'use client';

import { useState, useTransition } from 'react';

import TemplatePicker, { type Template } from '@/app/admin/components/TemplatePicker';
import { earlyClosing, lateOpening, usualBounds } from '@/lib/schedule/exceptions';
import type { ExceptionKind, Slot } from '@/lib/schedule/types';

import { MESSAGE_MAX_CHARS } from '@/lib/screen/contract';

import {
  deleteException,
  saveException,
  saveExceptionRange,
  translateExceptionNote,
} from './actions';

export type UpcomingDay = {
  date: string;
  label: string;
  isToday: boolean;
  isClosed: boolean;
  hoursText: string;
  kind: ExceptionKind;
  note: string | null;
  /** Only a stored exception can be removed; holidays and vacations live elsewhere. */
  canDelete: boolean;
};

/** A day the quick actions can target, with the hours it would normally have. */
export type SelectableDay = {
  date: string;
  label: string;
  usualSlots: Slot[];
  usualText: string;
  effectiveText: string;
  isException: boolean;
};

type Props = {
  canEdit: boolean;
  today: string;
  days: SelectableDay[];
  upcoming: UpcomingDay[];
  templates: Template[];
};

const KIND_LABELS: Record<string, { text: string; className: string }> = {
  MANUAL: { text: 'manuelle', className: 'bg-[var(--accent-tint)] text-[var(--accent-ink)]' },
  HOLIDAY: { text: 'jour férié', className: 'bg-[var(--surface-muted)] text-[var(--ink-muted)]' },
  VACATION: { text: 'vacances', className: 'bg-[var(--surface-muted)] text-[var(--ink-muted)]' },
};

export default function ExceptionsManager({ canEdit, today, days, upcoming, templates }: Props) {
  const [pending, startTransition] = useTransition();
  const [message, setMessage] = useState<{ kind: 'ok' | 'error'; text: string } | null>(null);

  function run(work: () => Promise<{ ok: true } | { ok: false; error: string }>, success: string) {
    setMessage(null);
    startTransition(async () => {
      const result = await work();
      setMessage(result.ok ? { kind: 'ok', text: success } : { kind: 'error', text: result.error });
    });
  }

  return (
    <div className="mt-8 space-y-8">
      {message ? (
        <p
          role="status"
          className={`rounded-[var(--radius-md)] px-4 py-3 text-sm ${
            message.kind === 'ok'
              ? 'bg-[var(--success-tint)] text-[var(--success)]'
              : 'bg-[var(--danger-tint)] text-[var(--danger)]'
          }`}
        >
          {message.text}
        </p>
      ) : null}

      {canEdit ? (
        <QuickPanel today={today} days={days} templates={templates} pending={pending} run={run} />
      ) : null}

      {canEdit ? <RangePanel templates={templates} pending={pending} run={run} /> : null}

      <section>
        <h2 className="text-lg">À venir</h2>
        {upcoming.length === 0 ? (
          <p className="mt-3 text-sm text-[var(--ink-muted)]">
            Aucun changement prévu dans les deux prochains mois.
          </p>
        ) : (
          <ul className="mt-3 divide-y divide-[var(--line)] overflow-hidden rounded-[var(--radius-md)] border border-[var(--line)] bg-[var(--surface)]">
            {upcoming.map((day) => {
              const badge = KIND_LABELS[day.kind ?? 'MANUAL'] ?? KIND_LABELS.MANUAL!;
              return (
                <li key={day.date} className="flex flex-wrap items-center gap-x-3 gap-y-1 px-4 py-3">
                  <span className="font-medium">
                    {day.label}
                    {day.isToday ? ' (aujourd’hui)' : ''}
                  </span>
                  <span className={day.isClosed ? 'text-[var(--ink-muted)]' : ''}>
                    {day.hoursText}
                  </span>
                  <span
                    className={`rounded-[var(--radius-sm)] px-2 py-0.5 text-xs ${badge.className}`}
                  >
                    {badge.text}
                  </span>
                  {day.note ? (
                    <span className="text-sm text-[var(--ink-muted)]">« {day.note} »</span>
                  ) : null}

                  {canEdit && day.canDelete ? (
                    <button
                      type="button"
                      disabled={pending}
                      onClick={() =>
                        run(() => deleteException(day.date), 'Changement supprimé.')
                      }
                      className="ml-auto text-sm text-[var(--ink-muted)] underline-offset-2 hover:text-[var(--danger)] hover:underline disabled:opacity-40"
                    >
                      Supprimer
                    </button>
                  ) : null}
                </li>
              );
            })}
          </ul>
        )}
      </section>
    </div>
  );
}

