feat: initial prototype

src/utils/calculateCost.ts

@@ -0,0 +1,30 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import type { Usage } from "@anthropic-ai/sdk/resources/index.js";
+
+/**
+ * Calculates the cost of a command run by a user, and sends to
+ * our logging service.
+ * @param usage -- The usage payload from Anthropic.
+ * @returns A string containing the usage and cost information.
+ */
+export const calculateCost = (
+  usage: Usage,
+): string => {
+  const inputCost = usage.input_tokens * ((usage.input_tokens > 200_000
+    ? 6
+    : 3) / 1_000_000);
+  const outputCost = usage.output_tokens * ((usage.output_tokens > 200_000
+    ? 22.5
+    : 15) / 1_000_000);
+  const totalCost = inputCost + outputCost;
+  return `-# Accepted ${usage.input_tokens.toString()} and generated ${usage.output_tokens.toString()}.
+    
+    -# Total cost: ${totalCost.toLocaleString("en-GB", {
+      currency: "USD",
+      style:    "currency",
+    })}`;
+};