add option for automatically enabling firefox's dark theme

fallbackui.go

@@ -51,8 +51,13 @@ func createFallbackUI() {
 
 	fmt.Print("\nWould you like to auto-generate UUIDs? [y/n] ")
 	fmt.Scanln(&choice)
+	uuids := (choice == "y" || choice == "Y")
 
-	message, err := install(profile, (choice == "y" || choice == "Y"))
+	fmt.Print("\nWould you like to automatically set the Firefox dark theme? [y/n] ")
+	fmt.Scanln(&choice)
+	theme := (choice == "y" || choice == "Y")
+
+	message, err := install(profile, uuids, theme)
 	if err != nil {
 		fmt.Printf("%s: %s", message, err.Error())
 		fmt.Scanln()

install.go

@@ -11,6 +11,10 @@ import (
 	"time"
 )
 
+const darkThemeConfig = `
+user_pref("lightweightThemes.selectedThemeID", "[email protected]");
+user_pref("devtools.theme", "dark");`
+
 func uninstall(profile string) (string, error) {
 	err := os.RemoveAll(filepath.Join(profile, "chrome", "ShadowFox_customization"))
 	if err != nil {
@@ -102,7 +106,7 @@ func addColorOverrides(source, colors string) string {
 	return source[:startI] + colors + source[endI:]
 }
 
-func install(profilePath string, generateUUIDs bool) (string, error) {
+func install(profilePath string, generateUUIDs bool, setTheme bool) (string, error) {
 	// Helper variables to keep things DRY
 	chromePath := filepath.Join(profilePath, "chrome")
 	customPath := filepath.Join(chromePath, "ShadowFox_customization")
@@ -215,6 +219,33 @@ func install(profilePath string, generateUUIDs bool) (string, error) {
 		}
 	}
 
+	// Set dark theme
+	if setTheme {
+		userJs := filepath.Join(profilePath, "user.js")
+		err = backUp(userJs)
+		if err != nil {
+			return "Couldn't backup user.js", err
+		}
+
+		err = createFile(userJs)
+		if err != nil {
+			return "Couldn't create user.js", err
+		}
+
+		userJsContent, err := ioutil.ReadFile(userJs)
+		if err != nil {
+			return "Couldn't read user.js", err
+		}
+
+		if !strings.Contains(string(userJsContent), darkThemeConfig) {
+			userJsContent = append(userJsContent, []byte(darkThemeConfig)...)
+
+			if err := ioutil.WriteFile(userJs, userJsContent, 0644); err != nil {
+				return "Couldn't write user.js", err
+			}
+		}
+	}
+
 	// Write new files
 	if err := ioutil.WriteFile(userChromePath, []byte(userChrome), 0644); err != nil {
 		return "Couldn't write userChrome.css to file", err

ui.go

@@ -34,8 +34,10 @@ func createUI() error {
 
 	uuidCheckBox := tview.NewCheckbox().SetLabel("Auto-Generate UUIDs: ").SetChecked(false)
 
+	themeCheckBox := tview.NewCheckbox().SetLabel("Set Firefox dark theme: ").SetChecked(false)
+
 	installButton := tview.NewButton("Install/Update ShadowFox").SetSelectedFunc(func() {
-		message, err := install(paths[profileIndex], uuidCheckBox.IsChecked())
+		message, err := install(paths[profileIndex], uuidCheckBox.IsChecked(), themeCheckBox.IsChecked())
 		if err != nil {
 			notifyErr(message, err)
 		} else {
@@ -66,6 +68,8 @@ func createUI() error {
 				case uninstallButton.HasFocus():
 					app.SetFocus(installButton)
 				case installButton.HasFocus():
+					app.SetFocus(themeCheckBox)
+				case themeCheckBox.HasFocus():
 					app.SetFocus(uuidCheckBox)
 				case uuidCheckBox.HasFocus():
 					app.SetFocus(profileSelect)
@@ -77,6 +81,8 @@ func createUI() error {
 				case profileSelect.HasFocus():
 					app.SetFocus(uuidCheckBox)
 				case uuidCheckBox.HasFocus():
+					app.SetFocus(themeCheckBox)
+				case themeCheckBox.HasFocus():
 					app.SetFocus(installButton)
 				case installButton.HasFocus():
 					app.SetFocus(uninstallButton)
@@ -103,6 +109,12 @@ func createUI() error {
 			AddItem(nil, 0, 1, false), 1, 0, true,
 		).
 		AddItem(nil, 1, 0, false).
+		AddItem(tview.NewFlex().
+			AddItem(nil, 0, 1, false).
+			AddItem(themeCheckBox, 0, 10, true).
+			AddItem(nil, 0, 1, false), 1, 0, true,
+		).
+		AddItem(nil, 1, 0, false).
 		AddItem(infoText, 5, 0, false).
 		AddItem(nil, 1, 0, false).
 		AddItem(tview.NewFlex().