import { z } from "zod";
const COINCAP_API_BASE = "https://api.coincap.io/v2";
interface RateData {
id: string;
symbol: string;
currencySymbol: string;
type: string;
rateUsd: string;
}
interface RateResponse {
data: RateData;
timestamp: number;
}
// Make API request to CoinCap with rate limiting and retries
async function makeCoinCapRequest<T>(url: string): Promise<T | null> {
const USER_AGENT = "realtime-crypto-app/1.0";
const MAX_RETRIES = 3;
const RETRY_DELAY = 1000; // 1 second
const headers = {
"User-Agent": USER_AGENT,
Accept: "application/json",
};
let retries = 0;
while (retries <= MAX_RETRIES) {
try {
const response = await fetch(url, { headers });
if (response.status === 429) {
// Rate limited - wait and retry
retries++;
console.log(`Rate limited by CoinCap API. Retry attempt ${retries}/${MAX_RETRIES} after ${RETRY_DELAY}ms delay`);
if (retries <= MAX_RETRIES) {
await new Promise(resolve => setTimeout(resolve, RETRY_DELAY * retries));
continue;
} else {
throw new Error("Rate limit exceeded. Maximum retries reached.");
}
}
if (!response.ok) {
throw new Error(`HTTP error! status: ${response.status}`);
}
return (await response.json()) as T;
} catch (error) {
if (retries >= MAX_RETRIES || (error instanceof Error && !error.message.includes("429"))) {
console.error("Error making CoinCap request:", error);
return null;
}
retries++;
await new Promise(resolve => setTimeout(resolve, RETRY_DELAY * retries));
}
}
return null;
}
// Format rate details
function formatRateDetails(data: RateData): string {
return [
`Symbol: ${data.symbol || "Unknown"} ${data.currencySymbol || ""}`,
`Type: ${data.type || "Unknown"}`,
`USD Rate: $${parseFloat(data.rateUsd).toLocaleString(undefined, { maximumFractionDigits: 2 })}`,
].join("\n");
}
// Tool definition for "get-rates"
export const getRatesTool = {
name: "get-rates",
description: "Get exchange rates for a cryptocurrency",
inputSchema: z.object({
currency: z.string().describe("Cryptocurrency ID (e.g., bitcoin, ethereum, litecoin)"),
}).shape,
execute: async (args: { currency: string }, extra: any) => {
try {
const currencyId = args.currency.toLowerCase();
const rateUrl = `${COINCAP_API_BASE}/rates/${currencyId}`;
const rateData = await makeCoinCapRequest<RateResponse>(rateUrl);
if (!rateData || !rateData.data) {
return {
content: [
{
type: "text" as const,
text: `Failed to retrieve rates for currency: ${currencyId}`,
},
],
};
}
const formattedDetails = formatRateDetails(rateData.data);
const rateText = `Current rate for ${rateData.data.id}:\n\n${formattedDetails}`;
return {
content: [
{
type: "text" as const,
text: rateText,
},
],
};
} catch (error) {
console.error("Error in getRatesTool.execute:", error);
return {
content: [
{
type: "text" as const,
text: `Error: ${error instanceof Error ? error.message : String(error)}`,
},
],
isError: true,
};
}
},
};