/**
 * The quick path.
 *
 * This is the gesture the shop actually makes, from a phone, standing behind
 * the counter — so it sits at the top and asks for as little as possible.
 * The date defaults to today and changing it costs one control: closing this
 * afternoon and closing next Thursday are the same decision, and neither
 * should cost more clicks than the other.
 */
function QuickPanel({
  today,
  days,
  templates,
  pending,
  run,
}: {
  today: string;
  days: SelectableDay[];
  templates: Template[];
  pending: boolean;
  run: (work: () => Promise<{ ok: true } | { ok: false; error: string }>, success: string) => void;
}) {
  const [date, setDate] = useState(today);
  const [note, setNote] = useState('');

  const day = days.find((candidate) => candidate.date === date) ?? days[0];
  const isToday = day?.date === today;
  const isOpenThatDay = (day?.usualSlots.length ?? 0) > 0;

  function apply(slots: Slot[], success: string) {
    if (!day) {
      return;
    }
    const text = note.trim();

    run(async () => {
      const saved = await saveException({
        date: day.date,
        isClosed: slots.length === 0,
        slots,
        reason: 'TEMPORARY',
        // Empty means no notice: the message now drives what the panel shows,
        // so it has to be something the shop chose to say rather than a
        // sentence the form filled in on its behalf.
        noteFr: text || null,
      });

      if (saved.ok && text) {
        // Separate from the save: a message is worth having, but not at the
        // price of making the two-click path wait for the translation
        // service. A failure simply leaves the French alone on screen.
        await translateExceptionNote(day.date);
      }
      return saved;
    }, success);
  }

  const when = isToday ? 'aujourd’hui' : `le ${day?.label.toLowerCase() ?? ''}`;

  return (
    <section className="rounded-[var(--radius-md)] border-2 border-[var(--accent)] bg-[var(--surface)] p-5">
      <div className="flex flex-wrap items-center gap-x-3 gap-y-2">
        <h2 className="text-lg">Modifier les horaires</h2>
        <label className="flex items-center gap-2 text-sm">
          <span className="text-[var(--ink-muted)]">du</span>
          <select
            // "du" alone collides with the range form's "Du" field below;
            // the accessible name has to say which control this is.
            aria-label="Jour à modifier"
            value={date}
            onChange={(event) => setDate(event.target.value)}
            className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-1.5 text-base"
          >
            {days.map((candidate) => (
              <option key={candidate.date} value={candidate.date}>
                {candidate.date === today ? `${candidate.label} (aujourd’hui)` : candidate.label}
              </option>
            ))}
          </select>
        </label>
      </div>

      <p className="mt-2 text-sm text-[var(--ink-muted)]">
        Habituellement {day?.usualText ?? 'Fermé'}.
        {day?.isException ? ` Actuellement : ${day.effectiveText}.` : ''}
      </p>

      <div className="mt-4 flex flex-wrap items-end gap-3">
        <label className="min-w-56 flex-1 text-sm">
          <span className="block text-[var(--ink-muted)]">Message affiché (facultatif)</span>
          <input
            type="text"
            value={note}
            maxLength={MESSAGE_MAX_CHARS}
            placeholder="Fermeture exceptionnelle, retour demain"
            onChange={(event) => setNote(event.target.value)}
            className="mt-1 w-full rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base"
          />
        </label>
        <TemplatePicker templates={templates} onPick={setNote} disabled={pending} />
      </div>
      <p className="mt-1 text-sm text-[var(--ink-muted)]">
        Affiché sur l’écran tant que la boutique est fermée ce jour-là, et retiré dès qu’elle ouvre.
      </p>

      <div className="mt-4 space-y-3">
        <button
          type="button"
          disabled={pending}
          onClick={() => apply([], `La boutique sera fermée ${when}.`)}
          className="w-full rounded-[var(--radius-md)] bg-[var(--accent)] px-4 py-3 font-medium text-[var(--on-accent)] transition-colors hover:bg-[var(--accent-hover)] disabled:opacity-40 sm:w-auto"
        >
          {isToday ? 'Fermé aujourd’hui' : `Fermé ${when}`}
        </button>

        {isOpenThatDay && day ? (
          // Keyed on the date: changing the day changes the hours these times
          // are relative to, and React resets the fields by remounting rather
          // than by an effect writing state back.
          <AdjustHours key={day.date} day={day} pending={pending} apply={apply} />
        ) : (
          <p className="text-sm text-[var(--ink-muted)]">
            La boutique est déjà fermée {when}&nbsp;: pour une ouverture exceptionnelle, utilisez le
            formulaire ci-dessous.
          </p>
        )}
      </div>
    </section>
  );
}

