From 621d78be606c22d737c5a664b469525e3862f901 Mon Sep 17 00:00:00 2001
From: platane <me@platane.me>
Date: Mon, 24 Mar 2025 21:23:37 +0100
Subject: [PATCH] .

---
 packages/solver-r/src/snake_compact.rs | 176 +++++++++++++++++++++++++
 1 file changed, 176 insertions(+)
 create mode 100644 packages/solver-r/src/snake_compact.rs

diff --git a/packages/solver-r/src/snake_compact.rs b/packages/solver-r/src/snake_compact.rs
new file mode 100644
index 0000000..872fb25
--- /dev/null
+++ b/packages/solver-r/src/snake_compact.rs
@@ -0,0 +1,176 @@
+use crate::grid::Point;
+
+#[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
+pub enum Direction {
+    Left = 0,
+    Right = 1,
+    Up = 2,
+    Down = 3,
+}
+
+fn get_direction_vector(dir: Direction) -> Point {
+    match dir {
+        Direction::Down => Point { x: 0, y: -1 },
+        Direction::Up => Point { x: 0, y: 1 },
+        Direction::Left => Point { x: -1, y: 0 },
+        Direction::Right => Point { x: 1, y: 0 },
+    }
+}
+fn get_direction_from_vector(v: &Point) -> Direction {
+    match v {
+        Point { x: 0, y: -1 } => Direction::Down,
+        Point { x: 0, y: 1 } => Direction::Up,
+        Point { x: -1, y: 0 } => Direction::Left,
+        Point { x: 1, y: 0 } => Direction::Right,
+        _ => panic!(),
+    }
+}
+
+#[derive(Clone)]
+pub struct SnakeC {
+    pub head: Point,
+    pub body: Vec<Direction>,
+}
+impl SnakeC {
+    pub fn get_cells(&self) -> Vec<Point> {
+        let mut e = self.head.clone();
+        let mut out = Vec::new();
+
+        out.push(e.clone());
+        for dir in self.body.iter() {
+            let v = get_direction_vector(*dir);
+            e.x -= v.x;
+            e.y -= v.y;
+            out.push(e.clone());
+        }
+
+        out
+    }
+
+    pub fn is_head_self_colliding(&self) -> bool {
+        self.get_cells()[1..].contains(&self.head)
+    }
+
+    pub fn advance(&mut self, dir: Direction) -> () {
+        let v = get_direction_vector(dir);
+
+        self.head.x += v.x;
+        self.head.y += v.y;
+
+        self.body.pop();
+        self.body.insert(0, dir);
+    }
+}
+
+impl From<Vec<Point>> for SnakeC {
+    fn from(value: Vec<Point>) -> Self {
+        let head = value.get(0).unwrap().clone();
+        let body = value
+            .windows(2)
+            .map(|w| {
+                let v = Point {
+                    x: w[0].x - w[1].x,
+                    y: w[0].y - w[1].y,
+                };
+                get_direction_from_vector(&v)
+            })
+            .collect();
+
+        Self { head, body }
+    }
+}
+
+#[test]
+fn it_should_get_the_snake_cell() {
+    let s = SnakeC {
+        head: Point { x: 10, y: 5 },
+        body: vec![Direction::Up, Direction::Up, Direction::Left],
+    };
+
+    assert_eq!(
+        s.get_cells(),
+        vec![
+            //
+            Point { x: 10, y: 5 },
+            Point { x: 10, y: 4 },
+            Point { x: 10, y: 3 },
+            Point { x: 11, y: 3 },
+        ]
+    );
+}
+
+#[test]
+fn it_should_get_snake_from_point_list() {
+    let s = SnakeC::from(vec![
+        //
+        Point { x: 10, y: 5 },
+        Point { x: 10, y: 4 },
+        Point { x: 10, y: 3 },
+        Point { x: 11, y: 3 },
+        Point { x: 12, y: 3 },
+        Point { x: 12, y: 2 },
+    ]);
+
+    assert_eq!(
+        s.get_cells(),
+        vec![
+            //
+            Point { x: 10, y: 5 },
+            Point { x: 10, y: 4 },
+            Point { x: 10, y: 3 },
+            Point { x: 11, y: 3 },
+            Point { x: 12, y: 3 },
+            Point { x: 12, y: 2 },
+        ]
+    );
+}
+
+#[test]
+fn it_should_advance_snake() {
+    let mut s = SnakeC::from(vec![
+        //
+        Point { x: 10, y: 3 },
+        Point { x: 11, y: 3 },
+        Point { x: 12, y: 3 },
+        Point { x: 12, y: 2 },
+    ]);
+
+    s.advance(Direction::Up);
+
+    assert_eq!(
+        s.get_cells(),
+        vec![
+            //
+            Point { x: 10, y: 4 },
+            Point { x: 10, y: 3 },
+            Point { x: 11, y: 3 },
+            Point { x: 12, y: 3 },
+        ]
+    );
+}
+
+#[test]
+fn it_should_detect_self_collision() {
+    let mut s = SnakeC::from(vec![
+        //
+        Point { x: 0, y: 0 },
+        Point { x: 0, y: 1 },
+        Point { x: 0, y: 2 },
+        Point { x: 0, y: 3 },
+        Point { x: 0, y: 4 },
+        Point { x: 0, y: 5 },
+        Point { x: 0, y: 6 },
+    ]);
+
+    assert_eq!(s.is_head_self_colliding(), false);
+
+    s.advance(Direction::Right);
+    s.advance(Direction::Up);
+    s.advance(Direction::Up);
+
+    assert_eq!(s.is_head_self_colliding(), false);
+
+    s.advance(Direction::Left);
+
+    assert_eq!(s.is_head_self_colliding(), true);
+}