import { useCallback, useEffect, useRef, useState } from 'react';
import { CheckCircle2, Loader2, Plug, ShieldAlert, Trash2, TriangleAlert } from 'lucide-react';
import { useClient } from 'hooks/useClient';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';

/**
 * The connection to Nginx Proxy Manager — both the setup wizard and the permanent settings page.
 *
 * One component for both, the same choice Jellyfin's `ConnectionSection` makes and for the same reason: a
 * connection edited months later goes through exactly the code path that stored the first one. `HostsPanel`
 * renders this in place of itself while nothing is configured, and `?config=1` renders it for good.
 *
 * ── Owner only, and it says so rather than failing oddly ──
 *
 * The manifest marks `/_config` `ownerOnly`, so every request from this component 403s for anybody else —
 * including the test button, deliberately, because that request carries the admin secret in its body. A
 * member reaching this screen should read a sentence explaining that, not a raw refusal.
 *
 * ── The secret is never loaded ──
 *
 * `GET /_config` returns `hasSecret`, never the secret. So the field starts empty even when one is stored,
 * and an empty field on save means "keep the stored one" — which is what lets a typo in the URL be fixed
 * without going to find the password again.
 */

type ConnectionView = {
  configured: boolean;
  url: string | null;
  identity: string | null;
  hasSecret: boolean;
  version: string | null;
  lastProbeAt: string | null;
  lastProbeOk: boolean | null;
};

type TestResult = {
  reachable: boolean;
  authenticated: boolean;
  version?: string;
  setup?: boolean;
  error?: string;
  likelyAuth?: boolean;
};

const HINT = 'text-[11px] leading-relaxed text-muted-foreground';

/**
 * NPM's admin UI port. Officer reaches it from the SERVER, so localhost here is the machine Officer runs
 * on — and on a host where NPM is a container, its address on the docker network works whether or not the
 * port is published. `docs/npm-api.md` has the measurements.
 */
const DEFAULT_URL = 'http://127.0.0.1:81';

const URL_HINT =
  'Where NPM answers, reached from the server rather than from this browser. A trailing slash is trimmed. ' +
  'If NPM runs as a container beside Officer, its address on the docker network works even with no ' +
  'published port.';

const SECRET_HINT =
  'The NPM admin password. Stored encrypted under this plugin’s own key and never returned by the ' +
  'API — not to a member, not to you. Leave it empty to keep the one already stored.';

type FieldProps = {
  label: string;
  hint?: string;
  value: string;
  onChange: (value: string) => void;
  placeholder: string;
  type?: string;
  autoFocus?: boolean;
};

const Field = ({ label, hint, value, onChange, placeholder, type, autoFocus }: FieldProps) => (
  <label className="flex flex-col gap-1.5">
    <span className="text-xs font-medium">{label}</span>
    <Input
      value={value}
      onChange={(ev) => onChange(ev.target.value)}
      placeholder={placeholder}
      type={type}
      autoFocus={autoFocus}
      autoComplete="off"
      spellCheck={false}
    />
    {hint && <span className={HINT}>{hint}</span>}
  </label>
);

/** A 403 here means the account is not the owner — the one refusal worth explaining rather than reporting. */
const isForbidden = (error: unknown): boolean => (error as { status?: number })?.status === 403;

/**
 * `useClient` throws `ApiError(status, message)` and nothing else — there is no `.body` to read, which is
 * the bug `HostsPanel`'s `asFailure` documents at length. The message is already the server's own text:
 * since 2026-08-25 the platform answers `{ error }` and the client unwraps it before throwing.
 */
const errorText = (error: unknown): string =>
  error instanceof Error ? error.message : 'Something went wrong.';

export const ConnectionPanel = () => {
  const client = useClient();
  // useClient() rebuilds its verbs every render, so it must never sit in a dependency list.
  const clientRef = useRef(client);
  clientRef.current = client;

  const [view, setView] = useState<ConnectionView | null>(null);
  const [forbidden, setForbidden] = useState(false);
  const [url, setUrl] = useState('');
  const [identity, setIdentity] = useState('');
  const [secret, setSecret] = useState('');
  const [test, setTest] = useState<TestResult | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [busy, setBusy] = useState<'test' | 'save' | 'delete' | null>(null);
  const [confirming, setConfirming] = useState(false);

  const load = useCallback(async () => {
    try {
      const next = await clientRef.current.get<ConnectionView>('/proxy-manager/_config');
      setView(next);
      setUrl(next.url ?? DEFAULT_URL);
      setIdentity(next.identity ?? '');
      setForbidden(false);
    } catch (err) {
      if (isForbidden(err)) return setForbidden(true);
      setError(errorText(err));
    }
  }, []);

  useEffect(() => {
    void load();
  }, [load]);

  const runTest = async () => {
    setBusy('test');
    setError(null);
    setTest(null);
    try {
      // The secret is sent only when the field was filled. Testing with the field empty checks the URL and
      // nothing else, which is still useful — it is how you find out you are pointed at the wrong thing.
      setTest(
        await clientRef.current.post<TestResult>('/proxy-manager/_config/test', {
          url,
          identity: identity || undefined,
          secret: secret || undefined,
        }),
      );
    } catch (err) {
      setError(errorText(err));
    } finally {
      setBusy(null);
    }
  };

  const save = async () => {
    setBusy('save');
    setError(null);
    try {
      const next = await clientRef.current.put<ConnectionView>('/proxy-manager/_config', {
        url,
        identity,
        // Omitted rather than sent empty — the server reads "absent" as keep, and an empty string as a
        // secret would be stored verbatim.
        ...(secret ? { secret } : {}),
      });
      setView(next);
      setSecret('');
      setTest(null);
    } catch (err) {
      setError(errorText(err));
    } finally {
      setBusy(null);
    }
  };

