feat: scaffold mvp shell and content runtime

js/gameplay/difficulty/random.js

@@ -0,0 +1,36 @@
+export function hashSeed(input) {
+  const value = String(input)
+  let hash = 2166136261
+
+  for (let index = 0; index < value.length; index += 1) {
+    hash ^= value.charCodeAt(index)
+    hash = Math.imul(hash, 16777619)
+  }
+
+  return hash >>> 0
+}
+
+export function createRng(seed) {
+  let state = typeof seed === 'number' ? seed >>> 0 : hashSeed(seed)
+
+  return function next() {
+    state += 0x6D2B79F5
+    let value = state
+    value = Math.imul(value ^ (value >>> 15), value | 1)
+    value ^= value + Math.imul(value ^ (value >>> 7), value | 61)
+    return ((value ^ (value >>> 14)) >>> 0) / 4294967296
+  }
+}
+
+export function shuffleWithRng(items, rng) {
+  const result = [...items]
+
+  for (let index = result.length - 1; index > 0; index -= 1) {
+    const swapIndex = Math.floor(rng() * (index + 1))
+    const temp = result[index]
+    result[index] = result[swapIndex]
+    result[swapIndex] = temp
+  }
+
+  return result
+}