/* 
 * Online study plan agreement generator
 *
 * version: 0.5
 * authors:     Daniel Tenbrinck <daniel.tenbrinck@fau.de> 
 *              Shreya Rajesh More
 *          
 * date: 21.10.2023
 */


// enable debugging messages
var debug = true

// define a global array to keep track of the number of rows - we initialize with two rows as headings and one data row
var number_of_rows = [3, 3, 3, 3, 3, 3, 3];

// define the relevant tables and their identifiers
var module_groups_data = [];
module_groups_data.push(['core', myData_core]);
module_groups_data.push(['major', myData_major]);
module_groups_data.push(['minor', myData_minor]);
module_groups_data.push(['app', myData_app]);
module_groups_data.push(['techqual', myData_techqual]);
module_groups_data.push(['seminar', null]);
module_groups_data.push(['thesis', null]);

////////////////////////////////////
// Called when document is loaded //
////////////////////////////////////
$(document).ready(function() {

    // create an event listener that changes the semesters based on a change in the chosen first semester
    document.getElementById("sem_first").addEventListener("change", function() {

        // console output for debugging
        if (debug) {
            console.log("Selection for first semester changed. Resetting all tables.")
        }

        // reset tables in form
        reconfigureTables();
    });

    // iterate over all defined tables, populate the first row and add functionality to buttons
    for (let i = 0; i < module_groups_data.length; i++) {

        // console output for debugging
        if (debug) {
            console.log("--- Populating fields for table " + module_groups_data[i][0] + " and configuring buttons.")
        }

        ////////// POPULATE EXISTING ROWS

        // populate dropdown element for semester choice (winter/summer semester)
        populateDropDown(document.getElementById("sem_" + module_groups_data[i][0]), getUniqueValues(myData_Sem, 0));

        // populate dropdown element for ects choice
        if (module_groups_data[i][0] != 'thesis' && module_groups_data[i][0] != 'seminar') {
            populateDropDown(document.getElementById("selectStyle_ects_" + module_groups_data[i][0]), ['Make a selection', '2.5', '5', '7.5', '10', '12.5', '15']);
        }

        // populate dropdown element for module group choice
        if (module_groups_data[i][0] == 'major' || module_groups_data[i][0] == 'minor') {
            populateDropDown(document.getElementById("selectStyle_mod_" + module_groups_data[i][0]), getUniqueValues(myData_major, 1));
        } else if (module_groups_data[i][0] == 'app') {
            populateDropDown(document.getElementById("selectStyle_mod_" + module_groups_data[i][0]), getUniqueValues(myData_app, 1));
        }

        //////// CONFIGURE BUTTONS

        // define functionality for ADD button in the current table
        $('#add_' + module_groups_data[i][0]).click(function() {

            // add a new row to the table and increase row counter
            addTableRow(i, module_groups_data[i], ++number_of_rows[i]);

            // User output for debugging
            if (debug) {
                console.log("This table now has " + number_of_rows[i] + " rows.");
            }

        });

        ///////// CONFIGURE EVENT LISTENERS

        // configure event listeners for selection elements
        configureEventListeners(i, module_groups_data[i], 3, 3);
    }
});

/////// Returns a specified row element <tr> for a given table id
function getTableRow(table_id, row_number) {

    // get the last row of table
    return $(table_id).find("tbody").find("tr")[row_number - 1];
}

/////// Returns last row element <tr> for a given table id
function getLastTableRow(table_id) {

    // get the table body
    $tableBody = $(table_id).find("tbody");

    // get the last row of table
    return $tableBody.find("tr:last");
}

/////// Returns first row element <tr> for a given table id
function getFirstTableRow(table_id) {

    // get the table body
    $tableBody = $(table_id).find("tbody");

    // get the last row of table
    return $tableBody.find("tr:first");
}

////// Configures events listeners for changes in certain selection fields in a table row
function configureEventListeners(table_number, module_data, row_number, row_id) {

    // generate the table id
    let table_id = '#table_data_' + module_data[0];

    // get present row of table
    let $tableRow = getTableRow(table_id, row_number);

    // console output for debugging
    if (debug) {
        console.log("Configuring event listener for selection field " + $tableRow.children[0].children[0].id + " for changing the semester.")
    }

