feat(GODT-2802): IMAP Serivce

Handles all IMAP related tasks. Unlike the previous iteration, this new
service automatically adds and removes users from Gluon by interfacing
with server manager.

internal/services/imapservice/sync_build.go

@@ -0,0 +1,174 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package imapservice
+
+import (
+	"bytes"
+	"html/template"
+	"time"
+
+	"github.com/ProtonMail/gluon/imap"
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/gopenpgp/v2/crypto"
+	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/algo"
+	"github.com/ProtonMail/proton-bridge/v3/pkg/message"
+	"github.com/bradenaw/juniper/xslices"
+)
+
+type buildRes struct {
+	messageID string
+	addressID string
+	update    *imap.MessageCreated
+	err       error
+}
+
+func defaultMessageJobOpts() message.JobOptions {
+	return message.JobOptions{
+		IgnoreDecryptionErrors: true, // Whether to ignore decryption errors and create a "custom message" instead.
+		SanitizeDate:           true, // Whether to replace all dates before 1970 with RFC822's birthdate.
+		AddInternalID:          true, // Whether to include MessageID as X-Pm-Internal-Id.
+		AddExternalID:          true, // Whether to include ExternalID as X-Pm-External-Id.
+		AddMessageDate:         true, // Whether to include message time as X-Pm-Date.
+		AddMessageIDReference:  true, // Whether to include the MessageID in References.
+	}
+}
+
+func buildRFC822(apiLabels map[string]proton.Label, full proton.FullMessage, addrKR *crypto.KeyRing, buffer *bytes.Buffer) *buildRes {
+	var (
+		update *imap.MessageCreated
+		err    error
+	)
+
+	buffer.Grow(full.Size)
+
+	if buildErr := message.BuildRFC822Into(addrKR, full.Message, full.AttData, defaultMessageJobOpts(), buffer); buildErr != nil {
+		update = newMessageCreatedFailedUpdate(apiLabels, full.MessageMetadata, buildErr)
+		err = buildErr
+	} else if created, parseErr := newMessageCreatedUpdate(apiLabels, full.MessageMetadata, buffer.Bytes()); parseErr != nil {
+		update = newMessageCreatedFailedUpdate(apiLabels, full.MessageMetadata, parseErr)
+		err = parseErr
+	} else {
+		update = created
+	}
+
+	return &buildRes{
+		messageID: full.ID,
+		addressID: full.AddressID,
+		update:    update,
+		err:       err,
+	}
+}
+
+func newMessageCreatedUpdate(
+	apiLabels map[string]proton.Label,
+	message proton.MessageMetadata,
+	literal []byte,
+) (*imap.MessageCreated, error) {
+	parsedMessage, err := imap.NewParsedMessage(literal)
+	if err != nil {
+		return nil, err
+	}
+
+	return &imap.MessageCreated{
+		Message:       toIMAPMessage(message),
+		Literal:       literal,
+		MailboxIDs:    usertypes.MapTo[string, imap.MailboxID](wantLabels(apiLabels, message.LabelIDs)),
+		ParsedMessage: parsedMessage,
+	}, nil
+}
+
+func newMessageCreatedFailedUpdate(
+	apiLabels map[string]proton.Label,
+	message proton.MessageMetadata,
+	err error,
+) *imap.MessageCreated {
+	literal := newFailedMessageLiteral(message.ID, time.Unix(message.Time, 0), message.Subject, err)
+
+	parsedMessage, err := imap.NewParsedMessage(literal)
+	if err != nil {
+		panic(err)
+	}
+
+	return &imap.MessageCreated{
+		Message:       toIMAPMessage(message),
+		MailboxIDs:    usertypes.MapTo[string, imap.MailboxID](wantLabels(apiLabels, message.LabelIDs)),
+		Literal:       literal,
+		ParsedMessage: parsedMessage,
+	}
+}
+
+func newFailedMessageLiteral(
+	messageID string,
+	date time.Time,
+	subject string,
+	syncErr error,
+) []byte {
+	var buf bytes.Buffer
+
+	if tmpl, err := template.New("header").Parse(failedMessageHeaderTemplate); err != nil {
+		panic(err)
+	} else if b, err := tmplExec(tmpl, map[string]any{
+		"Date": date.In(time.UTC).Format(time.RFC822),
+	}); err != nil {
+		panic(err)
+	} else if _, err := buf.Write(b); err != nil {
+		panic(err)
+	}
+
+	if tmpl, err := template.New("body").Parse(failedMessageBodyTemplate); err != nil {
+		panic(err)
+	} else if b, err := tmplExec(tmpl, map[string]any{
+		"MessageID": messageID,
+		"Subject":   subject,
+		"Error":     syncErr.Error(),
+	}); err != nil {
+		panic(err)
+	} else if _, err := buf.Write(lineWrap(algo.B64Encode(b))); err != nil {
+		panic(err)
+	}
+
+	return buf.Bytes()
+}
+
+func tmplExec(template *template.Template, data any) ([]byte, error) {
+	var buf bytes.Buffer
+
+	if err := template.Execute(&buf, data); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func lineWrap(b []byte) []byte {
+	return bytes.Join(xslices.Chunk(b, 76), []byte{'\r', '\n'})
+}
+
+const failedMessageHeaderTemplate = `Date: {{.Date}}
+Subject: Message failed to build
+Content-Type: text/plain
+Content-Transfer-Encoding: base64
+
+`
+
+const failedMessageBodyTemplate = `Failed to build message: 
+Subject:   {{.Subject}}
+Error:     {{.Error}}
+MessageID: {{.MessageID}}
+`