update calculations for lucky levels (#1161)

* update calculations for lucky levels

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Disp/HelperFunctions/CalculateLuckyLevels.js

@@ -0,0 +1,82 @@
+const SPECIAL_DIGIT = 7;
+
+/**
+ * Count the number of 7s in any number
+ * @param	{number}	number	The number to count sevens for
+ * @returns	{number}	The number of 7s in the provided number
+ */
+export function CountSevens(number) {
+  let localNumber = number;
+  let sevenCount = 0;
+
+  while (localNumber >= SPECIAL_DIGIT) {
+    if (localNumber % 10 === SPECIAL_DIGIT) sevenCount += 1;
+    localNumber = Math.floor(localNumber / 10);
+  }
+
+  return sevenCount;
+}
+
+/**
+ * Calculate the delta for the next number where the given digit is a 7
+ * @param	{number}	number			The starting number to calculate the delta for
+ * @param	{number}	digitPlace	1 for ones place, 10 for tens place, 100 for hundreds place, etc
+ * @returns	{number}	The calculated delta
+ */
+export function CalculateSevenDelta(number, digitPlace) {
+  const target = SPECIAL_DIGIT * digitPlace;
+  const modulus = digitPlace * 10;
+
+  let delta = target - (number % modulus) + (number % digitPlace);
+  if (delta < 0) delta += modulus;
+
+  return delta;
+}
+
+/**
+ * This function calculates each of the next "lucky" prestige levels
+ * @param	{number}	currentLevel	The user's prestige level, including levels earned since the last ascension
+ * @returns	{{number}, {number}, {number}}	luckyDigit, luckyNumber, luckyPayout	The next eligible level for each upgrade
+ */
+export default function CalculateLuckyLevels(currentLevel) {
+  const result = {};
+  let localLevel = currentLevel;
+  let sevenCount = CountSevens(currentLevel);
+
+  if (sevenCount < 1) {
+    // find the next 7 for the ones digit
+    const delta = CalculateSevenDelta(localLevel, 1);
+
+    localLevel += delta;
+    sevenCount = CountSevens(localLevel);
+  }
+
+  result.luckyDigit = localLevel;
+
+  while (sevenCount < 2) {
+    // find the next 7 in the ones or tens digit
+    let delta = CalculateSevenDelta(localLevel, 1);
+    if (delta === 0) delta = CalculateSevenDelta(localLevel, 10);
+
+    localLevel += delta;
+    sevenCount = CountSevens(localLevel);
+  }
+
+  result.luckyNumber = localLevel;
+
+  let digitPlace = 1;
+  while (sevenCount < 4) {
+    // look for missing 7s in the ones, tens, hundreds, thousands digits
+    const delta = CalculateSevenDelta(localLevel, digitPlace);
+    if (delta === 0) {
+      digitPlace *= 10;
+    } else {
+      localLevel += delta;
+      sevenCount = CountSevens(localLevel);
+    }
+  }
+
+  result.luckyPayout = localLevel;
+
+  return result;
+}