class RsvReservationSelector extends HTMLElement {
  static get observedAttributes() {
    return ['timetable-id', 'name', 'price-per-block'];
  }

  // ---- Attribute accessors ------------------------------------------------

  get timetableId()   { return parseInt(this.getAttribute('timetable-id')); }
  get inputName()     { return this.getAttribute('name') ?? 'reservation'; }
  get pricePerBlock() { return parseFloat(this.getAttribute('price-per-block')) || 0; }

  // ---- Lifecycle ----------------------------------------------------------

  connectedCallback() {
    this._slots = [];
    this.classList.add('rsv-timetable-selector');
    this._build();
  }

  attributeChangedCallback(_attr, oldVal, newVal) {
    if (oldVal === null || oldVal === newVal || !this.isConnected) return;
    this._build();
  }

  // ---- Public API ---------------------------------------------------------

  getValue() {
    return {
      timetable_id:           this.timetableId,
      timetable_reservations: this._slots.map(s => s.start_utc),
    };
  }

  clear() {
    this.querySelectorAll('.rsv-slots-slot-selected').forEach(s => s.classList.remove('rsv-slots-slot-selected'));
    this._slots = [];
    this._commit();
  }

  // ---- Private ------------------------------------------------------------

  _build() {
    this._slots = [];
    this.replaceChildren();

    const tid   = document.createElement('input');
    tid.type    = 'hidden';
    tid.name    = `${this.inputName}.timetable_id`;
    tid.value   = this.timetableId;
    this.appendChild(tid);

    const cal_el  = document.createElement('div');
    cal_el.classList.add('rsv-calendar');

    // Create rsv-timeline with timetable-id set before appending so
    // connectedCallback sees the correct attribute on first render.
    const time_el = document.createElement('rsv-timeline');
    time_el.setAttribute('timetable-id', this.timetableId);

    this.append(cal_el, time_el);

    this._calendar = RsvCalendarPicker.create(cal_el, this.inputName);

    // Date change: clear selection, then push new date to the timeline element.
    cal_el.addEventListener('change', () => {
      this.querySelectorAll('.rsv-slots-slot-selected').forEach(s => s.classList.remove('rsv-slots-slot-selected'));
      this._slots = [];
      this._commit();
      time_el.date = this._calendar.date;
    });

    // Slot toggle: read selected slots from timeline, then commit.
    time_el.addEventListener('input', e => {
      e.stopPropagation();
      this._slots = Array.from(time_el.querySelectorAll('.rsv-slots-slot-selected')).map(s => ({
        start_utc: s.dataset.start_utc,
        end_utc:   s.dataset.end_utc,
      }));
      this._commit();
    });

    this._commit();
  }

  _commit() {
    const name = this.inputName;

    this.querySelectorAll(`input[name="${name}.timetable_reservations[]"]`).forEach(i => i.remove());

    let json = [];
    this._slots.forEach(slot => {
      const inp = document.createElement('input');
      inp.type  = 'hidden';
      inp.name  = `${name}.timetable_reservations[]`;
      inp.value = slot.start_utc;
      this.appendChild(inp);
      json.push(slot.start_utc);
    });

    this.value = JSON.stringify({
      "timetable_id": this.timetableId,
      "timetable_reservations": json
    });

    this.dispatchEvent(new CustomEvent('rsv:slots-changed', {
      bubbles: true,
      detail: {
        name,
        slots:           this._slots,
        price_per_block: this.pricePerBlock,
        value:           this.getValue(),
      },
    }));
  }
}

customElements.define('rsv-reservation-selector', RsvReservationSelector);