feat: add configurable headers and instance branding (#6690)

apps/nextjs/src/theme/branding.ts

@@ -0,0 +1,43 @@
+import type { MantineColorsTuple, MantineThemeOverride } from "@mantine/core";
+import { createTheme, darken, lighten, mergeThemeOverrides } from "@mantine/core";
+
+import type { ServerSettings } from "@homarr/server-settings";
+import { theme as homarrTheme } from "@homarr/ui";
+
+export const generateColorScale = (hex: string) => {
+  const lightnessSteps = [-0.25, -0.2, -0.15, -0.1, -0.05, 0, 0.05, 0.1, 0.15, 0.2] as const;
+  const colors = lightnessSteps.map((lightness) => {
+    if (lightness < 0) return lighten(hex, -lightness);
+    return darken(hex, lightness);
+  });
+
+  return colors.map((color) => {
+    const channels = color.split("(")[1]?.replaceAll(" ", "").replace(")", "").split(",");
+    if (!channels) return hex;
+    const value = channels
+      .map((channel) => parseInt(channel, 10))
+      .slice(0, 3)
+      .map((channel) => channel.toString(16).padStart(2, "0"))
+      .join("");
+    return `#${value}`;
+  }) as unknown as MantineColorsTuple;
+};
+
+export const createBrandTheme = (branding: ServerSettings["branding"]): MantineThemeOverride =>
+  mergeThemeOverrides(
+    homarrTheme,
+    createTheme({
+      colors: {
+        primaryColor: generateColorScale(branding.primaryColor),
+        secondaryColor: generateColorScale(branding.secondaryColor),
+      },
+      primaryColor: "primaryColor",
+      defaultRadius: branding.defaultRadius,
+      components: {
+        ActionIcon: { defaultProps: { radius: branding.defaultRadius } },
+        Button: { defaultProps: { radius: branding.defaultRadius } },
+        Card: { defaultProps: { radius: branding.defaultRadius } },
+        Paper: { defaultProps: { radius: branding.defaultRadius } },
+      },
+    }),
+  );