let difficulty_selection = $(".difficulty-selection");
let btn_previous_question = $("#btn-previous-question");
let btn_next_question = $("#btn-next-question");
let control_btns = $(".control-btn");
let current_difficulty = 1;

difficulty_selection.on("click", change_difficulty);
btn_next_question.on("click", next_question);
btn_previous_question.on("click", previous_question);

update_question();

function get_new_question(difficulty) {
    control_btns.attr("disabled", true);
    $.ajax(next_question_url, {
        method: "GET",
        cache: false,
        data: {difficulty: difficulty},
        dataType: "json",
        success: (data, textStatus, jqXHR) => {
            control_btns.attr("disabled", false);
            question_received(data);
        },
    })
}

function change_difficulty(event) {
    difficulty_selection.removeClass("active");
    let target = $(event.target);
    target.addClass("active");
    if (target.prop("innerText") === "Easy") {
        current_difficulty = 1;
    } else if (target.prop("innerText") === "Medium") {
        current_difficulty = 2;
    } else {
        current_difficulty = 3;
    }
    update_question();
}

function next_question() {
    let difficulty = questions[current_difficulty-1]
    let question_index = difficulty["current_question"]+1;
    if (difficulty["questions"].length === question_index) {
        get_new_question(current_difficulty);
    } else {
        difficulty["current_question"] += 1;
        update_question();
    }
}

function previous_question() {
    questions[current_difficulty-1]["current_question"] -= 1;
    update_question();
}

function question_received(data) {
    let difficulty = questions[current_difficulty-1];
    if (data) {
          difficulty["questions"].push(data);
          difficulty["current_question"] += 1;
          update_question();
    } else {
          difficulty["last_index"] = difficulty["current_question"];
          update_question();
    }
}