import { useEffect, useRef, useState } from 'react';
import QRCode from 'qrcode';
import { Check, Copy, Loader2, Plus, QrCode, Share2, Smartphone, Trash2 } from 'lucide-react';
import type { HeadscaleInvite, HeadscaleInviteCreated, InviteStatus } from './shared';
import { INVITE_TTL_DEFAULT_SECONDS } from './shared';
import { useHeadscaleInvites } from './useHeadscaleInvites';
import { useHeadscaleUsers } from './useHeadscaleData';
import { headscaleErrorMessage } from './useHeadscaleServers';
import { fullDate, timeAgo, timeUntil } from './format';
import { Badge, Button, Card, Dot, ErrorNote, Field } from './Cards';
import { EmptyBody, ViewShell } from './ViewShell';
import { copyToClipboard } from 'helpers/clipboard';

// Device invites — the admin surface of COMMS/OFFSCALE_INVITE_ENROLLMENT.md §5.
//
// The point of the feature is that the person joining does nothing but tap a link and press Join: no app
// store hunt, no control-server URL typed by hand, no pre-auth key they have no way to generate. The admin
// does all of it here and sends one link.
//
// TWO RULES SHAPE THIS FILE.
//
//  1. The link exists exactly once. Its fragment carries the claim token, and §5 is explicit: never display,
//     log or store it beyond the moment it is handed to the admin. So the created invite lives in component
//     state only — never in the query cache, never in a URL, never in a toast that outlives the panel — and
//     the panel drops it on dismiss. Refreshing the page is meant to lose it; the admin mints another.
//  2. The token is not the key. Nothing here can join a machine to the tailnet: the pre-auth key is minted
//     by the server at claim time. A leaked link before it is claimed is revocable, which is the whole
//     reason the credential is not in the URL.

const STATUS_TONE: Record<InviteStatus, 'ok' | 'warn' | 'bad' | 'idle'> = {
  pending: 'warn',
  claimed: 'ok',
  expired: 'idle',
  revoked: 'bad',
};

/** Presets rather than a free number: every one is inside the spec's 60s–24h range by construction. */
const TTL_OPTIONS = [
  { seconds: 300, label: '5 minutes' },
  { seconds: INVITE_TTL_DEFAULT_SECONDS, label: '15 minutes' },
  { seconds: 3600, label: '1 hour' },
  { seconds: 86_400, label: '24 hours' },
] as const;

const CopyButton = ({ value, label }: { value: string; label: string }) => {
  const [done, setDone] = useState(false);
  const copy = () => {
    void copyToClipboard(value);
    setDone(true);
    window.setTimeout(() => setDone(false), 1500);
  };
  return (
    <Button onClick={copy} variant={done ? 'primary' : 'ghost'}>
      {done ? <Check className="h-3.5 w-3.5" /> : <Copy className="h-3.5 w-3.5" />}
      {done ? 'Copied' : label}
    </Button>
  );
};

/**
 * The QR, rendered client-side into a canvas.
 *
 * It never leaves the browser — an image endpoint would put the claim token in a request line and therefore
 * in a server log, which is the exact thing the fragment-only link format exists to prevent. Error
 * correction stays low so the modules stay large: this is scanned from a phone held next to the screen, not
 * printed and posted.
 */
const InviteQr = ({ url }: { url: string }) => {
  const canvas = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    if (!canvas.current) return;
    void QRCode.toCanvas(canvas.current, url, { errorCorrectionLevel: 'L', margin: 2, width: 220 });
  }, [url]);

  return <canvas ref={canvas} className="h-[220px] w-[220px] rounded-lg bg-white p-1" />;
};

type InviteLinkPanelProps = { invite: HeadscaleInviteCreated; onDismiss: () => void };

const InviteLinkPanel = ({ invite, onDismiss }: InviteLinkPanelProps) => {
  const [showQr, setShowQr] = useState(true);

