Added files.

internal/internal.go

@@ -0,0 +1,188 @@
+package internal
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/emersion/go-imap/v2"
+	"github.com/emersion/go-imap/v2/internal/imapwire"
+)
+
+const (
+	DateTimeLayout = "_2-Jan-2006 15:04:05 -0700"
+	DateLayout     = "2-Jan-2006"
+)
+
+const FlagRecent imap.Flag = "\\Recent" // removed in IMAP4rev2
+
+func DecodeDateTime(dec *imapwire.Decoder) (time.Time, error) {
+	var s string
+	if !dec.Quoted(&s) {
+		return time.Time{}, nil
+	}
+	t, err := time.Parse(DateTimeLayout, s)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("in date-time: %v", err) // TODO: use imapwire.DecodeExpectError?
+	}
+	return t, err
+}
+
+func ExpectDateTime(dec *imapwire.Decoder) (time.Time, error) {
+	t, err := DecodeDateTime(dec)
+	if err != nil {
+		return t, err
+	}
+	if !dec.Expect(!t.IsZero(), "date-time") {
+		return t, dec.Err()
+	}
+	return t, nil
+}
+
+func ExpectDate(dec *imapwire.Decoder) (time.Time, error) {
+	var s string
+	if !dec.ExpectAString(&s) {
+		return time.Time{}, dec.Err()
+	}
+	t, err := time.Parse(DateLayout, s)
+	if err != nil {
+		return time.Time{}, fmt.Errorf("in date: %v", err) // use imapwire.DecodeExpectError?
+	}
+	return t, nil
+}
+
+func ExpectFlagList(dec *imapwire.Decoder) ([]imap.Flag, error) {
+	var flags []imap.Flag
+	err := dec.ExpectList(func() error {
+		// Some servers start the list with a space, so we need to skip it
+		// https://github.com/emersion/go-imap/pull/633
+		dec.SP()
+
+		flag, err := ExpectFlag(dec)
+		if err != nil {
+			return err
+		}
+		flags = append(flags, flag)
+		return nil
+	})
+	return flags, err
+}
+
+func ExpectCap(dec *imapwire.Decoder) (imap.Cap, error) {
+	var name string
+	if !dec.ExpectAtom(&name) {
+		return "", dec.Err()
+	}
+	return canonicalCap(name), nil
+}
+
+func ExpectFlag(dec *imapwire.Decoder) (imap.Flag, error) {
+	isSystem := dec.Special('\\')
+	if isSystem && dec.Special('*') {
+		return imap.FlagWildcard, nil // flag-perm
+	}
+	var name string
+	if !dec.ExpectAtom(&name) {
+		return "", fmt.Errorf("in flag: %w", dec.Err())
+	}
+	if isSystem {
+		name = "\\" + name
+	}
+	return canonicalFlag(name), nil
+}
+
+func ExpectMailboxAttrList(dec *imapwire.Decoder) ([]imap.MailboxAttr, error) {
+	var attrs []imap.MailboxAttr
+	err := dec.ExpectList(func() error {
+		attr, err := ExpectMailboxAttr(dec)
+		if err != nil {
+			return err
+		}
+		attrs = append(attrs, attr)
+		return nil
+	})
+	return attrs, err
+}
+
+func ExpectMailboxAttr(dec *imapwire.Decoder) (imap.MailboxAttr, error) {
+	flag, err := ExpectFlag(dec)
+	return canonicalMailboxAttr(string(flag)), err
+}
+
+var (
+	canonOnce        sync.Once
+	canonFlag        map[string]imap.Flag
+	canonMailboxAttr map[string]imap.MailboxAttr
+)
+
+func canonInit() {
+	flags := []imap.Flag{
+		imap.FlagSeen,
+		imap.FlagAnswered,
+		imap.FlagFlagged,
+		imap.FlagDeleted,
+		imap.FlagDraft,
+		imap.FlagForwarded,
+		imap.FlagMDNSent,
+		imap.FlagJunk,
+		imap.FlagNotJunk,
+		imap.FlagPhishing,
+		imap.FlagImportant,
+	}
+	mailboxAttrs := []imap.MailboxAttr{
+		imap.MailboxAttrNonExistent,
+		imap.MailboxAttrNoInferiors,
+		imap.MailboxAttrNoSelect,
+		imap.MailboxAttrHasChildren,
+		imap.MailboxAttrHasNoChildren,
+		imap.MailboxAttrMarked,
+		imap.MailboxAttrUnmarked,
+		imap.MailboxAttrSubscribed,
+		imap.MailboxAttrRemote,
+		imap.MailboxAttrAll,
+		imap.MailboxAttrArchive,
+		imap.MailboxAttrDrafts,
+		imap.MailboxAttrFlagged,
+		imap.MailboxAttrJunk,
+		imap.MailboxAttrSent,
+		imap.MailboxAttrTrash,
+		imap.MailboxAttrImportant,
+	}
+
+	canonFlag = make(map[string]imap.Flag)
+	for _, flag := range flags {
+		canonFlag[strings.ToLower(string(flag))] = flag
+	}
+
+	canonMailboxAttr = make(map[string]imap.MailboxAttr)
+	for _, attr := range mailboxAttrs {
+		canonMailboxAttr[strings.ToLower(string(attr))] = attr
+	}
+}
+
+func canonicalFlag(s string) imap.Flag {
+	canonOnce.Do(canonInit)
+	if flag, ok := canonFlag[strings.ToLower(s)]; ok {
+		return flag
+	}
+	return imap.Flag(s)
+}
+
+func canonicalMailboxAttr(s string) imap.MailboxAttr {
+	canonOnce.Do(canonInit)
+	if attr, ok := canonMailboxAttr[strings.ToLower(s)]; ok {
+		return attr
+	}
+	return imap.MailboxAttr(s)
+}
+
+func canonicalCap(s string) imap.Cap {
+	// Only two caps are not fully uppercase
+	for _, cap := range []imap.Cap{imap.CapIMAP4rev1, imap.CapIMAP4rev2} {
+		if strings.EqualFold(s, string(cap)) {
+			return cap
+		}
+	}
+	return imap.Cap(strings.ToUpper(s))
+}