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