feat: replace next-themes with a custom ThemeProvider

To be honest, next-themes was working fine. However since I use a theme
provider for Prism code blocks, some code is duplicated between this
app and the library. So I prefer to use a custom Provider without the
options I don't need.

2 files changed, 19 insertions, 0 deletions

diff --git a/src/utils/helpers/index.ts b/src/utils/helpers/index.ts
index b2a4534..14487e6 100644
--- a/src/utils/helpers/index.ts
+++ b/src/utils/helpers/index.ts
@@ -4,3 +4,4 @@ export * from './pages';
 export * from './rss';
 export * from './schema-org';
 export * from './strings';
+export * from './themes';
diff --git a/src/utils/helpers/themes.ts b/src/utils/helpers/themes.ts
new file mode 100644
index 0000000..8ef3a19
--- /dev/null
+++ b/src/utils/helpers/themes.ts
@@ -0,0 +1,18 @@
+/**
+ * Check if the user prefers dark color scheme.
+ *
+ * @returns {boolean|undefined} True if `prefers-color-scheme` is set to `dark`.
+ */
+export const prefersDarkScheme = (): boolean | undefined => {
+  if (typeof window === 'undefined') return undefined;
+
+  return window.matchMedia('(prefers-color-scheme: dark)').matches;
+};
+
+/**
+ * Retrieve the theme to use depending on the user system theme.
+ */
+export const getThemeFromSystem = () => {
+  if (prefersDarkScheme()) return 'dark';
+  return 'light';
+};