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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package date
import "time"
const secondsPerDay = 60 * 60 * 24
// encode returns the number of days elapsed from date zero to the date
// corresponding to the given Time value.
func encode(t time.Time) PeriodOfDays {
// Compute the number of seconds elapsed since January 1, 1970 00:00:00
// in the location specified by t and not necessarily UTC.
// A Time value is represented internally as an offset from a UTC base
// time; because we want to extract a date in the time zone specified
// by t rather than in UTC, we need to compensate for the time zone
// difference.
_, offset := t.Zone()
secs := t.Unix() + int64(offset)
// Unfortunately operator / rounds towards 0, so negative values
// must be handled differently
if secs >= 0 {
return PeriodOfDays(secs / secondsPerDay)
}
return -PeriodOfDays((secondsPerDay - 1 - secs) / secondsPerDay)
}
// decode returns the Time value corresponding to 00:00:00 UTC of the date
// represented by d, the number of days elapsed since date zero.
func decode(d PeriodOfDays) time.Time {
secs := int64(d) * secondsPerDay
return time.Unix(secs, 0).UTC()
}
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