Feature: stock market service and info widget (#3617)

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/pages/api/widgets/stocks.js

@@ -0,0 +1,76 @@
+import cachedFetch from "utils/proxy/cached-fetch";
+import { getSettings } from "utils/config/config";
+
+export default async function handler(req, res) {
+  const { watchlist, provider, cache } = req.query;
+
+  if (!watchlist) {
+    return res.status(400).json({ error: "Missing watchlist" });
+  }
+
+  const watchlistArr = watchlist.split(",") || [watchlist];
+
+  if (!watchlistArr.length || watchlistArr[0] === "null" || !watchlistArr[0]) {
+    return res.status(400).json({ error: "Missing watchlist" });
+  }
+
+  if (watchlistArr.length > 8) {
+    return res.status(400).json({ error: "Max items in watchlist is 8" });
+  }
+
+  const hasDuplicates = new Set(watchlistArr).size !== watchlistArr.length;
+
+  if (hasDuplicates) {
+    return res.status(400).json({ error: "Watchlist contains duplicates" });
+  }
+
+  if (!provider) {
+    return res.status(400).json({ error: "Missing provider" });
+  }
+
+  if (provider !== "finnhub") {
+    return res.status(400).json({ error: "Invalid provider" });
+  }
+
+  const providersInConfig = getSettings()?.providers;
+
+  let apiKey;
+  Object.entries(providersInConfig).forEach(([key, val]) => {
+    if (key === provider) apiKey = val;
+  });
+
+  if (typeof apiKey === "undefined") {
+    return res.status(400).json({ error: "Missing or invalid API Key for provider" });
+  }
+
+  if (provider === "finnhub") {
+    // Finnhub allows up to 30 calls/second
+    // https://finnhub.io/docs/api/rate-limit
+    const results = await Promise.all(
+      watchlistArr.map(async (ticker) => {
+        if (!ticker) {
+          return { ticker: null, currentPrice: null, percentChange: null };
+        }
+        // https://finnhub.io/docs/api/quote
+        const apiUrl = `https://finnhub.io/api/v1/quote?symbol=${ticker}&token=${apiKey}`;
+        // Finnhub free accounts allow up to 60 calls/minute
+        // https://finnhub.io/pricing
+        const { c, dp } = await cachedFetch(apiUrl, cache || 1);
+
+        // API sometimes returns 200, but values returned are `null`
+        if (c === null || dp === null) {
+          return { ticker, currentPrice: null, percentChange: null };
+        }
+
+        // Rounding percentage, but we want it back to a number for comparison
+        return { ticker, currentPrice: c.toFixed(2), percentChange: parseFloat(dp.toFixed(2)) };
+      }),
+    );
+
+    return res.send({
+      stocks: results,
+    });
+  }
+
+  return res.status(400).json({ error: "Invalid configuration" });
+}