Initial commit: year overview app for Google Calendar ICS feeds

Local Node app that fetches a Google Calendar ICS URL server-side (to avoid
browser CORS restrictions) and renders a two-year overview with each day
split into morning/afternoon/evening segments, colored by emoji found at
the start of event titles (configured in tags.json).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

server.js

@@ -0,0 +1,87 @@
+'use strict';
+const http = require('node:http');
+const fs = require('node:fs');
+const path = require('node:path');
+const { buildOverview } = require('./days.js');
+
+const PORT = process.env.PORT || 3000;
+const TAGS_PATH = path.join(__dirname, 'tags.json');
+const INDEX_PATH = path.join(__dirname, 'public', 'index.html');
+
+function readTags() {
+  return JSON.parse(fs.readFileSync(TAGS_PATH, 'utf8'));
+}
+
+function sendJSON(res, status, body) {
+  res.writeHead(status, { 'Content-Type': 'application/json' });
+  res.end(JSON.stringify(body));
+}
+
+async function handleOverview(res, query) {
+  const icsUrl = query.get('url');
+  if (!icsUrl) return sendJSON(res, 400, { error: 'missing url parameter' });
+
+  let parsedUrl;
+  try {
+    parsedUrl = new URL(icsUrl);
+  } catch {
+    return sendJSON(res, 400, { error: 'invalid url' });
+  }
+  if (parsedUrl.protocol !== 'http:' && parsedUrl.protocol !== 'https:') {
+    return sendJSON(res, 400, { error: 'url must be http or https' });
+  }
+
+  let icsText;
+  try {
+    const fetchRes = await fetch(icsUrl);
+    if (!fetchRes.ok) throw new Error(`HTTP ${fetchRes.status}`);
+    icsText = await fetchRes.text();
+  } catch (err) {
+    return sendJSON(res, 502, { error: `could not fetch calendar: ${err.message}` });
+  }
+
+  const now = new Date();
+  const rangeStart = `${now.getFullYear()}-01-01`;
+  const rangeEnd = `${now.getFullYear() + 1}-12-31`;
+
+  let overview;
+  try {
+    overview = buildOverview(icsText, readTags(), rangeStart, rangeEnd);
+  } catch (err) {
+    return sendJSON(res, 500, { error: `could not parse calendar: ${err.message}` });
+  }
+
+  sendJSON(res, 200, { rangeStart, rangeEnd, days: overview });
+}
+
+const server = http.createServer(async (req, res) => {
+  const url = new URL(req.url, `http://localhost:${PORT}`);
+
+  if (req.method === 'GET' && url.pathname === '/') {
+    res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
+    res.end(fs.readFileSync(INDEX_PATH));
+    return;
+  }
+
+  if (req.method === 'GET' && url.pathname === '/tags.json') {
+    res.writeHead(200, { 'Content-Type': 'application/json' });
+    res.end(fs.readFileSync(TAGS_PATH));
+    return;
+  }
+
+  if (req.method === 'GET' && url.pathname === '/api/default-url') {
+    return sendJSON(res, 200, { url: process.env.CALURL || null });
+  }
+
+  if (req.method === 'GET' && url.pathname === '/api/overview') {
+    await handleOverview(res, url.searchParams);
+    return;
+  }
+
+  res.writeHead(404, { 'Content-Type': 'text/plain' });
+  res.end('not found');
+});
+
+server.listen(PORT, () => {
+  console.log(`http://localhost:${PORT}`);
+});