CORS support

CORS_ORIGIN environment variable

.env.example

@@ -1 +1,4 @@
-DATABASE_URL=postgres://eussi:password@localhost:5432/issue
+DATABASE_URL=postgres://eussi:password@localhost:5432/issue
+
+# comma separated list of allowed origins
+CORS_ORIGIN=http://localhost:1420

src/index.ts

@@ -6,36 +6,103 @@ import { createDemoData } from "./utils";
 const DEV = process.argv.find((arg) => ["--dev", "--developer", "-d"].includes(arg.toLowerCase())) != null;
 const PORT = process.argv.find((arg) => arg.toLowerCase().startsWith("--port="))?.split("=")[1] || 0;
 
+type RouteHandler<T extends Request = Request> = (req: T) => Response | Promise<Response>;
+
+const CORS_ALLOWED_ORIGINS = (process.env.CORS_ORIGIN ?? "http://localhost:1420")
+    .split(",")
+    .map((origin) => origin.trim())
+    .filter(Boolean);
+
+const CORS_ALLOW_METHODS = process.env.CORS_ALLOW_METHODS ?? "GET,POST,PUT,PATCH,DELETE,OPTIONS";
+const CORS_ALLOW_HEADERS_DEFAULT = process.env.CORS_ALLOW_HEADERS ?? "Content-Type, Authorization";
+const CORS_MAX_AGE = process.env.CORS_MAX_AGE ?? "86400";
+
+const getCorsAllowOrigin = (req: Request) => {
+    const requestOrigin = req.headers.get("Origin");
+    if (!requestOrigin) {
+        return "*";
+    }
+
+    if (CORS_ALLOWED_ORIGINS.includes("*")) {
+        return "*";
+    }
+
+    if (CORS_ALLOWED_ORIGINS.includes(requestOrigin)) {
+        return requestOrigin;
+    }
+
+    return null;
+};
+
+const buildCorsHeaders = (req: Request) => {
+    const headers = new Headers();
+
+    const allowOrigin = getCorsAllowOrigin(req);
+    if (allowOrigin) {
+        headers.set("Access-Control-Allow-Origin", allowOrigin);
+        if (allowOrigin !== "*") {
+            headers.set("Vary", "Origin");
+        }
+    }
+
+    headers.set("Access-Control-Allow-Methods", CORS_ALLOW_METHODS);
+
+    const requestedHeaders = req.headers.get("Access-Control-Request-Headers");
+    headers.set("Access-Control-Allow-Headers", requestedHeaders || CORS_ALLOW_HEADERS_DEFAULT);
+
+    headers.set("Access-Control-Max-Age", CORS_MAX_AGE);
+
+    return headers;
+};
+
+const withCors = <T extends Request>(handler: RouteHandler<T>): RouteHandler<T> => {
+    return async (req: T) => {
+        const corsHeaders = buildCorsHeaders(req);
+
+        if (req.method === "OPTIONS") {
+            return new Response(null, { status: 204, headers: corsHeaders });
+        }
+
+        const res = await handler(req);
+        const wrapped = new Response(res.body, res);
+
+        corsHeaders.forEach((value, key) => {
+            wrapped.headers.set(key, value);
+        });
+
+        return wrapped;
+    };
+};
+
 const main = async () => {
     const server = Bun.serve({
         port: Number(PORT),
         routes: {
-            "/": () => new Response(`title: eussi\ndev-mode: ${DEV}\nport: ${PORT}`),
-            "/issue/create": routes.issueCreate,
-            "/issue/update": routes.issueUpdate,
-            "/issue/delete": routes.issueDelete,
-            "/issues/:projectBlob": routes.issuesInProject,
-            "/issues/all": routes.issues,
+            "/": withCors(() => new Response(`title: eussi\ndev-mode: ${DEV}\nport: ${PORT}`)),
 
-            "/project/create": routes.projectCreate,
-            "/project/update": routes.projectUpdate,
-            "/project/delete": routes.projectDelete,
+            "/issue/create": withCors(routes.issueCreate),
+            "/issue/update": withCors(routes.issueUpdate),
+            "/issue/delete": withCors(routes.issueDelete),
+            "/issues/:projectBlob": withCors(routes.issuesInProject),
+            "/issues/all": withCors(routes.issues),
+
+            "/project/create": withCors(routes.projectCreate),
+            "/project/update": withCors(routes.projectUpdate),
+            "/project/delete": withCors(routes.projectDelete),
         },
     });
 
     console.log(`eussi (issue server) listening on ${server.url}`);
     await testDB();
 
-    let users = await db.select().from(User);
-
-    if (DEV && users.length === 0) {
-        console.log("creating demo data...");
-        await createDemoData();
-        console.log("demo data created");
-        users = await db.select().from(User);
+    if (DEV) {
+        const users = await db.select().from(User);
+        if (users.length === 0) {
+            console.log("creating demo data...");
+            await createDemoData();
+            console.log("demo data created");
+        }
     }
-
-    console.log(`serving ${users.length} user${users.length === 1 ? "" : "s"}`);
 };
 
 main();