import { useEffect, useState } from 'react';
import { useParams } from 'react-router';
import { Loader2, TriangleAlert } from 'lucide-react';
import { useClient } from 'hooks/useClient';
import { GiteaConnection, type ConnectionState } from './GiteaConnection';

// Gitea's own web interface, rendered in place.
//
// ── Why an iframe and not panels ──
//
// Gitea has a complete web interface. The version of this that shipped before was seventeen files
// reimplementing a fraction of it, and every one of those files was a promise to keep up with a project
// that moves faster than this plugin will.
//
// ── The one thing this component must do ──
//
// Get a cookie before the frame loads. Everything inside the iframe — stylesheets, scripts, avatars — is
// fetched by the browser with no Authorization header, so the frame's URL is served above the platform's
// gate and authenticates with a path-scoped cookie instead. That cookie is minted by a normal
// authenticated call, which is what this does first.
//
// Load the iframe before that call returns and every request in it is unauthenticated, which reads as
// Gitea being down.

const FRAME_SRC = '/api/gitea/_web/';

export const GiteaFrame = () => {
  // `/gitea/connection` renders the settings instead of the frame. The plugin route pair gives this for
  // free — `<route>` and `<route>/:section` are generated for every plugin — and it is the only way to
  // change a token once one is set: the form used to appear ONLY when nothing was configured, so a
  // member who mistyped theirs, or anyone rotating one, had nowhere to go.
  const { section } = useParams();
  const { get, post } = useClient();
  const [state, setState] = useState<'opening' | 'ready' | 'failed'>('opening');
  const [connection, setConnection] = useState<ConnectionState | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [attempt, setAttempt] = useState(0);

  useEffect(() => {
    let cancelled = false;
    // Not in a dependency array: `useClient()` returns a new object every render, so depending on `get`
    // or `post` would re-run this on every keystroke elsewhere in the app.
    void (async () => {
      try {
        // The connection FIRST. Without it the frame loads and every request inside it answers 503,
        // which reads as Gitea being down rather than as nobody having said where Gitea is.
        const conn = await get<ConnectionState>('/gitea/_config');
        if (cancelled) return;
        setConnection(conn);
        if (!conn.configured) {
          setState('ready');
          return;
        }
        await post('/gitea/session', {});
        if (!cancelled) setState('ready');
      } catch (err) {
        if (cancelled) return;
        setError(err instanceof Error ? err.message : 'could not open a session');
        setState('failed');
      }
    })();
    return () => {
      cancelled = true;
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [attempt]);

  if (state === 'opening') {
    return (
      <div className="flex h-full items-center justify-center text-muted-foreground">
        <Loader2 className="mr-2 h-4 w-4 animate-spin" />
        <span className="text-sm">Opening Gitea…</span>
      </div>
    );
  }

  if (state === 'failed') {
    return (
      <div className="flex h-full flex-col items-center justify-center gap-3 p-6 text-center">
        <TriangleAlert className="h-6 w-6 text-warning" />
        <div>
          <p className="text-sm font-medium">Could not open Gitea</p>
          {/* The message, not a generic one: the interesting failure here is almost always "the sidecar
              is not running" or "no instance is configured", and those want different answers. */}
          <p className="mt-1 text-xs text-muted-foreground">{error}</p>
        </div>
      </div>
    );
  }

  // Unconfigured goes straight to the form; `/gitea/connection` opens it deliberately.
  if (connection && (!connection.configured || section === 'connection')) {
    return <GiteaConnection state={connection} onSaved={() => setAttempt((n) => n + 1)} />;
  }

  return (
    <div className="relative h-full w-full">
      {/* The escape hatch, and it is not an admission of defeat: the whole point of proxying an app that
          already has a UI is that its own UI stays available. Anything the frame handles badly, this
          opens properly. */}
      <iframe
        src={FRAME_SRC}
        title="Gitea"
        className="h-full w-full border-0"
        // NO `sandbox`, deliberately.
        //
        // It needs `allow-same-origin` for Gitea to keep a session and `allow-scripts` for the interface
        // to work at all — and those two together give back everything the attribute takes away. The
        // browser says so itself: "an iframe which has both allow-scripts and allow-same-origin can
        // escape its sandboxing."
        //
        // So it was decoration that emitted a warning on every load, and a warning nobody can act on
        // teaches people to ignore warnings. What actually stands here is that this is Gitea's own
        // interface on the platform's own origin, reached through a proxy the platform wrote.
      />
    </div>
  );
};