import { useEffect, useMemo, useRef, useState } from 'react';

import { ApiError } from '@/api';
import { usePublicFormConfig, useSubmitPublicForm } from '@/api/hooks';
import type { PublicArtistOption } from '@/api/schema';
import { ErrorNote, Loading } from '@/components/state';
import { Btn, FieldLabel, Panel, PanelHeader, TextInput } from '@/components/ui';
import { t } from '@/i18n';
import { ENV } from '@/lib/env';
import { longDayLabel } from '@/lib/time';

const MAX_POSITION_WISHES = 2;

// Charge le script hCaptcha une seule fois, quel que soit le nombre de
// montages de <HCaptchaWidget> (StrictMode, navigation aller-retour…).
let hcaptchaScriptPromise: Promise<void> | null = null;
function loadHCaptchaScript(): Promise<void> {
  if (!hcaptchaScriptPromise) {
    hcaptchaScriptPromise = new Promise((resolve) => {
      const script = document.createElement('script');
      script.src = 'https://js.hcaptcha.com/1/api.js';
      script.async = true;
      script.defer = true;
      script.onload = () => resolve();
      document.head.appendChild(script);
    });
  }
  return hcaptchaScriptPromise;
}

/** Widget hCaptcha (rendu implicite) : le script scanne le DOM et rend les
 * `.h-captcha` qu'il trouve. `onToken` reçoit le jeton une fois résolu. */
function HCaptchaWidget({ onToken }: { onToken: (token: string) => void }) {
  const containerRef = useRef<HTMLDivElement>(null);
  const callbackName = useRef(`hcaptchaCallback${Math.random().toString(36).slice(2)}`);

  useEffect(() => {
    const win = window as unknown as Record<string, unknown>;
    const name = callbackName.current;
    win[name] = onToken;
    loadHCaptchaScript();
    return () => {
      delete win[name];
    };
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  return (
    <div
      ref={containerRef}
      className="h-captcha"
      data-sitekey={ENV.hcaptchaSiteKey}
      data-callback={callbackName.current}
    />
  );
}

function errorMessage(error: unknown): string {
  if (error instanceof ApiError) return t(error.code);
  return t('error.generic');
}

function groupArtistsByDay(artists: PublicArtistOption[]): Array<[string, PublicArtistOption[]]> {
  const byDay = new Map<string, PublicArtistOption[]>();
  for (const artist of artists) {
    const list = byDay.get(artist.performance_date) ?? [];
    list.push(artist);
    byDay.set(artist.performance_date, list);
  }
  return [...byDay.entries()].sort(([a], [b]) => a.localeCompare(b));
}

export function PublicSignupPage() {
  const config = usePublicFormConfig();
  const submit = useSubmitPublicForm();

  const [firstName, setFirstName] = useState('');
  const [lastName, setLastName] = useState('');
  const [email, setEmail] = useState('');
  const [phone, setPhone] = useState('');
  const [comment, setComment] = useState('');
  const [companionNote, setCompanionNote] = useState('');
  const [available, setAvailable] = useState(false);
  const [willingToPayFee, setWillingToPayFee] = useState(false);
  const [positionIds, setPositionIds] = useState<string[]>([]);
  const [artistByDay, setArtistByDay] = useState<Record<string, string>>({});
  const [photo, setPhoto] = useState<File | null>(null);
  const [captchaToken, setCaptchaToken] = useState('');
  const [submitError, setSubmitError] = useState<string | null>(null);
  const [volunteerId, setVolunteerId] = useState<string | null>(null);

  const artistsByDay = useMemo(
    () => groupArtistsByDay(config.data?.artists ?? []),
    [config.data?.artists],
  );

  if (config.isLoading) return <Loading />;
  if (config.error) return <ErrorNote error={config.error} />;
  if (!config.data) return null;

  if (volunteerId) {
    return (
      <div className="mx-auto flex max-w-[520px] flex-col gap-4 p-6">
        <Panel>
          <PanelHeader>{t('publicForm.success.title')}</PanelHeader>
          <p className="p-4 font-mono text-[12px] leading-relaxed">{t('publicForm.success.body')}</p>
        </Panel>
      </div>
    );
  }

