// Globals
// -----------------------------------------------------------------------------
var categories = [];
var table;



// Supplamentary functions
// -----------------------------------------------------------------------------

// array.indexOf polyfill
// --- -- -- - - -
if (!Array.prototype.indexOf)
{
  Array.prototype.indexOf = function(elt /*, from*/)
  {
    var len = this.length >>> 0;

    var from = Number(arguments[1]) || 0;
    from = (from < 0)
         ? Math.ceil(from)
         : Math.floor(from);
    if (from < 0)
      from += len;

    for (; from < len; from++)
    {
      if (from in this &&
          this[from] === elt)
        return from;
    }
    return -1;
  };
}


// function for sorting an array by 'breadcrumb' attribute
// --- -- -- - - -
function compare_breadcrumb (a,b) {
    if ( a.breadcrumb < b.breadcrumb ) { return -1; }
    if ( a.breadcrumb > b.breadcrumb ) { return 1; }
    return 0;
}

// return category record by category-id
// --- -- -- - - -
function category_record(id) {
    var record = 0;
    categories.forEach(el => { if (el.id == id) record = el; });
   
    return record;
}


// return children of parent
// --- -- -- - - -
function childs_of_parents(list) {
    // if 'list' is integer then make it an one-item list
    parents = (Number.isInteger(list)) ? [ list ] : list;

    var childs = [];

    if (parents.length == 0) { return []; }

    parents.forEach( pid => {
        categories.forEach( el => { if (el.parent == pid) childs.push(el.id)});
    });

    var grandchilds = childs_of_parents(childs);

    return childs.concat(grandchilds);
}


// create actions html (edit and delete buttons)
// --- -- -- - - -
function create_actions_html(id) {

    var del, edit;

    del = "";

    edit = [
        '<button type="button" class="btn btn-xs btn-warning"',
            'data-toggle="modal" data-target="#manageCategory"',
            'data-id="'+ id +'">',
            '<i class="fas fa-pencil-alt"></i>',
        '</button>'
    ].join('\n');

    return edit +' '+ del;
}



$(document).ready(function() {

    // When document is ready
    // -------------------------------------------------------------------------

    
    /** init selec2 element (used to specify parent-category)
     * --- -- -- - - -
     */
    $("#parent_id").select2({
        placeholder: 'Γονική Κατηγορία',
        width: '100%',
        // dropdownParent: "#manageCategory"   // ref: https://github.com/select2/select2-bootstrap-theme/issues/41
    });

    
    /** init_table
     * --- -- -- - - -
     * get categories
     * constuct categories array
     * render dataTable 
     */
    function init_table() {

        // get all categories from server (ajax)
        $.getJSON( "/wiki/ajax", { action: "get_categories_array", exclude: '0' } )
        .done(function( json ) {
            // then ...

            // reset categories
            categories.length = 0;

            // construct (new) categories data
            Object.keys(json).forEach( key => {
                el = json[key];
                categories.push({
                    id: parseInt(el.rec.id),
                    title: el.rec.title,
                    breadcrumb: el.breadcrumb.replaceAll('\t', ' / '),
                    parent: parseInt(el.rec.parent),
                    actions: create_actions_html(el.rec.id)
                });
            });

            // sort by breadcrumb
            categories.sort( compare_breadcrumb );

            // destroy previous datatable table instances
            $('#dt-categories').dataTable().fnClearTable();
            $('#dt-categories').dataTable().fnDestroy();

            // (re-)create categories datatable
            table = $('#dt-categories').DataTable({
                language: { url: '/libs/DataTables/localization/Greek.json' },           
                data: categories,
                ordering: false,
                columns: [
                    { data: 'breadcrumb' },
                    { data: 'actions' }
                ]
            });

        })
        .fail(function( jqxhr, textStatus, error ) {
            console.log( "Request Failed (" + error +")" );
        });

    }
    init_table();   // init table on first run



    /** When modal show-up
     * -------------------------------------------------------------------------
     * ... prepare the manage-category form 
     * ... update select2 with possible parents
     */
    $('#manageCategory').on('show.bs.modal', event => {
        var button = $(event.relatedTarget);        // Button that triggered the modal
        var id = parseInt( button.data('id') );     // category_id from data-id
        // var modal = $(this);    // modal object     
        
        // update modal literature
        // ---
        $('#manageCategory .modal-title').html(             // modal title
            (id) ? 'Ενημέρωση Κατηγορίας' : 'Δημιουργία Κατηγορίας'
        );
        $('#manageCategory form input[name=id]').val( id );     // category id (hidden)
        $('#manageCategory form input[name=title]').val(    // category title
            (id) ? category_record(id).title : ""
        );
        prepare_parents_element(id);        // prepare <select> for parents
    })

    /** prepare_parents_element()
     * ---
     * @param id (int) : id of selected category
     * -> Get all posible parents
     * -> call set_parent_options() to render the options
     */
    function prepare_parents_element(id) {
        var parents = [];

        if (id) {   // get all possible parents

            // id-category and subcategories are fobiden parents
            var forbiden = childs_of_parents(id);
            forbiden.push(id);

            // filter catogories adn prepare parents
            categories.forEach( el => {
                if (!forbiden.includes(el.id))  {
                    parents.push({
                        id: el.id,
                        breadcrumb: el.breadcrumb,
                    });
                }
            });
            set_parent_options(parents, category_record(id).parent);


        } else {    // new record; all categories are possible parrents
            categories.forEach( el => {
                parents.push({
                    id: el.id,
                    breadcrumb: el.breadcrumb,
                });
            })
            set_parent_options(parents, -1);
        }
    }

    /** set_parent_options()
     * -> create options for parents <select>
     * -> choose selected parent
     * @param parents (array): array of parents
     * @param selected (int): selected parent
     */
    function set_parent_options(parents, selected) {
        // sort parents by breadcrumb
        parents.sort( compare_breadcrumb );

        // remove any olded options from select2
        $('#parent_id option').each(function() { $(this).remove(); });

        // first option is the root category
        $('#parent_id').append('<option value="0">Root</option>')

        // add all other parent options
        parents.forEach( i => {
            $('#parent_id').append(`<option value="${i.id}">${i.breadcrumb}</option>`);
        });

        if (selected == -1) {   // new category; remove any parent pre-selection
            $('#parent_id').val(null).trigger('change');

        } else {    // category exists; choose selected parent
            $('#parent_id').val(selected).trigger('change');
        }
    }




    // When form is submited
    // -------------------------------------------------------------------------

    $('#manageCategory form').submit( event => {
        event.preventDefault();

        // prepare data to POST
        var data = {
            id: parseInt($('#manageCategory form input[name=id]').val()),
            title: $('#manageCategory form input[name=title]').val(),
            parent_id: parseInt($('#parent_id').select2('data')[0].id)
        };

        // select action url (add or update)
        var request = '/wiki/ajax?action=' + ((data.id == 0)  ? 'add_category' : 'update_category');

        // send POST request
        $.post(request, data)
        .done(function( data ) {

            $('#manageCategory').modal('hide');     // when done, close modal

            init_table();       // reload table of categories
        });       

    });

});