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package imap
import (
"fmt"
"regexp"
"time"
)
// Date and time layouts.
// Dovecot adds a leading zero to dates:
// https://github.com/dovecot/core/blob/4fbd5c5e113078e72f29465ccc96d44955ceadc2/src/lib-imap/imap-date.c#L166
// Cyrus adds a leading space to dates:
// https://github.com/cyrusimap/cyrus-imapd/blob/1cb805a3bffbdf829df0964f3b802cdc917e76db/lib/times.c#L543
// GMail doesn't support leading spaces in dates used in SEARCH commands.
const (
// Defined in RFC 3501 as date-text on page 83.
DateLayout = "_2-Jan-2006"
// Defined in RFC 3501 as date-time on page 83.
DateTimeLayout = "_2-Jan-2006 15:04:05 -0700"
// Defined in RFC 5322 section 3.3, mentioned as env-date in RFC 3501 page 84.
envelopeDateTimeLayout = "Mon, 02 Jan 2006 15:04:05 -0700"
// Use as an example in RFC 3501 page 54.
searchDateLayout = "2-Jan-2006"
)
// time.Time with a specific layout.
type (
Date time.Time
DateTime time.Time
envelopeDateTime time.Time
searchDate time.Time
)
// Permutations of the layouts defined in RFC 5322, section 3.3.
var envelopeDateTimeLayouts = [...]string{
envelopeDateTimeLayout, // popular, try it first
"_2 Jan 2006 15:04:05 -0700",
"_2 Jan 2006 15:04:05 MST",
"_2 Jan 2006 15:04 -0700",
"_2 Jan 2006 15:04 MST",
"_2 Jan 06 15:04:05 -0700",
"_2 Jan 06 15:04:05 MST",
"_2 Jan 06 15:04 -0700",
"_2 Jan 06 15:04 MST",
"Mon, _2 Jan 2006 15:04:05 -0700",
"Mon, _2 Jan 2006 15:04:05 MST",
"Mon, _2 Jan 2006 15:04 -0700",
"Mon, _2 Jan 2006 15:04 MST",
"Mon, _2 Jan 06 15:04:05 -0700",
"Mon, _2 Jan 06 15:04:05 MST",
"Mon, _2 Jan 06 15:04 -0700",
"Mon, _2 Jan 06 15:04 MST",
}
// TODO: this is a blunt way to strip any trailing CFWS (comment). A sharper
// one would strip multiple CFWS, and only if really valid according to
// RFC5322.
var commentRE = regexp.MustCompile(`[ \t]+\(.*\)$`)
// Try parsing the date based on the layouts defined in RFC 5322, section 3.3.
// Inspired by https://github.com/golang/go/blob/master/src/net/mail/message.go
func parseMessageDateTime(maybeDate string) (time.Time, error) {
maybeDate = commentRE.ReplaceAllString(maybeDate, "")
for _, layout := range envelopeDateTimeLayouts {
parsed, err := time.Parse(layout, maybeDate)
if err == nil {
return parsed, nil
}
}
return time.Time{}, fmt.Errorf("date %s could not be parsed", maybeDate)
}
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