Initial commit

lib/format.ts

@@ -0,0 +1,52 @@
+import { RateAsset } from "@/lib/rates";
+
+function trimTrailingZeroes(value: string): string {
+  return value.replace(/\.?0+$/, "");
+}
+
+export function formatAmount(value: number, asset: RateAsset): string {
+  if (!Number.isFinite(value)) {
+    return "-";
+  }
+
+  if (asset.type === "crypto") {
+    if (value === 0) {
+      return "0";
+    }
+
+    if (Math.abs(value) < 0.00000001) {
+      return "<0.00000001";
+    }
+
+    const precision = asset.decimals ?? 8;
+    const formatted = value.toLocaleString("en-US", {
+      minimumFractionDigits: value < 1 ? 4 : 2,
+      maximumFractionDigits: precision
+    });
+
+    return trimTrailingZeroes(formatted);
+  }
+
+  return value.toLocaleString("en-US", {
+    minimumFractionDigits: 2,
+    maximumFractionDigits: value < 1 ? 6 : 4
+  });
+}
+
+export function formatRate(from: RateAsset, to: RateAsset): string {
+  const rate = from.usdPrice / to.usdPrice;
+  return formatAmount(rate, to);
+}
+
+export function formatInverseRate(from: RateAsset, to: RateAsset): string {
+  const inverse = to.usdPrice / from.usdPrice;
+  return formatAmount(inverse, from);
+}
+
+export function formatTimestamp(value: string): string {
+  const date = new Date(value);
+  return new Intl.DateTimeFormat("en-US", {
+    dateStyle: "medium",
+    timeStyle: "short"
+  }).format(date);
+}