function solve() {
    function addToClient(e) {
        let innerDiv = e.target.parentElement;
        let li = innerDiv.parentElement;
        let strong = li.getElementsByTagName("strong")[0];
        let quantity = strong.innerHTML.split(" ")[1];
        quantity--;
        strong.innerHTML = `Available: ${quantity}`;
        if (quantity <= 0) {
            li.remove();
        }
        let newLi = document.createElement("li");
        let oldSpan = Array.from(li.getElementsByTagName("span"))[0];
        newLi.innerHTML = oldSpan.innerHTML;
        let newStrong = document.createElement("strong");
        newStrong.innerHTML = Array.from(li.getElementsByTagName("strong"))[1].innerHTML;
        newLi.appendChild(newStrong);
        let toAppend = document.querySelector("#myProducts > ul");
        toAppend.appendChild(newLi);
        let totalPrice = document.querySelector("body > h1:nth-child(4)");
        let currentSum = Number(totalPrice.innerHTML.split(" ")[2]);
        let price = Number(Array.from(innerDiv.getElementsByTagName("strong"))[0].innerHTML);
        let newPrice = currentSum + price;
        let newTextPrice = `Total Price: ${newPrice.toFixed(2)}`
        totalPrice.innerHTML = newTextPrice;
    }

    function createHTML(name, quantity, price) {
        let li = document.createElement("li");
        let span = document.createElement("span");
        span.innerHTML = name;
        let strong = document.createElement("strong");
        strong.innerHTML = `Available: ${quantity}`;
        let div = document.createElement("div");
        let divStrong = document.createElement("strong");
        divStrong.innerHTML = Number(price).toFixed(2);
        let button = document.createElement("button");
        button.innerHTML = "Add to Client's List";
        button.addEventListener("click", addToClient);
        div.appendChild(divStrong);
        div.appendChild(button);
        li.appendChild(span);
        li.appendChild(strong);
        li.appendChild(div);
        let toAppend = document.querySelector("#products > ul");
        toAppend.appendChild(li);
    }

    function filterHandler(value) {
        let list = document.querySelector("#products > ul");
        Array.from(list.getElementsByTagName("li")).forEach(el => {
            let liValue = el.getElementsByTagName("span")[0].innerHTML;
            if (!liValue.toLowerCase().startsWith(value.toLowerCase())) {
                if (el.style.display === "") {
                    el.style.display = "block";
                }
                if (el.style.display !== "none") {
                    el.style.display = "none";
                }
            } else if (liValue.toLowerCase().startsWith(value.toLowerCase())) {
                if (el.style.display === "") {
                    el.style.display = "block";
                }
                if (el.style.display === "none") {
                    el.style.display = "block";
                }
            }
        });
    }

    function buyHandler() {
        let ul = document.querySelector("#myProducts > ul");
        Array.from(ul.getElementsByTagName("li")).forEach(el=>el.remove());
        let totalPrice = document.querySelector("body > h1:nth-child(4)");
        let newTextPrice = `Total Price: 0.00`
        totalPrice.innerHTML = newTextPrice;
    }

    function handler(e) {
        if (e.target.innerHTML === "Add") {
            e.preventDefault();
            let [name, quantity, price] = Array.from(document.getElementById("add-new").getElementsByTagName("input"));
            if (name.value !== "" && quantity.value !== "" && price.value !== "") {
                createHTML(name.value, quantity.value, price.value);
            }
        } else if (e.target.innerHTML === "Filter") {
            let filter = document.getElementById("filter");
            filterHandler(filter.value);
        } else if (e.target.innerHTML === "Buy") {
            buyHandler();
        }
    }

    Array.from(document.getElementsByTagName("button")).forEach(btn => btn.addEventListener("click", handler));
}