import { useQueryClient } from '@tanstack/react-query';
import { useState } from 'react';
import { Navigate, useLocation } from 'react-router';
import { ApiError, unwrap } from '../../api/client';
import { useApi, useSessionStore } from '../../api/useApi';
import { webDeviceName } from '../../app/buildInfo';
import { paths } from '../../app/routes';
import { useDocumentTitle } from '../../app/useDocumentTitle';
import { useSession } from '../../app/useSession';
import { Button } from '../../components/Button';
import { Card } from '../../components/Card';
import { TextField } from '../../components/TextField';
import { Icon } from '../../design/Icon';
import type { StringKey } from '../../i18n/catalog';
import { useI18n } from '../../i18n/useI18n';
import { formatInviteCode, inviterFromLink, isValidInviteCode, normaliseInviteCode } from './inviteCode';
import styles from './LoginPage.module.css';

/** SPEC §9.6: a display name is 1 to 40 code points after trimming. */
const DISPLAY_NAME_MAX = 40;

function errorKey(error: unknown): StringKey {
  if (!(error instanceof ApiError)) return 'error_server';
  switch (error.code) {
    case 'network':
      return 'onboarding_error_network';
    case 'invite_invalid':
      return 'onboarding_error_invite_invalid';
    case 'rate_limited':
      return 'onboarding_error_rate_limited';
    case 'household_full':
      return 'error_household_full';
    case 'validation_failed':
    case 'invalid_request':
      return 'error_validation';
    default:
      return 'error_server';
  }
}

/**
 * Sign-in like a phone's pairing (S-1): the server is this origin, the user types an invite code (12 characters in
 * groups of 4) and the browser becomes a device ("Web · <browser>") through E-3. A display name is asked for only
 * when the code turns out to need one (`admin_setup` or `partner` invites: `invalid_request` on `display_name`).
 * After a 401 it says why the session ended: S-18's text for `device_revoked` (D-130), otherwise "Du loggades ut".
 */
export default function LoginPage() {
  const { t, tp } = useI18n();
  const api = useApi();
  const sessionStore = useSessionStore();
  const session = useSession();
  const queryClient = useQueryClient();
  const location = useLocation();
  const [code, setCode] = useState('');
  const [inviter, setInviter] = useState<string | null>(null);
  const [name, setName] = useState('');
  const [needsName, setNeedsName] = useState(false);
  const [codeError, setCodeError] = useState<string | null>(null);
  const [nameError, setNameError] = useState<string | null>(null);
  const [formError, setFormError] = useState<string | null>(null);
  const [busy, setBusy] = useState(false);
  const [landing, setLanding] = useState<string | null>(null);
  useDocumentTitle(t('web_login_title'));

  const from = (location.state as { from?: string } | null)?.from ?? paths.home;
  if (session !== null) return <Navigate to={landing ?? from} replace />;
  const signedOut = sessionStore.lastSignOut();

  const onCodeChange = (text: string) => {
    const name = inviterFromLink(text);
    if (name !== null) setInviter(name);
    setCode(formatInviteCode(normaliseInviteCode(text).slice(0, 12)));
    setCodeError(null);
    setFormError(null);
  };

