commit 63adf7d53ee1356162b87664a901df048b18b810
Author: Adrian Hedqvist <adrian@tollyx.net>
Date:   Wed Aug 9 22:32:40 2023 +0200

    initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ea8c4bf
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/target
diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..c311279
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "timer"
+version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..b213788
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "timer"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..83395f9
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,51 @@
+use std::io::Write;
+
+const HOUR: u64 = 60 * 60;
+const MINUTE: u64 = 60;
+
+fn main() {
+    let Some(arg) = std::env::args().nth(1) else {
+        eprintln!("Missing time argument");
+        return;
+    };
+    let start = std::time::Instant::now();
+
+    let parts: Vec<&str> = arg.split(':').collect();
+    let secs = match parts[..] {
+        [s] => s.parse::<u64>().expect("parse seconds"),
+        [m, s] => {
+            s.parse::<u64>().expect("parse seconds")
+                + m.parse::<u64>().expect("parse minutes") * MINUTE
+        }
+        [h, m, s] => {
+            s.parse::<u64>().expect("parse seconds")
+                + m.parse::<u64>().expect("parse minutes") * MINUTE
+                + h.parse::<u64>().expect("parse hours") * HOUR
+        }
+        _ => {
+            eprintln!("Invalid time format: {arg}");
+            return;
+        }
+    };
+    let show_hours = secs > HOUR;
+    let duration = std::time::Duration::from_secs(secs);
+    let stop = start + duration;
+    let mut now = std::time::Instant::now();
+
+    while now < stop {
+        let rem = stop - now;
+        let rems = rem.as_secs();
+        let h = rems / HOUR;
+        let m = (rems / MINUTE) % 60;
+        let s = rems % 60;
+        if show_hours {
+            print!("\r{h:02}:{m:02}:{s:02}");
+        } else {
+            print!("\r{m:02}:{s:02}");
+        }
+        std::io::stdout().lock().flush().expect("stdout lock");
+        std::thread::sleep(std::time::Duration::from_secs(1));
+        now = std::time::Instant::now();
+    }
+    println!();
+}