import { useState } from 'react';
import { useNavigate } from 'react-router';
import { CheckCircle2, Loader2, TriangleAlert } from 'lucide-react';
import { useClient } from 'hooks/useClient';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';

// Where the instance and the token are set.
//
// Two halves, and which one you get depends on who you are. The URL is the OWNER'S — one instance per
// server — and everyone else supplies only a token, inheriting the owner's URL. That is not a UI choice:
// `service_connections` stores a member's row with a null URL for exactly this reason, so that "members
// never see the instance URL" is a property of the schema rather than a filter somebody has to remember.
//
// A blank token on save means "keep the stored one", so the URL can be corrected without re-pasting a
// token. There is no way to read one back out.

export type ConnectionState = {
  configured: boolean;
  url?: string | null;
  user?: string | null;
  isOwner?: boolean;
  /** Whether the OWNER has set the instance URL. Members inherit it and never set one. */
  instanceConfigured?: boolean;
  /**
   * A token is stored but cannot be decrypted.
   *
   * The platform's encryption key is minted on first use and not backed up, so losing it re-mints one
   * and every previously encrypted column becomes unreadable. Reported separately from "not configured"
   * because the person needs telling that nothing is broken and their URL is still there — only the
   * token has to be pasted again.
   */
  unreadable?: boolean;
  /** What `tea` already has for this instance. Null when it has no login for it. */
  tea?: { name: string; url?: string; user: string | null; hasToken: boolean } | null;
  /** False when this account has no OS user, so there is nowhere to write a config. */
  canStoreToken?: boolean;
};

type Props = { state: ConnectionState; onSaved: () => void };

export const GiteaConnection = ({ state, onSaved }: Props) => {
  const { get, put } = useClient();
  const navigate = useNavigate();
  // Loopback is the right default and worth putting in front of someone: the sidecar fetches
  // SERVER-SIDE, so `localhost` means the machine Officer runs on. It needs no TLS and never leaves the
  // box — where the public URL would take the same traffic out and back.
  // Seeded from what tea already knows before falling back to a guess. On a machine where somebody ran
  // `tea login` by hand, the URL is already on disk and asking for it again is asking for something the
  // box can see.
  const [url, setUrl] = useState(state.url ?? state.tea?.url ?? 'http://localhost:3000');
  const [token, setToken] = useState('');
  const [busy, setBusy] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [tested, setTested] = useState<{ ok: boolean; user?: string; error?: string } | null>(null);

  // Runs `tea whoami` AS this account. It proves the token the AGENT will use, not one the platform read
  // out of a database — which is the only test worth having, since those are now the same thing.
  const test = async () => {
    setBusy(true);
    setTested(null);
    try {
      setTested(await get<{ ok: boolean; user?: string; error?: string }>('/gitea/_test'));
    } catch (err) {
      setTested({ ok: false, error: err instanceof Error ? err.message : 'could not test' });
    } finally {
      setBusy(false);
    }
  };

  // ONE THING AT A TIME. Until the platform knows where Gitea is, a token cannot be checked — there is
  // nothing to check it against — and once the URL is known, tea may already hold a working token, in
  // which case the second step never appears at all.
  //
  // Members skip step one entirely: the instance is the owner's.
  const needsUrl = state.isOwner !== false && !state.instanceConfigured;

  const save = async (ev?: React.FormEvent) => {
    ev?.preventDefault();
    setBusy(true);
    setError(null);
    try {
      await put('/gitea/_config', state.isOwner === false ? { token } : { url, token });
      // ORDER MATTERS. `onSaved` re-reads the connection and re-mints the frame session; navigating
      // first would swap to the frame while that is still in flight, and the frame would load against a
      // session that does not exist yet.
      onSaved();
      // Back to the frame. Saving from `/gitea/connection` otherwise leaves you looking at the form you
      // just submitted, which reads as nothing having happened.
      //
      // Only when there is a frame to go back TO: after the URL-only step there is still a token to
      // set, and bouncing to a frame that immediately sends you back is worse than staying put.
      if (!needsUrl) navigate('/gitea');
    } catch (err) {
      setError(err instanceof Error ? err.message : 'could not save');
    } finally {
      setBusy(false);
    }
  };