    // create an event listener that changes the available modules and available semester numbers based on a change in the chosen semester
    $tableRow.children[0].children[0].addEventListener("change", function() {
        //table_id = '#table_data_' + module_data[0]; // needed due to some weird local/global variable scope problem
        configureDropdownsPerRow(table_number, table_id, module_data[1], row_id, true);
    });


    if (table_id == '#table_data_major' || table_id == "#table_data_minor" || table_id == "#table_data_app") {

        // create an event listener that changes the available modules based on a change in the chosen module group (if dropdown exists)
        $tableRow.children[2].children[0].addEventListener("change", function() {
            configureDropdownsPerRow(table_number, table_id, module_data[1], row_id, false);
        });

        // create an event listener that changes the ECTS field on a change in the chosen module field
        $tableRow.children[3].children[0].addEventListener("change", function() {

            let semester_choice = $tableRow.children[0].children[0].value;

            // get module group choice
            let module_group_choice = $tableRow.children[2].children[0].value;

            // get module selection element (4th field)
            let module_choice = $tableRow.children[3].children[0].value;

            // set filter array accordingly
            let filterAsArray = [semester_choice, module_group_choice, module_choice];

            const filteredArray = filterArray(module_data[1], filterAsArray);
            const uniqueList = getUniqueValues(filteredArray, filterAsArray.length);

            $tableRow.children[4].children[0].value = uniqueList[0];

        });
    } else if (table_id == '#table_data_core' || table_id == "#table_data_techqual") {
        // create an event listener that changes the ECTS field on a change in the chosen module field
        $tableRow.children[2].children[0].addEventListener("change", function() {

            // get semester selection
            let semester_choice = $tableRow.children[0].children[0].value;

            // get module selection (3th field)
            let module_choice = $tableRow.children[2].children[0].value;

            // set filter array accordingly
            let filterAsArray = [semester_choice, module_choice];

            const filteredArray = filterArray(module_data[1], filterAsArray);
            const uniqueList = getUniqueValues(filteredArray, filterAsArray.length);

            $tableRow.children[3].children[0].value = uniqueList[0];

        });
    }

    // create an event listener that changes the module selection field to a text field if 'Other' is selected
    if (table_id != '#table_data_seminar' && table_id != "#table_data_thesis") {

        var $selectField;

        if (table_id == '#table_data_core' || table_id == "#table_data_techqual") {
            $selectField = $tableRow.children[2];
        } else {
            $selectField = $tableRow.children[3];
        }

        $selectField.addEventListener("change", function() {

            if (table_id == '#table_data_core' || table_id == "#table_data_techqual") {
                $selectField = $tableRow.children[2];
            } else {
                $selectField = $tableRow.children[3];
            }

            if ($selectField.children[0].value == "Other") {
                //$selectField.children[0].replaceWith('<input type="text" name="' + table_id + '_text" id="' + table_id + '_text">');
                $($selectField.children[0]).replaceWith(decodeURI('<input type="text" placeholder="Put module name here">'));
            }

        });

        // define functionality for REMOVE button in the current table
        elemEventHandler = function() {

            if (number_of_rows[table_number] > 3) {

                // User output for debugging
                if (debug) {
                    console.log("Removing row " + (row_id + 2) + " of table " + module_data[0] + ".");
                }

                //$('#remove_' + module_data[0] + '_' + row_id).parent().parent().remove();
                $(this).parent().parent().remove();

                // reduce the row number of all subsequent <tr> elements and remove buttons
                for (laterRow = row_id + 1; laterRow <= number_of_rows[table_number]; laterRow++) {

                    // get table row
                    let curTableRow = getTableRowByID(table_number, table_id, laterRow);

                    // adapt row number in id of this row
                    let newRow = laterRow - 1;
                    let newId = table_id + "_row_" + newRow;
                    curTableRow.id = newId.slice(1);

                    // adapt row number in remove button of this row
                    curTableRow.lastElementChild.children[0].id = curTableRow.lastElementChild.children[0].id.slice(0, -1) + newRow;

                }

                --number_of_rows[table_number];
            }

        }

        // add remove functionality to button
        $('#remove_' + module_data[0] + '_' + row_id).on('click', elemEventHandler);
    }