  // Plain https now — the link lands on a page the companion serves, which bounces into the app. It goes in
  // `url` rather than `text` so share targets treat it as a link and preserve the fragment. A cancelled sheet
  // rejects — nothing to report there, the link is still on screen.
  const share = () => {
    void navigator
      .share?.({ title: 'Join the tailnet', text: `Tap to join as ${invite.user}`, url: invite.url })
      .catch(() => {});
  };

  return (
    <div className="overflow-hidden rounded-xl border border-primary/30 bg-primary/[0.06]">
      <div className="flex items-start gap-2.5 border-b border-primary/20 px-4 py-3">
        <Smartphone className="mt-0.5 h-4 w-4 shrink-0 text-primary" />
        <div className="min-w-0">
          <div className="text-sm font-semibold text-zinc-100">Send this link to the device</div>
          <p className="mt-0.5 text-xs leading-snug text-zinc-400">
            It opens OffScale, shows one confirmation screen and joins as{' '}
            <span className="text-zinc-200">{invite.user}</span>. Single use, and it stops working{' '}
            {timeUntil(invite.expiresAt ?? null)}. Officer does not keep a copy — dismiss this and it is gone.
          </p>
        </div>
      </div>

      <div className="flex flex-col gap-3 p-4">
        <div className="rounded-lg border border-white/10 bg-black/50 px-3 py-2 font-mono text-xs break-all text-zinc-300">
          {invite.url}
        </div>

        {showQr && (
          <div className="flex justify-center py-1">
            <InviteQr url={invite.url} />
          </div>
        )}

        <div className="flex flex-wrap items-center gap-2">
          <CopyButton value={invite.url} label="Copy link" />
          {/* Only where the OS actually has a share sheet — a button that silently does nothing is worse
              than no button, and on desktop Chrome/Firefox navigator.share is simply absent. */}
          {typeof navigator.share === 'function' && (
            <Button onClick={share}>
              <Share2 className="h-3.5 w-3.5" />
              Share
            </Button>
          )}
          <Button onClick={() => setShowQr((v) => !v)}>
            <QrCode className="h-3.5 w-3.5" />
            {showQr ? 'Hide QR' : 'Show QR'}
          </Button>
          <Button variant="danger" onClick={onDismiss}>
            Done
          </Button>
        </div>
      </div>
    </div>
  );
};

type CreateInviteFormProps = { onCreated: (invite: HeadscaleInviteCreated) => void; onClose: () => void };

const CreateInviteForm = ({ onCreated, onClose }: CreateInviteFormProps) => {
  const { users } = useHeadscaleUsers();
  const { create } = useHeadscaleInvites();
  const [user, setUser] = useState('');
  const [note, setNote] = useState('');
  const [ttl, setTtl] = useState(INVITE_TTL_DEFAULT_SECONDS);
  const [ephemeral, setEphemeral] = useState(false);
  const [tags, setTags] = useState('');
  const [error, setError] = useState<string | null>(null);

  const submit = async () => {
    setError(null);
    // The invite API names the Headscale USER, not its uint64 id — the server it is sent to may not be the
    // one this list came from by the time it is claimed.
    const chosen = user || users[0]?.name;
    if (!chosen) return setError('Create a user first — an invite files the joining device under one.');

    try {
      const invite = await create.mutateAsync({
        user: chosen,
        ttlSeconds: ttl,
        ephemeral,
        note: note.trim(),
        tags: tags
          .split(/[\s,]+/)
          .map((t) => t.trim())
          .filter(Boolean),
      });
      onCreated(invite);
      onClose();
    } catch (err) {
      setError(headscaleErrorMessage(err));
    }
  };

  return (
    <Card>
      <form
        onSubmit={(ev) => {
          ev.preventDefault();
          void submit();
        }}
        className="flex flex-col gap-3 p-4"
      >
        <div className="text-sm font-semibold text-zinc-100">Authorize a new device</div>

