import { updateCart,
	 updateCartIcon,
	 updateTable,
	 updateProductURL,
	 displayProductSelectable } from './cart.js';


async function processForm(form) {
  // handle form by preventing default behaviour
  // and instead manipulate data appropriately:
  // - send form to backend via POST
  // - receive response and update DOM w/o hard-refresh

  form.addEventListener('submit', async(e) => {
    e.preventDefault();

    // -- update form data
    const data = await updateCart(form);

    // -- update cart icon
    updateCartIcon(data);

    // -- display product availability
    const btnSubmit = document.querySelector('.btn-submit');
    const isProductSelectable = data.is_product_selectable;
    const isProductAvailable = data.is_product_available;
    displayProductSelectable(btnSubmit, isProductSelectable, isProductAvailable);

    // -- update URL
    updateProductURL(data.product_selected);

  });
};

async function checkProductAvailability(product_path, searchParams){
  const res = await fetch(`/${product_path}?js=true&${searchParams.toString()}`);

  if (res.ok) {
    return res.json();
  } else {
    return {status: res.status, error: res.statusText};
  }
};

async function changeProductURLOnInputRadio(form) {
  // add on-change listener to all .input-listen input fields
  // and update URL accordingly

  const inputs = Array.from(form.querySelectorAll('.input-listen'));
  await Promise.all(inputs.map(async(input) => {
    input.addEventListener('change', async(e) => {

      let key = e.target.name;
      let value = e.target.value;

      if ('URLSearchParams' in window) {

	// send request to `/products/<product-id>?<params>`
	// to get back an instant result for this and update UI
	const product_path = form.querySelector('#product_path').value;
	const searchParams = new URLSearchParams(window.location.search);
	searchParams.set(key, value);

	// update URL only if a key combination of size and style are selected,
	// else do nothing — otherwise the item would be seen as sold out.
	let size = searchParams.get('size');
	let style = searchParams.get('style');

	if (size || style) {
	  const data = await checkProductAvailability(product_path, searchParams);

	  // -- update product availability
	  const btnSubmit = document.querySelector('.btn-submit');
	  const isProductSelectable = data.is_product_selectable;
	  const isProductAvailable = data.is_product_available;
	  displayProductSelectable(btnSubmit, isProductSelectable, isProductAvailable);
	}	

	history.pushState(null, '', `?${searchParams.toString()}`);

      };
      
    });    
  }));
}

window.addEventListener('load', () => {
  ;(async() => {

    const forms = Array.from(document.querySelectorAll('.product-item'));
    await Promise.all(forms.map(async(form) => {
      processForm(form);
      changeProductURLOnInputRadio(form);
    }));

  })();
});