function solve() {
    let divElementCollection = document.querySelectorAll('.admin-view .action form div');
    let addButtonElement = divElementCollection[3].children[0];
    addButtonElement.addEventListener('click', addButtonHandler);
    let datesObj = {};

    function addButtonHandler(e) {
        e.preventDefault();
        let divElementCollection = document.querySelectorAll('.admin-view .action form div');
        let lectureNameElement = divElementCollection[0].children[1];
        let dateElement = divElementCollection[1].children[1];
        let moduleElement = divElementCollection[2].children[1];

        if (validateInputs(lectureNameElement.value, dateElement.value, moduleElement.value) === false) {
            return;
        }

        let modulesListElement = document.querySelector('.user-view .modules');

        if (checkIfModuleExists(Array.from(modulesListElement.children), moduleElement.value) === false) {
            let currentModule = createModule(moduleElement.value);
            modulesListElement.appendChild(currentModule);
        }

        let targetedModule = getModule(Array.from(modulesListElement.children), moduleElement.value);

        let newLecture = createLecture(lectureNameElement.value, dateElement.value, datesObj);
        let lectureDate = getDate(dateElement.value);

        datesObj[lectureDate] = newLecture;

        datesObj = sortDates(datesObj);



        setLectures(datesObj, targetedModule, modulesListElement);
    }


    function validateInputs(lecture, date, module) {
        if (!(lecture.trim() == '' || date.trim() == '' || module == 'Select module')) {
            return true;
        }
        return false;
    }

    function createModule(module) {
        let divElement = document.createElement('div');
        divElement.setAttribute('class', 'module');

        let moduleh3Element = document.createElement('h3');
        moduleh3Element.textContent = `${module.toUpperCase()}-MODULE`;

        divElement.appendChild(moduleh3Element);
        let ulElement = document.createElement('ul');
        divElement.appendChild(ulElement);

        return divElement;
    }

    function checkIfModuleExists(modulesArray, moduleName) {
        let isName = false;

        for (let el of modulesArray) {
            let currentModuleName = el.children[0].textContent;
            if (currentModuleName === `${moduleName.toUpperCase()}-MODULE`) {
                isName = true;
                break
            }
        }

        return isName;
    }

    function getModule(modulesArray, moduleName) {
        let moduleElement = undefined;
        for (let el of modulesArray) {
            let currentModuleName = el.children[0].textContent;
            if (currentModuleName === `${moduleName.toUpperCase()}-MODULE`) {
                moduleElement = el;
                break;
            }
        }
        return moduleElement;
    }
    function getDate(dateInfo) {
        let date = dateInfo.split('T');
        let editedDate = date[0].replaceAll('-', '/');
        return editedDate;
    }



    function createLecture(name, dateInfo) {
        let editedDate = getDate(dateInfo);
        let time = dateInfo.split('T')[1];
        let liElement = document.createElement('li');
        liElement.setAttribute('class', 'flex');
        let h4Element = document.createElement('h4');
        h4Element.textContent = `${name.toUpperCase()} - ${editedDate} - ${time}`;
        let deleteButtonElement = document.createElement('button');
        deleteButtonElement.setAttribute('class', 'red');
        deleteButtonElement.textContent = 'Del';
        deleteButtonElement.addEventListener('click', deleteButtonHandler)
        liElement.appendChild(h4Element);
        liElement.appendChild(deleteButtonElement);
        return liElement;
    }

    function deleteButtonHandler(e) {
        let currentModule = e.currentTarget.parentElement.parentElement.parentElement;
        let lecturesList = e.currentTarget.parentElement.parentElement;
        let currentLecture = e.currentTarget.parentElement;

        currentLecture.remove();

        if (lecturesList.children.length === 0) {
            currentModule.remove();
        }


    }

    function sortDates(datesObject) {
        let datesArray = Object.keys(datesObject);
        sortedDatesObject = datesArray
        .sort((a,b) => a.localeCompare(b)).
        reduce((obj, key) => {
            obj[key] = datesObject[key];
            return obj;
        },
        {})

        return sortedDatesObject;
    }

    function setLectures(datesObject, module) {
        let listWithLectures = module.children[1];
        listWithLectures.innerHTML = '';
        for (let key in datesObject) {
            listWithLectures.appendChild(datesObject[key]);
        }
    }
}