.
+    pub fn winner(&self, trump_suit: Option<Suit>) -> Player {
+        let suit = self.suit();
+        let value = |c: &Card| {
+            if Some(c.suit()) == trump_suit {
+                14 + c.rank() as i8
+            } else if Some(c.suit()) == suit {
+                c.rank() as i8
+            } else {
+                0
+            }
+        };
+
+        let (i, _) = self.cards_played
+            .iter()
+            .enumerate()
+            .max_by(|&(_, c1), &(_, c2)| value(c1).cmp(&value(c2))).unwrap();
+        self.leader.many_next(i)
     }
 }
 
@@ -151,6 +170,7 @@ impl TurnInPlay {
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
 pub struct DealInPlay {
     deal: Deal,
+    trump_suit: Option<Suit>,
     tricks_played: Vec<Trick>,
     in_progress: TurnInPlay,
 }
@@ -162,9 +182,14 @@ pub enum DealInPlayResult {
 }
 
 impl DealInPlay {
-    pub fn new(leader: Player, deal: Deal) -> DealInPlay {
+    pub fn new(
+        leader: Player,
+        trump_suit: Option<Suit>,
+        deal: Deal,
+    ) -> DealInPlay {
         DealInPlay {
             deal,
+            trump_suit,
             tricks_played: Vec::with_capacity(13),
             in_progress: TurnInPlay::new(leader),
         }
@@ -199,7 +224,9 @@ impl DealInPlay {
         let player_cards = player.get_cards_mut(&mut self.deal);
 
         if let Some(suit) = self.in_progress.suit() {
-            if card.suit() != suit && player_cards.iter().find(|c| c.suit() == suit).is_some() {
+            if card.suit() != suit
+                && player_cards.iter().find(|c| c.suit() == suit).is_some()
+            {
                 return Err(anyhow!("Must follow {suit} suit"));
             }
         }
@@ -223,7 +250,7 @@ impl DealInPlay {
                 })
             }
             TurnInPlayResult::Trick(trick) => {
-                let trick_winner = trick.winner();
+                let trick_winner = trick.winner(self.trump_suit);
                 let mut tricks = self.tricks_played;
                 tricks.push(trick);
 
@@ -231,6 +258,7 @@ impl DealInPlay {
                     DealInPlayResult::PlayFinished(tricks)
                 } else {
                     DealInPlayResult::InProgress(Self {
+                        trump_suit: self.trump_suit,
                         in_progress: TurnInPlay::new(trick_winner),
                         tricks_played: tricks,
                         deal: self.deal,
@@ -636,8 +664,11 @@ pub struct PlayState {
 
 impl PlayState {
     pub fn new(deal: Deal, contract: Contract, bidding: Bidding) -> Self {
-        let playing_deal =
-            DealInPlay::new(contract.declarer.many_next(3), deal.clone());
+        let playing_deal = DealInPlay::new(
+            contract.declarer.many_next(3),
+            contract.highest_bid.suit,
+            deal.clone(),
+        );
         Self {
             deal,
             contract,
@@ -1329,7 +1360,7 @@ mod tests {
 
     #[test]
     fn play_hand() {
-        let deal = DealInPlay::new(Player::West, mini_deal());
+        let deal = DealInPlay::new(Player::West, None, mini_deal());
         assert_eq!(deal.tricks_played, vec!());
         {
             let err = deal.clone().play(mkcard("♥9")).unwrap_err().to_string();
@@ -1354,5 +1385,8 @@ mod tests {
                 cards_played: mkcards("♢A ♢Q ♢7 ♡10"),
             })
         );
+        let trick = &deal.tricks_played[0];
+        assert_eq!(trick.winner(None), Player::West);
+        assert_eq!(trick.winner(Some(Suit::Heart)), Player::South);
     }
 }
-- 
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