/** A specific date, or a short run of days. Longer closures are holidays. */
function RangePanel({
  templates,
  pending,
  run,
}: {
  templates: Template[];
  pending: boolean;
  run: (work: () => Promise<{ ok: true } | { ok: false; error: string }>, success: string) => void;
}) {
  const [start, setStart] = useState('');
  const [end, setEnd] = useState('');
  const [note, setNote] = useState('');

  return (
    <section className="rounded-[var(--radius-md)] border border-[var(--line)] bg-[var(--surface)] p-5">
      <h2 className="text-lg">Fermer une date ou une période</h2>

      <div className="mt-4 flex flex-wrap items-end gap-3">
        <label className="text-sm">
          <span className="block text-[var(--ink-muted)]">Du</span>
          <input
            type="date"
            value={start}
            onChange={(event) => {
              setStart(event.target.value);
              if (!end) {
                setEnd(event.target.value);
              }
            }}
            className="mt-1 rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base"
          />
        </label>
        <label className="text-sm">
          <span className="block text-[var(--ink-muted)]">Au (inclus)</span>
          <input
            type="date"
            value={end}
            onChange={(event) => setEnd(event.target.value)}
            className="mt-1 rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base"
          />
        </label>
        <label className="min-w-48 flex-1 text-sm">
          <span className="block text-[var(--ink-muted)]">Message affiché (facultatif)</span>
          <input
            type="text"
            value={note}
            maxLength={MESSAGE_MAX_CHARS}
            placeholder="Fermeture exceptionnelle"
            onChange={(event) => setNote(event.target.value)}
            className="mt-1 w-full rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base"
          />
        </label>
        <TemplatePicker templates={templates} onPick={setNote} disabled={pending} />
      </div>

      <button
        type="button"
        disabled={pending || !start || !end}
        onClick={() =>
          run(
            () => saveExceptionRange({ start, end, noteFr: note.trim() || null }),
            'Période enregistrée.',
          )
        }
        className="mt-4 rounded-[var(--radius-md)] border border-[var(--line-strong)] px-4 py-2.5 transition-colors hover:bg-[var(--surface-muted)] disabled:opacity-40"
      >
        Fermer ces dates
      </button>

      <p className="mt-2 text-sm text-[var(--ink-muted)]">
        Pour une fermeture longue (congés annuels), utilisez plutôt la page Vacances.
      </p>
    </section>
  );
}

function summarise(slots: Slot[]): string {
  return slots.map((slot) => `${slot.open} – ${slot.close}`).join(' · ');
}

/**
 * "Opens later at" and "closes earlier at", for one day.
 *
 * The fields start from the day's own hours. An arbitrary 14:00 is wrong on
 * most days and leaves the preview showing hours nobody asked for until both
 * have been corrected.
 */
function AdjustHours({
  day,
  pending,
  apply,
}: {
  day: SelectableDay;
  pending: boolean;
  apply: (slots: Slot[], success: string) => void;
}) {
  const bounds = usualBounds(day.usualSlots);
  const [openFrom, setOpenFrom] = useState(bounds.open);
  const [closeAt, setCloseAt] = useState(bounds.close);

  const lateResult = lateOpening(day.usualSlots, openFrom);
  const earlyResult = earlyClosing(day.usualSlots, closeAt);

  return (
    <>
      <div className="flex flex-wrap items-center gap-2">
        <button
          type="button"
          disabled={pending || lateResult.length === 0}
          onClick={() =>
            apply(lateResult, `Ouverture repoussée à ${openFrom}.`)
          }
          className="rounded-[var(--radius-md)] border border-[var(--line-strong)] px-4 py-2.5 transition-colors hover:bg-[var(--surface-muted)] disabled:opacity-40"
        >
          Ouvre plus tard, à
        </button>
        <input
          type="time"
          aria-label="Nouvelle heure d’ouverture"
          value={openFrom}
          onChange={(event) => setOpenFrom(event.target.value)}
          className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base tabular-nums"
        />
        <span className="text-sm text-[var(--ink-muted)]">
          → {lateResult.length === 0 ? 'fermé' : summarise(lateResult)}
        </span>
      </div>

      <div className="flex flex-wrap items-center gap-2">
        <button
          type="button"
          disabled={pending || earlyResult.length === 0}
          onClick={() =>
            apply(earlyResult, `Fermeture avancée à ${closeAt}.`)
          }
          className="rounded-[var(--radius-md)] border border-[var(--line-strong)] px-4 py-2.5 transition-colors hover:bg-[var(--surface-muted)] disabled:opacity-40"
        >
          Ferme plus tôt, à
        </button>
        <input
          type="time"
          aria-label="Nouvelle heure de fermeture"
          value={closeAt}
          onChange={(event) => setCloseAt(event.target.value)}
          className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-2 py-2 text-base tabular-nums"
        />
        <span className="text-sm text-[var(--ink-muted)]">
          → {earlyResult.length === 0 ? 'fermé' : summarise(earlyResult)}
        </span>
      </div>
    </>
  );
}