refactor: separate regional briefing and weather sources

server/providers/regional/weather-effects.js

@@ -0,0 +1,108 @@
+import { makeRateLimiter, clientKey } from '../common/rate-limit.js';
+import { fetchRegionalWeather } from './weather.js';
+import { validRegionalPoint } from './query.js';
+import { coalesceProxyRequest } from '../common/http.js';
+
+const WEATHER_EFFECTS_CACHE_MS = 5 * 60_000;
+
+const WEATHER_EFFECTS_STALE_MS = 30 * 60_000;
+
+const WEATHER_EFFECTS_MAX_CACHE = 180;
+
+const _weatherEffectsCache = new Map();
+
+const _weatherEffectsInFlight = new Map();
+
+const _weatherEffectsRateLimiter = makeRateLimiter({ windowMs: 60_000, max: 45, globalMax: 120 });
+
+function trimWeatherEffectsCache() {
+  while (_weatherEffectsCache.size > WEATHER_EFFECTS_MAX_CACHE) {
+    const oldest = _weatherEffectsCache.keys().next().value;
+    if (oldest === undefined) break;
+    _weatherEffectsCache.delete(oldest);
+  }
+}
+
+function weatherEffectsProxy() {
+  async function refresh(point, key) {
+    const weather = await fetchRegionalWeather(point);
+    if (!weather) throw new Error('Weather observation unavailable');
+    const payload = {
+      status: 'ready',
+      retrievedAt: new Date().toISOString(),
+      coordinates: point,
+      weather,
+    };
+    _weatherEffectsCache.set(key, { payload, cachedAt: Date.now() });
+    trimWeatherEffectsCache();
+    return payload;
+  }
+
+  function install(middlewares) {
+    middlewares.use('/api/weather-effects', async (req, res) => {
+      if (req.method !== 'GET') {
+        res.writeHead(405, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Method Not Allowed' }));
+        return;
+      }
+      if (!_weatherEffectsRateLimiter(clientKey(req))) {
+        res.writeHead(429, { 'Content-Type': 'application/json', 'Retry-After': '10' });
+        res.end(JSON.stringify({ error: 'Rate limit exceeded' }));
+        return;
+      }
+      const url = new URL(req.url || '', 'http://localhost');
+      const point = validRegionalPoint(url.searchParams);
+      if (!point) {
+        res.writeHead(400, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ error: 'Valid latitude and longitude are required' }));
+        return;
+      }
+      const key = `${(Math.round(point.latitude * 10) / 10).toFixed(1)},${(Math.round(point.longitude * 10) / 10).toFixed(1)}`;
+      const now = Date.now();
+      const cached = _weatherEffectsCache.get(key);
+      if (cached && now - cached.cachedAt <= WEATHER_EFFECTS_CACHE_MS) {
+        res.writeHead(200, {
+          'Content-Type': 'application/json',
+          'Cache-Control': 'public, max-age=60',
+          'X-Weather-Effects': 'HIT',
+        });
+        res.end(JSON.stringify({ ...cached.payload, status: 'cached' }));
+        return;
+      }
+      const request = coalesceProxyRequest(_weatherEffectsInFlight, key, () => refresh(point, key));
+      try {
+        const payload = await request.promise;
+        res.writeHead(200, {
+          'Content-Type': 'application/json',
+          'Cache-Control': 'public, max-age=60',
+          'X-Weather-Effects': request.shared ? 'INFLIGHT' : 'MISS',
+        });
+        res.end(JSON.stringify(payload));
+      } catch {
+        if (cached && now - cached.cachedAt <= WEATHER_EFFECTS_STALE_MS) {
+          res.writeHead(200, {
+            'Content-Type': 'application/json',
+            'Cache-Control': 'no-store',
+            'X-Weather-Effects': 'STALE',
+          });
+          res.end(JSON.stringify({ ...cached.payload, status: 'stale' }));
+          return;
+        }
+        res.writeHead(503, { 'Content-Type': 'application/json', 'Cache-Control': 'no-store' });
+        res.end(JSON.stringify({ error: 'Weather effects are temporarily unavailable' }));
+      }
+    });
+  }
+
+  return {
+    name: 'weather-effects-proxy',
+    configureServer(server) {
+      install(server.middlewares);
+    },
+    configurePreviewServer(server) {
+      install(server.middlewares);
+    },
+  };
+}
+
+export { weatherEffectsProxy };