import type { Context } from 'hono';
import { createRouter, type HonoVariables } from '@@/create-router';
import { deleteConnection, readConnection, readCredentials, recordProbe, saveConnection } from './connection';
import { NpmError, npmRequest, probe, forgetToken } from './npm-client';

/**
 * Mounted at `/api/proxy-manager`.
 *
 * Everything here is a read except the enable/disable pair and the settings under `/_config`, which the
 * manifest marks owner-only. The platform's permission gate enforces that — this file does not check it
 * again, because two places deciding the same thing is how they come to disagree.
 *
 * ── What this deliberately does not do ──
 *
 * No creating, editing or deleting hosts, and no certificate issuance. NPM's own UI does those well, it
 * is one click away, and each one is a form with real consequences — a wrong proxy host takes a domain
 * off the internet. This surface answers "what is running, and is it healthy" and lets you take one out
 * of service. Building the editor is a decision to make deliberately, not to arrive at by accretion.
 */
export const router = createRouter();

/** NPM's shape, narrowed to what the panels render. */
type ProxyHost = {
  id: number;
  domain_names: string[];
  forward_scheme: string;
  forward_host: string;
  forward_port: number;
  enabled: number;
  ssl_forced: number;
  certificate_id: number;
  access_list_id: number;
  meta?: { nginx_online?: boolean; nginx_err?: string | null };
};

type Certificate = {
  id: number;
  provider: string;
  nice_name: string;
  domain_names: string[];
  expires_on: string | null;
};

/**
 * Every NPM failure becomes a shaped body rather than a stack trace.
 *
 * `likelyAuth` is the interesting field: NPM answers 404 when unauthenticated, so without saying this
 * out loud the UI would show "not found" for what is actually a wrong password. The panel turns it into
 * a sentence pointing at settings.
 */
const asError = (error: unknown) => {
  if (error instanceof NpmError) {
    return {
      body: { error: error.message, likelyAuth: error.likelyAuth, unreachable: error.status === 0 },
      // 503 when NPM is not answering at all, 502 for everything it did answer — including a refused
      // credential, which is upstream's verdict rather than this request's. `likelyAuth` in the body is
      // what the panel branches on; it does not need a status of its own.
      status: error.status === 0 ? 503 : 502,
    } as const;
  }
  return { body: { error: error instanceof Error ? error.message : String(error) }, status: 500 } as const;
};

/** Loads the credential, or answers 409 — "configured" is a state the UI has to distinguish. */
async function withCredentials<T>(handler: (c: NonNullable<Awaited<ReturnType<typeof readCredentials>>>) => Promise<T>) {
  const credentials = await readCredentials();
  if (!credentials) return { ok: false as const, status: 409, body: { error: 'No Nginx Proxy Manager connection is configured.', unconfigured: true } };
  try {
    return { ok: true as const, data: await handler(credentials) };
  } catch (error) {
    const shaped = asError(error);
    return { ok: false as const, status: shaped.status, body: shaped.body };
  }
}

// `Context` is imported rather than derived from `router.get`. `Parameters<typeof router.get>` resolves
// Hono's FIRST overload, `[path: string]`, so index 1 is `undefined` and every handler here typed as
// `never` — twelve errors from one clever line, and `bunx tsgo` is shared with the platform.
const respond = (ctx: Context<{ Variables: HonoVariables }>, result: Awaited<ReturnType<typeof withCredentials>>) =>
  result.ok ? ctx.json(result.data) : ctx.json(result.body, result.status as 409 | 502 | 503 | 500);

// ── Status ────────────────────────────────────────────────────────────────────────────────────────

/**
 * The last probe, in memory, so a polled endpoint does not write to Postgres on every call.
 *
 * `GET /status` is meant to be polled — two panels open is two callers — and it used to `recordProbe`
 * unconditionally, so a READ endpoint issued an UPDATE per poll per panel. The row exists to answer
 * "when was this last known good" across a restart, which needs a write when the answer CHANGES, not
 * when it is confirmed.
 *
 * So: the probe itself is cached for `PROBE_TTL_MS`, and the row is written only when the verdict or the
 * version differs from what is already stored. A flapping NPM still writes every transition, which is
 * exactly the case worth recording.
 */
const PROBE_TTL_MS = 30_000;

type ProbeResult = { ok: boolean; version: string | null; error?: string };
let cachedProbe: { at: number; url: string; result: ProbeResult } | null = null;

async function probeCached(url: string): Promise<ProbeResult> {
  if (cachedProbe && cachedProbe.url === url && Date.now() - cachedProbe.at < PROBE_TTL_MS) {
    return cachedProbe.result;
  }

  let result: ProbeResult;
  try {
    const info = await probe(url);
    result = { ok: true, version: info.version };
  } catch (error) {
    result = { ok: false, version: null, error: asError(error).body.error };
  }

  cachedProbe = { at: Date.now(), url, result };
  return result;
}

/** Forget the cache when the credential changes — the next status must not answer for the old server. */
const forgetProbe = (): void => {
  cachedProbe = null;
};

/** Cheap enough for a panel to poll: whether a connection exists, and whether it currently works. */
router.get('/status', async (ctx) => {
  const connection = await readConnection();
  if (!connection.configured) return ctx.json({ ...connection, reachable: false });

  const credentials = await readCredentials();
  if (!credentials) return ctx.json({ ...connection, reachable: false });

  const result = await probeCached(credentials.url);
  const version = result.version ?? connection.version;

