182 lines
5.1 KiB
Go
182 lines
5.1 KiB
Go
package txt
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import (
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"fmt"
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"math"
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"strings"
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"time"
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)
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// TimeZone returns a time zone for the given UTC offset string.
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func TimeZone(offset string) *time.Location {
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if IsUtcOffset(offset) {
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sec := TimeOffset(offset)
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if sec == 0 {
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return time.UTC
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}
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return time.FixedZone(fmt.Sprintf("UTC%+d", sec/3600), sec)
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} else if location, err := time.LoadLocation(offset); err == nil {
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return location
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}
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return nil
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}
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// IsUtcOffset checks if the string is a valid UTC time offset.
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func IsUtcOffset(s string) bool {
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if l := len(s); l < 3 || l > 6 {
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return false
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} else if s == "UTC" {
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return true
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} else if !strings.HasPrefix(s, "UTC") {
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return false
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}
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return TimeOffset(s) != 0
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}
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// NormalizeUtcOffset returns a normalized UTC time offset string.
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func NormalizeUtcOffset(s string) string {
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s = strings.TrimSpace(s)
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if s == "" {
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return ""
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}
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switch s {
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case "-12", "-12:00", "UTC-12", "UTC-12:00":
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return "UTC-12"
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case "-11", "-11:00", "UTC-11", "UTC-11:00":
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return "UTC-11"
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case "-10", "-10:00", "UTC-10", "UTC-10:00":
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return "UTC-10"
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case "-9", "-09", "-09:00", "UTC-9", "UTC-09:00":
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return "UTC-9"
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case "-8", "-08", "-08:00", "UTC-8", "UTC-08:00":
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return "UTC-8"
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case "-7", "-07", "-07:00", "UTC-7", "UTC-07:00":
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return "UTC-7"
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case "-6", "-06", "-06:00", "UTC-6", "UTC-06:00":
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return "UTC-6"
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case "-5", "-05", "-05:00", "UTC-5", "UTC-05:00":
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return "UTC-5"
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case "-4", "-04", "-04:00", "UTC-4", "UTC-04:00":
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return "UTC-4"
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case "-3", "-03", "-03:00", "UTC-3", "UTC-03:00":
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return "UTC-3"
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case "-2", "-02", "-02:00", "UTC-2", "UTC-02:00":
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return "UTC-2"
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case "-1", "-01", "-01:00", "UTC-1", "UTC-01:00":
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return "UTC-1"
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case "+0", "+00", "00:00", "+00:00", "-00:00", "Z", "Z00:00", "UTC", "UTC+0", "UTC-0", "UTC+00:00", "UTC-00:00":
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return time.UTC.String()
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case "01:00", "+1", "+01", "+01:00", "UTC+1", "UTC+01:00":
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return "UTC+1"
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case "02:00", "+2", "+02", "+02:00", "UTC+2", "UTC+02:00":
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return "UTC+2"
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case "03:00", "+3", "+03", "+03:00", "UTC+3", "UTC+03:00":
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return "UTC+3"
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case "04:00", "+4", "+04", "+04:00", "UTC+4", "UTC+04:00":
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return "UTC+4"
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case "05:00", "+5", "+05", "+05:00", "UTC+5", "UTC+05:00":
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return "UTC+5"
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case "06:00", "+6", "+06", "+06:00", "UTC+6", "UTC+06:00":
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return "UTC+6"
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case "07:00", "+7", "+07", "+07:00", "UTC+7", "UTC+07:00":
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return "UTC+7"
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case "08:00", "+8", "+08", "+08:00", "UTC+8", "UTC+08:00":
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return "UTC+8"
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case "09:00", "+9", "+09", "+09:00", "UTC+9", "UTC+09:00":
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return "UTC+9"
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case "10:00", "+10", "+10:00", "UTC+10", "UTC+10:00":
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return "UTC+10"
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case "11:00", "+11", "+11:00", "UTC+11", "UTC+11:00":
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return "UTC+11"
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case "12:00", "+12", "+12:00", "UTC+12", "UTC+12:00":
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return "UTC+12"
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}
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return ""
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}
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// UtcOffset returns the time difference as UTC offset string.
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func UtcOffset(local, utc time.Time, offset string) string {
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if offset = NormalizeUtcOffset(offset); offset != "" {
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return offset
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}
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if local.IsZero() || utc.IsZero() || local == utc {
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return ""
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}
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d := local.Sub(utc).Hours()
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// Return if time difference includes fractions of an hour.
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if math.Abs(d-float64(int64(d))) > 0.1 {
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return ""
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}
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// Check if time difference is within expected range (hours).
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if d < -12 || d > 12 {
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return ""
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} else if d == 0 {
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return time.UTC.String()
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}
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return fmt.Sprintf("UTC%+d", int(d))
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}
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func TimeOffset(s string) (seconds int) {
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switch s {
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case "-12", "-12:00", "UTC-12", "UTC-12:00":
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return -12 * 3600
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case "-11", "-11:00", "UTC-11", "UTC-11:00":
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return -11 * 3600
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case "-10", "-10:00", "UTC-10", "UTC-10:00":
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return -10 * 3600
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case "-9", "-09", "-09:00", "UTC-9", "UTC-09:00":
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return -9 * 3600
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case "-8", "-08", "-08:00", "UTC-8", "UTC-08:00":
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return -8 * 3600
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case "-7", "-07", "-07:00", "UTC-7", "UTC-07:00":
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return -7 * 3600
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case "-6", "-06", "-06:00", "UTC-6", "UTC-06:00":
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return -6 * 3600
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case "-5", "-05", "-05:00", "UTC-5", "UTC-05:00":
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return -5 * 3600
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case "-4", "-04", "-04:00", "UTC-4", "UTC-04:00":
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return -4 * 3600
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case "-3", "-03", "-03:00", "UTC-3", "UTC-03:00":
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return -3 * 3600
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case "-2", "-02", "-02:00", "UTC-2", "UTC-02:00":
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return -2 * 3600
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case "-1", "-01", "-01:00", "UTC-1", "UTC-01:00":
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return -1 * 3600
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case "01:00", "+1", "+01", "+01:00", "UTC+1", "UTC+01:00":
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return 1 * 3600
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case "02:00", "+2", "+02", "+02:00", "UTC+2", "UTC+02:00":
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return 2 * 3600
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case "03:00", "+3", "+03", "+03:00", "UTC+3", "UTC+03:00":
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return 3 * 3600
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case "04:00", "+4", "+04", "+04:00", "UTC+4", "UTC+04:00":
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return 4 * 3600
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case "05:00", "+5", "+05", "+05:00", "UTC+5", "UTC+05:00":
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return 5 * 3600
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case "06:00", "+6", "+06", "+06:00", "UTC+6", "UTC+06:00":
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return 6 * 3600
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case "07:00", "+7", "+07", "+07:00", "UTC+7", "UTC+07:00":
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return 7 * 3600
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case "08:00", "+8", "+08", "+08:00", "UTC+8", "UTC+08:00":
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return 8 * 3600
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case "09:00", "+9", "+09", "+09:00", "UTC+9", "UTC+09:00":
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return 9 * 3600
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case "10:00", "+10", "+10:00", "UTC+10", "UTC+10:00":
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return 10 * 3600
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case "11:00", "+11", "+11:00", "UTC+11", "UTC+11:00":
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return 11 * 3600
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case "12:00", "+12", "+12:00", "UTC+12", "UTC+12:00":
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return 12 * 3600
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default:
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return 0
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}
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}
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