Add progress bar to list

src/progress_bar.rs

@@ -0,0 +1,41 @@
+use anyhow::{bail, Result};
+use std::fmt::Write;
+
+pub fn progress_bar(progress: u16, total: u16, line_width: u16) -> Result<String> {
+    if progress > total {
+        bail!("The progress of the progress bar is higher than the maximum");
+    }
+
+    // "Progress: [".len() == 11
+    // "] xxx/xxx".len() == 9
+    // 11 + 9 = 20
+    let wrapper_width = 20;
+
+    // If the line width is too low for a progress bar, just show the ratio.
+    if line_width < wrapper_width + 4 {
+        return Ok(format!("Progress: {progress}/{total}"));
+    }
+
+    let mut line = String::with_capacity(usize::from(line_width));
+    line.push_str("Progress: [");
+
+    let remaining_width = line_width.saturating_sub(wrapper_width);
+    let filled = (remaining_width * progress) / total;
+
+    for _ in 0..filled {
+        line.push('=');
+    }
+
+    if filled < remaining_width {
+        line.push('>');
+    }
+
+    for _ in 0..(remaining_width - filled).saturating_sub(1) {
+        line.push(' ');
+    }
+
+    line.write_fmt(format_args!("] {progress:>3}/{total:<3}"))
+        .unwrap();
+
+    Ok(line)
+}