  // Only when something actually changed. `lastProbeOk` is null on a row that has never been probed, so
  // the first poll after configuring always writes.
  if (connection.lastProbeOk !== result.ok || connection.version !== version) {
    await recordProbe(version, result.ok);
  }

  return result.ok
    ? ctx.json({ ...connection, version, reachable: true })
    : ctx.json({ ...connection, version, reachable: false, error: result.error });
});

// ── The four kinds of host NPM manages ────────────────────────────────────────────────────────────

router.get('/hosts', async (ctx) =>
  respond(
    ctx,
    await withCredentials(async (c) => {
      const hosts = await npmRequest<ProxyHost[]>(c, { path: '/nginx/proxy-hosts?expand=certificate,access_list' });
      // Sorted by first domain rather than by NPM's creation order: a list read by a person should be
      // findable, and NPM's own UI sorts this way too.
      return hosts.sort((a, b) => (a.domain_names[0] ?? '').localeCompare(b.domain_names[0] ?? ''));
    }),
  ),
);

router.get('/redirections', async (ctx) =>
  respond(ctx, await withCredentials((c) => npmRequest(c, { path: '/nginx/redirection-hosts' }))),
);

router.get('/streams', async (ctx) => respond(ctx, await withCredentials((c) => npmRequest(c, { path: '/nginx/streams' }))));

/** NPM calls these "404 hosts" — a domain it serves deliberately as nothing. */
router.get('/dead-hosts', async (ctx) =>
  respond(ctx, await withCredentials((c) => npmRequest(c, { path: '/nginx/dead-hosts' }))),
);

router.get('/hosts/:id', async (ctx) =>
  respond(
    ctx,
    await withCredentials((c) =>
      npmRequest(c, { path: `/nginx/proxy-hosts/${encodeURIComponent(ctx.req.param('id'))}?expand=certificate,access_list,owner` }),
    ),
  ),
);

// ── Certificates and access lists ─────────────────────────────────────────────────────────────────

router.get('/certificates', async (ctx) =>
  respond(
    ctx,
    await withCredentials(async (c) => {
      const certificates = await npmRequest<Certificate[]>(c, { path: '/nginx/certificates' });
      // The panel's whole job is "which of these is about to expire", so compute it once here rather
      // than parsing dates in the browser and getting the timezone wrong.
      const now = Date.now();
      return certificates
        .map((certificate) => ({
          ...certificate,
          daysUntilExpiry: certificate.expires_on
            ? Math.floor((Date.parse(certificate.expires_on) - now) / 86_400_000)
            : null,
        }))
        .sort((a, b) => (a.daysUntilExpiry ?? 1e9) - (b.daysUntilExpiry ?? 1e9));
    }),
  ),
);

router.get('/access-lists', async (ctx) =>
  respond(ctx, await withCredentials((c) => npmRequest(c, { path: '/nginx/access-lists?expand=items,clients' }))),
);

// ── The one mutation ──────────────────────────────────────────────────────────────────────────────

/**
 * Taking a host in or out of service. The only write, and it is reversible in one click — which is why
 * it is here when creating and deleting are not.
 */
router.post('/hosts/:id/:action', async (ctx) => {
  const action = ctx.req.param('action');
  if (action !== 'enable' && action !== 'disable') return ctx.json({ error: 'Expected enable or disable.' }, 400);

  return respond(
    ctx,
    await withCredentials(async (c) => {
      await npmRequest(c, { path: `/nginx/proxy-hosts/${encodeURIComponent(ctx.req.param('id'))}/${action}`, method: 'POST' });
      return { id: Number(ctx.req.param('id')), enabled: action === 'enable' };
    }),
  );
});

// ── Settings — owner only, by the manifest ────────────────────────────────────────────────────────

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

router.put('/_config', async (ctx) => {
  const body = (await ctx.req.json().catch(() => null)) as { url?: string; identity?: string; secret?: string } | null;
  if (!body?.url || !body.identity) return ctx.json({ error: 'url and identity are required.' }, 400);

  try {
    const saved = await saveConnection({ url: body.url, identity: body.identity, secret: body.secret });
    // The old credential's token must not outlive the credential itself.
    const credentials = await readCredentials();
    if (credentials) forgetToken(credentials);
    forgetProbe();
    return ctx.json(saved);
  } catch (error) {
    return ctx.json({ error: error instanceof Error ? error.message : String(error) }, 400);
  }
});

router.delete('/_config', async (ctx) => {
  const credentials = await readCredentials();
  if (credentials) forgetToken(credentials);
  forgetProbe();
  await deleteConnection();
  return ctx.json({ configured: false });
});

/**
 * Test a credential WITHOUT storing it, so a wrong password never replaces a working one.
 *
 * Declared in the manifest as a `readOnlyWrites` path: it is a POST that changes nothing.
 */
router.post('/_config/test', async (ctx) => {
  const body = (await ctx.req.json().catch(() => null)) as { url?: string; identity?: string; secret?: string } | null;
  if (!body?.url) return ctx.json({ error: 'url is required.' }, 400);

  try {
    const info = await probe(body.url);
    if (!body.identity || !body.secret) {
      return ctx.json({ reachable: true, authenticated: false, version: info.version, setup: info.setup });
    }
    await npmRequest<unknown>({ url: body.url, identity: body.identity, secret: body.secret }, { path: '/nginx/proxy-hosts' });
    return ctx.json({ reachable: true, authenticated: true, version: info.version, setup: info.setup });
  } catch (error) {
    const shaped = asError(error);
    return ctx.json({ reachable: !(shaped.body as { unreachable?: boolean }).unreachable, authenticated: false, ...shaped.body }, 200);
  }
});