Add CardDav and CalDav servers (#80)

* Add CardDav and CalDav servers

This implements the servers, but not the clients (yet). The implementation is essentially a proxy to Radicale (as a container in `docker-compose.yml`), with certain security assurances.

If you're upgrading, basically you'll need to create a new `data-radicale` directory, and everything else should just work.

This will also release v2.3.0 with those enabled by default. Tested with Thunderbird and Apple Calendar + Contacts.

To disable these, simply add the new config details and comment out or don't add the new `radicale` service from `docker-compose.yml`.

Related to #56

routes/caldav.tsx

@@ -0,0 +1,69 @@
+import { Handler, RouteConfig } from 'fresh/server.ts';
+
+import { FreshContextState } from '/lib/types.ts';
+import { AppConfig } from '/lib/config.ts';
+
+interface Data {}
+
+export const config: RouteConfig = {
+  routeOverride: '/caldav/:path*',
+};
+
+export const handler: Handler<Data, FreshContextState> = async (request, context) => {
+  const calendarConfig = await AppConfig.getCalendarConfig();
+
+  if (!calendarConfig.enableCalDavServer) {
+    return new Response('Not Found', { status: 404 });
+  }
+
+  if (!context.state.user) {
+    return new Response('Unauthorized', {
+      status: 401,
+      headers: { 'www-authenticate': 'Basic realm="bewCloud", charset="UTF-8"' },
+    });
+  }
+
+  const { path } = context.params;
+
+  const userId = context.state.user.id;
+
+  try {
+    const requestBodyText = await request.clone().text();
+
+    // Remove the `/caldav/` prefix from the hrefs in the request
+    const parsedRequestBodyText = requestBodyText.replaceAll('<href>/caldav/', `<href>/`).replaceAll(
+      ':href>/caldav/',
+      `:href>/`,
+    );
+
+    const response = await fetch(`${calendarConfig.calDavUrl}/${path}`, {
+      headers: {
+        ...Object.fromEntries(request.headers.entries()),
+        'X-Remote-User': `${userId}`,
+      },
+      method: request.method,
+      body: parsedRequestBodyText,
+    });
+
+    if (response.status === 204) {
+      return new Response(null, { status: 204 });
+    }
+
+    const responseBodyText = await response.clone().text();
+
+    // Add the `/caldav/` prefix to the hrefs in the response
+    const parsedBodyResponseText = responseBodyText.replaceAll('<href>/', `<href>/caldav/`).replaceAll(
+      ':href>/',
+      `:href>/caldav/`,
+    );
+
+    return new Response(parsedBodyResponseText, {
+      status: response.status,
+      headers: response.headers,
+    });
+  } catch (error) {
+    console.error(error);
+  }
+
+  return new Response(null, { status: 405 });
+};