summaryrefslogtreecommitdiff
path: root/chronos
diff options
context:
space:
mode:
Diffstat (limited to 'chronos')
-rw-r--r--chronos/chronos.go163
-rw-r--r--chronos/chronos_test.go37
2 files changed, 200 insertions, 0 deletions
diff --git a/chronos/chronos.go b/chronos/chronos.go
new file mode 100644
index 0000000..18bf775
--- /dev/null
+++ b/chronos/chronos.go
@@ -0,0 +1,163 @@
+package chronos
+
+import (
+ "math"
+ "time"
+)
+
+type TimeUnit int
+
+const (
+ Minute TimeUnit = iota
+ Hour
+ Day
+ Week
+ Month
+ Year
+)
+
+var NilTime time.Time
+
+func (tu TimeUnit) String() string {
+ switch tu {
+ case Minute:
+ return "Minute"
+ case Hour:
+ return "Hour"
+ case Day:
+ return "Day"
+ case Week:
+ return "Week"
+ case Month:
+ return "Month"
+ case Year:
+ return "Year"
+ default:
+ return "(Unknown TimeUnit)"
+ }
+}
+
+func (tu TimeUnit) minApprox() time.Duration {
+ const (
+ maMinute = time.Minute
+ maHour = time.Hour
+ maDay = 24*time.Hour - time.Second
+ maWeek = 7 * maDay
+ maMonth = 28 * maDay
+ maYear = 365 * maDay
+ )
+
+ switch tu {
+ case Minute:
+ return maMinute
+ case Hour:
+ return maHour
+ case Day:
+ return maDay
+ case Week:
+ return maWeek
+ case Month:
+ return maMonth
+ case Year:
+ return maYear
+ default:
+ return 0
+ }
+}
+
+func (tu TimeUnit) maxApprox() time.Duration {
+ const (
+ maMinute = time.Minute
+ maHour = time.Hour
+ maDay = 24*time.Hour + time.Second
+ maWeek = 7 * maDay
+ maMonth = 31 * maDay
+ maYear = 366 * maDay
+ )
+
+ switch tu {
+ case Minute:
+ return maMinute
+ case Hour:
+ return maHour
+ case Day:
+ return maDay
+ case Week:
+ return maWeek
+ case Month:
+ return maMonth
+ case Year:
+ return maYear
+ default:
+ return 0
+ }
+}
+
+type Frequency struct {
+ Unit TimeUnit
+ Count uint
+}
+
+func (f Frequency) addTo(t time.Time, mul uint) time.Time {
+ sec := t.Second()
+ min := t.Minute()
+ hour := t.Hour()
+ day := t.Day()
+ month := t.Month()
+ year := t.Year()
+ loc := t.Location()
+
+ fq := int(f.Count * mul)
+
+ switch f.Unit {
+ case Minute:
+ return t.Add(time.Minute * time.Duration(fq))
+ case Hour:
+ return t.Add(time.Hour * time.Duration(fq))
+ case Day:
+ return time.Date(year, month, day+fq, hour, min, sec, 0, loc)
+ case Week:
+ return time.Date(year, month, day+fq*7, hour, min, sec, 0, loc)
+ case Month:
+ return time.Date(year, month+time.Month(fq), day, hour, min, sec, 0, loc)
+ case Year:
+ return time.Date(year+fq, month, day, hour, min, sec, 0, loc)
+ default:
+ return NilTime
+ }
+}
+
+func (f Frequency) minApprox() time.Duration { return time.Duration(f.Count) * f.Unit.minApprox() }
+func (f Frequency) maxApprox() time.Duration { return time.Duration(f.Count) * f.Unit.maxApprox() }
+
+type Chronos struct {
+ Start, End time.Time
+ Freq Frequency
+}
+
+func (c Chronos) NextAfter(t time.Time) time.Time {
+ if !t.After(c.Start) {
+ return c.Start
+ }
+ if c.Freq.Count == 0 {
+ return NilTime
+ }
+
+ d := t.Sub(c.Start)
+
+ fmin := uint(math.Floor(float64(d) / float64(c.Freq.maxApprox())))
+ fmax := uint(math.Ceil(float64(d) / float64(c.Freq.minApprox())))
+
+ for f := fmin; f <= fmax; f++ {
+ t2 := c.Freq.addTo(c.Start, f)
+ if t2.Before(c.Start) || t2.Before(t) {
+ continue
+ }
+ if (!c.End.IsZero()) && t2.After(c.End) {
+ return NilTime
+ }
+ return t2
+ }
+
+ return NilTime // Should actually never happen...
+}
diff --git a/chronos/chronos_test.go b/chronos/chronos_test.go
new file mode 100644
index 0000000..5efb7e9
--- /dev/null
+++ b/chronos/chronos_test.go
@@ -0,0 +1,37 @@
+package chronos
+
+import (
+ "testing"
+ "time"
+)
+
+func mktime(y int, month time.Month, d, h, min int) time.Time {
+ return time.Date(y, month, d, h, min, 0, 0, time.Local)
+}
+
+func TestChronos(t *testing.T) {
+ tbl := []struct {
+ start time.Time
+ end time.Time
+ unit TimeUnit
+ count uint
+ now time.Time
+ want time.Time
+ }{
+ {mktime(1991, 4, 30, 0, 0), NilTime, Year, 1, mktime(2013, 8, 26, 13, 37), mktime(2014, 4, 30, 0, 0)},
+ {mktime(2013, 1, 1, 0, 0), NilTime, Year, 0, mktime(2013, 8, 26, 13, 37), NilTime},
+ {mktime(2013, 1, 1, 0, 0), NilTime, Year, 0, mktime(2012, 1, 1, 0, 0), mktime(2013, 1, 1, 0, 0)},
+ {mktime(1900, 12, 24, 12, 34), NilTime, Year, 5, mktime(2013, 8, 26, 13, 37), mktime(2015, 12, 24, 12, 34)},
+ {mktime(1900, 12, 24, 12, 34), mktime(2010, 1, 1, 1, 1), Year, 5, mktime(2013, 8, 26, 13, 37), NilTime},
+ {mktime(2013, 8, 1, 4, 2), NilTime, Week, 3, mktime(2013, 8, 26, 13, 37), mktime(2013, 9, 12, 4, 2)},
+ {mktime(2013, 8, 26, 13, 37), NilTime, Year, 0, mktime(2013, 8, 26, 13, 37), mktime(2013, 8, 26, 13, 37)},
+ {mktime(2013, 8, 25, 13, 37), NilTime, Day, 1, mktime(2013, 8, 26, 13, 37), mktime(2013, 8, 26, 13, 37)},
+ }
+
+ for i, e := range tbl {
+ have := Chronos{e.start, e.end, Frequency{e.unit, e.count}}.NextAfter(e.now)
+ if !have.Equal(e.want) {
+ t.Errorf("#%d: Want: %s, Have: %s", i, e.want, have)
+ }
+ }
+}