Cleanup error handling and everything in general (#20)

- Better error handling
- Add settings file to enabling storing data file in separate location
- Add some basic docs and example tests

Author: chdsbd

Cargo.lock

@@ -16,3 +16,7 @@ serde = "1.0.15"
 serde_derive = "1.0.15"
 serde_json = "1.0.4"
 colored = "1.5"
+chrono-english = "0.1.3"
+
+[dev-dependencies]
+tempfile = "3.0.4"

Cargo.toml

@@ -0,0 +1,32 @@
+use chrono::{DateTime, Duration, Local, Utc};
+
+pub fn datetime(time: DateTime<Utc>) -> String {
+    time.with_timezone(&Local).format("%F %H:%M").to_string()
+}
+
+pub fn time(time: DateTime<Utc>) -> String {
+    time.with_timezone(&Local).format("%H:%M").to_string()
+}
+
+pub fn duration(duration: Duration) -> String {
+    let hours = duration.num_hours();
+    let minutes = duration.num_minutes() % 60;
+    let seconds = duration.num_seconds() % 60;
+
+    if duration.num_minutes() == 0 {
+        format!("{}s", seconds)
+    } else if duration.num_hours() == 0 {
+        format!(
+            "{minutes}m {seconds:>2}s",
+            minutes = minutes,
+            seconds = seconds
+        )
+    } else {
+        format!(
+            "{hours}h {minutes:>2}m {seconds:>2}s",
+            hours = hours,
+            minutes = minutes,
+            seconds = seconds
+        )
+    }
+}