  return (
    // A real <form>, so Enter submits. Typing a URL and pressing return is what anyone does, and a div
    // full of inputs silently swallows it — the button becomes the only way in, which is a keyboard trap
    // wearing a layout.
    <form onSubmit={save} className="mx-auto flex h-full max-w-md flex-col justify-center gap-4 p-6">
      <div>
        <h2 className="text-base font-semibold">{state.unreadable ? 'Re-enter your token' : 'Connect Gitea'}</h2>
        <p className="mt-1 text-sm text-muted-foreground">
          {state.unreadable
            ? "The stored token can no longer be read — this server's encryption key changed. Nothing else is lost; paste it again."
            : needsUrl
              ? 'Where Gitea runs. Officer reaches it from the server, so localhost means the machine Officer runs on.'
              : state.isOwner === false
                ? 'Your own access token. The instance is already set.'
                : 'Your own access token for this instance.'}
        </p>
      </div>

      {needsUrl && (
        <label className="space-y-1.5">
          <span className="text-xs font-medium text-muted-foreground">Instance URL</span>
          <Input value={url} onChange={(ev) => setUrl(ev.target.value)} placeholder="http://localhost:3000" />
        </label>
      )}

      {/* Not shown while the instance is still unknown: a token cannot be validated without one, and
          tea may already hold one for whatever URL is entered above. */}
      {needsUrl ? null : (
      <label className="space-y-1.5">
        <span className="text-xs font-medium text-muted-foreground">Access token</span>
        <Input
          type="password"
          value={token}
          onChange={(ev) => setToken(ev.target.value)}
          placeholder={state.tea?.hasToken && !state.unreadable ? '•••••••• (unchanged)' : 'Settings → Applications in Gitea'}
        />
      </label>
      )}

      {/* What tea already has, read from the account's own config. On a machine where someone ran
          `tea login` by hand, this says so instead of demanding a token they already gave. */}
      {state.tea?.hasToken ? (
        <p className="flex items-center gap-1.5 text-xs text-success">
          <CheckCircle2 className="h-3.5 w-3.5" />
          tea is configured{state.tea.user ? ` as ${state.tea.user}` : ''} — leave the field blank to keep it
        </p>
      ) : null}

      {state.canStoreToken === false ? (
        <p className="flex items-start gap-1.5 text-xs text-warning">
          <TriangleAlert className="mt-0.5 h-3.5 w-3.5 shrink-0" />
          This account has no system user yet, so a token cannot be stored for the command line. The web
          view above works regardless.
        </p>
      ) : null}

      {tested ? (
        <p className={`text-xs ${tested.ok ? 'text-success' : 'text-destructive'}`}>
          {tested.ok ? `Authenticated as ${tested.user}` : tested.error}
        </p>
      ) : null}

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

      <div className="flex gap-2">
        <Button type="submit" disabled={busy || (needsUrl ? !url.trim() : !state.tea?.hasToken && !token)}>
          {busy ? <Loader2 className="mr-2 h-3.5 w-3.5 animate-spin" /> : null}
          {needsUrl ? 'Continue' : state.configured ? 'Save' : 'Connect'}
        </Button>
        {/* Only offered when there is something to test. */}
        {state.tea?.hasToken ? (
          <Button type="button" variant="outline" onClick={test} disabled={busy}>
            Test
          </Button>
        ) : null}
        {/* Only once there is something to go back TO. */}
        {state.configured && !state.unreadable ? (
          <Button type="button" variant="outline" onClick={() => navigate('/gitea')} disabled={busy}>
            Cancel
          </Button>
        ) : null}
      </div>
    </form>
  );
};