From f57560a1440065c10e10609954d1e34067b9b6f4 Mon Sep 17 00:00:00 2001
From: Timothy Warren <twarren@nabancard.com>
Date: Wed, 30 Dec 2020 10:37:26 -0500
Subject: [PATCH] Restart on game over

---
 src/main.rs | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/src/main.rs b/src/main.rs
index c2487f0..8c24470 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,6 +36,7 @@ struct Materials {
 
 struct SnakeMoveTimer(Timer);
 
+struct GameOverEvent;
 struct GrowthEvent;
 
 #[derive(Default)]
@@ -130,6 +131,7 @@ fn spawn_segment(
 fn snake_movement(
     keyboard_input: Res<Input<KeyCode>>,
     snake_timer: ResMut<SnakeMoveTimer>,
+    mut game_over_events: ResMut<Events<GameOverEvent>>,
     mut last_tail_position: ResMut<LastTailPosition>,
     segments: ResMut<SnakeSegments>,
     mut heads: Query<(Entity, &mut SnakeHead)>,
@@ -173,6 +175,21 @@ fn snake_movement(
                 head_pos.y -= 1;
             }
         };
+
+        // Check if we've hit a wall
+        if head_pos.x < 0
+            || head_pos.y < 0
+            || head_pos.x as u32 >= ARENA_WIDTH
+            || head_pos.y as u32 >= ARENA_HEIGHT
+        {
+            game_over_events.send(GameOverEvent);
+        }
+
+        // Check if we've hit our tail
+        if segment_positions.contains(&head_pos) {
+            game_over_events.send(GameOverEvent);
+        }
+
         segment_positions
             .iter()
             .zip(segments.0.iter().skip(1))
@@ -183,6 +200,23 @@ fn snake_movement(
     }
 }
 
+fn game_over(
+    commands: &mut Commands,
+    mut reader: Local<EventReader<GameOverEvent>>,
+    game_over_events: Res<Events<GameOverEvent>>,
+    materials: Res<Materials>,
+    segments_res: ResMut<SnakeSegments>,
+    food: Query<Entity, With<Food>>,
+    segments: Query<Entity, With<SnakeSegment>>,
+) {
+    if reader.iter(&game_over_events).next().is_some() {
+        for ent in food.iter().chain(segments.iter()) {
+            commands.despawn(ent);
+        }
+        spawn_snake(commands, materials, segments_res);
+    }
+}
+
 fn snake_eating(
     commands: &mut Commands,
     snake_timer: ResMut<SnakeMoveTimer>,
@@ -284,6 +318,7 @@ fn main() {
         .add_resource(SnakeSegments::default())
         .add_resource(LastTailPosition::default())
         .add_event::<GrowthEvent>()
+        .add_event::<GameOverEvent>()
         .add_startup_system(setup.system())
         .add_startup_stage("game_setup", SystemStage::single(spawn_snake.system()))
         .add_system(snake_movement.system())
@@ -293,6 +328,7 @@ fn main() {
         .add_system(snake_timer.system())
         .add_system(snake_eating.system())
         .add_system(snake_growth.system())
+        .add_system(game_over.system())
         .add_plugins(DefaultPlugins)
         .run();
 }