import { createRouter } from '@@/create-router';
import { deleteConnection, readConnection, readCredentials, normaliseUrl, probe, recordProbe, saveConnection } from './connection';

/**
 * Mounted at `/api/openseo`.
 *
 * ── One surface, not two ──
 *
 * proxy-manager has curated routes for its panels AND a pass-through for agents, and gives a good
 * reason for each. This has only the pass-through, and the difference is the reason: OpenSEO already
 * ships an MCP server designed for agents, and a web UI designed for people. There is nothing to curate
 * — no list this plugin can sort better than the app that owns the data, and no shape a panel needs that
 * the app does not already produce.
 *
 * So the plugin holds the address, holds the credential, and is the door. Building a second, worse
 * OpenSEO in front of the real one is the failure mode proxy-manager's own comment warns about, and
 * here there is not even the excuse that the upstream API is awkward.
 *
 * ── The door is the whole security model ──
 *
 * Upstream self-hosts with `AUTH_MODE=local_noauth`: every request that reaches the instance is
 * unauthenticated, by design, and their docs say to put it behind auth. Officer's permission gate IS
 * that auth. Which means two things that are not optional:
 *
 *   - nothing here may publish OpenSEO's own port, and
 *   - `/_config` is owner-only, because the address alone is enough to bypass this plugin entirely.
 *
 * The manifest declares the second. The first is a property of never writing the code that would.
 */
export const router = createRouter();

router.get('/status', async (ctx) => {
  const connection = await readConnection();
  return ctx.json({
    configured: Boolean(connection.url),
    ...connection,
  });
});

router.get('/_config', async (ctx) => ctx.json(await readConnection()));

router.put('/_config', async (ctx) => {
  const { url, key } = (ctx.get('body') ?? {}) as { url?: string; key?: string };
  try {
    const saved = await saveConnection({ url: url ?? '', key });
    // Probed immediately, so the form can say whether it WORKS rather than only that it saved. A stored
    // address that answers nothing is the thing somebody needs to know now, not on first use.
    const result = await probe(saved.url!);
    await recordProbe(result);
    return ctx.json({ ...(await readConnection()), probe: result });
  } catch (error) {
    return ctx.json({ error: (error as Error).message }, 400);
  }
});

router.delete('/_config', async (ctx) => {
  await deleteConnection();
  return ctx.json(await readConnection());
});

/**
 * Test an address WITHOUT storing it.
 *
 * So a wrong one never replaces a working one — the same reason proxy-manager has this route. It takes
 * the value from the form rather than from storage, because testing what is saved while somebody looks
 * at something different is worse than not testing.
 */
router.post('/_config/test', async (ctx) => {
  const { url } = (ctx.get('body') ?? {}) as { url?: string };
  try {
    return ctx.json(await probe(normaliseUrl(url ?? '')));
  } catch (error) {
    return ctx.json({ ok: false, version: null, detail: (error as Error).message }, 400);
  }
});

/**
 * Everything else — the pass-through.
 *
 * Method, path, query and body forwarded unchanged; the instance's own status and body come back
 * unchanged, including its errors. `/api/openseo/mcp` reaches OpenSEO's MCP server; `/api/openseo/<the
 * app's own paths>` reaches its API and its UI.
 *
 * ── Streaming is preserved, deliberately ──
 *
 * MCP replies as `text/event-stream` when the client asks for it, and long tool calls arrive in frames.
 * Buffering the body here would turn a progressive answer into a silent wait and then everything at
 * once, which for a crawl or a rank check is the difference between watching it work and wondering
 * whether it hung. So the response body is handed back as it arrives.
 */
router.all('/*', async (ctx) => {
  const credentials = await readCredentials();
  if (!credentials) return ctx.json({ error: 'No OpenSEO instance is configured.' }, 409);

  const incoming = new URL(ctx.req.url);
  // Everything after the mount, so `/mcp` reaches the instance as `/mcp`.
  const path = incoming.pathname.replace(/^\/api\/openseo/, '') || '/';
  const target = `${credentials.url}${path}${incoming.search}`;

  /*
    The hop-by-hop and identity headers are dropped rather than forwarded.

    `host` would name Officer to an app that builds absolute URLs from it; `content-length` stops being
    true the moment anything re-encodes; and Officer's own `authorization` is about Officer, not about
    the instance, which under local_noauth wants no credential at all and could only be confused by one.
  */
  const headers = new Headers();
  for (const [name, value] of ctx.req.raw.headers) {
    if (['host', 'content-length', 'connection', 'authorization', 'cookie'].includes(name.toLowerCase())) continue;
    headers.set(name, value);
  }

  try {
    const response = await fetch(target, {
      method: ctx.req.method,
      headers,
      body: ['GET', 'HEAD'].includes(ctx.req.method) ? undefined : ctx.req.raw.body,
      // Bun requires this to send a stream as a body rather than buffering it first.
      // @ts-expect-error — `duplex` is standard fetch and not yet in the DOM types Bun ships against.
      duplex: 'half',
      redirect: 'manual',
      signal: AbortSignal.timeout(10 * 60 * 1000),
    });

    // Its body, its status, its content type — unbuffered. See the note above.
    const out = new Headers(response.headers);
    out.delete('content-encoding');
    out.delete('content-length');
    return new Response(response.body, { status: response.status, headers: out });
  } catch (error) {
    const message = (error as Error).message;
    return ctx.json(
      {
        error: message.includes('timed out')
          ? 'The OpenSEO instance did not answer within ten minutes.'
          : `Could not reach the OpenSEO instance: ${message}`,
      },
      502,
    );
  }
});