From 2d4647a618234ef496899d875f75d57b5af1a6e5 Mon Sep 17 00:00:00 2001
From: Justin Worthe <justin@worthe-it.co.za>
Date: Sun, 7 Jul 2019 22:59:01 +0200
Subject: Compiles again now at least

---
 src/strategy/minimax.rs | 45 +++++++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/src/strategy/minimax.rs b/src/strategy/minimax.rs
index deba92e..2ed84b2 100644
--- a/src/strategy/minimax.rs
+++ b/src/strategy/minimax.rs
@@ -16,7 +16,7 @@ pub fn choose_move(
         None => Node {
             score_sum: ScoreSum::new(),
             player_score_sums: [HashMap::new(), HashMap::new()],
-            unexplored: mcts_move_combo(state),
+            unexplored: move_combos(state),
             children: HashMap::new(),
         },
         Some(mut node) => node
@@ -27,17 +27,16 @@ pub fn choose_move(
             .unwrap_or_else(|| {
                 eprintln!("Previous round did not appear in the cache");
                 Node {
-                    state: state.clone(),
                     score_sum: ScoreSum::new(),
                     player_score_sums: [HashMap::new(), HashMap::new()],
-                    unexplored: mcts_move_combo(state),
+                    unexplored: move_combos(state),
                     children: HashMap::new(),
                 }
             }),
     };
 
     while start_time.to(PreciseTime::now()) < max_time {
-        let _ = mcts(&mut root_node);
+        let _ = expand_tree(&mut root_node, &state);
     }
 
     eprintln!("Number of simulations: {}", root_node.score_sum.visit_count);
@@ -126,21 +125,20 @@ impl AddAssign<Score> for ScoreSum {
 }
 
 // TODO: Transform this into more of a minimax with AB pruning approach?
-fn mcts(node: &mut Node) -> Score {
-    if node.state.outcome != SimulationOutcome::Continue {
-        score(&node.state)
+fn expand_tree(node: &mut Node, state: &GameBoard) -> Score {
+    if state.outcome != SimulationOutcome::Continue {
+        score(state)
     } else if let Some(commands) = node.unexplored.pop() {
-        let mut new_state = node.state.clone();
+        let mut new_state = state.clone();
         new_state.simulate(commands);
         let score = score(&new_state);
         let unexplored = if new_state.outcome == SimulationOutcome::Continue {
-            mcts_move_combo(&new_state)
+            move_combos(&new_state)
         } else {
             Vec::new()
         };
 
         let new_node = Node {
-            state: new_state,
             score_sum: ScoreSum::with_initial(score),
             player_score_sums: [HashMap::new(), HashMap::new()],
             unexplored,
@@ -152,19 +150,22 @@ fn mcts(node: &mut Node) -> Score {
         score
     } else {
         let commands = choose_existing(node);
-        let score = mcts(
+        let mut new_state = state.clone();
+        new_state.simulate(commands);
+        let score = expand_tree(
             node.children
                 .get_mut(&commands)
                 .expect("The existing node hasn't been tried yet"),
+            &new_state,
         );
         update(node, commands, score);
         score
     }
 }
 
-fn mcts_move_combo(state: &GameBoard) -> Vec<[Command; 2]> {
-    let player_moves = valid_moves(state, 0);
-    let opponent_moves = valid_moves(state, 1);
+fn move_combos(state: &GameBoard) -> Vec<[Command; 2]> {
+    let player_moves = pruned_moves(state, 0);
+    let opponent_moves = pruned_moves(state, 1);
     debug_assert!(!player_moves.is_empty(), "No player moves");
     debug_assert!(!opponent_moves.is_empty(), "No opponent moves");
 
@@ -187,10 +188,11 @@ fn best_player_move(node: &Node) -> Command {
 }
 
 fn score(state: &GameBoard) -> Score {
+    // TODO: Try adding new features here, like max worm health, weighted in some way
     Score {
         val: match state.outcome {
-            SimulationOutcome::PlayerWon(0) => 500.,
-            SimulationOutcome::PlayerWon(1) => -500.,
+            SimulationOutcome::PlayerWon(0) => 2000.,
+            SimulationOutcome::PlayerWon(1) => -2000.,
             _ => (state.players[0].score() - state.players[1].score()) as f32,
         },
     }
@@ -224,6 +226,17 @@ fn update(node: &mut Node, commands: [Command; 2], score: Score) {
     node.score_sum += score;
 }
 
+fn pruned_moves(state: &GameBoard, player_index: usize) -> Vec<Command> {
+    // TODO: Play one move into the future and make sure this doesn't
+    // hurt me or do something dumb? Should I rather specialize this
+    // to each type of move?
+
+    // TODO: Ensure that there are at least some moves left here. If
+    // there's nothing, at least return a vector that contains a
+    // nothing move.
+    valid_moves(state, player_index)
+}
+
 fn valid_moves(state: &GameBoard, player_index: usize) -> Vec<Command> {
     state
         .valid_shoot_commands(player_index)
-- 
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