auth-yes/src/core/sse_adapter.ts

import type { Context } from "jsr:@hono/hono@4";
import { streamSSE } from "jsr:@hono/hono@4/streaming";

export interface DatastarSSEEvent {
  event?: string; // usually 'datastar-fragment', 'datastar-signal', etc
  data: string; // The HTML fragment or JSON payload
  id?: string;
  retry?: number;
}

export function streamDatastar(
  c: Context,
  callback: (stream: {
    write: (event: DatastarSSEEvent) => Promise<void>;
    close: () => Promise<void>;
    sleep: (ms: number) => Promise<void>;
    aborted: boolean;
  }) => Promise<void>,
) {
  // Set anti-buffering headers for Nginx / Traefik reverse proxies
  c.header("X-Accel-Buffering", "no");
  c.header("Cache-Control", "no-cache, no-transform");

  return streamSSE(c, async (stream) => {
    // Add custom datastar helper methods
    const adapter = {
      write: async (event: DatastarSSEEvent) => {
        await stream.writeSSE({
          data: event.data,
          event: event.event || "datastar-fragment",
          id: event.id,
          retry: event.retry,
        });
      },
      close: async () => {
        await stream.close();
      },
      sleep: async (ms: number) => {
        await stream.sleep(ms);
      },
      get aborted() {
        return stream.aborted;
      },
    };

    await callback(adapter);
  });
}