document.addEventListener("DOMContentLoaded" , function() {
    const list = [];

    const form = document.querySelector(".shopping-form");
    const itemInput = document.querySelector(".shopping-form-item-input");
    const quantityInput = document.querySelector(".shopping-form-quantity-input");
    const incrementButton = document.querySelector(".shopping-form-increment-button");
    const decrementButton = document.querySelector(".shopping-form-decrement-button");
    const items = document.querySelector(".shopping-items");

    incrementButton.addEventListener("click" , incrementQuantity);
    decrementButton.addEventListener("click" , decrementQuantity);
    form.addEventListener("submit" , addItemToList)

    function incrementQuantity() {
        const currentValue = Number(quantityInput.value);
        const newValue = currentValue + 1;

        quantityInput.value = newValue;
    }

    function decrementQuantity() {
        const currentValue = Number(quantityInput.value);
        const newValue = currentValue - 1;

        if (newValue > 0) {
            quantityInput.value = newValue;
        }
    }

    function addItemToList(event) {
        event.preventDefault();

        const itemName = event.target["item-name"].value;
        const itemQuantity = event.target["item-quantity"].value;

        if (itemName != "") {
            const item = {
                name: itemName,
                quantity: itemQuantity,
            };
    
            list.push(item);
            
            renderListItems();
            resetInputs();
        }
    }

    function renderListItems() {
        let itemsStructure = "";

        list.forEach(function(item) {
            itemsStructure += ` 
            <li class="shopping-item">
                <spam>${item.name}</spam>
                <spam>${item.quantity}</spam>
            </li>
            `
        });

        items.innerHTML = itemsStructure;
    }

    function resetInputs() {
        itemInput.value = "";
        quantityInput.value = 1;
    }
});