Massively rework the time tracker, mainly to support times across midnight

src/time.rs

@@ -0,0 +1,72 @@
+use chrono::{Duration, Local, DateTime, Date};
+use anyhow::{Result, anyhow};
+use std::iter::Iterator;
+use regex::Regex;
+
+fn parse_datetime(reference_date: &Date<Local>, s: &str) -> Result<DateTime<Local>> {
+    let re = Regex::new(r"^\s*([12]?\d):([012345]\d)\s*$")?;
+    let (_, [hrs, mins]) = re.captures(s).ok_or(anyhow!(format!("Failed to parse \"{s}\" as a time")))?.extract();
+    let mins: u32 = mins.parse()?;
+    let mut hrs: u32 = hrs.parse()?;
+    let mut date = *reference_date;
+
+    if hrs > 23 {
+        let num_days = hrs / 24;
+        date = *reference_date + Duration::days(num_days.into());
+        hrs = hrs % 24;
+    }
+    Ok(date.and_hms_opt(hrs, mins, 0).ok_or(anyhow!(format!("{hrs}:{mins} not a real time")))?)
+}
+
+pub fn from_stream<'a>(reference_date: &Date<Local>, stream: impl Iterator<Item = &'a String>) -> Result<Vec<DateTime<Local>>> {
+    let mut durations: Vec<DateTime<Local>> = vec![];
+    for val in stream {
+        durations.push(parse_datetime(reference_date, val)?);
+    }
+    return Ok(durations);
+}
+
+fn show_time(hours: i64, minutes: i64) -> String {
+    let pluralized_hours = match hours {
+        1 => "1 hour".to_string(),
+        _ => format!("{hours} hours"),
+    };
+    let pluralized_minutes = match minutes {
+        1 => "1 minute".to_string(),
+        _ => format!("{minutes} minutes"),
+    };
+
+    if hours == 0 {
+        return pluralized_minutes.to_string();
+    }
+
+    if minutes == 0 {
+        return pluralized_hours.to_string();
+    }
+
+    return format!("{pluralized_hours} and {pluralized_minutes}");
+}
+
+fn to_hrs_minutes(total_minutes: i64) -> (i64, i64) {
+    let minutes = total_minutes % 60;
+    let hours = total_minutes / 60;
+    (hours, minutes)
+}
+
+pub fn get_charaterized_time_remaining(total_minutes: i64, target_minutes: i64) -> String {
+    if total_minutes == target_minutes {
+        return "Exactly done".to_string();
+    }
+
+    if total_minutes > target_minutes {
+        let diff = total_minutes - target_minutes;
+        let (hours, minutes) = to_hrs_minutes(diff);
+        return format!("You have overworked {}", show_time(hours, minutes))
+    } else {
+        let diff = target_minutes - total_minutes;
+        let (hours, minutes) = to_hrs_minutes(diff);
+        let end_at = (Local::now() + Duration::minutes(diff)).time();
+        let end_str = end_at.format("%-I:%M %p");
+        return format!("You have {} remaining (end at {} starting now)", show_time(hours, minutes), end_str)
+    }
+}