feat(cli): Add "next" to run the next unsolved exercise. (#785)

* Add "run next" to run the next unsolved exercise.

* Fix a grammar error in the message.

* Update README.md with the suggested change

Co-authored-by: marisa <mokou@fastmail.com>

* Update the README.md for "rustlings hint next".

Co-authored-by: marisa <mokou@fastmail.com>

1 files changed, 18 insertions, 7 deletions

diff --git a/src/main.rs b/src/main.rs
index a80ce88..985fe34 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -286,13 +286,24 @@ fn spawn_watch_shell(failed_exercise_hint: &Arc<Mutex<Option<String>>>) {
 }
 
 fn find_exercise<'a>(name: &str, exercises: &'a [Exercise]) -> &'a Exercise {
-    exercises
-        .iter()
-        .find(|e| e.name == name)
-        .unwrap_or_else(|| {
-            println!("No exercise found for '{}'!", name);
-            std::process::exit(1)
-        })
+    if name.eq("next") {
+        exercises
+            .iter()
+            .find(|e| !e.looks_done())
+            .unwrap_or_else(|| {
+                println!("🎉 Congratulations! You have done all the exercises!");
+                println!("🔚 There are no more exercises to do next!");
+                std::process::exit(1)
+            })
+    } else {
+        exercises
+            .iter()
+            .find(|e| e.name == name)
+            .unwrap_or_else(|| {
+                println!("No exercise found for '{}'!", name);
+                std::process::exit(1)
+            })
+    }
 }
 
 fn watch(exercises: &[Exercise], verbose: bool) -> notify::Result<()> {