}

function getTableRowByID(table_number, table_id, row_id) {
    //$(table_id).find("tbody").children[row_number].remove();
    pattern = new RegExp("_" + row_id + "$")
    for (row = 0; row < number_of_rows[table_number]; row++) {
        $tableRow = $(table_id).find("tbody")[0].rows[row];
        if ($tableRow.id.search(pattern) != -1) {
            return $tableRow
        }
    }
}

/////// Adds a new row to the table by cloning the last row
function addTableRow(table_number, group_data, row_number) {

    // generate the table id
    table_id = 'table_data_' + group_data[0];

    // get the table body via its id
    $tableBody = $(table_id).find("tbody");

    // get the last table row
    $trLast = getLastTableRow('#' + table_id) //getFirstTableRow(table_id);

    // get last row number via regular expression
    lastRowID = Number($trLast[0].id.match(/\d+$/)[0]) + 1;

    // generate a table row based on the type of module group // TODO: ugly implemented!
    if (group_data[0] == 'core' || group_data[0] == 'techqual') {

        $tableBody.append(
            '<tr id="table_data_' + group_data[0] + '_row_' + lastRowID + '">' +
            '<td><select id="sem_' + group_data[0] + '"><option>Make a selection</option><option>Winter Semester</option><option>Summer Semester</option></select></td>' +
            '<td><select id="selectStyle_sem_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_ects_' + group_data[0] + '"><option value="0">Make a selection</option><option value="2.5">2.5</option><option value="5">5</option><option value="7.5">7.5</option><option value="10">10</option><option value="12.5">12.5</option><option value="15">15</option></select></td>' +
            '<td><input type="button" name="rmv" id="remove_' + group_data[0] + '_' + lastRowID + '" value="Remove row"></td>' +
            '</tr>'
        );


    } else if (group_data[0] == 'major' || group_data[0] == 'minor') {

        $tableBody.append(
            '<tr id="table_data_' + group_data[0] + '_row_' + lastRowID + '">' +
            '<td> <select id="sem_' + group_data[0] + '"><option>Make a selection</option><option>Winter Semester</option><option>Summer Semester</option></select></td>' +
            '<td><select id="selectStyle_sem_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_mod_' + group_data[0] + '"><option>Make a selection</option><option>Machine Learning / Artificial Intelligence</option><option>Simulation and Numerics</option><option>Mathematical Statistical Data Analysis</option><option>Mathematische Theorie / Grundlagen der Data Science</option><option>Databased Optimization</option><option>Databases and Knowledge Representation</option></select></td>' +
            '<td> <select id="selectStyle_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_ects_' + group_data[0] + '"><option value="0">Make a selection</option><option value="2.5">2.5</option><option value="5">5</option><option value="7.5">7.5</option><option value="10">10</option><option value="12.5">12.5</option><option value="15">15</option></select></td>' +
            '<td><input type="button" name="rmv" id="remove_' + group_data[0] + '_' + lastRowID + '" value="Remove row"></td>' +
            '</tr>'
        );

    } else {

        $tableBody.append(
            '<tr id="table_data_' + group_data[0] + '_row_' + lastRowID + '">' +
            '<td> <select id="sem_' + group_data[0] + '"><option>Make a selection</option><option>Winter Semester</option><option>Summer Semester</option></select></td>' +
            '<td><select id="selectStyle_sem_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_mod_' + group_data[0] + '"><option>Make a selection</option><option>Chemistry</option><option>Digital Humanities</option><option>Geographie</option><option>Geoscience</option><option>International Information Systems</option><option>Medical Data Science</option><option>Physics</option><option>Material Science</option><option>Artificial Intelligence in Biomedical Engineering</option><option>Multimedia Engineering</option></select></td>' +
            '<td> <select id="selectStyle_' + group_data[0] + '"></select></td>' +
            '<td><select id="selectStyle_ects_' + group_data[0] + '"><option value="0">Make a selection</option><option value="2.5">2.5</option><option value="5">5</option><option value="7.5">7.5</option><option value="10">10</option><option value="12.5">12.5</option><option value="15">15</option></select></td>' +
            '<td><input type="button" name="rmv" id="remove_' + group_data[0] + '_' + lastRowID + '" value="Remove row"></td>' +
            '</tr>'
        );

    }

    // configure event listeners for the new table row
    configureEventListeners(table_number, group_data, row_number, lastRowID);
}


