feat: Implemented Inventory.find_free_space

- Added tests for find_free_space

src/inventory/item.rs

@@ -1,3 +1,5 @@
+use std::mem::swap;
+
 use bevy::prelude::*;
 
 #[derive(Component, Clone)]
@@ -32,4 +34,16 @@ impl Item {
         
         !rect.intersect(other_rect).is_empty()
     }
+
+    /// Swap size.x with size.y
+    pub fn swap_size(&mut self) {
+        swap(&mut self.size.x, &mut self.size.y);
+    }
+
+    /// Get clone of item with swapped size
+    pub fn clone_swapped(&self) -> Self {
+        let mut new = self.clone();
+        new.swap_size();
+        new
+    }
 }

src/inventory/mod.rs

@@ -53,4 +53,39 @@ impl Inventory {
             .collect::<Vec<Entity>>();
         self.can_fit(item_query, children.as_slice(), *size, queried_position)
     }
+
+    fn find_free_space_inner(
+        &self,
+        item_query: Query<&item::Item>,
+        contained_items: &[Entity],
+        queried_size: UVec2,
+        was_swapped: bool,
+    ) -> Option<(UVec2, bool)> {
+        let Some(UVec2 {x: tries_x, y: tries_y}) = self.size.checked_sub(queried_size) else {
+            return None;
+        };
+        for x in 0..=tries_x {
+            for y in 0..=tries_y {
+                let tested_pos = UVec2::new(x, y);
+                if self.can_fit(item_query, contained_items, queried_size, tested_pos) {
+                    return Some((tested_pos, was_swapped));
+                }
+            }
+        }
+        None
+    }
+
+    pub fn find_free_space(
+        &self,
+        item_query: Query<&item::Item>,
+        contained_items: &[Entity],
+        queried_size: UVec2,
+    ) -> Option<(UVec2, bool)> {
+        let result = self.find_free_space_inner(item_query, contained_items, queried_size, false);
+        if result.is_some() {
+            return result;
+        }
+        let swapped_size = UVec2::new(queried_size.y, queried_size.x);
+        self.find_free_space_inner(item_query, contained_items, swapped_size, true)
+    }
 }