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';
import { readableError } from './errors';
import { useFofosChanged } from './channel';

/**
 * Where fofos is, and the token to reach it. Both the first-run setup and the permanent settings.
 *
 * One component for both — the same choice `plugins/proxy-manager/web/ConnectionPanel.tsx` makes, and
 * for the same reason: a connection edited months later goes through exactly the code path that
 * stored the first one, so there is no second path to rot.
 *
 * ── 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 token in its body.
 * A member who reaches this screen should read a sentence explaining that, not a raw refusal.
 *
 * ── The token is never loaded ──
 *
 * `GET /_config` returns `hasToken`, never the token. 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 credential again.
 */

type ConnectionView = {
  configured: boolean;
  url: string | null;
  hasToken: boolean;
  sections: string[] | null;
  lastProbeAt: string | null;
  lastProbeOk: boolean | null;
};

type TestResult = {
  reachable: boolean;
  authenticated: boolean;
  sections?: string[];
  error?: string;
};

export const ConnectionPanel = () => {
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;

  const [view, setView] = useState<ConnectionView | null>(null);
  const [url, setUrl] = useState('');
  const [token, setToken] = useState('');

  const [busy, setBusy] = useState(false);
  const [result, setResult] = useState<TestResult | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [forbidden, setForbidden] = useState(false);

  const [, bump] = useFofosChanged();

  const load = useCallback(async () => {
    try {
      const current = await clientRef.current.get<ConnectionView>('/fofos-admin/_config');
      setView(current);
      setUrl(current.url ?? '');
    } catch (failure) {
      // A 403 here is not a fault — it is a member looking at an owner-only screen, and it needs a
      // different sentence from "that did not work".
      if ((failure as { status?: number })?.status === 403) setForbidden(true);
      else setError(readableError(failure));
      setView({ configured: false, url: null, hasToken: false, sections: null, lastProbeAt: null, lastProbeOk: null });
    }
  }, []);

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

  const test = async () => {
    setBusy(true);
    setError(null);
    try {
      // Sent only when typed. Omitted, the server tests what is STORED — which is how "is my
      // connection still good?" is answered without retyping a secret.
      const body: Record<string, string> = {};
      if (url.trim()) body.url = url.trim();
      if (token.trim()) body.token = token.trim();

      setResult(await clientRef.current.post<TestResult>('/fofos-admin/_config/test', body));
    } catch (failure) {
      setError(readableError(failure));
    } finally {
      setBusy(false);
    }
  };

  const save = async () => {
    setBusy(true);
    setError(null);
    try {
      const body: Record<string, string> = { url: url.trim() };
      if (token.trim()) body.token = token.trim();

      const saved = await clientRef.current.put<ConnectionView & { probe?: TestResult }>(
        '/fofos-admin/_config',
        body,
      );
      setView(saved);
      setResult(saved.probe ?? null);
      // Cleared on success: it is stored now, and keeping it on screen serves nobody.
      setToken('');
      // Everything else re-reads. Saving a connection is the one action that changes what every other
      // panel can see.
      bump();
    } catch (failure) {
      setError(readableError(failure));
    } finally {
      setBusy(false);
    }
  };

  const forget = async () => {
    setBusy(true);
    try {
      setView(await clientRef.current.delete<ConnectionView>('/fofos-admin/_config'));
      setUrl('');
      setToken('');
      setResult(null);
      bump();
    } catch (failure) {
      setError(readableError(failure));
    } finally {
      setBusy(false);
    }
  };

  if (forbidden) {
    return (
      <div className="flex size-full flex-col items-center justify-center gap-2 p-6 text-center">
        <ShieldAlert className="size-6 text-muted-foreground/60" />
        <p className="text-sm">Only the owner can change this connection.</p>
        <p className="max-w-sm text-xs text-muted-foreground">
          The token stored here can rewrite the whole public site, so setting it belongs to whoever owns the
          server. You can still edit content.
        </p>
      </div>
    );
  }

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

  return (
    <div className="flex size-full flex-col gap-4 overflow-auto p-5">
      <div className="space-y-1">
        <h2 className="flex items-center gap-2 text-sm font-medium">
          <Plug className="size-4" />
          The fofos server
        </h2>
        <p className="text-xs text-muted-foreground">
          Where the site lives, and a token to edit it. The token is fofos's <code>FOFOS_API_TOKEN</code>.
        </p>
      </div>

      <label className="space-y-1.5">
        <span className="text-xs text-muted-foreground">Address</span>
        <Input
          value={url}
          onChange={(event) => setUrl(event.target.value)}
          placeholder="http://localhost:3010"
          autoComplete="off"
          spellCheck={false}
        />
        <span className="block text-xs text-muted-foreground/80">
          The live fofos server, not the published static site — the static one serves no API.
        </span>
      </label>

      <label className="space-y-1.5">
        <span className="text-xs text-muted-foreground">Token</span>
        <Input
          type="password"
          value={token}
          onChange={(event) => setToken(event.target.value)}
          placeholder={view.hasToken ? 'A token is stored — leave empty to keep it' : ''}
          autoComplete="new-password"
          spellCheck={false}
        />
      </label>

      <div className="flex flex-wrap items-center gap-2">
        <Button size="sm" onClick={() => void save()} disabled={busy || !url.trim()}>
          {busy && <Loader2 className="size-3.5 animate-spin" />}
          Save
        </Button>
        <Button variant="outline" size="sm" onClick={() => void test()} disabled={busy || (!url.trim() && !view.configured)}>
          Test
        </Button>
        {view.configured && (
          <Button variant="ghost" size="sm" onClick={() => void forget()} disabled={busy}>
            <Trash2 className="size-3.5" />
            Forget
          </Button>
        )}
      </div>

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

      {result && (
        <div
          className={`flex items-start gap-2 rounded-md p-3 text-xs ${
            result.authenticated ? 'bg-success/15 text-success' : 'bg-destructive/15 text-destructive'
          }`}
        >
          {result.authenticated ? (
            <CheckCircle2 className="mt-0.5 size-3.5 shrink-0" />
          ) : (
            <TriangleAlert className="mt-0.5 size-3.5 shrink-0" />
          )}
          <span>
            {result.authenticated
              ? `Connected. ${result.sections?.length ?? 0} sections available.`
              : (result.error ?? 'That did not work.')}
          </span>
        </div>
      )}

      {view.configured && !result && (
        <p className="text-xs text-muted-foreground">
          {view.lastProbeOk === null
            ? 'Saved, and not yet checked.'
            : view.lastProbeOk
              ? `Last checked ${view.lastProbeAt ? new Date(view.lastProbeAt).toLocaleString() : ''} — working.`
              : 'The last check failed. Press Test to try again.'}
        </p>
      )}
    </div>
  );
};