bottles...

rust/bottle-song/src/lib.rs

@@ -0,0 +1,34 @@
+pub fn recite(start_bottles: u32, take_down: u32) -> String {
+    let end_bottles = start_bottles - take_down;
+    
+    ((end_bottles + 1)..=start_bottles)
+        .rev()
+        .map(|n| verse(n))
+        .collect::<Vec<_>>()
+        .join("\n\n")
+}
+
+fn verse(n: u32) -> String {
+    let current_bottle = bottle_str(n);
+    let next_bottle = bottle_str(n - 1).to_lowercase();
+
+    format!(
+        "{0} hanging on the wall,\n\
+         {0} hanging on the wall,\n\
+         And if one green bottle should accidentally fall,\n\
+         There'll be {1} hanging on the wall.",
+        current_bottle, next_bottle
+    )
+}
+
+fn bottle_str(n: u32) -> String {
+    let count_str = match n {
+        10 => "Ten", 9 => "Nine", 8 => "Eight", 7 => "Seven", 6 => "Six",
+        5 => "Five", 4 => "Four", 3 => "Three", 2 => "Two", 1 => "One",
+        _ => "No",
+    };
+
+    let plural = if n == 1 { "bottle" } else { "bottles" };
+    
+    format!("{count_str} green {plural}")
+}