'use client';

import { useMemo, useState, useTransition } from 'react';

import { MAX_SLOTS_PER_DAY } from '@/lib/schedule/validate';
import {
  changedDays,
  DAY_NAMES_FR,
  DAY_SHORT_FR,
  duplicateToOpenDays,
  validateWeek,
  type WeekDraft,
} from '@/lib/schedule/week';

import { saveWeek } from './actions';

type Props = {
  initial: WeekDraft;
  canEdit: boolean;
};

/**
 * The reference week, as one row per day.
 *
 * Density is the point: all seven days have to be readable at a glance on a
 * phone held behind the counter, so the whole week fits on one screen and a
 * change can be checked without scrolling back up.
 */
export default function WeekEditor({ initial, canEdit }: Props) {
  const [week, setWeek] = useState<WeekDraft>(initial);
  const [saved, setSaved] = useState<WeekDraft>(initial);
  const [pending, startTransition] = useTransition();
  const [message, setMessage] = useState<{ kind: 'ok' | 'error'; text: string } | null>(null);
  const [serverErrors, setServerErrors] = useState<Record<number, string[]>>({});

  const errors = useMemo(() => validateWeek(week), [week]);
  const pendingChanges = useMemo(() => changedDays(saved, week), [saved, week]);
  const blocked = Object.keys(errors).length > 0;

  function touch() {
    setMessage(null);
    setServerErrors({});
  }

  function update(dayOfWeek: number, patch: Partial<WeekDraft[number]>) {
    touch();
    setWeek((current) =>
      current.map((day) => (day.dayOfWeek === dayOfWeek ? { ...day, ...patch } : day)),
    );
  }

  function updateSlot(dayOfWeek: number, index: number, field: 'open' | 'close', value: string) {
    touch();
    setWeek((current) =>
      current.map((day) =>
        day.dayOfWeek === dayOfWeek
          ? {
              ...day,
              slots: day.slots.map((slot, position) =>
                position === index ? { ...slot, [field]: value } : slot,
              ),
            }
          : day,
      ),
    );
  }

  function submit() {
    touch();
    startTransition(async () => {
      const result = await saveWeek(week);
      if (result.ok) {
        setSaved(week);
        const count = result.changed.length;
        setMessage({
          kind: 'ok',
          text:
            count === 0
              ? 'Aucun changement à enregistrer.'
              : `Enregistré — ${count} jour${count > 1 ? 's' : ''} modifié${count > 1 ? 's' : ''}.`,
        });
      } else {
        setServerErrors(result.dayErrors ?? {});
        setMessage({ kind: 'error', text: result.error });
      }
    });
  }

  return (
    <div className="mt-6">
      {!canEdit ? (
        <p className="mb-4 rounded-[var(--radius-md)] border border-[var(--line-strong)] bg-[var(--surface-muted)] px-3 py-2 text-sm text-[var(--ink-muted)]">
          Compte en lecture seule&nbsp;: consultation uniquement.
        </p>
      ) : null}

      <div className="overflow-hidden rounded-[var(--radius-md)] border border-[var(--line)] bg-[var(--surface)]">
        {week.map((day, position) => {
          const dayErrors = [
            ...(errors[day.dayOfWeek] ?? []),
            ...(serverErrors[day.dayOfWeek] ?? []),
          ];
          const isChanged = pendingChanges.includes(day.dayOfWeek);
          const fullName = DAY_NAMES_FR[day.dayOfWeek] ?? '';

          return (
            <div
              key={day.dayOfWeek}
              className={`${position > 0 ? 'border-t border-[var(--line)]' : ''} ${
                dayErrors.length > 0 ? 'bg-[var(--danger-tint)]' : ''
              }`}
            >
              <div className="flex flex-wrap items-center gap-x-3 gap-y-2 px-3 py-2">
                <span
                  className={`w-9 shrink-0 text-sm font-medium tabular-nums ${
                    day.isClosed ? 'text-[var(--ink-muted)]' : ''
                  }`}
                >
                  <span aria-hidden>{DAY_SHORT_FR[day.dayOfWeek]}</span>
                  <span className="sr-only">{fullName}</span>
                </span>

                <input
                  type="checkbox"
                  role="switch"
                  aria-label={`Ouvert le ${fullName.toLowerCase()}`}
                  className="size-4 shrink-0 accent-[var(--accent)]"
                  checked={!day.isClosed}
                  disabled={!canEdit}
                  onChange={(event) =>
                    update(day.dayOfWeek, {
                      isClosed: !event.target.checked,
                      slots:
                        event.target.checked && day.slots.length === 0
                          ? [{ open: '10:00', close: '18:30' }]
                          : day.slots,
                    })
                  }
                />

