adding habit_streak_milestones

lib/coins.ts

@@ -0,0 +1,28 @@
+export const COINS_PER_TASK_COMPLETE = 50;
+export const COINS_PER_TASK_UNCHECK = -50;
+
+export const STREAK_MILESTONE_COINS: Record<number, number> = {
+  5: 50,
+  7: 75,
+  10: 100,
+  20: 150,
+  30: 200,
+  50: 350,
+  100: 750,
+};
+
+export const STREAK_MILESTONES = Object.keys(STREAK_MILESTONE_COINS)
+  .map(Number)
+  .sort((a, b) => a - b);
+
+export function getStreakMilestoneBonus(streak: number) {
+  return STREAK_MILESTONE_COINS[streak] ?? null;
+}
+
+export function formatCoinsDelta(delta: number) {
+  if (delta === 0) {
+    return "0 points";
+  }
+
+  return `${delta > 0 ? "+" : ""}${delta} points`;
+}