GODT-22: Frontend-backend

- GODT-1246 Implement settings view.
- GODT-1257 GODT-1246: Account and Help view
- GODT-1298: Minimal working build (panics)
- GODT-1298: loading QML (needs Popup window)
- GODT-1298: WARN: Adding PopupWindow not possible!
    In therecipe qt the `quickwidgets` classes are within `quick` module, but
    forgot to add library and include paths into cgo flags. Therefore
    compilation fails and it would be hard to patch therecipe in order to
    fix it.

    I am not sure if rewrite PopupWindow into go would make any difference,
    therefore I decided to use normal QML Window without borders.
- GODT-1298: Rework status window, add backend props, slots and signals.
- GODT-1298: Users
- GODT-1298: Login
- GODT-1298: WIP Help and bug report
- GODT-1178: MacOS dock icon control
- GODT-1298: Help, bug report, update and events
- GODT-1298: Apple Mail config and Settings (without cache on disk)

internal/frontend/qt/qml_users.go

@@ -0,0 +1,135 @@
+// Copyright (c) 2021 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail 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.
+//
+// ProtonMail 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 ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+// +build build_qt
+
+package qt
+
+import (
+	"github.com/ProtonMail/proton-bridge/internal/frontend/types"
+	"github.com/therecipe/qt/core"
+)
+
+// QMLUserModel stores list of of users
+type QMLUserModel struct {
+	core.QAbstractListModel
+
+	_ map[int]*core.QByteArray     `property:"roles"`
+	_ int                          `property:"count"`
+	_ func()                       `constructor:"init"`
+	_ func(row int) *core.QVariant `slot:"get"`
+
+	users []*QMLUser
+}
+
+func (um *QMLUserModel) init() {
+	um.SetRoles(map[int]*core.QByteArray{
+		int(core.Qt__UserRole + 1): newQByteArrayFromString("object"),
+	})
+	um.ConnectRowCount(um.rowCount)
+	um.ConnectData(um.data)
+	um.ConnectGet(um.get)
+	um.users = []*QMLUser{}
+	um.setCount()
+}
+
+func (um *QMLUserModel) data(index *core.QModelIndex, property int) *core.QVariant {
+	if !index.IsValid() {
+		return core.NewQVariant()
+	}
+	return um.get(index.Row())
+}
+
+func (um *QMLUserModel) get(index int) *core.QVariant {
+	if index < 0 || index >= um.rowCount(nil) {
+		return core.NewQVariant()
+	}
+	return um.users[index].ToVariant()
+}
+
+func (um *QMLUserModel) rowCount(*core.QModelIndex) int {
+	return len(um.users)
+}
+
+func (um *QMLUserModel) setCount() {
+	um.SetCount(len(um.users))
+}
+
+func (um *QMLUserModel) addUser(user *QMLUser) {
+	um.BeginInsertRows(core.NewQModelIndex(), um.rowCount(nil), um.rowCount(nil))
+	um.users = append(um.users, user)
+	um.setCount()
+	um.EndInsertRows()
+}
+
+func (um *QMLUserModel) removeUser(row int) {
+	um.BeginRemoveRows(core.NewQModelIndex(), row, row)
+	um.users = append(um.users[:row], um.users[row+1:]...)
+	um.setCount()
+	um.EndRemoveRows()
+}
+
+func (um *QMLUserModel) clear() {
+	um.BeginRemoveRows(core.NewQModelIndex(), 0, um.rowCount(nil))
+	um.users = []*QMLUser{}
+	um.setCount()
+	um.EndRemoveRows()
+}
+
+func (um *QMLUserModel) indexByID(id string) int {
+	for i, qu := range um.users {
+		if id == qu.ID {
+			return i
+		}
+	}
+	return -1
+}
+
+// QMLUser holds data, slots and signals and for user.
+type QMLUser struct {
+	core.QObject
+
+	_ string   `property:"username"`
+	_ string   `property:"avatarText"`
+	_ bool     `property:"loggedIn"`
+	_ bool     `property:"splitMode"`
+	_ bool     `property:"setupGuideSeen"`
+	_ float32  `property:"usedBytes"`
+	_ float32  `property:"totalBytes"`
+	_ string   `property:"password"`
+	_ []string `property:"addresses"`
+
+	_ func(makeItActive bool) `slot:"toggleSplitMode"`
+	_ func()                  `signal:"toggleSplitModeFinished"`
+	_ func()                  `slot:"logout"`
+	_ func(address string)    `slot:"configureAppleMail"`
+
+	ID string
+}
+
+func (qu *QMLUser) update(user types.User) {
+	username := user.Username()
+	qu.SetAvatarText(getInitials(username))
+	qu.SetUsername(username)
+	qu.SetLoggedIn(user.IsConnected())
+	qu.SetSplitMode(!user.IsCombinedAddressMode())
+	qu.SetSetupGuideSeen(true)
+	qu.SetUsedBytes(1.0)      // TODO
+	qu.SetTotalBytes(10000.0) // TODO
+	qu.SetPassword(user.GetBridgePassword())
+	qu.SetAddresses(user.GetAddresses())
+}