1 files changed, 110 insertions, 0 deletions
diff --git a/www/assets/res/js/color-scheme.ts b/www/assets/res/js/color-scheme.ts
new file mode 100644
index 0000000..db6a3aa
--- /dev/null
+++ b/www/assets/res/js/color-scheme.ts
@@ -0,0 +1,110 @@
+function createResetTimer(cleanup: () => void, timeout = 1) {
+  let tag = 0
+  return () => {
+    clearTimeout(tag)
+    tag = setTimeout(() => {
+      cleanup()
+    }, timeout * 1000)
+  }
+}
+
+function createToast(duration: number = 1): (text: string) => void {
+  const toast = document.createElement("div")
+  toast.className = "toast"
+
+  const reset = createResetTimer(() => {
+      toast.remove()
+  }, duration)
+
+  return (text) => {
+    if (!toast.isConnected) {
+      document.body.appendChild(toast)
+    }
+    toast.textContent = text
+    reset()
+  }
+}
+
+const setToast = createToast()
+
+const key = "force-color-scheme"
+const dark = "dark"
+const light = "light"
+type Scheme = typeof dark | typeof light
+
+const mediaQuery = window.matchMedia("(prefers-color-scheme: dark)")
+
+function fromMediaQuery(value: boolean | null): Scheme {
+  if (value == null) { value = mediaQuery.matches}
+  return value ? dark : light
+}
+
+function opposite(scheme: Scheme): Scheme {
+  return scheme === dark ? light : dark
+}
+
+function updateScheme(theme: Scheme | null): Scheme {
+  if (theme == null) { theme = fromMediaQuery(null) }
+  document.querySelector("html")!.dataset["theme"] = theme
+  return theme
+}
+
+mediaQuery.addEventListener("change", (e) => updateScheme(current || fromMediaQuery(e.matches)))
+
+let current: Scheme | null = null
+
+{
+  const saved = localStorage.getItem(key)
+  if ([null, dark, light].includes(saved)) {
+    current = saved as never
+  } else {
+    console.log(`invalid saved theme: ${saved}`)
+    localStorage.removeItem(key)
+  }
+}
+
+updateScheme(current)
+
+function saveScheme(value: Scheme | null) {
+  current = value
+
+  if (value == null) {
+    localStorage.removeItem(key)
+  } else {
+    localStorage.setItem(key, value)
+  }
+
+  const real = updateScheme(value)
+  setToast(`theme: ${current == null ? "system" : "force"}(${real})`)
+}
+
+function next(): Scheme | null {
+  const sys = fromMediaQuery(null)
+  if (current == null) {
+    return opposite(sys)
+  } else {
+    if (current === sys) {
+      return null;
+    } else {
+      return opposite(current)
+    }
+  }
+}
+
+window.addEventListener("load", () => {
+  const slogon = document.getElementById("slogan")!
+  let clicks: number = 0
+
+  const reset = createResetTimer(() => {
+    clicks = 0
+  })
+
+  slogon.addEventListener("click", () => {
+    reset()
+    clicks += 1
+    if (clicks === 3) {
+      saveScheme(next())
+      clicks = 0
+    }
+  })
+})