From a8dc087bc277839fcc40d51701330e6f31a22ccd Mon Sep 17 00:00:00 2001
From: Christian Nieves <cnieves@google.com>
Date: Mon, 9 Dec 2024 16:56:57 -0600
Subject: [PATCH] game over working

---
 src/snake/main.rs | 45 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/src/snake/main.rs b/src/snake/main.rs
index 2fc1ad0..e396514 100644
--- a/src/snake/main.rs
+++ b/src/snake/main.rs
@@ -47,7 +47,7 @@ struct LastTailPosition(Option<Position>);
 #[derive(Component)]
 struct Food;
 
-#[derive(Component, Clone, Copy, Eq, PartialEq)]
+#[derive(Component, Clone, Copy, Eq, PartialEq, Debug)]
 struct Position {
     x: i32,
     y: i32,
@@ -93,6 +93,7 @@ fn snake_movement(
     heads: Query<(Entity, &SnakeHead)>,
     mut positions: Query<&mut Position>,
     mut last_tail_position: ResMut<LastTailPosition>,
+    mut game_over_writer: EventWriter<GameOverEvent>,
 ) {
     // Filter positions to just the segments
     let segment_positions = segments
@@ -109,6 +110,21 @@ fn snake_movement(
         Direction::Left => head_pos.x -= 1,
         Direction::Right => head_pos.x += 1,
     }
+
+    // Before we move the tail, check if the head has collided with 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_writer.send(GameOverEvent);
+    }
+    // Before we move the tail, check if the head has collided with the tail.
+    if segment_positions.contains(&head_pos) {
+        println!("triggering GAME OVER tail hit {:?}", &head_pos);
+        game_over_writer.send(GameOverEvent);
+    }
+
     segment_positions
         .iter()
         .zip(segments.0.iter().skip(1))
@@ -118,6 +134,23 @@ fn snake_movement(
     last_tail_position.0 = Some(*segment_positions.last().unwrap());
 }
 
+fn game_over(
+    mut commands: Commands,
+    mut game_over_reader: EventReader<GameOverEvent>,
+    segments_resource: ResMut<SnakeSegments>,
+    segments: Query<Entity, With<SnakeSegment>>,
+    head: Query<Entity, With<SnakeHead>>,
+    food: Query<Entity, With<Food>>,
+) {
+    if game_over_reader.read().next().is_some() {
+        println!("GAME OVER");
+        for e in food.iter().chain(segments.iter()).chain(head.iter()) {
+            commands.entity(e).despawn();
+        }
+        spawn_snake(commands, segments_resource);
+    }
+}
+
 fn scale_translation(
     mut windows: Query<&mut Window, With<PrimaryWindow>>,
     mut q: Query<(&Size, &mut Transform)>,
@@ -194,15 +227,18 @@ fn spawn_snake(mut commands: Commands, mut segments: ResMut<SnakeSegments>) {
             })
             .insert(Size::square(1.0))
             .insert(Name::new(String::from("Snake Head")))
-            .insert(Position { x: 5, y: 0 })
+            .insert(Position { x: 1, y: 0 })
             .id(),
-        spawn_segment(&mut commands, Position { x: 4, y: 0 }),
+        spawn_segment(&mut commands, Position { x: 0, y: 0 }),
     ])
 }
 
 #[derive(Event)]
 struct GrowthEvent;
 
+#[derive(Event)]
+struct GameOverEvent;
+
 fn snake_eating(
     mut commands: Commands,
     mut growth_writer: EventWriter<GrowthEvent>,
@@ -248,7 +284,7 @@ impl Plugin for SnakePlugin {
             )
             .add_systems(
                 FixedUpdate,
-                (snake_movement, snake_eating, snake_growth)
+                (snake_movement, snake_eating, snake_growth, game_over)
                     .chain()
                     .run_if(on_timer(Duration::from_millis(500))),
             )
@@ -260,6 +296,7 @@ impl Plugin for SnakePlugin {
         // Events must be added to the app before they can be used
         // using the 'add_event' method
         app.add_event::<GrowthEvent>();
+        app.add_event::<GameOverEvent>();
     }
 }