use chrono crate for human-readable times

Cargo.lock

@@ -148,6 +148,17 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "chrono"
+version = "0.4.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "80094f509cf8b5ae86a4966a39b3ff66cd7e2a3e594accec3743ff3fabeab5b2"
+dependencies = [
+ "num-integer",
+ "num-traits",
+ "time",
+]
+
 [[package]]
 name = "cookie"
 version = "0.11.3"
@@ -179,6 +190,7 @@ name = "device-battery-timer"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "chrono",
  "rocket",
 ]
 
@@ -389,6 +401,25 @@ dependencies = [
  "log 0.3.9",
 ]
 
+[[package]]
+name = "num-integer"
+version = "0.1.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d59457e662d541ba17869cf51cf177c0b5f0cbf476c66bdc90bf1edac4f875b"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac267bcc07f48ee5f8935ab0d24f316fb722d7a1292e2913f0cc196b29ffd611"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.13.0"

Cargo.toml

@@ -9,3 +9,4 @@ edition = "2018"
 [dependencies]
 rocket = "0.4.5"
 anyhow = "1.0"
+chrono = "0.4"

src/main.rs

@@ -6,6 +6,9 @@ extern crate rocket;
 #[macro_use]
 extern crate anyhow;
 
+extern crate chrono;
+
+use chrono::prelude::*;
 use rocket::{http::RawStr, State};
 use std::{
     collections::BTreeMap,
@@ -21,26 +24,24 @@ struct LoggedAccesses {
 
 #[derive(Default)]
 struct DeviceLog {
-    access_times: Vec<SystemTime>,
+    access_times: Vec<DateTime<Local>>,
 }
 
 impl LoggedAccesses {
     pub fn log_device_access(&mut self, device_name: &str) {
         let device = self.devices.entry(String::from(device_name)).or_default();
 
-        let now = SystemTime::now();
+        let now = Local::now();
         device.access_times.push(now)
     }
 }
 
 impl DeviceLog {
-    pub fn get_duration(&self) -> Result<(Duration, &SystemTime, &SystemTime), anyhow::Error> {
+    pub fn get_duration(&self) -> Result<(i64, &DateTime<Local>, &DateTime<Local>), anyhow::Error> {
         let start = self.access_times.first().ok_or(anyhow!("No start time"))?;
         let end = self.access_times.last().ok_or(anyhow!("No end time"))?;
 
-        let duration = end
-            .duration_since(start.clone())
-            .map_err(|_| anyhow!("Times could not be diffed"))?;
+        let duration = end.timestamp() - start.timestamp();
 
         Ok((duration, &start, &end))
     }
@@ -59,10 +60,8 @@ impl Display for DeviceLog {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self.get_duration() {
             Ok((duration, start, end)) => f.write_fmt(format_args!(
-                "{} seconds between first ({:?}) and last ({:?}) call",
-                duration.as_secs(),
-                start,
-                end
+                "{} seconds between first ({}) and last ({}) call",
+                duration, start, end
             )),
             Err(e) => f.write_fmt(format_args!("Error getting duration: {}", e)),
         }