        <label className="flex flex-col gap-1.5">
          <span className="text-xs font-medium text-zinc-400">User</span>
          <select
            value={user || users[0]?.name || ''}
            onChange={(ev) => setUser(ev.target.value)}
            className="rounded-lg border border-white/10 bg-black/40 px-3 py-2 text-sm text-zinc-100 outline-none focus:border-primary/50"
          >
            {users.map((entry) => (
              <option key={entry.id} value={entry.name}>
                {entry.name}
              </option>
            ))}
          </select>
        </label>

        <Field
          label="Device name (optional)"
          value={note}
          onChange={setNote}
          placeholder="andre-iphone"
          hint="Prefilled on the phone's join screen and used as the node's name, which the person can edit. It labels this invite in your list too."
        />

        <label className="flex flex-col gap-1.5">
          <span className="text-xs font-medium text-zinc-400">Link valid for</span>
          <select
            value={ttl}
            onChange={(ev) => setTtl(Number(ev.target.value))}
            className="rounded-lg border border-white/10 bg-black/40 px-3 py-2 text-sm text-zinc-100 outline-none focus:border-primary/50"
          >
            {TTL_OPTIONS.map((option) => (
              <option key={option.seconds} value={option.seconds}>
                {option.label}
              </option>
            ))}
          </select>
          <span className="text-[11px] leading-snug text-zinc-600">
            How long the link can be claimed for. Short is safer — you can always mint another.
          </span>
        </label>

        <label className="flex cursor-pointer items-start gap-2.5">
          <input
            type="checkbox"
            checked={ephemeral}
            onChange={(ev) => setEphemeral(ev.target.checked)}
            className="mt-0.5 h-3.5 w-3.5 cursor-pointer accent-primary"
          />
          <span className="min-w-0">
            <span className="block text-xs font-medium text-zinc-300">Ephemeral</span>
            <span className="block text-[11px] leading-snug text-zinc-600">
              The node is removed when it goes offline. Wrong for a phone; right for a container.
            </span>
          </span>
        </label>

        <Field
          label="ACL tags (optional)"
          value={tags}
          onChange={setTags}
          placeholder="phone, family"
          hint="Comma or space separated. The tag: prefix is added for you, and the device cannot change them."
        />

        {error && <ErrorNote>{error}</ErrorNote>}

        <div className="flex items-center gap-2 pt-1">
          <Button type="submit" variant="primary" disabled={create.isPending}>
            {create.isPending && <Loader2 className="h-3.5 w-3.5 animate-spin" />}
            Create invite
          </Button>
          <Button onClick={onClose} disabled={create.isPending}>
            Cancel
          </Button>
        </div>
      </form>
    </Card>
  );
};

type InviteRowProps = { invite: HeadscaleInvite; onError: (message: string) => void };

const InviteRow = ({ invite, onError }: InviteRowProps) => {
  const { revoke } = useHeadscaleInvites();
  const [confirming, setConfirming] = useState(false);

  const run = async () => {
    try {
      await revoke.mutateAsync(invite.id);
    } catch (err) {
      onError(headscaleErrorMessage(err));
    }
  };

  return (
    <Card>
      <div className="flex flex-wrap items-center gap-3 p-3.5">
        <Dot tone={STATUS_TONE[invite.status] ?? 'idle'} />
        <div className="min-w-0 flex-1">
          <div className="flex flex-wrap items-center gap-2">
            <span className="truncate text-sm text-zinc-200">{invite.note || 'Untitled invite'}</span>
            <Badge>{invite.user}</Badge>
            {invite.ephemeral && <Badge>ephemeral</Badge>}
            {invite.tags?.map((tag) => (
              <Badge key={tag} tone="active">
                {tag}
              </Badge>
            ))}
          </div>
          <div className="mt-0.5 flex flex-wrap items-center gap-x-2 text-[11px] text-zinc-500">
            <span>{invite.status}</span>
            {invite.status === 'pending' && (
              <span title={fullDate(invite.expiresAt ?? null)}>· expires {timeUntil(invite.expiresAt ?? null)}</span>
            )}
            {invite.status === 'claimed' && (
              <span title={fullDate(invite.claimedAt ?? null)}>
                · claimed {timeAgo(invite.claimedAt ?? null)}
                {invite.claimedFromIp ? ` from ${invite.claimedFromIp}` : ''}
              </span>
            )}
            <span>· created {timeAgo(invite.createdAt ?? null)}</span>
          </div>
        </div>

