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/shared_labels.go

@@ -0,0 +1,132 @@
+// 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 (
+	"sync"
+
+	"github.com/ProtonMail/go-proton-api"
+	"github.com/ProtonMail/proton-bridge/v3/internal/usertypes"
+	"golang.org/x/exp/maps"
+)
+
+type labelMap = map[string]proton.Label
+
+// sharedLabels holds the shared state of all the available API labels which can safely be shared among
+// all IMAP states. It's written this way to prevent issues with invalid use of the locks.
+type sharedLabels interface {
+	Read() labelsRead
+	Write() labelsWrite
+}
+
+type labelsRead interface {
+	Close()
+	GetLabel(id string) (proton.Label, bool)
+	GetLabels() []proton.Label
+}
+
+type labelsWrite interface {
+	labelsRead
+	SetLabel(id string, label proton.Label)
+	Delete(id string)
+}
+
+type rwLabels struct {
+	lock   sync.RWMutex
+	labels labelMap
+}
+
+func (r *rwLabels) Read() labelsRead {
+	r.lock.RLock()
+	return &rwLabelsRead{rw: r}
+}
+
+func (r *rwLabels) Write() labelsWrite {
+	r.lock.Lock()
+	return &rwLabelsWrite{rw: r}
+}
+
+func (r *rwLabels) getLabelUnsafe(id string) (proton.Label, bool) {
+	v, ok := r.labels[id]
+
+	return v, ok
+}
+
+func (r *rwLabels) getLabelsUnsafe() []proton.Label {
+	return maps.Values(r.labels)
+}
+
+func (r *rwLabels) SetLabels(labels []proton.Label) {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
+	r.labels = usertypes.GroupBy(labels, func(label proton.Label) string { return label.ID })
+}
+
+func (r *rwLabels) GetLabelMap() labelMap {
+	r.lock.Lock()
+	defer r.lock.Unlock()
+
+	return maps.Clone(r.labels)
+}
+
+func newRWLabels() *rwLabels {
+	return &rwLabels{
+		labels: make(labelMap),
+	}
+}
+
+type rwLabelsRead struct {
+	rw *rwLabels
+}
+
+func (r rwLabelsRead) Close() {
+	r.rw.lock.RUnlock()
+}
+
+func (r rwLabelsRead) GetLabel(id string) (proton.Label, bool) {
+	return r.rw.getLabelUnsafe(id)
+}
+
+func (r rwLabelsRead) GetLabels() []proton.Label {
+	return r.rw.getLabelsUnsafe()
+}
+
+type rwLabelsWrite struct {
+	rw *rwLabels
+}
+
+func (r rwLabelsWrite) Close() {
+	r.rw.lock.Unlock()
+}
+
+func (r rwLabelsWrite) GetLabel(id string) (proton.Label, bool) {
+	return r.rw.getLabelUnsafe(id)
+}
+
+func (r rwLabelsWrite) GetLabels() []proton.Label {
+	return r.rw.getLabelsUnsafe()
+}
+
+func (r rwLabelsWrite) SetLabel(id string, label proton.Label) {
+	r.rw.labels[id] = label
+}
+
+func (r rwLabelsWrite) Delete(id string) {
+	delete(r.rw.labels, id)
+}