zenno/doc/fans: new data coverage and fix off-by-ones

zenno/src/routes/doc/fans/fans.ts

@@ -1,3 +1,15 @@
+const placementPms = [1000, 400, 250, 150, 100, 90, 80, 70, 60, 50, 40, 30, 25, 20, 15, 10, 10, 10] as const;
+
+/**
+ * Calculate base fans for a given placement in a race.
+ * @param winBase Base fans for a win, as displayed in the race menu
+ * @param finishOrder Placement of the trainee, with winner being 1
+ * @returns Base fans for the race and placement together
+ */
+export function baseFans(winBase: number, finishOrder: number): number {
+	return Math.round(winBase * placementPms[finishOrder - 1] / 1000);
+}
+
 const margins = [
 	[0.75, 0.0, 0.09],
 	[2.5, 0.02, 0.06],
@@ -9,15 +21,15 @@ const margins = [
 /**
  * Calculate fans gained from a career race due to the margin of the finish.
  * @param baseFans Base fans from the race and finish order
- * @param finishOrder Placement of the trainee
+ * @param finishOrder Placement of the trainee, with winner being 1
  * @param margin Margin in lengths between the trainee and second if a win, or the winner and trainee if a loss
  * @returns Fans gained due to finish margin
  */
 export function marginFans(baseFans: number, finishOrder: number, margin: number): number {
-	if (finishOrder > 3) {
+	if (finishOrder > 5) {
 		return 0;
 	}
-	const [, wb, lb] = margins.find(([m]) => margin < m)!;
+	const [, wb, lb] = margins.find(([m]) => margin <= m)!;
 	const b = finishOrder === 1 ? wb : lb;
 	return Math.floor(baseFans * b);
 }
@@ -52,7 +64,10 @@ export function skillFans(baseFans: number, skillsActivated: number): number {
  */
 export function gained(baseFans: number, marginFans: number, skillFans: number, fanBonus: number, itemBonus?: number): number {
 	const f = baseFans + marginFans + skillFans;
-	const d = Math.round(f * (1 + fanBonus / 100));
+	const s = Math.fround(f * Math.fround(1 + fanBonus / 100));
+	const p = Math.exp((4 - Math.floor(Math.log10(s))) * Math.LN10);
+	// Add half a significant figure to account for precision.
+	const d = Math.floor(Math.round(s * p + 5e-6) / p + 5e-6);
 	const b = itemBonus ?? 0;
 	return Math.floor(d * (1 + b / 100));
 }