Implemented a lottery system

assets/common/items/loot_table.ron

@@ -0,0 +1,5 @@
+Lottery(
+    items : Vec(
+        // All loot rates go here
+    )
+)

common/src/comp/inventory/item/lottery.rs

@@ -0,0 +1,44 @@
+use crate::{
+    assets::{self, Asset},
+};
+use rand::prelude::*;
+use std::{fs::File, io::BufReader};
+
+// Generate a random float between 0 and 1
+pub fn rand() -> f32 {
+    let mut rng = rand::thread_rng();
+    rng.gen()
+}
+
+pub struct Lottery<T> {
+    items: Vec<f32, T>,
+    total: f32,
+}
+
+impl Asset for Lottery<&str> {
+    const ENDINGS: &'static [&'static str] = &["ron"];
+
+    fn parse(buf_reader: BufReader<File>) -> Result<Self, assets::Error> {
+        ron::de::from_reader(buf_reader).map_err(assets::Error::parse_error)
+    }
+}
+
+impl<T> Lottery<T> {
+    pub fn from_rates(items: impl Iterator<Item=(f32, T)>) -> Self {
+        let mut total = 0.0;
+        let items = items
+            .map(|(rate, item| {
+                total += rate;
+                (total - rate, item)
+            })
+            .collect();
+        Self { items, total }
+    }
+
+    pub fn choose(&self) -> &T {
+        let x = rand() * self.total;
+        &self.items[self.items
+            .binary_search_by(|(y, _)|, y.partial_cmp(&x).unwrap())
+            .unwrap_or_else(|i| i.saturating_sub(1))].1
+    }
+}

common/src/comp/inventory/item/mod.rs

@@ -181,6 +181,7 @@ impl Item {
             BlockKind::Coconut => Some(assets::load_expect_cloned("common.items.coconut")),
             BlockKind::Chest => Some(assets::load_expect_cloned(
                 [
+                    // TODO: Throw it all out and replace with the loot table (common/items/loot_table.ron)
                     //miscellaneous
                     "common.items.velorite",
                     "common.items.veloritefrag",