/*
 * RsvAdminForm — shared submit handler for wp-admin forms.
 *
 * Serializes a <form> to JSON (via RsvFormEncoder), sends it to the form's
 * `action` using the HTTP verb in `data-method`, always attaches the REST
 * nonce, and reports the outcome through show_notice(). The only part that
 * legitimately differs between forms — shaping the request body — is handled
 * by the optional `transform(body, form)` hook.
 *
 * Usage:
 *   RsvAdminForm.bind(my_form, {
 *     transform: (body, form) => ({ ...body, block_size: parseInt(body.block_size) }),
 *     refresh:   () => my_datagrid.refresh(),
 *   });
 */
const RsvAdminForm = {
  // Attach a submit listener that sends the form as JSON.
  bind(form, options = {}) {
    if (!form) return;
    form.addEventListener('submit', (event) => {
      event.preventDefault();
      RsvAdminForm.submit(form, options);
    });
  },

  // Send the form now. Returns the fetch promise.
  submit(form, { transform, refresh, onSuccess } = {}) {
    let body = RsvFormEncoder.encode_form(form);
    if (transform) body = transform(body, form);

    // `form.method` always returns a string (default 'get'), so default to POST
    // explicitly unless the view opted into a verb via data-method.
    const method = (form.dataset.method || 'POST').toUpperCase();

    return fetch(form.action, {
      method,
      credentials: 'same-origin',
      headers: {
        'Content-Type': 'application/json',
        'Accept': 'application/json',
        'X-WP-Nonce': ReservairServiceAPI.nonce,
      },
      body: JSON.stringify(body),
    })
      .then(async (response) => {
        const data = await response.json().catch(() => null);
        if (!response.ok) throw new Error(data?.error || data?.message || 'Request failed');
        return data;
      })
      .then((data) => {
        show_notice(form, 'success', form.dataset.successMsg ?? 'Saved.');
        if (refresh) refresh();
        if (onSuccess) onSuccess(data);
      })
      .catch((error) => show_notice(form, 'error', error.message));
  },
};