Add method to remove gems with bounds check

src/main.rs

@@ -61,7 +61,12 @@ fn main() -> BError {
     for (i, tile) in &mut map.get_tiles().iter().enumerate() {
         if rng.roll_dice(1, 16) < 2 && *tile == TileType::Floor {
             let position = map.index_to_point2d(i);
-            let kind = MonsterKind::Slow;
+            let kind = match rng.range(0, 3) {
+                0 => MonsterKind::Slow,
+                1 => MonsterKind::Medium,
+                2 => MonsterKind::Fast,
+                _ => MonsterKind::Slow,
+            };
             ecs.create_entity()
                 .with(Position {
                     x: position.x,

src/resources/mod.rs

@@ -48,3 +48,18 @@ pub struct Stats {
     pub teleports: u32,
     pub keys: u32,
 }
+
+type PlayerSurvived = bool;
+
+impl Stats {
+    pub fn take_gems(&mut self, num_gems: u32) -> PlayerSurvived {
+        let new_num_gems = self.gems as i64 - num_gems as i64;
+        if new_num_gems <= 0 {
+            self.gems = 0;
+            false
+        } else {
+            self.gems = new_num_gems as u32;
+            true
+        }
+    }
+}

src/state.rs

@@ -111,9 +111,7 @@ impl State {
                     } else {
                         if let Some(e) = map.get_tile_content(map.point2d_to_index(destination)) {
                             if let Some(monster) = monsters.get(e) {
-                                if stats.gems > 0 {
-                                    stats.gems -= damage_for_kind(monster.kind);
-                                }
+                                stats.take_gems(damage_for_kind(monster.kind));
                                 let _ = entities.delete(e);
                             }
                         }

src/systems/monster_ai_system.rs

@@ -77,9 +77,7 @@ impl<'a> System<'a> for MonsterAiSystem {
                     if let Some(e) = map.get_tile_content(map.point2d_to_index(destination)) {
                         if let Some(_player) = players.get(e) {
                             // TODO: Sound
-                            if stats.gems > 0 {
-                                stats.gems -= damage_for_kind(monster.kind);
-                            }
+                            stats.take_gems(damage_for_kind(monster.kind));
                             let _ = entities.delete(*entity);
                         }
                     } else {