1 files changed, 72 insertions, 0 deletions
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 0000000..5d13902
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,72 @@
+use crate::canvas::Canvas;
+
+#[derive(Debug, Clone)]
+pub struct State {
+    width: u32,
+    height: u32,
+    cells: Vec::<bool>,
+}
+
+impl State {
+    pub fn new(width: u32, height: u32) -> State {
+        let cells = (0..width * height)
+            .map(|_| js_sys::Math::random() < 0.5)
+            .collect();
+
+        State {
+            width,
+            height,
+            cells,
+        }
+    }
+
+    pub fn neighbor_count(&self, x: u32, y: u32) -> u32 {
+        let mut count = 0;
+        for delta_x in [self.height - 1, 0, 1].iter().clone() {
+            for delta_y in [self.width - 1, 0, 1].iter().clone() {
+                let neighbor_x = (x + delta_x) % self.width;
+                let neighbor_y = (y + delta_y) % self.height;
+
+                if (*delta_x, *delta_y) != (0, 0) && self.is_on(neighbor_x, neighbor_y) {
+                    count += 1;
+                }
+            }
+        }
+        count
+    }
+
+    pub fn next(&self) -> State {
+        let cells = (0..self.width * self.height)
+            .map(|i| {
+                let x = i % self.width;
+                let y = i / self.width;
+                let neighbor_count = self.neighbor_count(x, y);
+                neighbor_count == 3 || self.is_on(x, y) && neighbor_count == 2
+            })
+            .collect();
+
+        State {
+            width: self.width,
+            height: self.height,
+            cells,
+        }
+    }
+
+    fn is_on(&self, x: u32, y: u32) -> bool {
+        let inside_x = (x + self.width) % self.width;
+        let inside_y = (y + self.height) % self.height;
+        self.cells[(inside_x + inside_y * self.width) as usize]
+    }
+
+    pub fn draw(&self, canvas: &Canvas) {
+        canvas.clear();
+
+        for y in 0..self.height {
+            for x in 0..self.width {
+                if self.is_on(x, y) {
+                    canvas.draw(x, y, "green");
+                }
+            }
+        }
+    }
+}