  if (!config.data.is_open) {
    return (
      <div className="mx-auto flex max-w-[520px] flex-col gap-4 p-6">
        <Panel>
          <PanelHeader>{t('publicForm.closed.title')}</PanelHeader>
          <p className="p-4 font-mono text-[12px] leading-relaxed">{t('publicForm.closed.body')}</p>
        </Panel>
      </div>
    );
  }

  const fields = new Set(config.data.fields);
  const toggleEnabled = ENV.hcaptchaSiteKey.length > 0;

  const togglePosition = (id: string) => {
    setPositionIds((prev) => {
      if (prev.includes(id)) return prev.filter((x) => x !== id);
      if (prev.length >= MAX_POSITION_WISHES) return prev;
      return [...prev, id];
    });
  };

  const pickArtistForDay = (day: string, artistId: string) => {
    setArtistByDay((prev) => {
      const next = { ...prev };
      if (!artistId) delete next[day];
      else next[day] = artistId;
      return next;
    });
  };

  const canSubmit =
    firstName.trim().length > 0 &&
    lastName.trim().length > 0 &&
    (toggleEnabled ? captchaToken.length > 0 : true) &&
    !submit.isPending;

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setSubmitError(null);
    try {
      const result = await submit.mutateAsync({
        first_name: firstName,
        last_name: lastName,
        hcaptcha_token: captchaToken || 'dev',
        email: fields.has('EMAIL') ? email : undefined,
        phone: fields.has('PHONE') ? phone : undefined,
        comment: fields.has('COMMENT') ? comment : undefined,
        companion_wish_note: fields.has('COMPANION_WISH') ? companionNote : undefined,
        available: fields.has('AVAILABLE') ? available : undefined,
        willing_to_pay_fee: fields.has('WILLING_TO_PAY_FEE') ? willingToPayFee : undefined,
        position_wish_ids: fields.has('POSITION_WISHES') ? positionIds : undefined,
        artist_wish_ids: fields.has('ARTIST_WISHES') ? Object.values(artistByDay) : undefined,
        photo: fields.has('PHOTO') ? photo : undefined,
      });
      setVolunteerId(result.volunteer_id);
    } catch (err) {
      setSubmitError(errorMessage(err));
    }
  };

  return (
    <div className="mx-auto flex max-w-[560px] flex-col gap-4 p-4">
      <Panel>
        <PanelHeader>{t('publicForm.title')}</PanelHeader>
        <form onSubmit={handleSubmit} className="flex flex-col gap-4 p-4">
          <div className="grid grid-cols-2 gap-3">
            <label className="block">
              <FieldLabel>{t('config.vol.field.firstName')}</FieldLabel>
              <TextInput value={firstName} onChange={setFirstName} />
            </label>
            <label className="block">
              <FieldLabel>{t('config.vol.field.lastName')}</FieldLabel>
              <TextInput value={lastName} onChange={setLastName} />
            </label>
          </div>

          {fields.has('EMAIL') ? (
            <label className="block">
              <FieldLabel>{t('form.field.email')}</FieldLabel>
              <TextInput mono value={email} onChange={setEmail} />
            </label>
          ) : null}

          {fields.has('PHONE') ? (
            <label className="block">
              <FieldLabel>{t('form.field.phone')}</FieldLabel>
              <TextInput mono value={phone} onChange={setPhone} />
            </label>
          ) : null}

