pushers

kiln-core/src/game.rs

@@ -1,4 +1,5 @@
 use crate::action::Action;
+use crate::archetype::Archetype;
 use crate::board::Board;
 use crate::log::LogLine;
 use crate::script::ScriptHost;
@@ -10,6 +11,9 @@ use crate::utils::{Direction, ObjectId, Player, ScriptArg, Solid};
 /// How long a `say()` speech bubble stays on screen, in seconds.
 pub const SAY_DURATION: f64 = 3.0;
 
+/// How often pusher archetypes fire, in seconds.
+const PUSHER_INTERVAL: f64 = 0.5;
+
 // Re-export ScrollLine so kiln-tui can pattern-match scroll content without
 // accessing the private `action` module directly.
 pub use crate::action::ScrollLine;
@@ -61,6 +65,9 @@ pub struct GameState {
     /// by [`enter_board`](GameState::enter_board). Front-ends tick this down and
     /// may block input or show a visual effect while it is `Some(t)` where `t > 0`.
     pub board_transition: Option<f64>,
+    /// Countdown to the next global pusher heartbeat. When it reaches zero all
+    /// [`Archetype::Pusher`] cells fire and the timer resets to [`PUSHER_INTERVAL`].
+    pusher_timer: f64,
 }
 
 impl GameState {
@@ -84,6 +91,7 @@ impl GameState {
             speech_bubbles: Vec::new(),
             active_scroll: None,
             board_transition: None,
+            pusher_timer: PUSHER_INTERVAL,
         };
         state.drain_errors();
         state
@@ -161,9 +169,39 @@ impl GameState {
         // Expire speech bubbles before resolving new actions so a fresh say()
         // this frame isn't immediately culled.
         self.speech_bubbles.retain_mut(|b| { b.remaining -= secs; b.remaining > 0.0 });
+        self.tick_pushers(secs);
         self.resolve();
     }
 
+    /// Fires the global pusher heartbeat: every [`PUSHER_INTERVAL`] seconds each
+    /// [`Archetype::Pusher`] cell shoves the occupant directly in front of it.
+    ///
+    /// Two-phase to avoid holding the board borrow while calling `push()` (which
+    /// needs `&mut Board`): phase A collects target coordinates, phase B applies them.
+    fn tick_pushers(&mut self, secs: f64) {
+        self.pusher_timer -= secs;
+        if self.pusher_timer > 0.0 {
+            return;
+        }
+        self.pusher_timer += PUSHER_INTERVAL;
+        let pushers: Vec<(usize, usize)> = {
+            let board = self.board();
+            let mut v = Vec::new();
+            for y in 0..board.height {
+                for x in 0..board.width {
+                    if matches!(board.get(x, y).1, Archetype::Pusher(_)) {
+                        v.push((x, y));
+                    }
+                }
+            }
+            v
+        };
+        let mut board = self.board_mut();
+        for (x, y) in pushers {
+            board.advance_pusher(x, y);
+        }
+    }
+
     /// Drains errors collected by the script host into the game log.
     fn drain_errors(&mut self) {
         // TODO: errors are only logged for now. This is the place to halt execution /