// Checks if all mandatory fields are completed
// ToDo: Put in all fields!
function validateForm() {
    let a = document.forms["studyplan"]["fname"].value;
    if (a == "") {
        alert("First Name must be filled out");
        return false;
    }
    let b = document.forms["studyplan"]["name"].value;
    if (b == "") {
        alert("Name must be filled out");
        return false;
    }
}

////// Fills in data in the selection dropdown fields in a given table row
function configureDropdownsPerRow(table_number, table_id, module_group_data, row_id, change_semester_numbers) {

    // get current value of semester options for the specified row, i.e., summer or winter semester
    const $table_row = getTableRowByID(table_number, table_id, row_id)
    const semester_choice = $table_row.children[0].children[0].value;

    // initialize variables
    var filterArray = [];
    var module_dropdown_element = null;

    // check if we process the core or technical qualifications module groups, which have one field less
    if (table_id == '#table_data_major' || table_id == "#table_data_minor" || table_id == "#table_data_app") {

        // get module group choice
        module_group_choice = $table_row.children[2].children[0].value;

        // set filter array accordingly
        filterArray = [semester_choice, module_group_choice];

        // get module selection element (4th field)
        module_dropdown_element = $table_row.children[3].children[0];

        // get ects selection element (5th element)
        ects_dropdown_element = $table_row.children[4].children[0];
        // total_ects = 0
        // for (i = 1; $table_row.length; i++) {
        //     total_ects = total_ects + ects_dropdown_element
        //         //console.log(total_ects)

        // }

    } else if (table_id == '#table_data_core' || table_id == "#table_data_techqual") {

        // set filter array accordingly
        filterArray = [semester_choice];

        // get module selection element (3rd field)
        module_dropdown_element = $table_row.children[2].children[0];
    }

    // check if we process the seminar or thesis module groups, which have one field less
    if (table_id != '#table_data_seminar' && table_id != "#table_data_thesis") {
        // populate selection dropdown field for modules
        makeDropDown(module_group_data, filterArray, module_dropdown_element);
    }

    // check if semester numbers have to be adapted
    if (change_semester_numbers) {

        // get choice of the first semester field at the top of the form
        const first_semester = document.getElementById("sem_first").value;

        // get the semester selection dropdown element for this row
        const semester_dropdown_element = $table_row.children[1].children[0];

        // populate selection dropdown field for semester numbers
        makeDropDown(myData_Sem, [first_semester, semester_choice], semester_dropdown_element);
    }
}

////// Resets all table data. Is only called when the first semester field is changed
function reconfigureTables() {

    // iterate over all defined tables
    for (let i = 0; i < module_groups_data.length; i++) {

        // configure event listeners for selection elements
        table_id = '#table_data_' + module_groups_data[i][0];

        // iterate over all rows in the current table
        for (let j = 3; j <= number_of_rows[i]; j++) {

            // get the row element
            row_id = $(table_id).find("tbody").find("tr")[j - 1].id.search(/\d+$/);

            // populate the selection dropdown fields for this row
            configureDropdownsPerRow(i, table_id, module_groups_data[i][1], row_id, true);
        }
    }
}

function getUniqueValues(data, index) {
    const uniqueOptions = new Set();
    data.forEach(r => uniqueOptions.add(r[index]));
    return [...uniqueOptions];
}

function populateDropDown(el, listAsArray) {

    // console output for debugging
    if (debug) {
        console.log("Populating field " + el.id + " with the following data: " + listAsArray)
    }

    el.innerHTML = "";
    listAsArray.forEach(item => {
        const option = document.createElement("option");
        option.textContent = item;
        el.appendChild(option);
    });
}

function makeDropDown(selectionList, filtersAsArray, targetElement) {
    const filteredArray = filterArray(selectionList, filtersAsArray);
    const uniqueList = getUniqueValues(filteredArray, filtersAsArray.length);
    populateDropDown(targetElement, uniqueList);
}

function filterArray(data, filtersAsArray) {
    return data.filter(r => filtersAsArray.every((item, i) => item === r[i]));
}
/////////////////////////////////////////////////////////////////////////////////

// function CheckEcts(table_number, table_id, module_group_data,row_id){

// if (table_id != '#table_data_core' && table_id != "#table_data_techqual") {


// }}