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/frontend.go

@@ -0,0 +1,146 @@
+// 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 provides communication between Qt/QML frontend and Go backend
+package qt
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/ProtonMail/go-autostart"
+	"github.com/ProtonMail/proton-bridge/internal/config/settings"
+	"github.com/ProtonMail/proton-bridge/internal/config/useragent"
+	"github.com/ProtonMail/proton-bridge/internal/frontend/types"
+	"github.com/ProtonMail/proton-bridge/internal/locations"
+	"github.com/ProtonMail/proton-bridge/internal/updater"
+	"github.com/ProtonMail/proton-bridge/pkg/listener"
+	"github.com/ProtonMail/proton-bridge/pkg/pmapi"
+	"github.com/sirupsen/logrus"
+	"github.com/therecipe/qt/qml"
+	"github.com/therecipe/qt/widgets"
+)
+
+type FrontendQt struct {
+	programName, programVersion string
+
+	panicHandler     types.PanicHandler
+	locations        *locations.Locations
+	settings         *settings.Settings
+	eventListener    listener.Listener
+	updater          types.Updater
+	userAgent        *useragent.UserAgent
+	bridge           types.Bridger
+	noEncConfirmator types.NoEncConfirmator
+	autostart        *autostart.App
+	restarter        types.Restarter
+
+	authClient pmapi.Client
+	auth       *pmapi.Auth
+	password   []byte
+
+	newVersionInfo updater.VersionInfo
+
+	log      *logrus.Entry
+	usersMtx sync.Mutex
+
+	app    *widgets.QApplication
+	engine *qml.QQmlApplicationEngine
+	qml    *QMLBackend
+}
+
+func New(
+	version,
+	buildVersion,
+	programName string,
+	showWindowOnStart bool,
+	panicHandler types.PanicHandler,
+	locations *locations.Locations,
+	settings *settings.Settings,
+	eventListener listener.Listener,
+	updater types.Updater,
+	userAgent *useragent.UserAgent,
+	bridge types.Bridger,
+	_ types.NoEncConfirmator,
+	autostart *autostart.App,
+	restarter types.Restarter,
+) *FrontendQt {
+	return &FrontendQt{
+		programName:    "Proton Mail Bridge",
+		programVersion: version,
+		log:            logrus.WithField("pkg", "frontend/qt"),
+
+		panicHandler:  panicHandler,
+		locations:     locations,
+		settings:      settings,
+		eventListener: eventListener,
+		updater:       updater,
+		userAgent:     userAgent,
+		bridge:        bridge,
+		autostart:     autostart,
+		restarter:     restarter,
+	}
+}
+
+func (f *FrontendQt) Loop() error {
+	err := f.initiateQtApplication()
+	if err != nil {
+		return err
+	}
+
+	go func() {
+		defer f.panicHandler.HandlePanic()
+		f.watchEvents()
+	}()
+
+	if ret := f.app.Exec(); ret != 0 {
+		err := fmt.Errorf("Event loop ended with return value: %v", ret)
+		f.log.Warn("App exec", err)
+		return err
+	}
+
+	return nil
+}
+
+func (f *FrontendQt) NotifyManualUpdate(version updater.VersionInfo, canInstall bool) {
+	if canInstall {
+		f.qml.UpdateManualReady(version.Version.String())
+	} else {
+		f.qml.UpdateManualError()
+	}
+}
+
+func (f *FrontendQt) SetVersion(version updater.VersionInfo) {
+	f.newVersionInfo = version
+	f.qml.SetReleaseNotesLink(version.ReleaseNotesPage)
+	f.qml.SetLandingPageLink(version.LandingPage)
+}
+
+func (f *FrontendQt) NotifySilentUpdateInstalled() {
+	f.qml.UpdateSilentRestartNeeded()
+}
+
+func (f *FrontendQt) NotifySilentUpdateError(err error) {
+	f.log.WithError(err).Warn("Update failed, asking for manual.")
+	f.qml.UpdateManualError()
+}
+
+func (f *FrontendQt) WaitUntilFrontendIsReady() {
+	// TODO: Implement
+}