  const submit = async (event: { preventDefault: () => void }) => {
    event.preventDefault();
    const normalised = normaliseInviteCode(code);
    if (!isValidInviteCode(normalised)) {
      setCodeError(t('onboarding_error_code_length'));
      return;
    }
    const displayName = name.trim();
    if (needsName) {
      if (displayName.length === 0) {
        setNameError(t('onboarding_error_name_required'));
        return;
      }
      if (Array.from(displayName).length > DISPLAY_NAME_MAX) {
        setNameError(tp('error_too_long', DISPLAY_NAME_MAX));
        return;
      }
    }
    setBusy(true);
    setFormError(null);
    try {
      const accepted = await unwrap(
        api.POST('/invites/accept', {
          body: {
            code: normalised,
            device_name: webDeviceName(navigator.userAgent),
            ...(needsName ? { display_name: displayName } : {}),
          },
        }),
      );
      queryClient.clear();
      // After a partner invite the first page is the profile, like the app's S-2 (AC-2.10, D-086).
      setLanding(accepted.invite_kind === 'partner' ? paths.settingsProfile : from);
      sessionStore.signIn({
        token: accepted.token,
        userId: accepted.user.id,
        deviceId: accepted.device.id,
        inviteKind: accepted.invite_kind,
      });
    } catch (error) {
      if (error instanceof ApiError && error.code === 'invalid_request' && error.field === 'display_name') {
        setNeedsName(true);
      } else if (error instanceof ApiError && error.code === 'validation_failed' && error.field === 'display_name') {
        setNeedsName(true);
        setNameError(tp('error_too_long', DISPLAY_NAME_MAX));
      } else if (error instanceof ApiError && error.code === 'invite_invalid') {
        setCodeError(t('onboarding_error_invite_invalid'));
      } else {
        setFormError(t(errorKey(error)));
      }
    } finally {
      setBusy(false);
    }
  };

  const paste = async () => {
    try {
      onCodeChange(await navigator.clipboard.readText());
    } catch (error) {
      // Clipboard access refused or unavailable: the user types or pastes into the field instead.
      if (!(error instanceof DOMException) && !(error instanceof TypeError)) throw error;
    }
  };

  return (
    <main className={styles.page}>
      <div className={styles.column}>
        <div className={styles.brand}>
          <span className={styles.mark} aria-hidden="true">
            <Icon name="receipt_long" filled size={32} />
          </span>
          <p className={styles.wordmark}>{t('common_wordmark')}</p>
          <p className={styles.tagline}>{t('common_tagline')}</p>
        </div>
        <Card>
          <h1 className={styles.title}>{t('web_login_title')}</h1>
          {signedOut === 'device_revoked' ? (
            <div className={styles.notice} role="status">
              <p className={styles.noticeTitle}>{t('onboarding_removed_title')}</p>
              <p>{t('onboarding_removed_new_code')}</p>
            </div>
          ) : signedOut === 'unauthorized' ? (
            <p className={styles.notice} role="status">
              {t('web_signed_out')}
            </p>
          ) : null}
          <form className={styles.form} onSubmit={(event) => void submit(event)} noValidate>
            <div className={styles.server}>
              <span className={styles.serverLabel}>{t('web_login_server')}</span>
              <span className={styles.serverValue}>
                <Icon name="dns" size={18} />
                {window.location.host}
              </span>
            </div>
            <TextField
              label={t('common_invite_code')}
              value={code}
              onChange={onCodeChange}
              error={codeError}
              supporting={inviter === null ? t('web_login_body') : t('onboarding_code_help', inviter)}
              placeholder={t('onboarding_code_placeholder')}
              autoComplete="one-time-code"
              autoCapitalize="characters"
              spellCheck={false}
              autoFocus
              inputClassName={styles.code}
              suffix={
                <Button variant="text" onClick={() => void paste()} icon={<Icon name="content_paste" size={20} />}>
                  {t('onboarding_code_paste')}
                </Button>
              }
            />
            {needsName ? (
              <>
                <p className={styles.hint}>{t('web_login_name_needed')}</p>
                <TextField
                  label={t('onboarding_name_label')}
                  value={name}
                  onChange={(value) => {
                    setName(value);
                    setNameError(null);
                  }}
                  error={nameError}
                  autoComplete="given-name"
                />
              </>
            ) : null}
            {formError === null ? null : (
              <p className={styles.error} role="alert">
                {formError}
              </p>
            )}
            <Button type="submit" size="medium" disabled={busy}>
              {busy ? t('onboarding_pairing') : t('onboarding_pair')}
            </Button>
          </form>
        </Card>
      </div>
    </main>
  );
}