exercism/go/meetup/meetup.go

77 lines
1.6 KiB
Go
Raw Normal View History

2016-09-09 16:24:29 +00:00
package meetup
import "time"
const testVersion = 3
type WeekSchedule int
const (
First WeekSchedule = iota
Second
Third
Fourth
Last
Teenth
)
// Day calculates which day of the month the requested day falls on
func Day(week WeekSchedule, weekday time.Weekday, month time.Month, year int) int {
var t time.Time
switch week {
case First:
t = time.Date(year, month, 1, 0, 0, 0, 0, time.UTC)
if t.Weekday() == weekday {
return t.Day()
}
case Second:
t = time.Date(year, month, 8, 0, 0, 0, 0, time.UTC)
if t.Weekday() == weekday {
return t.Day()
}
case Third:
t = time.Date(year, month, 15, 0, 0, 0, 0, time.UTC)
if t.Weekday() == weekday {
return t.Day()
}
case Fourth:
t = time.Date(year, month, 22, 0, 0, 0, 0, time.UTC)
if t.Weekday() == weekday {
return t.Day()
}
case Last:
t = time.Date(year, month+1, 1, 0, 0, 0, 0, time.UTC)
t = t.AddDate(0, 0, -1)
if t.Weekday() == weekday {
return t.Day()
}
return findPrevDay(weekday, t).Day()
case Teenth:
t = time.Date(year, month, 13, 0, 0, 0, 0, time.UTC)
if t.Weekday() == weekday {
return t.Day()
}
}
return findNextDay(weekday, t).Day()
}
// findNextDay finds the next 'weekday' after t
func findNextDay(weekday time.Weekday, t time.Time) time.Time {
t = t.AddDate(0, 0, 1)
dow := t.Weekday()
for ; dow != weekday; dow = t.Weekday() {
t = t.AddDate(0, 0, 1)
}
return t
}
// findPrevDay finds the previous 'weekday' before t
func findPrevDay(weekday time.Weekday, t time.Time) time.Time {
t = t.AddDate(0, 0, -1)
dow := t.Weekday()
for ; dow != weekday; dow = t.Weekday() {
t = t.AddDate(0, 0, -1)
}
return t
}