[pbs-devel] [PATCH proxmox-backup 1/3] tools/systemd/time: implement some Traits for TimeSpan

[Dominik Csapak <d.csapak@proxmox.com>]

namely
* From<Duration> (to convert easily from duration to timespan)
* Display (for better formatting)

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
if wanted, we can optimize the display trait a bit further, e.g.
only showing the biggest two units instead

 src/tools/systemd/time.rs | 84 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/src/tools/systemd/time.rs b/src/tools/systemd/time.rs
index 7cc42415..75fb0ea2 100644
--- a/src/tools/systemd/time.rs
+++ b/src/tools/systemd/time.rs
@@ -141,6 +141,90 @@ impl From<TimeSpan> for f64 {
     }
 }
 
+impl From<std::time::Duration> for TimeSpan {
+    fn from(duration: std::time::Duration) -> Self {
+        let mut duration = duration.as_nanos();
+        let nsec = (duration % 1000) as u64;
+        duration /= 1000;
+        let usec = (duration % 1000) as u64;
+        duration /= 1000;
+        let msec = (duration % 1000) as u64;
+        duration /= 1000;
+        let seconds = (duration % 60) as u64;
+        duration /= 60;
+        let minutes = (duration % 60) as u64;
+        duration /= 60;
+        let hours = (duration % 24) as u64;
+        duration /= 24;
+        let years = (duration as f64 / 365.25) as u64;
+        let ydays = (duration as f64 % 365.25) as u64;
+        let months = (ydays as f64 / 30.44) as u64;
+        let mdays = (ydays as f64 % 30.44) as u64;
+        let weeks = mdays / 7;
+        let days = mdays % 7;
+        Self {
+            nsec,
+            msec,
+            usec,
+            seconds,
+            minutes,
+            hours,
+            days,
+            weeks,
+            months,
+            years,
+        }
+    }
+}
+
+impl std::fmt::Display for TimeSpan {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        let mut single = true;
+        if self.years > 0 {
+            write!(f, "{}y", self.years)?;
+            single = false;
+        }
+        let write_space = |single: bool, f: &mut std::fmt::Formatter| -> Result<bool, std::fmt::Error> {
+            if !single {
+                write!(f, " ")?;
+            }
+            Ok(false)
+        };
+        if self.months > 0 {
+            single = write_space(single, f)?;
+            write!(f, "{}m", self.months)?;
+        }
+        if self.weeks > 0 {
+            single = write_space(single, f)?;
+            write!(f, "{}w", self.weeks)?;
+        }
+        if self.days > 0 {
+            single = write_space(single, f)?;
+            write!(f, "{}d", self.days)?;
+        }
+        if self.hours > 0 {
+            single = write_space(single, f)?;
+            write!(f, "{}h", self.hours)?;
+        }
+        if self.minutes > 0 {
+            single = write_space(single, f)?;
+            write!(f, "{}min", self.minutes)?;
+        }
+        let seconds = self.seconds as f64 + (self.msec as f64 / 1000.0);
+        if seconds >= 0.1 {
+            write_space(single, f)?;
+            if seconds >= 1.0 || !single {
+                write!(f, "{:.0}s", seconds)?;
+            } else {
+                write!(f, "{:.1}s", seconds)?;
+            }
+        } else if single {
+            write_space(single, f)?;
+            write!(f, "<0.1s")?;
+        }
+        Ok(())
+    }
+}
 
 pub fn verify_time_span(i: &str) -> Result<(), Error> {
     parse_time_span(i)?;
-- 
2.20.1