                {day.isClosed ? (
                  <span className="text-sm text-[var(--ink-muted)]">Fermé</span>
                ) : (
                  <div className="flex flex-wrap items-center gap-x-2 gap-y-1">
                    {day.slots.map((slot, index) => (
                      <span key={index} className="flex items-center gap-1">
                        <input
                          type="time"
                          aria-label={`${fullName} — ouverture ${index + 1}`}
                          value={slot.open}
                          disabled={!canEdit}
                          onChange={(event) =>
                            updateSlot(day.dayOfWeek, index, 'open', event.target.value)
                          }
                          className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-1.5 py-1 text-sm tabular-nums"
                        />
                        <span aria-hidden className="text-[var(--ink-muted)]">
                          –
                        </span>
                        <input
                          type="time"
                          aria-label={`${fullName} — fermeture ${index + 1}`}
                          value={slot.close}
                          disabled={!canEdit}
                          onChange={(event) =>
                            updateSlot(day.dayOfWeek, index, 'close', event.target.value)
                          }
                          className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] bg-[var(--surface)] px-1.5 py-1 text-sm tabular-nums"
                        />
                        {canEdit && day.slots.length > 1 ? (
                          <button
                            type="button"
                            title={`Retirer cette plage du ${fullName.toLowerCase()}`}
                            aria-label={`Retirer la plage ${index + 1} du ${fullName.toLowerCase()}`}
                            onClick={() =>
                              update(day.dayOfWeek, {
                                slots: day.slots.filter((_, at) => at !== index),
                              })
                            }
                            className="rounded-[var(--radius-sm)] px-1 text-[var(--ink-muted)] hover:text-[var(--danger)]"
                          >
                            ×
                          </button>
                        ) : null}
                      </span>
                    ))}
                  </div>
                )}

                {canEdit && !day.isClosed ? (
                  <span className="ml-auto flex shrink-0 items-center gap-1">
                    {day.slots.length < MAX_SLOTS_PER_DAY ? (
                      <button
                        type="button"
                        title="Ajouter une plage (pause de midi)"
                        aria-label={`Ajouter une plage le ${fullName.toLowerCase()}`}
                        onClick={() =>
                          update(day.dayOfWeek, {
                            slots: [...day.slots, { open: '14:00', close: '18:30' }],
                          })
                        }
                        className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] px-2 py-0.5 text-sm text-[var(--ink-muted)] hover:bg-[var(--surface-muted)] hover:text-[var(--ink)]"
                      >
                        +&nbsp;plage
                      </button>
                    ) : null}
                    <button
                      type="button"
                      title="Appliquer ces horaires aux autres jours ouverts"
                      aria-label={`Appliquer les horaires du ${fullName.toLowerCase()} aux autres jours ouverts`}
                      onClick={() => {
                        touch();
                        setWeek(duplicateToOpenDays(week, day.dayOfWeek));
                      }}
                      className="rounded-[var(--radius-sm)] border border-[var(--line-strong)] px-2 py-0.5 text-sm text-[var(--ink-muted)] hover:bg-[var(--surface-muted)] hover:text-[var(--ink)]"
                    >
                      copier
                    </button>
                  </span>
                ) : null}

                {isChanged ? (
                  <span
                    aria-label="modifié"
                    title="Modifié, pas encore enregistré"
                    className="size-1.5 shrink-0 rounded-full bg-[var(--accent)]"
                  />
                ) : null}
              </div>

              {dayErrors.length > 0 ? (
                <ul role="alert" className="px-3 pb-2 text-sm text-[var(--danger)]">
                  {dayErrors.map((error) => (
                    <li key={error}>{error}</li>
                  ))}
                </ul>
              ) : null}
            </div>
          );
        })}
      </div>

      {canEdit ? (
        <div className="sticky bottom-0 mt-4 flex flex-wrap items-center gap-x-3 gap-y-2 border-t border-[var(--line)] bg-[var(--canvas)] py-3">
          <button
            type="button"
            onClick={submit}
            disabled={pending || blocked || pendingChanges.length === 0}
            className="rounded-[var(--radius-md)] bg-[var(--accent)] px-4 py-2 font-medium text-[var(--on-accent)] transition-colors hover:bg-[var(--accent-hover)] disabled:cursor-not-allowed disabled:opacity-40"
          >
            {pending ? 'Enregistrement…' : 'Enregistrer'}
          </button>

          {pendingChanges.length > 0 ? (
            <button
              type="button"
              onClick={() => {
                setWeek(saved);
                touch();
              }}
              className="text-sm text-[var(--ink-muted)] underline-offset-2 hover:underline"
            >
              Annuler
            </button>
          ) : null}

          <p className="text-sm text-[var(--ink-muted)]" aria-live="polite">
            {blocked
              ? 'Corrigez les erreurs signalées.'
              : pendingChanges.length === 0
                ? 'Aucune modification.'
                : `Sera modifié : ${pendingChanges.map((d) => DAY_SHORT_FR[d]).join(', ')}.`}
          </p>
        </div>
      ) : null}

      {message ? (
        <p
          role="status"
          className={`mt-3 rounded-[var(--radius-md)] px-3 py-2 text-sm ${
            message.kind === 'ok'
              ? 'bg-[var(--success-tint)] text-[var(--success)]'
              : 'bg-[var(--danger-tint)] text-[var(--danger)]'
          }`}
        >
          {message.text}
        </p>
      ) : null}
    </div>
  );
}