        {/* Revoking a claimed invite does nothing to the node that used it — that is a separate removal in
            Nodes, and conflating the two here would make "revoke" mean two different things. */}
        {invite.status === 'pending' && (
          <div className="flex shrink-0 flex-wrap items-center gap-2">
            {confirming ? (
              <>
                <Button variant="danger" onClick={() => void run()} disabled={revoke.isPending}>
                  <Trash2 className="h-3.5 w-3.5" />
                  Confirm revoke
                </Button>
                <Button onClick={() => setConfirming(false)} disabled={revoke.isPending}>
                  Cancel
                </Button>
              </>
            ) : (
              <Button variant="danger" onClick={() => setConfirming(true)} disabled={revoke.isPending}>
                <Trash2 className="h-3.5 w-3.5" />
                Revoke
              </Button>
            )}
          </div>
        )}
      </div>
    </Card>
  );
};

export const InvitesView = () => {
  const { invites, unavailable, isLoading, error } = useHeadscaleInvites();
  const [creating, setCreating] = useState(false);
  const [created, setCreated] = useState<HeadscaleInviteCreated | null>(null);
  const [actionError, setActionError] = useState<string | null>(null);

  const pending = invites.filter((i) => i.status === 'pending').length;

  return (
    <ViewShell isLoading={isLoading} error={error} label="device invites">
      <div className="mx-auto flex w-full max-w-2xl flex-col gap-3">
        <div className="flex items-start justify-between gap-4 px-1 pb-1">
          <div className="min-w-0">
            <h2 className="text-sm font-semibold text-zinc-100">Device invites</h2>
            <p className="mt-0.5 text-xs text-zinc-500">
              {unavailable ? 'Not available on this server' : `${pending} pending of ${invites.length}`}
            </p>
          </div>
          {!creating && !unavailable && (
            <Button variant="primary" onClick={() => setCreating(true)}>
              <Plus className="h-3.5 w-3.5" />
              Authorize new device
            </Button>
          )}
        </div>

        {/* Most registered servers have no enrolment API, and that is a normal state — the rest of the
            Headscale sections work regardless, so this must not read as a broken screen. */}
        {unavailable && (
          <EmptyBody
            icon={<Smartphone className="h-6 w-6" />}
            title="This server cannot mint invites"
            hint={`${unavailable}. Invites are served by the Officer Companion next to Headscale, because the joining phone has to reach it without an Officer account. Until it is deployed, use a pre-auth key.`}
          />
        )}

        {created && <InviteLinkPanel invite={created} onDismiss={() => setCreated(null)} />}
        {creating && <CreateInviteForm onCreated={setCreated} onClose={() => setCreating(false)} />}
        {actionError && <ErrorNote>{actionError}</ErrorNote>}

        {!unavailable && invites.length === 0 && !creating && (
          <EmptyBody
            icon={<Smartphone className="h-6 w-6" />}
            title="No invites yet"
            hint="An invite is a link you send to whoever needs to join. They tap it, confirm once, and they are on the tailnet — no key to paste and nothing to configure."
          />
        )}

        {invites.map((invite) => (
          <InviteRow key={invite.id} invite={invite} onError={setActionError} />
        ))}
      </div>
    </ViewShell>
  );
};