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/clientconfig/config_applemail.go

@@ -0,0 +1,121 @@
+// 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 darwin
+
+package clientconfig
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/ProtonMail/proton-bridge/internal/bridge"
+	"github.com/ProtonMail/proton-bridge/internal/config/useragent"
+	"github.com/ProtonMail/proton-bridge/internal/frontend/types"
+	"github.com/ProtonMail/proton-bridge/pkg/mobileconfig"
+)
+
+const (
+	bigSurPreferncesPane = "/System/Library/PreferencePanes/Profiles.prefPane"
+)
+
+func init() { //nolint[gochecknoinit]
+	available[AppleMailClient] = &appleMail{}
+}
+
+type appleMail struct{}
+
+func (c *appleMail) Name() string { return AppleMailClient }
+
+func (c *appleMail) Configure(imapPort, smtpPort int, imapSSL, smtpSSL bool, user types.User, address string) error {
+	mc := prepareMobileConfig(imapPort, smtpPort, imapSSL, smtpSSL, user, address)
+
+	confPath, err := saveConfigTemporarily(mc)
+	if err != nil {
+		return err
+	}
+
+	if useragent.IsBigSurOrNewer() {
+		return exec.Command("open", bigSurPreferncesPane, confPath).Run() //nolint[gosec] G204: open command is safe, mobileconfig is generated by us
+	}
+
+	return exec.Command("open", confPath).Run() //nolint[gosec] G204: open command is safe, mobileconfig is generated by us
+}
+
+func prepareMobileConfig(imapPort, smtpPort int, imapSSL, smtpSSL bool, user types.User, address string) *mobileconfig.Config {
+	displayName := address
+	addresses := address
+
+	if user.IsCombinedAddressMode() {
+		displayName = user.GetPrimaryAddress()
+		addresses = strings.Join(user.GetAddresses(), ",")
+	}
+
+	timestamp := strconv.FormatInt(time.Now().Unix(), 10)
+
+	return &mobileconfig.Config{
+		EmailAddress: addresses,
+		DisplayName:  displayName,
+		Identifier:   "protonmail " + displayName + timestamp,
+		IMAP: &mobileconfig.IMAP{
+			Hostname: bridge.Host,
+			Port:     imapPort,
+			TLS:      imapSSL,
+			Username: displayName,
+			Password: user.GetBridgePassword(),
+		},
+		SMTP: &mobileconfig.SMTP{
+			Hostname: bridge.Host,
+			Port:     smtpPort,
+			TLS:      smtpSSL,
+			Username: displayName,
+		},
+	}
+}
+
+func saveConfigTemporarily(mc *mobileconfig.Config) (fname string, err error) {
+	dir, err := ioutil.TempDir("", "protonmail-autoconfig")
+	if err != nil {
+		return
+	}
+
+	// Make sure the temporary file is deleted.
+	go (func() {
+		<-time.After(10 * time.Minute)
+		_ = os.RemoveAll(dir)
+	})()
+
+	// Make sure the file is only readable for the current user.
+	fname = filepath.Clean(filepath.Join(dir, "protonmail.mobileconfig"))
+	f, err := os.OpenFile(fname, os.O_RDWR|os.O_CREATE, 0600)
+	if err != nil {
+		return
+	}
+
+	if err = mc.WriteOut(f); err != nil {
+		_ = f.Close()
+		return
+	}
+	_ = f.Close()
+
+	return
+}