feat: add ability to send login code via email (#457)

Co-authored-by: Kyle Mendell <kmendell@ofkm.us>

backend/internal/utils/date_time_util.go

@@ -0,0 +1,52 @@
+package utils
+
+import (
+	"fmt"
+	"time"
+)
+
+// DurationToString converts a time.Duration to a human-readable string. Respects minutes, hours and days.
+func DurationToString(duration time.Duration) string {
+	// For a duration less than a day
+	if duration < 24*time.Hour {
+		hours := int(duration.Hours())
+		mins := int(duration.Minutes()) % 60
+
+		switch hours {
+		case 0:
+			return fmt.Sprintf("%d minutes", mins)
+		case 1:
+			if mins == 0 {
+				return "1 hour"
+			}
+			return fmt.Sprintf("1 hour and %d minutes", mins)
+		default:
+			if mins == 0 {
+				return fmt.Sprintf("%d hours", hours)
+			}
+			return fmt.Sprintf("%d hours and %d minutes", hours, mins)
+		}
+	} else {
+		// For durations of a day or more
+		days := int(duration.Hours() / 24)
+		hours := int(duration.Hours()) % 24
+
+		switch hours {
+		case 0:
+			if days == 1 {
+				return "1 day"
+			}
+			return fmt.Sprintf("%d days", days)
+		case 1:
+			if days == 1 {
+				return "1 day and 1 hour"
+			}
+			return fmt.Sprintf("%d days and 1 hour", days)
+		default:
+			if days == 1 {
+				return fmt.Sprintf("1 day and %d hours", hours)
+			}
+			return fmt.Sprintf("%d days and %d hours", days, hours)
+		}
+	}
+}