export const RsvFormSender = {
  get_form_url(form_id) {
    return ReservairServiceAPI.restUrl + '/form/' + form_id;
  },

  clear_feedback(form) {
    form.querySelectorAll('.rsv-field-error').forEach(el => el.remove());
    form.querySelectorAll('.rsv-invalid').forEach(el => el.classList.remove('rsv-invalid'));
    form.querySelector('.rsv-error-summary')?.remove();
  },

  show_errors(form, errors) {
    this.clear_feedback(form);

    const ul = document.createElement('ul');
    for (const err of errors) {
      const li = document.createElement('li');
      li.textContent = err.message;
      ul.appendChild(li);

      if (err.element) {
        const field = form.querySelector(`[name="${err.element}"]`);
        if (field) {
          field.classList.add('rsv-invalid');
          const msg = document.createElement('span');
          msg.classList.add('rsv-field-error');
          msg.textContent = err.message;
          field.insertAdjacentElement('afterend', msg);
        }
      }
    }

    const summary = document.createElement('div');
    summary.classList.add('rsv-error-summary');
    summary.appendChild(ul);
    form.prepend(summary);
  },

  show_success(form, _data) {
    const s       = ReservairStrings.form;
    const wrapper = form.parentElement;
    const existing = Array.from(wrapper.children);

    const svgNS = 'http://www.w3.org/2000/svg';
    const path  = document.createElementNS(svgNS, 'path');
    path.setAttribute('d', 'M6 14l6 6L22 8');
    path.setAttribute('stroke', '#16a34a');
    path.setAttribute('stroke-width', '2.5');
    path.setAttribute('stroke-linecap', 'round');
    path.setAttribute('stroke-linejoin', 'round');
    const svg = document.createElementNS(svgNS, 'svg');
    svg.setAttribute('width', '28');
    svg.setAttribute('height', '28');
    svg.setAttribute('viewBox', '0 0 28 28');
    svg.setAttribute('fill', 'none');
    svg.appendChild(path);

    const icon = document.createElement('div');
    icon.className = 'rsv-success-icon';
    icon.appendChild(svg);

    const body = this.build_success_body(form, s);

    const state = document.createElement('div');
    state.className = 'rsv-success-state';
    state.append(icon, body);

    const msg = document.createElement('div');
    msg.appendChild(state);

    existing.forEach(child => child.style.display = 'none');
    wrapper.appendChild(msg);

    // The form catches every data-rsv-reset button in the card and links it to
    // its cleanup — so new buttons just need the marker, no wiring here.
    const reset = () => {
      msg.remove();
      form.reset();
      // Native reset leaves custom controls untouched; reset the reservation
      // selectors so their slots, hidden inputs and the summary clear, the date
      // stays selected and availability reloads with the just-booked slots.
      form.querySelectorAll('rsv-reservation-selector').forEach(sel => sel.reset());
      this.clear_feedback(form);
      existing.forEach(child => child.style.display = '');
    };
    state.querySelectorAll('[data-rsv-reset]').forEach(btn => btn.addEventListener('click', reset));
  },

  // Body of the success card. Uses the admin-configured template when the form
  // ships one, filling the .rsv-success-summary placeholder (expanded server-side
  // from <reservation-summary>) with a snapshot of the selected slots; otherwise
  // falls back to the default text.
  build_success_body(form, strings) {
    const tpl = form.parentElement?.querySelector('template.rsv-form-success');

    if (!tpl) {
      const subtitle = document.createElement('p');
      subtitle.className   = 'rsv-success-msg';
      subtitle.textContent = strings.success_subtitle;
      return subtitle;
    }

    const body = document.createElement('div');
    body.className = 'rsv-success-msg';
    body.appendChild(tpl.content.cloneNode(true));

    const placeholder = body.querySelector('.rsv-success-summary');
    if (placeholder) {
      const summary = form.querySelector('rsv-reservation-summary');
      if (summary && typeof summary.snapshot === 'function') {
        placeholder.replaceWith(summary.snapshot());
      } else {
        placeholder.remove();
      }
    }

    return body;
  },

  set_loading(form, is_loading) {
    const btn = form.querySelector('button[type="submit"], button:not([type])');
    if (!btn) return;
    btn.disabled = is_loading;
    btn.classList.toggle('rsv-loading', is_loading);
  },

  encode_to_json(form) {
    const fields = form.querySelectorAll('.rsv-form-field');
    const body = {};
    fields.forEach(field => {
      const name = field.name ?? field.getAttribute('name');
      try {
        body[name] = JSON.parse(field.value);
      } catch {
        body[name] = field.value;
      }
    });
    return body;
  },

  send_form(event) {
    event.preventDefault();
    const form = event.target;
    this.clear_feedback(form);
    this.set_loading(form, true);
    const body = this.encode_to_json(form);

    fetch(this.get_form_url(form.id), {
      method:  'POST',
      headers: { 'Content-Type': 'application/json' },
      body:    JSON.stringify(body),
    })
    .then(async response => {
      const data = await response.json().catch(() => null);
      if (!response.ok) throw { status: response.status, body: data };
      return data;
    })
    .then(data => {
      this.show_success(form, data);
    })
    .catch(error => {
      const errors = error?.body?.errors
        ?? [{ element: '', message: ReservairStrings.form.error_generic }];
      this.show_errors(form, errors);
    })
    .finally(() => {
      this.set_loading(form, false);
    });
  },
};