feat(ui): Allow configuring default dark-mode value (#1015)

* fix: theme flickering

* chore(ui): added dark mode tests

* feat(ui): Expose new ui.dark-mode parameter to set default theme

* refactor(ui): Rename theme variable to themeFromCookie for clarity

---------

Co-authored-by: TwiN <twin@linux.com>
Co-authored-by: TwiN <chris@twin.sh>

config/ui/ui.go

@@ -18,6 +18,8 @@ const (
 )
 
 var (
+	defaultDarkMode = true
+
 	ErrButtonValidationFailed = errors.New("invalid button configuration: missing required name or link")
 )
 
@@ -30,6 +32,14 @@ type Config struct {
 	Link        string   `yaml:"link,omitempty"`        // Link to open when clicking on the logo
 	Buttons     []Button `yaml:"buttons,omitempty"`     // Buttons to display below the header
 	CustomCSS   string   `yaml:"custom-css,omitempty"`  // Custom CSS to include in the page
+	DarkMode    *bool    `yaml:"dark-mode,omitempty"`   // DarkMode is a flag to enable dark mode by default
+}
+
+func (cfg *Config) IsDarkMode() bool {
+	if cfg.DarkMode != nil {
+		return *cfg.DarkMode
+	}
+	return defaultDarkMode
 }
 
 // Button is the configuration for a button on the UI
@@ -55,6 +65,7 @@ func GetDefaultConfig() *Config {
 		Logo:        defaultLogo,
 		Link:        defaultLink,
 		CustomCSS:   defaultCustomCSS,
+		DarkMode:    &defaultDarkMode,
 	}
 }
 
@@ -78,6 +89,9 @@ func (cfg *Config) ValidateAndSetDefaults() error {
 	if len(cfg.CustomCSS) == 0 {
 		cfg.CustomCSS = defaultCustomCSS
 	}
+	if cfg.DarkMode == nil {
+		cfg.DarkMode = &defaultDarkMode
+	}
 	for _, btn := range cfg.Buttons {
 		if err := btn.Validate(); err != nil {
 			return err
@@ -89,5 +103,10 @@ func (cfg *Config) ValidateAndSetDefaults() error {
 		return err
 	}
 	var buffer bytes.Buffer
-	return t.Execute(&buffer, cfg)
+	return t.Execute(&buffer, ViewData{UI: cfg, Theme: "dark"})
+}
+
+type ViewData struct {
+	UI    *Config
+	Theme string
 }