From 996f83e92a62cff027db74a55974bf27273d0109 Mon Sep 17 00:00:00 2001
From: jeangab <jg@nationtech.io>
Date: Mon, 14 Aug 2023 10:05:46 -0400
Subject: [PATCH] wip: Spacial index coming along pretty well, some tests and
 documentation left to write and should be good to go

---
 src/space_colonization/mod.rs           |   1 +
 src/space_colonization/spacial_index.rs | 110 ++++++++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 src/space_colonization/spacial_index.rs

diff --git a/src/space_colonization/mod.rs b/src/space_colonization/mod.rs
index 2d6669e..85b6528 100644
--- a/src/space_colonization/mod.rs
+++ b/src/space_colonization/mod.rs
@@ -5,6 +5,7 @@ pub use point::*;
 mod space_colonization;
 pub use space_colonization::*;
 mod math;
+mod spacial_index;
 
 #[wasm_bindgen]
 extern "C" {
diff --git a/src/space_colonization/spacial_index.rs b/src/space_colonization/spacial_index.rs
new file mode 100644
index 0000000..d5158b0
--- /dev/null
+++ b/src/space_colonization/spacial_index.rs
@@ -0,0 +1,110 @@
+use super::Point;
+
+#[derive(Debug)]
+struct SpatialIndex<T> {
+    elements: Vec<Vec<T>>,
+    number_cells_x: i32,
+    cell_size: i32,
+}
+
+impl<T> SpatialIndex<T> {
+    pub fn new(max_point: Point, cell_size: i32) -> SpatialIndex<T> {
+        // Here we add 1 to number cells x and y to handle the right and bottom edges where
+        // x = max_point.x or y = max_point.y
+        // For example, with max_point of (100,100)
+        // the point 100,100 is valid but 100/10 = 10, which is out of bounds of a zero based
+        // array of length 10. So we add 1 to the length and 10 is a valid index in a zero based
+        // array of length 11
+        let number_cells_x = (max_point.x / cell_size) + 1;
+        let number_cells = number_cells_x * ((max_point.y / cell_size) + 1);
+        let mut elements = Vec::with_capacity(number_cells as usize);
+        for _ in 0..number_cells {
+            elements.push(Vec::new());
+        }
+        SpatialIndex {
+            elements,
+            cell_size,
+            number_cells_x,
+        }
+    }
+
+    /// Adds an element in the cell of point
+    ///
+    /// panics if the point is outside of
+    pub fn add(&mut self, point: &Point, element: T) {
+        let element_index = self.get_index_from_position(point);
+        dbg!(element_index);
+        self.elements
+            .get_mut(element_index as usize)
+            .unwrap()
+            .push(element);
+    }
+
+    pub fn get_surrounding_elements<'a>(&'a self, point: &Point) -> Vec<&'a Vec<T>> {
+        let element_index = self.get_index_from_position(point);
+        dbg!(element_index);
+        vec![&self.elements[element_index]]
+    }
+
+    fn get_index_from_position(&self, point: &Point) -> usize {
+        ((point.x / self.cell_size) + ((point.y / self.cell_size) * self.number_cells_x)) as usize
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn when_no_element_surrounding_nodes_returns_empty_vec() {
+        let index: SpatialIndex<usize> = SpatialIndex::new(Point::new((100, 100)), 10);
+        assert_eq!(
+            index.get_surrounding_elements(&Point::new((0, 0))),
+            vec![&Vec::<usize>::new()]
+        );
+    }
+
+    #[test]
+    fn added_point_is_surrounding_itself() {
+        let mut index: SpatialIndex<usize> = SpatialIndex::new(Point::new((100, 100)), 10);
+        index.add(&Point::new((50, 50)), 132);
+        assert_eq!(
+            index.get_surrounding_elements(&Point::new((50, 50))),
+            vec![&vec![132]]
+        );
+    }
+
+    #[test]
+    fn adding_point_outside_grid_panics() {
+        todo!();
+    }
+
+    #[test]
+    fn point_on_top_edge_is_close_to_first_cell() {
+        todo!();
+    }
+
+    #[test]
+    fn point_on_bottom_edge_is_close_to_first_cell() {
+        todo!();
+    }
+
+    #[test]
+    fn point_on_right_edge_is_close_to_first_cell() {
+        todo!();
+    }
+    #[test]
+    fn point_on_left_edge_is_close_to_first_cell() {
+        todo!();
+    }
+
+    #[test]
+    fn when_elements_too_far_surrounding_is_empty() {
+        let mut index: SpatialIndex<usize> = SpatialIndex::new(Point::new((100, 100)), 10);
+        index.add(&Point::new((0, 0)), 132);
+        assert_eq!(
+            index.get_surrounding_elements(&Point::new((99, 99))),
+            vec![&Vec::<usize>::new()]
+        );
+    }
+}