DateTime function to convert to time.Time value (close #115)

types.go

@@ -9,6 +9,7 @@ import (
  "regexp"
  "strconv"
  "strings"
+ "time"
  "unicode"
 )
 
@@ -384,6 +385,24 @@ func ParseDate(ddmmyy string) (Date, error) {
  return Date{true, dd, mm, yy}, nil
 }
 
+// DateTime converts the provided Date and Time values to a standard UTC time.Time.
+// The referenceYear parameter is used to determine the offset (century) for the two-digit year in Date.
+// For example, if the referenceYear is 2024, the offset used is 2000; and the input date's year is prepended with 20.
+// If referenceYear is 0, the current UTC year is used.
+// If either Date or Time is not valid, DateTime returns the zero time.Time.
+func DateTime(referenceYear int, d Date, t Time) time.Time {
+ if !d.Valid || !t.Valid {
+ return time.Time{}
+ }
+ if referenceYear == 0 {
+ referenceYear = time.Now().UTC().Year()
+ }
+ century := referenceYear / 100 * 100 // truncate the last two digits (year within century); keep first two digits of the full year
+ return time.Date(century+d.YY, time.Month(d.MM), d.DD,
+ t.Hour, t.Minute, t.Second, t.Millisecond*1e6,
+ time.UTC)
+}
+
 // LatDir returns the latitude direction symbol
 func LatDir(l float64) string {
  if l < 0.0 {

types_test.go

@@ -3,6 +3,7 @@ package nmea
 import (
  "fmt"
  "testing"
+ "time"
 
  "github.com/stretchr/testify/assert"
 )
@@ -220,6 +221,60 @@ func TestDateString(t *testing.T) {
  }
 }
 
+func TestDateTime(t *testing.T) {
+ for i, testCase := range []struct {
+ refYear int
+ date Date
+ time Time
+ expect time.Time
+ }{
+ {
+ refYear: 2024,
+ date: Date{DD: 1, MM: 2, YY: 3, Valid: true},
+ time: Time{Hour: 1, Minute: 2, Second: 3, Millisecond: 4, Valid: true},
+ expect: time.Date(2003, time.February, 1, 1, 2, 3, 4e6, time.UTC),
+ },
+ {
+ refYear: 1999,
+ date: Date{DD: 1, MM: 2, YY: 3, Valid: true},
+ time: Time{Hour: 1, Minute: 2, Second: 3, Millisecond: 4, Valid: true},
+ expect: time.Date(1903, time.February, 1, 1, 2, 3, 4e6, time.UTC),
+ },
+ {
+ refYear: 2025,
+ date: Date{DD: 23, MM: 7, YY: 24, Valid: true},
+ time: Time{Hour: 18, Minute: 5, Second: 12, Millisecond: 1, Valid: true},
+ expect: time.Date(2024, time.July, 23, 18, 5, 12, 1e6, time.UTC),
+ },
+ // zero reference year; this test will fail starting in the year 3000
+ {
+ refYear: 0,
+ date: Date{DD: 1, MM: 2, YY: 3, Valid: true},
+ time: Time{Hour: 1, Minute: 2, Second: 3, Millisecond: 4, Valid: true},
+ expect: time.Date(2003, time.February, 1, 1, 2, 3, 4e6, time.UTC),
+ },
+ // invalid date
+ {
+ refYear: 2024,
+ date: Date{DD: 1, MM: 2, YY: 3},
+ time: Time{Hour: 1, Minute: 2, Second: 3, Millisecond: 4, Valid: true},
+ expect: time.Time{},
+ },
+ // invalid time
+ {
+ refYear: 2024,
+ date: Date{DD: 1, MM: 2, YY: 3, Valid: true},
+ time: Time{Hour: 1, Minute: 2, Second: 3, Millisecond: 4},
+ expect: time.Time{},
+ },
+ } {
+ actual := DateTime(testCase.refYear, testCase.date, testCase.time)
+ if !actual.Equal(testCase.expect) {
+ t.Fatalf("Test %d (refYear=%d date=%s time=%s): Expected %s but got %s", i, testCase.refYear, testCase.date, testCase.time, testCase.expect, actual)
+ }
+ }
+}
+
 func TestLatDir(t *testing.T) {
  tests := []struct {
  value float64