add theming

internal/report/themes.go

@@ -0,0 +1,55 @@
+package report
+
+import "sort"
+
+// themeAssets bundles everything a report or index page needs to render in
+// one visual theme: the shared stylesheet (cards, tables, nav, badges, ...),
+// report-only CSS (map + map label), and the color/URL values referenced by
+// the inline Chart.js / Leaflet JS.
+type themeAssets struct {
+	CSS      string // shared :root + component stylesheet
+	ExtraCSS string // report-only overrides (map, map label)
+
+	ChartFont string // Chart.js font-family
+	ChartText string // Chart.js default text color
+	ChartGrid string // Chart.js default grid/border color
+
+	Chart1     string // 2xx / success series color
+	Chart2     string // 3xx / timeline series color
+	Chart2Fill string // timeline area fill (rgba)
+	Chart3     string // top-paths bar color / decorative accent
+	ChartWarn  string // 4xx series color
+	ChartErr   string // 5xx series color
+
+	MapTileURL     string
+	MapAttribution string
+	MarkerColor    string
+}
+
+// DefaultTheme is used when no theme is specified or an unknown name is given.
+const DefaultTheme = "cyberpunk"
+
+var themeRegistry = map[string]themeAssets{
+	"cyberpunk":  cyberpunkTheme,
+	"purplerain": purplerainTheme,
+	"cactus":     cactusTheme,
+}
+
+// ThemeNames returns the sorted list of valid --theme values.
+func ThemeNames() []string {
+	names := make([]string, 0, len(themeRegistry))
+	for name := range themeRegistry {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+	return names
+}
+
+// themeFor looks up a theme by name, falling back to DefaultTheme for an
+// empty or unrecognized name.
+func themeFor(name string) themeAssets {
+	if t, ok := themeRegistry[name]; ok {
+		return t
+	}
+	return themeRegistry[DefaultTheme]
+}