/**
 * Group deck card rows for the deck detail view.
 * @param {Array<object>|undefined} cards
 * @param {'type'|'cmc'|'color'|'rarity'|string} groupBy
 */
export function groupDeckCards(cards, groupBy) {
  if (!cards) {
    return {};
  }

  return cards.reduce((groups, card) => {
    let key;

    switch (groupBy) {
      case 'type':
        key = card.card_type ? card.card_type.split(' — ')[0] : 'Unknown';
        break;
      case 'cmc':
        key = `${card.cmc || 0} Mana`;
        break;
      case 'color':
        try {
          const colors = card.colors ? JSON.parse(card.colors) : [];
          key = colors.length === 0 ? 'Colorless' : colors.join('');
        } catch {
          key = 'Colorless';
        }
        break;
      case 'rarity':
        key = card.rarity || 'Unknown';
        break;
      default:
        key = 'All Cards';
    }

    if (!groups[key]) {
      groups[key] = [];
    }
    groups[key].push(card);
    return groups;
  }, {});
}