          {fields.has('POSITION_WISHES') && config.data.positions.length > 0 ? (
            <div>
              <FieldLabel>
                {t('form.field.positionWishes')} — {t('publicForm.positionWishes.count', {
                  count: positionIds.length,
                  max: MAX_POSITION_WISHES,
                })}
              </FieldLabel>
              <div className="flex flex-col gap-[6px] border-2 border-ink bg-cream p-[9px]">
                {config.data.positions.map((p) => {
                  const checked = positionIds.includes(p.id);
                  const disabled = !checked && positionIds.length >= MAX_POSITION_WISHES;
                  return (
                    <label
                      key={p.id}
                      className={`flex items-center gap-[8px] font-mono text-[12px] ${disabled ? 'opacity-40' : 'cursor-pointer'}`}
                    >
                      <input
                        type="checkbox"
                        checked={checked}
                        disabled={disabled}
                        onChange={() => togglePosition(p.id)}
                        className="h-[15px] w-[15px] accent-ink"
                      />
                      {p.name}
                    </label>
                  );
                })}
              </div>
            </div>
          ) : null}

          {fields.has('ARTIST_WISHES') && artistsByDay.length > 0 ? (
            <div>
              <FieldLabel>{t('form.field.artistWishes')}</FieldLabel>
              <div className="flex flex-col gap-[8px]">
                {artistsByDay.map(([day, artists]) => (
                  <label key={day} className="block">
                    <span className="mb-[3px] block font-mono text-[10px] opacity-60">
                      {longDayLabel(`${day}T12:00`)}
                    </span>
                    <select
                      value={artistByDay[day] ?? ''}
                      onChange={(e) => pickArtistForDay(day, e.target.value)}
                      className="w-full border-2 border-ink bg-cream p-[8px] font-mono text-[12px]"
                    >
                      <option value="">{t('publicForm.artistWishes.none')}</option>
                      {artists.map((a) => (
                        <option key={a.id} value={a.id}>
                          {a.name}
                        </option>
                      ))}
                    </select>
                  </label>
                ))}
              </div>
            </div>
          ) : null}

          {fields.has('COMPANION_WISH') ? (
            <label className="block">
              <FieldLabel>{t('form.field.companionWish')}</FieldLabel>
              <TextInput value={companionNote} onChange={setCompanionNote} />
            </label>
          ) : null}

          {fields.has('COMMENT') ? (
            <label className="block">
              <FieldLabel>{t('form.field.comment')}</FieldLabel>
              <textarea
                value={comment}
                onChange={(e) => setComment(e.target.value)}
                rows={3}
                className="w-full border-2 border-ink bg-cream p-[9px] font-mono text-[12px]"
              />
            </label>
          ) : null}

          {fields.has('AVAILABLE') ? (
            <label className="flex cursor-pointer items-center gap-[8px]">
              <input
                type="checkbox"
                checked={available}
                onChange={(e) => setAvailable(e.target.checked)}
                className="h-[16px] w-[16px] accent-ink"
              />
              <span className="font-mono text-[12px]">{t('publicForm.field.available')}</span>
            </label>
          ) : null}

          {fields.has('WILLING_TO_PAY_FEE') ? (
            <label className="flex cursor-pointer items-center gap-[8px]">
              <input
                type="checkbox"
                checked={willingToPayFee}
                onChange={(e) => setWillingToPayFee(e.target.checked)}
                className="h-[16px] w-[16px] accent-ink"
              />
              <span className="font-mono text-[12px]">{t('publicForm.field.willingToPayFee')}</span>
            </label>
          ) : null}

          {fields.has('PHOTO') ? (
            <label className="block">
              <FieldLabel>{t('form.field.photo')}</FieldLabel>
              <input
                type="file"
                accept="image/*"
                capture="environment"
                onChange={(e) => setPhoto(e.target.files?.[0] ?? null)}
                className="w-full border-2 border-ink bg-cream p-[8px] font-mono text-[11px]"
              />
            </label>
          ) : null}

          {toggleEnabled ? (
            <HCaptchaWidget onToken={setCaptchaToken} />
          ) : (
            <p className="font-mono text-[9.5px] opacity-50">{t('publicForm.captcha.disabled')}</p>
          )}

          {submitError ? (
            <p className="font-mono text-[11px] font-bold text-orange-dark">{submitError}</p>
          ) : null}

          <Btn type="submit" disabled={!canSubmit}>
            {submit.isPending ? t('publicForm.submitting') : t('publicForm.submit')}
          </Btn>
        </form>
      </Panel>
    </div>
  );
}