  const disconnect = async () => {
    setBusy('delete');
    setError(null);
    try {
      await clientRef.current.delete('/proxy-manager/_config');
      setConfirming(false);
      setTest(null);
      setSecret('');
      await load();
    } catch (err) {
      setError(errorText(err));
    } finally {
      setBusy(null);
    }
  };

  if (forbidden) {
    return (
      <div className="flex size-full flex-col items-center justify-center gap-3 p-6 text-center">
        <ShieldAlert className="size-8 text-muted-foreground" />
        <p className="text-sm text-muted-foreground">Only the server owner can change this connection.</p>
        <p className={`max-w-sm ${HINT}`}>
          It is an Nginx Proxy Manager admin login, and NPM has no read-only role — anyone holding it can
          redirect any hostname this machine serves. You can still see the hosts and certificates.
        </p>
      </div>
    );
  }

  if (!view) return <div className="flex size-full items-center justify-center p-6 text-sm text-muted-foreground">Loading…</div>;

  // An empty secret is fine on an existing connection and not on a new one — the server enforces this too,
  // and would answer 400. Saying so here means the button explains itself instead of failing.
  const canSave = !!url.trim() && !!identity.trim() && (view.hasSecret || !!secret);

  return (
    <div className="flex size-full flex-col overflow-auto">
      <header className="flex items-center gap-2 border-b px-3 py-2">
        <Plug className="size-4 text-muted-foreground" />
        <span className="text-sm font-medium">{view.configured ? 'Connection' : 'Connect Nginx Proxy Manager'}</span>
      </header>

      <div className="flex flex-col gap-4 p-4">
        {view.configured && (
          <div className="rounded-lg border p-3 text-xs">
            <div className="flex items-center gap-2">
              {view.lastProbeOk === false ? (
                <TriangleAlert className="size-3.5 text-amber-500" />
              ) : (
                <CheckCircle2 className="size-3.5 text-emerald-500" />
              )}
              <span className="font-medium">{view.url}</span>
              {view.version && <span className="text-muted-foreground">NPM {view.version}</span>}
            </div>
            <p className={`mt-1 ${HINT}`}>
              {view.identity}
              {view.hasSecret ? ' · a secret is stored' : ' · no secret stored'}
              {view.lastProbeAt ? ` · last checked ${new Date(view.lastProbeAt).toLocaleString()}` : ''}
            </p>
          </div>
        )}

        <Field label="URL" hint={URL_HINT} value={url} onChange={setUrl} placeholder={DEFAULT_URL} autoFocus={!view.configured} />
        <Field
          label="Email"
          hint="NPM calls this the identity. It is the address you sign in to NPM with."
          value={identity}
          onChange={setIdentity}
          placeholder="admin@example.com"
        />
        <Field
          label="Password"
          hint={SECRET_HINT}
          value={secret}
          onChange={setSecret}
          placeholder={view.hasSecret ? 'unchanged' : '••••••••'}
          type="password"
        />

        {test && (
          <div className="rounded-lg border p-3 text-xs">
            {test.authenticated ? (
              <p className="flex items-center gap-2 text-emerald-600 dark:text-emerald-400">
                <CheckCircle2 className="size-3.5" /> Reached NPM {test.version} and the credential works.
              </p>
            ) : test.reachable ? (
              <>
                <p className="flex items-center gap-2 text-amber-600 dark:text-amber-400">
                  <TriangleAlert className="size-3.5" /> Reached NPM {test.version}, but not signed in.
                </p>
                <p className={`mt-1 ${HINT}`}>
                  {test.setup === false
                    ? 'That NPM has not finished its own setup yet — create its first admin user in NPM before connecting.'
                    : (test.error ??
                      'Fill in the email and password to check them. NPM answers 404 when unauthenticated, so a "not found" here is almost always the credential.')}
                </p>
              </>
            ) : (
              <>
                <p className="flex items-center gap-2 text-destructive">
                  <TriangleAlert className="size-3.5" /> Could not reach it.
                </p>
                <p className={`mt-1 ${HINT}`}>{test.error}</p>
              </>
            )}
          </div>
        )}

        {error && <p className="text-xs text-destructive">{error}</p>}

        <div className="flex flex-wrap items-center gap-2">
          {/* Test comes first, and testing never stores anything — so a wrong password cannot replace a
              working one just because someone wanted to check it. */}
          <Button type="button" variant="outline" size="sm" onClick={() => void runTest()} disabled={!url.trim() || busy !== null}>
            {busy === 'test' ? <Loader2 className="size-3.5 animate-spin" /> : null} Test
          </Button>
          <Button type="button" size="sm" onClick={() => void save()} disabled={!canSave || busy !== null}>
            {busy === 'save' ? <Loader2 className="size-3.5 animate-spin" /> : null}
            {view.configured ? 'Save' : 'Connect'}
          </Button>

          {view.configured &&
            (confirming ? (
              <>
                <Button type="button" variant="destructive" size="sm" onClick={() => void disconnect()} disabled={busy !== null}>
                  {busy === 'delete' ? <Loader2 className="size-3.5 animate-spin" /> : null} Really disconnect
                </Button>
                <Button type="button" variant="ghost" size="sm" onClick={() => setConfirming(false)}>
                  Cancel
                </Button>
              </>
            ) : (
              <Button type="button" variant="ghost" size="sm" onClick={() => setConfirming(true)} disabled={busy !== null}>
                <Trash2 className="size-3.5" /> Disconnect
              </Button>
            ))}
        </div>

        {!view.configured && (
          <p className={HINT}>
            Nothing is created or changed in NPM by connecting. This reads what is there, and the only write
            it ever makes is taking a host in or out of service.
          </p>
        )}
      </div>
    </div>
  );
};